golden ideas mining
TRANSCRIPT
GOLDEN IDEAS MINING
Gold Project Feasibility Study
RIVER NILE STATE
PREPARED BY:
Consultant geologist/ELhadi TAgelsir Mohammed Amjad Ahmed Faisal Batran
Anas Mohammed
April, 2020
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Contents 1-lntroduction ....................................................................................................................................9
1.1Location and accessibility:...........................................................................................................9
1.2 Topography ......................................................................................................................... 10
1.3 Drainage ................................................................................................................................. 10
1.4 climates: ................................................................................................................................. 10
1.5Previous work .......................................................................................................................... 10
2-Regional geology of Bayuda desert ................................................................................................. 12
2.1Introduction............................................................................................................................. 12
2.2 Lithological rock unites of Bayuda desert .................................................................................. 14
2-2-1 High-grade Gneisses and Migmatites: ................................................................................ 16
2-2-2 The Ophiolitic Rocks:......................................................................................................... 17
2-2-3 Metavolcanosedimentary Sequences: ................................................................................ 17
2.2.4Syn-to late Orogenic Intrusions: .......................................................................................... 19
2.2.5 Post Orogenic Intrusions:................................................................................................... 21
2.2.6 Dyke Swarms .................................................................................................................... 22
2.2.7 Cretaceous – Tertiary Sediments: ....................................................................................... 23
2.2.8 Cenozoic Volcanics: ........................................................................................................... 25
2.2.9Quaternary- to Recent Sediments ....................................................................................... 25
2.2.10 The geology and Mineralization ....................................................................................... 26
3-Exploration activity (recent work) ................................................................................................... 27
3.1Remote sensing........................................................................................................................ 27
3.2 Digital Image Processing .......................................................................................................... 30
3.3 color composites ..................................................................................................................... 30
3.4 Principal Component Analysis (PCA).................................................................................... 33
3.5 Mapping of alteration zones .................................................................................................... 33
3.6 Alteration mapping using Feature Oriented PCA........................................................................ 33
3.7Conclusion & recommendations................................................................................................ 35
3.8Rock & Chip Sampling ............................................................................................................... 36
3.9 Designing a Soil Sampling Program ........................................................................................... 36
3.10 Trenching.............................................................................................................................. 41
3.11 Design and location of trenches.............................................................................................. 43
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3.12 Sampling method ................................................................................................................. 43
3.13 Sample preparation ............................................................................................................... 47
3.14 Sample Procedures and Processing......................................................................................... 48
3.15 Trenches modeling ................................................................................................................ 49
3.16 Drilling .................................................................................................................................. 53
3.17 Drilling and Sampling Procedures ........................................................................................... 55
3.17.1 Drilling and Sampling Method ............................................................................................. 55
3.17.2 Drill Sample Quality ........................................................................................................ 57
3.17.3 Drill hole Surveying......................................................................................................... 57
3.17.4 Geological Logging .......................................................................................................... 59
3.17.5 Sample preparation, analyses and security ....................................................................... 61
4.1.6 Sample Submission Procedures.......................................................................................... 61
4.1.7 Sample Preparation and Analysis ....................................................................................... 61
4. Resources estimation .................................................................................................................... 63
4.1Introduction............................................................................................................................. 63
4.2Models .................................................................................................................................... 63
4.3 Drilling modeling ..................................................................................................................... 66
4.4 Solids Models .......................................................................................................................... 69
4.5 Sample compositing ................................................................................................................ 71
4.6 Basic statistic results of the Gold assay data ........................................................................... 72
4.7 Grade outlier restriction (top cut)............................................................................................. 73
4.8 Block model ............................................................................................................................ 74
4.9 Block Constraints ..................................................................................................................... 75
4.10 Blocks and Attributes ............................................................................................................. 75
4.11 Variogram map...................................................................................................................... 77
4.12 Classification of mineral resources.......................................................................................... 81
4.13 Pit optimization ..................................................................................................................... 82
4.14 Pit Slopes .............................................................................................................................. 82
4.15 Design Parameters ................................................................................................................ 83
4.16 Classification of Mineral reserve ............................................................................................. 89
5.Mining methods ............................................................................................................................ 90
5.1 Open Pit Mine Plan.................................................................................................................. 90
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5.2 Mine design ............................................................................................................................ 91
5.3 Mine roads & ramps ................................................................................................................ 92
5.4. Waste dump design ................................................................................................................ 93
5.5. Mining Equipment .................................................................................................................. 93
5.6. Drilling and blasting ................................................................................................................ 93
6. Recovery method- Heap leaching process ...................................................................................... 94
6.1Introduction............................................................................................................................. 94
6.2 Heap Leaching Operation......................................................................................................... 97
6.3 The stages for heap leaching .................................................................................................. 100
6.4 Elution, Carbon Regeneration and Gold Room Operations ..................................................... 100
6.5Acid Wash.............................................................................................................................. 101
6.7 Electrowinning ...................................................................................................................... 101
6.8 Gold Room ............................................................................................................................ 102
7. Capital and operating costs.......................................................................................................... 103
7.1Direct Capital Costs ‐ Mining ................................................................................................... 103
7.2 Capital Cost Estimate – Process Plant and Infrastructure.......................................................... 104
7 .3 Manpower ........................................................................................................................... 107
7.4 Camp / Accommodation ........................................................................................................ 108
7.5 Plant Buildings...................................................................................................................... 108
7.6 Mine Buildings ...................................................................................................................... 108
7.7 Operating Costs – Mining ....................................................................................................... 112
7.8 Operating Cost – Plant and Infrastructure ............................................................................... 112
7.9 Summary costs ...................................................................................................................... 113
8 -References ................................................................................................................................. 115
9 -Appendices......................................................................................... Error! Bookmark not defined.
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List of figures:
- Fig.(1): location map……………………………………………………………………………….…………………….8 - Fig.(2 )Geological Map of Bayuda Desert…………………………………………………….……………………………………….12
- Fig (3) Geological map showing the lithological rock unites of Bayuda desert………………..………………………..13
- Fig (4) the lithostratigraphic sequence of Bayuda desert……………………………………………………………………14
- Fig (5): OLI colour composite obtained using bands 4, 3, 2 in RGB, respectively…………….28
- Fig.(6): OLI color composite obtained using bands 7, 5, 2 in RGB, respectively………….….30
- Fig (7):OLIcolourcomposite obtainedusingbands6,5,3inRGB, respectively………………….….31
- Fig. (8) The PCA color composite image obtained using PC4( 'hydroxyl), PC2(hydroxyl "PC4"
+ iron-oxide "PC3") and PC3 (iron- oxide) in RGB, respectively…………….………………...34
- Fig. (9)grade distribution in trenches (yellow color indicates grade greater than0.5 ppm)……48
- Fig. (10)Lithological distribution in the area (red color indicates quartz veins and veinlets, while blue color represents hosted and country rocks)…………………………………….…….49
- Fig.(11 ): solid model in term of grade distribution……………………………………..……..50
- Fig. (12): solid model in terms of lithology……………………………………………………50
- Fig. (13 )distribution of gold grade by colors: blue=0-0.5 ppm, grey=0.5-1 ppm 1green = 1-2 ppm, yellow 2-3 ppm, red greater than 3 ppm……………………………………………….…..51
- Figure (15 ) Zone One location…………………………………………………………………….……53
- Figure ( 16) Picture showing a 1m interval sieved RC chip sample in a chip tray…………….………59
- Figure (17 ). Example of an RC geological Log………………………………………………………………………..64
- Figure(18): topographic map………………………………………………….………..………66
- Figure(19):Drilling modeling………………………………………………………….……….67
- Figure(20):Combination of trenches and drill holes model……………….……………………69
- Figure (21): Different views of geological solid models……………………………………….71
- Figure (22 ): 1 meter composite length was used………………………………71
- Figure (23): a histogram showing the frequency and cumulative frequency of gold grade…....72
- Figure ( 24): Grade outlier restriction (top cut) used in the study…………………………….72
- Figure ( 25 ): Grade outlier restriction histogram…………………..………………………….73
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- Figure (26): cumulative frequency curves after appl ying cut off……………..…….……..74
- Figure (27 ): The block model of 5x5x5 m & 2.5x2.5x5 m sub block……............……………75
- Figure (28 ): Block model coloured by attribute values…………..……………………………76
- Figure (29):Variogram map………………………………………………………….…………79
- Figure (30):block model showing attribute values…………………..…………………………79
- Figure(31):Ordinary kriging (Interpolate block values using kriging with variogram parameters………………………………………………………………………………….…….83
- Figure(32):bottom view of pit in zone one………………….……………………84
- Figure (33):3D view of final pit design…………………………….…………………………..85
- Figure (34): Plane view of final pit design…………………………………………..…………86
- Figure (35):Block model and 3D pit design…………………………..………………………..87
- Figure (36):Block model and plane pit design……………………………………..…………..90
- Figure (37): open pit terminology………………………………………………………………………………………….91
- Figure (38) bench dimensions…………………………………………………………………………….……………………………91
- Figure (39) mine road and ramps design…………………………………………………………………..……………93 - Figure (40): Overall Process Flow Diagram…………………………………………...………94
-Figure (41): A design comprises 8 cells with a 100m length and 50m …...……………………95
-Figure (42) Golden Ideas main camp and office design……………………………………………………………….………106
-Figure (43): Operating Expenses Split………………………………………...………………111
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Tables & plates
Table (1): coordinates of study area……………………………………………………………….8 Table (2) summarized the spectral bands, wavelength and spatial resolution of Landsat 8….….26
Table (3) OLI bands selection for feature oriented principal component analysis……….…..33
Table (4): rock samples location & analysis…………………………………………..…………37
Table (5): Planned location of trenches……………………………………………….…………41
Table (6) proposed drilling location and depths…………………………………………………53
Table (7): Summary of ultimate pit stripping ratio……………………………………...………89
Table (8) equipment list……………………………………………...…………………………101
Table (9): heap leach plant vendor quotation…………………………..………………………103
Table (10): Labour rates and overhead costs……………………………………………...……105
Table (11) Capital Estimate Summary…………………………………………….……………108 Table (12): average open pit operating cost (US$ /t mined)……………………………………109
Table (13): average operating cost (US$ /t mined)……………………………………………..110
Table (14): Summary costs…………………………………………………………………………………………………………………110
Plate (1) High grade gneiss……………………………………………………………………………………………16 Plate (2) Muscovite schist low lain outcrop………………..…………………………………….18
Plate (3) Marble……………………………………………….…………………………………19
Plate (4) Syn Orogenic Granite…………………………………………..………………………21
Plate (5) J. Nabati complex………………………………………………………………………22
Plate (6): Dyke Swarms……………………………..…………………………………………...23
Plate (7) Cretaceous sandstone…………………………………………………………………..25
Plate (8) HudiChert………………………………………………………………………..……..25
Plate (9) Rock sampling………………………………………………………………………….40
Plate (10) Rock sampling plan& mineralization zones……………………………….………….41
Plate (11)The default sample length is 5 meter taking into account the nature of the lithology’s
and mineralization…………………………………………………………….………………….45
Plate (12) General view of the trenches…………………………………………...……………..46
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Plate(13) trench six intersecting a quartz vein…………………………………………………..46
Plate (14) Trenches samples collection…………………………..………………………………47
Plate (15)the sampling channel is marked horizontally along the trench wall using measuring
tape……………………………………………………………………………………………….48
Plate (16) Plastic sacks with sealable lids are used to transport the completed samples to the Sats Lab……………………………………………………………………………………………….50
Plate(17):Atlas Copco Explorac 100RC Drilling at Zone One……….…………………………57
Plate (18) RC samples are collected at 1 m intervals from the base of the RC cyclone with new
plastic bags……………………………………………………………………………...58 Plate (19): All collars were surveyed using differential GPS………………..…………………60
Figure (20) Picture showing a 1m interval sieved RC chip sample in a chip tray…….…………………61
Plate (21)Trimble Gps……………………………………………….……………65
Plate (22): a flat area with an impermeable foundation where heaps plant is going to be built....99
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Executive summary
The area surveyed in this study constitutes part of the eastern Bayuda Desert. It
covers about 2.2 square kilometers; the area could be reached from Khartoum by
asphalt road (Khartoum – Atbara – Berber highway) and also (Khartoum – Atbara
– Abu Hammed Railway). The area is accessible also by local ferries at Berber to
Kadabas village on the western bank of River Nile. The project area is underlain
by Late Proterozoic Basement Complex rocks that are intruded by various
anorogenic ring- complexes and overlain partially by sedimentary and basaltic
volcanics of Paleozoic to Mesozoic age the crystalline Basement Complex
rocks are exposed due to the uplifting and erosion as erosion windows. The
River Nile represents the only perennial drainage system together with the seasonal
Atbara River are the main prominent drainage system in the area. However, there
is a complete, dense dendritic, dendritic-rectangular drainage system represented
by the consequent and subsequent seasonal wadies in the western bank of the River
Nile. The area under investigation belongs to the arid region, which is
temperature ranging from 45o C up to 50o C.Bayuda Desert is situated in the great
bend of the River Nile and lies between the Nubian Shield in the east with
predominantly late Proterozoic ages, and Jebel Uweinat area to the west with
Archaean ages (Ries et.al.1985). The eastern part of the Bayuda Desert has
been the subject of previous investigations (Vail, 1971; Meinhold,1979, 1983;
Dawood, 1980; Reis et.al., 1985; Kuster and Liegeois, 2001). It is dominated by
high-grade metasediments while the Red Sea Hills sector (the Nubian Shield)
is underlain by green schist metavolcano-sedimentary sequences as suggested
by Almond and Ahmed (1987). They concluded that the high-grade rocks in the
west might represent a lower Proterozoic reworked silica basement covered
by the green schist assemblage. Exploration work conducted during this period
,remote sensing study ,collection of 59 rock samples, defining four mineralization
zones and 18 trenches of about 4392m length resulting in collection of 878 channel
samples. Next exploration phase will be deep drilling, a plan was set according to
the amount of data obtained during first phase of exploration, resource estimation,
and mine design and hence a prefeasibility study will be prepared after.
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1-lntroduction
1.1Location and accessibility:
Bayuda Desert is located in a remote area of the northern Sudan; the area surveyed
in this study constitutes part of the eastern Bayuda Desert. It covers about
2.2square kilometers and it is bounded by the following latitudes and longitude:
Table (1): coordinates of study area
Fig.(1): location map
The area could be reached from Khartoum by asphalt road (Khartoum – Atbara –
Berber highway) and also (Khartoum – Atbara – Abu Hammed Railway). The area
is accessible also by local ferries at Berber to Kadabas village on the western bank
of River Nile.
POINT NORTHING EASTING
A 17°59'44.42"N 33°39'36.66"E
B 17°59'44.42"N 33°40'47.46"E C 17°59'9.60"N 33°40'47.46"E
D 17°59'9.60"N 33°39'36.66"E
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1.2 Topography
The project area is underlain by Late Proterozoic Basement Complex rocks that
are intruded by various anorogenic ring- complexes and overlain partially by
sedimentary and basaltic volcanics of Paleozoic to Mesozoic age the crystalline
Basement Complex rocks are exposed due to the uplifting and erosion as
erosion windows. The River Nile signifies the local erosion base, the old gneisses
and migmatites of these windows form large flat pen plain, surrounded by
tableland Phanerozoic Formation. The altitudes over the erosion level. The
volcanic extrusive formed cinder cones which rise up to 300-400 meter above the
surrounding plain (Barth and Meinhold, 1979).
1.3 Drainage
The River Nile represents the only perennial drainage system together with the
seasonal Atbara River are the main prominent drainage system in thearea.
However, there is a complete, dense dendritic, dendritic-rectangulardrainage
system represented by the consequent and subsequent seasonalwadies in the
western bank of the River Nile.
1.4 climates:
The area under investigation belongs to the arid region, which is temperature
ranging from 45o C up to 50o C. The rainy season is short with low rainfall
between July - September with average less than 50 mm per annum. The winter
season extends from November to February with low temperature that sometimes
drops down to 10oC in nights.
1.5Previous work
El Rabaa (1976) defined the polymetamorphic and the multi-deformational
Basement and the rift tectonics of Bayuda Desert. Almond (1977) describedsome
selected ring complexes. Also, Dawoud (1980) conducted structuraland
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metamorphic project and mapped the Mograt area. The work of UNDPProject,
prospecting for mica in the Shereik Area, Northern Sudan, waspublished in
Technical Report No. 2 (DN/SF/UN/79 - Technical Report No.
2). Meinhold and Barth, (1979) described the geology of the BayudaDesertwithin
the work of Sudanese-German joint mineral exploration program, and produced a
geological map in a scale 1:250 000. Reis, et. al. (1985) made geochronological
and geochemical studies in NE Bayuda Desert. Almond and Ahmed (1987)
identified and named the Keraf Shear Zone.
3)Abdelsalam, etal. (1994, 1995, 1996, and 1998) investigated the KerafShearZone
and its tectonic and deformational history, based on shuttle radarimagery. They
defined four-phases of deformation. Abdelrahman (1993) recognized ophiolitic
fragments in the Keraf Shear Zone and interpreted them as remnant of a marginal
oceanic basin, which once existed betweenthe composite arc terranes of the Nubian
Shield in the east and the NileCraton in the west
4)Ibrahim (2005) he conducted a detailed exploration work includingdetailed
geological mapping, litho geochemical survey, soil and stream sediments
geochemical surveys.
5)Bailo (2000) did structural, petrological, geochronological and isotopicInvestigations of the Keraf petro tectonic assemblage. Küster and
Liégeois(2000) used Sr and Nb isotopes and geochemistry to propose that the high-grade metamorphic basement of Bayuda desert constitute a Neo-
Proterozoicoceanic convergent margin succession with limited late input of old material.Ali (2005) studies the geology and tectonic events of Bayuda desert in the
area around River Nile between Atbara and Abidiya. Nagashi (2005) study the geology and structural geology of the Bayuda desert by detailed map in the
AbuKhalag area and to apply geochemical exploration techniques to study the gold mineralization there.
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2-Regional geology
2.1Introduction
Bayuda Desert is situated in the great bend of the River Nile and lies between the
Nubian Shield in the east with predominantly late Proterozoic ages, and
Jebel Uweinat area to the west with Archaean ages (Ries et.al.1985). The eastern
part of theBayuda Desert has been the subject of previous investigations
(Vail, 1971;Meinhold,1979, 1983; Dawood, 1980; Reis et.al., 1985; Kuster and
Liegeois, 2001). It is dominated by high-grade metasediments while the Red
Sea Hills sector (the Nubian Shield) is underlain by green schist metavolcano-
sedimentary sequences as suggested by Almond and Ahmed (1987). They
concluded that the high-grade rocks in the west might represent a lower
Proterozoic reworked silica basement covered by the green schist assemblage.
Vail (1979) classified the Precambrian rocks of the Bayuda Desert into three
groups separated by unconformities:
(1) Older group of gneisses (Grey geisses);
(2) Amphibolite facies metasediments;
(3) Upper group of volcanoclastic rocks (the green schist assemblage).
Dawoud (1980) mapped the northeastern part of the Bayuda Desert where
metasediments, metavolcanics, older granites and younger granites have been
described. Abdurrahman (1993) studied the geology of the Bayuda-Gabgaba area
and classified the rock units on the basis of field evidence and previous
work into: high-grade- gneisses and migmatites, high-grade supra crustal
metasediments, low-grade metasediments, ophiolitic complex, volcano
sedimentary sequence and molasses units. Bailo (2000) described the geology
north of Latitude 18 º 30 N along the Keraf Shear Zone. KusterandLiegeois
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(2001) subdivided the high-grade metamorphic lithologies of the Bayuda Desert
into two geographical units:
Fig.(2 )Geological Map of Bayuda Desert
1) A monotousmigmatised series of mainly granitiod gneisses and
subordinate amphibolite’s in the western and central Bayuda Desert (Grey gneisses
of Vail).
2) A heterogeneous non-migmatised succession metavolcanosedimentary
sequence),which includes felsic gneisses, amphibolites, schist rocks, marbles,
quartzite in the easternBayuda Desert.
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2.2 Lithological rock unites of Bayuda desert
The lithological rock unites of Bayuda desert (fig 3-4\ 3-5) can be summarized as
follow
- Cenozoic volcanic rocks.
- Paleozoic and Mesozoic sedimentary formations.
- Paleozoic and Mesozoic igneous rocks.
- Precambrian basement complex.
Fig (3) Geological map showing the lithological rock unites of Bayuda desert.
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Fig (4) the lithostratigraphic sequence of Bayuda desert.
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2-2-1 High-grade Gneisses and Migmatites:
This rock unit is represented by high– grade of upper–amphibolite facies of
metamorphosed gneisses and migmatites with metasedimentary schist and
carbonates. Some of these gneisses are lithologically and stratigraphically similarto
the high-grade gneisses reported in J. Uweinat.The high-grade infracrustal
gneisses are founded to be overlain by high-gradesupra-crustal metasediments
and frequently contain quartzite lenses (plate 3-1).They are strongly deformed
with fold axes striking 20° 30°and gently plunging SW.In some places, the fold
axes strike E- W with gentle dip to E and W (Barth and Meinhold,1979).
Plate (1) High grade gneiss
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2-2-2 The Ophiolitic Rocks:
The origin of these ophiolitic rocks can be one of these three types of rocks;
- Sedimentary origin, some of the amphibolite show impressive features in the
field which are attributable to sedimentary origin. They are characterized by close
association with rocks of definite sedimentary origin and they develop very regular
banding similar to original bedding. This banding can be attributed to formation of
some of the amphibolites with marbles, calc-silicates, and metapelites. The
gradational contacts with other gneisses and their association with quartzite may
support that these types of amphibolites have been derived from a
sedimentary protolith.
- Igneous origin, some of the amphibolites have no gradational contact with
the adjacent sedimentary rocks. There is a general absence of marble bands in them
and have irregular shapes of outcrops. Weak relicts of ophitic and sub-ophitic
textures are common. These textures suggest an igneous origin for these units.-
Meta volcano sedimentary origin, mixed between terrigenous material, volcanic
flows and tuffaceous clasts witch they had been metamorphosed under
amphibolites facies.
These rocks founded like outcrops of serpentinized ultramafic and banded
metagabbros have been reported by Ali, (2005) between wadikurmut and
wadiAbuHaraz.
They founded vertical to sub-vertical highly deformed and sheared N-S linear belt
extending for more than 15Km.These rocks are intruded like syn-tectonic
intrusions as allochthones masses.
2-2-3 Metavolcanosedimentary Sequences:
These sequences are represented by a series of low to medium grade amphibolite
Faciesmetavolcanics and associated metasediments, which structurally overlie the
high-grade gneisses and migmatites together with the ophiolitic sequences (Hag el
khidir, 2006). They outcrop west of the River Nile as results of imbricate thrust
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faulting (Barth and Meinhold, 1979).The principal lithologies are acidic to
basic and intermediate volcanics, volcanoclastics, tuffeaous material and
turbidite sediments of pelitic and semi pelitic composition including (pyriteferous
chlorite) schist, (garnet-chlorite, muscovite) schist (plate 3-2), garnet (quartzo-
felspathic)schist, (garnet-chlorite, muscovite) schist (plate 3-2), garnet
(quartzo-felspathic) schist and meta-chert. These sediments display cyclic
graded bedding that is repeated from very coarse to medium and fine-grained
components. The cycles are separated and/or intercalated with massive volcanic
flows. These intercalations represent the best evidence of turbidity environments
(Ali, 2005).
Plate (2) Muscovite schist low lain outcrop
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Plate (3) Marble
2.2.4Syn-to late Orogenic Intrusions:
Intrusive rocks belonging to the syn- Orogenic granite include foliated
biotitegranite, biotite muscovite granite and diorites- granodiorites cutting the older
mafic ultramafic units and the associated low-medium grade
Metavolcanosedimentary sequences(Khalifa, 2008).These rocks are
cataclastically deformed andmylonitized by Keraf shear zone (Hag El khidir,
2006). The foliated biotite-granite crops out west of the River Nile. These rocks
were considered earlier by (Barth and Meinhold, 1979) as high-grade gneisses
of Abu Harik series. They are well-foliated to weekly-foliated, showing multi-
phases of deformation with numerous basic xenolithic imprints indicating their
igneous origin (plate 3-4). In area of Atbara cement quarry, these rocks were
folded in isoclinal recumbent folds verging south and refolded in gentle open
folds with axial planes plunging 15° S (Ali,2005). Mafic xenoliths have been
20
found in this mica granites east of Qurunarea.This is one of the field evidence that
the granites and biotite-foliated granites are younger than the opholitic mafic
ultramafic rocks (Ali, 2005).
Plate (4) Syn Orogenic Granite
.
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2.2.5 Post Orogenic Intrusions:
The distribution of the Sudanese alkaline ring complexes is described from
five areas: The Red Sea Hills, along the Nile in the Bayuda Desert and north
Khartoum,Nuba Mountains in Kordofan, upper White Nile and the J.
Uweinat inlier inNorthwestern Sudan (Vail, 1985). The complexes in NE Sudan
were considered by Embleton et.al (1982) to probably be associated with tensional
tectonics of the Red Sea and East African Rift system.
The best examples of post-Orogenic intrusions in Bayuda desert is J.
Nabaticomplex (plate 3-5) in the north of the mapped area west of the Nile at the
fifth cataract, J. Abu Salim, J. Kurbei, J. Abu Nahal and J. Abu Handel, which
form as a ring shape structure and J. Abu Nahal is the largest continuous ring
structure inBayuda desert. These post-tectonic rocks are mainly alkali granites
and alkali syenites. The initial Sr87:Sr86 ratio shows that the Nabati complex
is not remobilized basement but intrusive granite belonging to the late
Orogenic ringcomplex of the Bayuda Desert (Mienhold, 1979). The age of
emplacement of these rocks is less than 550 Ma (Ries, et al., 1985).
Plate (5) J. Nabati complex
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2.2.6 Dyke Swarms
They are forming characteristic features in the area. Most of the dykes seem to be
emplaced after the main igneous activity and tectonic movement. Some postdated
the younger granite complexes and cross cut them. Some of the individual dykes
are irregular in form and most of them on close inspection don’t follow an ideal
straight, parallel sided course, although most of the dykes are vertical or steeply
dipping. Thicknesses range from half a meter to several meters. In some parts onset
of a particular trend displaced another set indicating different phases of
emplacement. Many of the individual dykes wedge out at their termination and
enechelon structure is a common feature. This may indicate shearing stresses rather
than tension produced by normal stresses (Dawoud, 1980). Most of the dykes are
Rhyolite, micro granites, micro syenites, trachyte, diorites, and dolerite.
Plate (6): Dyke Swarms
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2.2.7 Cretaceous – Tertiary Sediments:
These sediments have been founded uncomfortably on the basement complex in
the northern Sudan generally and were referred formerly to cretaceous sandstone
formation. They have been classified into three main unites;
- Cretaceous Nubian Sandstone, in a large continuous formation a long a narrow
belt of sedimentary rocks to the eastern side of the River Nile. These sediments are
medium grained sandstone (plate 3-6). In some places, the sandstone is overlain by
very fine grained Hudi Chert forming small outcrops rising a few meters above the
surrounding plains NE of Atbara town.
- Hudi Chert , The Hudi chert was first identified by Cox (1932) from Hudi
Railway Station about 40 km NE of Atbara and he reported that the Hudi chert is
an upper Eocene/lower Oligocene Formation, which contains some types of fossils
such as Gastropods and plant fossils (plate 3-7). The Hudichert rocks were
regarded as lacustrine chalky deposits that have been silicified into chert (Andrew
and Karkains, 1945). The source of silica was probably from silica flow from the
young volcanic activity of Jebel Umm-Marafieb of NW Berber (Kheiralla, 1966
\Barth and Meinhold, 1979).This rock unit is present as scattered yellowish
brownsub-rounded boulders that range in size from 2 to 5 cm (Hag El-kidir, 2006).
- J. Nakhara series, in the area east of the River Nile, these sediments comprise
conglomerates, pebbly sandstone and fossiliferous carbonaceous pebbly sandstone.
The lower part of these sediments is poorly sorted conglomerate, which is
only exposed east of the River Nile north and south of Artoli village (plate 3-8) .
These sediments studied by Hamed (2005) and concluded that these sediments
represent the upper part of the Nubian sandstone formation in Shendi-
Atbara region and crop out west of the River Nile between the Cenozoic
volcanics of J. Umm Arafiba and the Nile. These rocks overlie the basement
discordantly and in turn are covered unconformably by the Cenozoic volcanics.
24
Plate (7) Cretaceous sandstone
Plate (8) HudiChert
25
2.2.8 Cenozoic Volcanics:
First descriptions of these volcanics were given by (Andrew, 1948) and Vail
(1971) described them in more detail and related them to Tertiary-
Quaternary volcanic activity (plate 3-9). Almond et. al. (1969 and 1977)
suggested a late Pliocene to Recent ages for the younger Bayuda volcanic rocks
based on the slight degree of erosion. They are widespread in Bayuda desert to N-
W of Berber town and represented by the huge shield volcano of J. Umm Arafieba
and J. El Jar lava flow. The lava flows outcrop is faulted in the eastern side of J.
Nakhara (plate 3-8), thus showing the unconformity relationship with the
underlying sandstone (Ali, 2005). Their intrusion is connected with post-Nubian
N-S and E-W striking faults (Vail, 1978).
2.2.9Quaternary- to Recent Sediments
Most of the peneplains in Bayuda desert west of the River Nile are covered with
residual coarse sands and pebbles, which have been derived from the
Nubian Sandstones Formation. These unite of sediments represent unconsolidated
gravels; sands, clays, sandy clays and silt result from weathering of rocks. Alluvial
deposits around Nile and Wadies, Aeolian deposits like dunes or ripple marks.
26
2.2.10 The geology and Mineralization
The gold mineralization in the study area is hosted by the metavolcano-
sedimentary rocks of wadi Abu Haraz, consisting mainly of amphibolite schists,
quartzites, gneisses, and some bands of marbles, and lenses of calcsilicats. These
rocks are intercalated resulting in variable succession. They are foliated sheared
and strongly deformed. The grade of metamorphism is that of amphibolite facies.
Gold Mineralization of the area is connected with quartz veins and veinlets. Most
of the major auriferous quartz veins are hosted with amphibolite schists, while the
minor bodies and veinlets are associated with gneisses. Although the shearing have
affected both the amphibolite schists and quartzite which are in contact with each
others, the auriferous quartz veins occur within the amphibolite schists probably
due to permeability of the amphibolite, that response to deformation and provide
favorable environment for the hydrothermal solutions to precipitate than that of the
brittle quartzite. This behavior suggests the lithological control of the
mineralization. At the same time the auriferous veins always occupy the planes of
the fault systems indicating structural control of the mineralization as well as its
lithological control. Alteration zone are identified on both hanging and foot walls
of the auriferous quartz veins which appear in from zones of carbonization, and
chloritization with thickness do not exceed30 cm. In some localities they contain
gold mineralization. Generally the size of auriferous quartz veins varies length
from 20 m up to 300 m average thickness 30cm.
27
3-Exploration activity (recent work)
3.1Remote sensing
Remote sensing techniques have been used like images enhancements, band
combination and band rationing on satellite Landsat 7 ETM+ to identify
lithological differentiation, mineralization zones (chloritic,sericitic and phyllic
alteration signatures and gossan rich zones) and structure as shown in figures
below also regional geological survey has-been carried out to checked
remote sensing signature and improve the geological/structural maps. Also
chips samples have been collected and analyzed for gold and base metals.
Landsat 8 OLI7 images were used to determine the hydro-thermal alteration and
tectonic features in this study. Landsat 8 OLI consist 11 bands, images consist of 9
spectral bands with a spatial resolution of 30 m from Bands 1 to 7 and 9. The
resolution for Band 8 (panchromatic) is 15 m. Band 1 (ultra-blue) is useful for
coastal and aerosol studies and band 9 is useful for cirrus cloud detection. Thermal
bands 10 and 11 are useful in providing more accurate surface temperatures and
are collected at 100 m.
Landsat8Op
erationalLan
dImager(OL
I)
andTher
malInfr
ared
Sensor(
TIRS)
LaunchedFebruary1
1,2013
Bands
Wavelength(mi
crometers)
Resolution(m
eters)
Band1- Coastal aerosol 0.43 -0.45 30
Band2- Blue 0.45 -0.51 30
Band3- Green 0.53 -0.59 30
Band4- Red 0.64 -0.67 30
Band5-NearInfrared (NIR) 0.85 -0.88 30
Band6-SWIR 1 1.57 -1.65 30
Band7-SWIR 2 2.11 -2.29 30
Band8-Panchromatic 0.50 -0.68 15
Band9-Cirrus 1.36 -1.38 30 Table (2) summarized the spectral bands, wavelength and spatial resolution of Landsat 8.
28
The following remotely sensed data have been used in this study: Landsat 8 OLI
data, path 173, row 48 obtained from USGS http://landsat.usgs.gov/. The
acquisition date 2018‐12‐11, with 7 multispectral bands and panchromatic of
spatial resolution 30 m and 15 m, respectively.
29
Fig (5): OLI colour composite obtained using bands 4, 3, 2 in RGB, respectively.
30
3.2 Digital Image Processing
Different algorithms have been utilized in this study in order to obtain different
color composite images, which are used in visual interpretation, such as:
1. Equalization histogram enhancement.
2. Pan Sharpening to obtain high resolution images.
3.3 color composites
Different color composites were created during this study. For instance, (Figure 3)
shows a false color composite of bands 7, 5and 2 in RGB, respectively. Another
color composite image was prepared by using the infrared bands of the image set,
i.e. utilizing bands 4, 3, and 2 in RGB respectively (Figure 2). The last color
composite image prepared using band 6, 5 and 3 in RGB respectively (Figure 4).
It’s very difficult to differentiate between the rock units because the area is small
and low relief topography.
31
Fig.(6): OLI color composite obtained using bands 7, 5, 2 in RGB, respectively.
32
Fig (7):OLI colour composite obtained using bands6,5,3inRGB, respectively
33
3.4 Principal Component Analysis (PCA)
Colour composite image of PC1, PC2 and PC3 in RGB (Fig.5) has provided much
lithological information and discrimination between units. In this image, the rocks
appear in light blue color and dark brown colour
3.5 Mapping of alteration zones
Mineral deposits are valuable indicator of possible ore deposits.Alteration can be
defining any change in mineralogical composition of the rock brought about by
physical or chemical means (Guilderland Park, 1986). The most common type of
alteration is the breakdown no feldspars and ferromagnesian minerals to variety
of clays and other hydroxyl bearing minerals (Drury, 1993).Since most alterations
involve some or all of the semimetals their detection has been used for many
exploration projects (Kenea,1997).
Remote sensing and digital image process ing can be using to recognize altered
rocks because their reflectance spectra differ from those unaltered country
hydrothermal alteration zones and weathering of the sulphide mineralization
within the acid volcanic represent as significant mineral province (Elsayed
Zeinelabdein and Albieky,2008).The are generally two common types of images
used to map hydrothermal alteration: ratios and selected principal components
analysis also known as Feature Oriented PCA(Loughlin,1991).
3.6 Alteration mapping using Feature Oriented PCA.
Feature Oriented Principal Component Analysis (FOPCA) is a method to select
some bands of the image to run a principal component transformation. The selected
bands are believed to exhibit spectral information over an intended target (Crosta
34
and Mc.Moore, 1989). This method developed by Loughlin (1991) to map
alteration zones.
For enhancement of both iron-oxides and hydroxyl-bearing minerals, two sets of
four OLI bands were selected, namely: bands 2, 4, 5, and 7, and bands 2, 5, 6, and
7, respectively. This selection based on the fact that the iron-oxides have
contrasting signatures in OLI bands 2 and 4, and the hydroxyl in OLI bands 6 and
7. The selected OLI bands as corresponding to the TM bands of Loughlin (1991)
are presented in Table (2).
Purpose OLIbands
Hydroxylbearingminerals Band2,5,6,and7
Ironoxides Band2,4,5,and7
Table (3).OLI bands selection for feature oriented principal component analysis.
Within the frame of this study, the FOPCA selection was conducted for the image
set of the study area. The basic statistics of the selected bands involved in the
transformation and shows the engine vector loadings of the band sets 2, 5, 6 and 7
in order to obtain the hydroxyl component. As it clear, PC4 has mapped
hydroxylated minerals as (-1.26) in OLI-6 and as (0.208) in OLI-7. Also the engine
vector loadings of 2, 4, 5 and 7 bands set chosen to obtain the Iron-oxide
component. As might be observed, PC3 has mapped iron-oxide as (1.27) in OLI
band 2 and as (0.146) in OLI band 4. A linear combination of PC4 from the first
data set and PC 3 from the second data set was produced in order to map the
hydroxyl-bearing minerals and iron oxides.
A false colour composite image "Crosta alteration image" was produced after
displaying the hydroxyl (PC4) in the Red, (hydroxyl "PC4" + iron-oxide "PC3") in
the Green and the iron- oxide (PC3) in the Blue guns (Figure).
The produced image (Fig.5) displayed the alteration zones in, Red hues and clays
minerals in white and bright blue. This result reinforced the conclusions of the
previous techniques in mapping the alteration zones.
35
Fig. (8) The PCA color composite image obtained using PC4( 'hydroxyl), PC2(hydroxyl "PC4" +
iron-oxide "PC3") and PC3 (iron- oxide) in RGB, respectively.
3.7Conclusion & recommendations
Landsat ETM+ and ASTER images have been used to generate base geologic and
structural maps to understand the litho-structural setup of the area and to locate
possible targets or indicators for mineralization. Geology of the concession area
comprises underlain an assemblage of high grade metamorphosed,
36
metasedimentary sequence and alkaline complex. These rock units have been
subjected to four phases of deformation. Field investigation has shown that gold
mineralization is lithologically and structurally controlled and can be found either
along the shear zones or faults (lineaments) affecting metasediments,
mesothermal gold mineralization in quartz veins (orogenic gold). Indications
of shear zone alteration mineralization such as ferruginization, silicification,
pyritization and malachite in amphibolite facies are common. Chip samples
collected during the survey shown many anomalies of gold the geochemical
anomalies coincided well with the remote sensing signatures. The geology and
structure of the area have exerted a significant control on the distribution of
gold mineralization, especially in the central part of the area where the lithological
units have been affected by major shear zones. The western part of the block area
comprises granite intruded by felsic dyke and give positive signatures of remote
sensing and intensive artisanal activities.
3.8Rock & Chip Sampling
Rock chip sampling is sampling of exposed potentially mineral-bearing rocks.
Chips are taken during initial mapping, and if promising results are returned, a
subsequent soil sampling survey undertaken. Alternatively, in many cases,
outcrops maybe either minor or non-existent, and soil sampling is a key next step
for an exploration program.
3.9 Designing a Soil Sampling Program
A sampling program was designed to ensure that it tests the structure which is
causing the geochemical anomaly. A grid of 200*200m had been proposed to
the areas of buried ore and very low degree of outcropping. A number of 56
rock samples have been collected varying in depth from 20 to 50cm. Samples
analysis results and locations are shown in below table. Analysis results show
ed gold content ranging from 0 to 15.553 ppm.
37
Sample_id northing easting Gold grade g/t Rock 61 17 59 25.98 33 39 55.71 0.3
Rock 60 17 5920.1 33 40 01.1 0.8
Rock 59 17 59 26.5 33 39 55.76 1.9
Rock 58 17 59 27.99 33 39 55.94 1
Rock 57 17 59 29.58 33 39 54.44 6.1
Rock 56 17 59 28.66 33 39 53.16 1.8
Rock55 17 59 26.73 33 39 53.53 2.1
Rock 54 17 59 41.18 33 39 49.66 1.1
Rock 53 17 59 37.39 33 39 49.09 0.8
Rock 52 17 59 28.0 33 39 46.71 0.5
Rock 52 17 59 36.59 33 39 34.31 7.1
Rock 51 17 59 36.24 33 39 36 5.7
Rock 50 17 59 36.72 33 39 33.53 1.2
Rock 49 17 59 33.3 33 40 26 0.9
Rock 48 17 59 33.3 33 40 26 4.1
Rock 47 17 59 34.6 33 40 26 2.1
Rock 46 17 59 34.2 33 40 22.4 3.1
Rock 45 17 59 35.5 33 40 22.2 9.5
Rock 44 17 59 37.0 33 40 23.0 5.4
Rock 43 17 59 37.7 33 40 22.2 0.9
Rock 42 17 59 39.2 33 40 23.7 3.1
Rock 41 17 59 38 33 40 23.7 4.7
Rock 40 17 59 37 33 40 24.6 1.6
Rock 39 17 59 37.5 33 40 27.3 1.6
Rock 38 17 59 36.9 33 40 27.7 1.5
Rock 37 17 59 37.9 33 40 28.1 0.3
Rock 36 17 59 40.6 33 4028.5 18.8
Rock35 17 59 41.0 33 40 28.3 0.4
Rock 34 17 59 48.4 33 40 27.6 1.6
Rock 33 17 59 50.6 33 40 27.3 0.7
Rock 32 17 59 37 33 39 31.27 16.9
Rock 31 17 59 27.41 33 39 42.05 0.8
Rock 30 17 59 25.84 33 39 41.4 0.2
Rock 29 17 59 32.88 33 39 53.75 0.1
Rock 28 17 59 34.66 33 39 52.65 0.1
Rock 27 17 59 43.2 33 39 50.63 0.1
Rock 26 17 59 42.87 33 39 50.51 0.1
38
Table (4): rock samples location & analysis
Rock 25 17 59 45.26 33 39 54.96 0.1
Rock 24 17 59 45.5 33 39 51.0 0.1
Rock 23 17 59 42.35 33 39 53.5 0.1
Rock 22 17 59 38.23 33 39 56.62 0.1
Rock 21 17 59 38.56 33 39 57.84 0.1
Rock 20 17 59 39.62 33 39 58.94 0.2
Rock 19 17 59 40.45 33 40 00.4 0.6
Rock 18 17 59 42.39 33 40 0.36 9.9
Rock 17 17 59 43.86 33 39 59 0.1
Rock 16 17 59 45.2 33 39 59.8 0.5
Rock 14 17 59 46.43 33 40 0.66 0.1
Rock 13 17 59 46.21 33 40 0.08 0.1
Rock 12 17 59 45.26 33 40 01.69 0.2
Rock 11 17 59 42.85 33 40 04.09 0.1
Rock 10 17 59 42.29 33 40 04.97 26.4
Rock 9 17 59 41.95 33 40 05.15 0.1
Rock 8 17 59 43.71 33 40 11.58 0.1
Rock 7 17 59 43.86 33 39 59.96 0.1
Rock 5 17 59 46.24 33 40 11.33 0.1
Rock 4 17 59 46.54 33 40 09.57 0.1
Rock 3 17 59 47.78 33 40 09.12 0.1
Rock 2 17 59 47.8 33 40 07.85 0.1
Rock 1 17 59 49.52 33 40 08.4 0.1
39
Plate (9) Rock sampling
40
Plate (10) Rock sampling plan& mineralization zones
According to the rock analysis and also geological observation the block area is
subdivided into four main mineralization zones named zone 1, 2, 3 and 4
respectively.
41
3.10 Trenching
Trenches can be a quick and relatively cheap way of obtaining lithological and
structural information in areas of shallow cover. They are an excellent supplement
to Rotary air Blast (RAB) or Reverse Circulation (RC) drilling programs, where
the structural data from trench mapping is needed to complement the lithological
information obtained from the drill cuttings. The purpose of trenching is to log
structures, record lithological boundaries and obtain samples that can provide
continuous surface data for grade variations across a known or inferred mineralized
zone or structure, as well as potential extensional targets this data can be correlated
with the subsurface information from drilling. And therefore provide information
on structure, true thickness of structures, Lithology. Size and orientation of
mineralization and assist with understanding grade distribution.
19 out of 23 planned trenches were typically excavated into bedrock with a total
length 4392 m, average depth of 1-2.0 meters and a width of 1.5 meters, using an
Hyundai 220 L excavator. Loose rock is cleared away from the floor of the trench
to expose a clean smooth bedrock surface. Sample intervals, typically five meters
in length, but sometimes variable depending upon the nature of the mineralization
and bedrock. These trenches exposed the altered and mineralized trend of the study
area main zone.
The strike of the quartz veins vary from NNE-SSW, NE-SW and to N-S with the
dips varying from 75-65 degrees. The veins at some places contain sulphides
mostly near the contact with the host rock. The host rock is amphibolite schist with
or without alteration. Most of the major auriferous quartz veins are hosted with
amphibolite schist, while the minor bodies and veinlets are associated with gneiss.
Alteration zones are identified on both hanging and foot walls of the auriferous
quartz veins, generally the size of auriferous quartz vein varies from 20 m to 300 m
in length with an average thickness of 30cm.
42
TRENCH NAME START END T1 17°59'41.48"N 33°40'10.12"E 17°59'39.92"N 33°40'12.31"E T2 17°59'40.95"N 33°40'9.51"E 17°59'39.43"N 33°40'11.70"E T3 17°59'40.34"N 33°40'8.99"E 17°59'38.82"N 33°40'11.13"E
T4 17°59'39.71"N 33°40'8.49"E 17°59'38.24"N 33°40'10.60"E T5 17°59'39.07"N 33°40'7.97"E 17°59'37.59"N 33°40'10.09"E
T6 17°59'38.44"N 33°40'7.49"E 17°59'36.98"N 33°40'9.50"E T7 17°59'37.74"N 33°40'7.02"E 17°59'36.38"N 33°40'8.92"E
T8 17°59'37.05"N 33°40'6.55"E 17°59'35.70"N 33°40'8.49"E
T9 17°59'36.43"N 33°40'6.01"E 17°59'35.09"N 33°40'7.94"E T10 17°59'35.84"N 33°40'5.45"E 17°59'34.44"N 33°40'7.40"E
T11 17°59'35.31"N 33°40'4.87"E 17°59'33.81"N 33°40'6.83"E T12 17°59'34.70"N 33°40'4.35"E 17°59'33.20"N 33°40'6.27"E
T13 17°59'34.08"N 33°40'3.83"E 17°59'32.64"N 33°40'5.70"E T14 17°59'33.48"N 33°40'3.28"E 17°59'32.04"N 33°40'5.18"E T15 17°59'32.84"N 33°40'2.75"E 17°59'31.45"N 33°40'4.61"E
T16 17°59'32.26"N 33°40'2.21"E 17°59'30.90"N 33°40'4.02"E T17 17°59'42.12"N 33°40'10.63"E 17°59'40.55"N 33°40'12.89"E
T18 17°59'42.75"N 33°40'11.23"E 17°59'41.10"N33°40'13.56"E
T19 17°59'43.31"N 33°40'11.87"E 17°59'41.59"N 33°40'14.30"E T20 17°59'43.94"N 33°40'12.35"E 17°59'42.20"N 33°40'14.89"E
T21 17°59'44.47"N33°40'13.08"E 17°59'42.72"N 33°40'15.57"E T22 17°59'45.03"N 33°40'13.76"E 17°59'43.24"N 33°40'16.28"E
T23 17°59'45.61"N 33°40'14.30"E 17°59'43.76"N 33°40'16.93"E
Table (5): Planned location of trenches
43
3.11 Design and location of trenches
The trenches are designed perpendicular to the strike of the structures, vein(s) or
ore bodies to be investigated. The trench extended to cover at least “50” m on
either side of the mineralized zone to ensure coverage of potentially mineralized
structures in the footwall and hanging wall rocks, since there are many veinlets and
quartz stringers. A spacing of 25 m between each trench and other were selected to
ensure maximum coverage of sampling to the targeted mineralization zone.
3.12 Sampling method
Since the mineralization is dipping towards the north western direction, the
appropriate sample was taken from a channel perpendicular to that dip along the
trench wall, this is method was found be the most appropriate to be used within the
study area. One side (west wall) was selected for sampling and the sample
intervals marked out on the walls of the trench (using paint) respecting geological
boundaries. Sample log sheet was used to record lithological, structural boundaries
and the sample location, length and orientation were recorded on sample sheet,
trenches have been start from the north side of each one.
The default sample length is 5 meter taking into account the nature of the
lithology’s and mineralization. Where long areas of a single, homogenous
lithology are encountered in the trench, the first and last samples were collected
next to the lithological boundary should be one meter in length and the intervening
sample lengths may be increased to 5 m mark these intervals out along the trench
using spray paint, but adjust intervals if geological changes are encountered. Due
to the flat surface topography of the region and the uneven level of the trench floor,
the level of the sample channel is to be measured down from surface to a
44
predetermined depth on the wall. The sampling channel is then to be marked
horizontally along the trench wall using nails hammered into the wall and string or
measuring tape tied horizontally between the nails. This will allow an even,
horizontal charnel along the wall.
Plate (11)The default sample length is 5 meter taking into account the nature of the lithology’s
and mineralization
45
Plate (12) General view of the trenches
Plate(13) trench six intersecting a quartz vein
46
Plate (14) Trenches samples collection
47
Plate (15)the sampling channel is marked horizontally along the trench wall using measuring
tape
3.13 Sample preparation
All samples collected on the project by comapny were subject to quality control pr
ocedures which ensured the use of industry best practice in respect of the handling,
sampling, transport, analysis, storage and documentation of sample materials and
their analytical results.
All trench, channel, rock chip samples were crushed to a nominal crush size of 80% passing <2 mm. Samples are weighed before and after crushing.
A single tier splitter was used to produce a split of the original sample for dispatch to the assay laboratory. Sampling this split was 250 – 300 g.
Compressed air is used to clean the crusher and splitter between samples.
48
Laboratory samples were placed in new plastic bags, with the sample ticket included and the sample number written on the outside of the bag. The
plastic bag containing the assay sample is then sealed with a cable tie. Plastic sacks with sealable lids are used to transport the completed samples
to the Sats Lab.For drill core, trench and rock chip sample batches a crusher flushing sample of barren vein quartz was used to clean the crusher plates
after 20 samples and at the end of individual sample batches.
3.14 Sample Procedures and Processing
Samples are received directly from the field in plastic sample bags. The sample
bags are laid out in numerical order with the plastic bags open at the top to aid in
drying.
Plate (16) Plastic sacks with sealable lids are used to transport the completed samples to the Sats
Lab
49
3.15 Trenches modeling
7 trenches were (out of planned 22 trenches) analyzed for gold, so only those
trenches will be used here as an example in this technical report to demonstrate
mineralization and lithology distribution pattern of ore.
Fig. (9) grade distribution in trenches (yellow color indicates grade greater than0.5 ppm)
50
Fig. (10)Lithological distribution in the area (red color indicates quartz veins and veinlets, while
blue color represents hosted and country rocks)
51
Fig.(11 ): solid model in term of grade distribution
Fig. (12): solid model in terms of lithology
52
Fig. (13) Distribution of gold grade by colors: blue=0-0.5 ppm, grey=0.5-1 ppm
1green = 1-2 ppm, yellow 2-3 ppm, red greater than 3 ppm
Fig. (14) Block model for first ore body
53
3.16 Drilling
A total of 500 meters of drilling has been proposed. The type of drilling is
Reverse Circulation (RC) based on type of mineralization. The location and collar
of the boreholes are given in the following table:
.
Table (6) proposed drilling location and depths
NO Hole_id Y X Z Dip Azimuth Max_depth
1 H1 1989715 570875 427 -60 126 50
2 H2 1989729 570859 427 -60 126 20
3 H3 1989674 570843 427 -60 126 50
4 H4 1989720 570822 427 -60 126 50
5 H5 1989692 570862 427 -60 126 20
6 H6 1989641 570854 427 -60 126 20
7 H7 1989700 570723 427 -60 126 20
8 H8 1989632 570778 427 -60 126 20
9 H9 1989572 570734 427 -60 126 20
10 H10 1989582 570711 427 -60 126 50
11 H11 1989551 570710 427 -60 126 20
12 H12 1989563 570688 427 -60 126 50
13 H13 1989529 570659 427 -60 126 50
14 H14 1989617 570749 427 -60 126 20
15 H15 1989516 570642 427 -60 126 20
16 H16 1989660 570702 427 -60 126 20
54
Reverse Circulation (RC) drilling in zone one project area commenced in February
2020. During this period, drilling was focused at zone one, figure ( ).
Figure (15) Zone One location
55
3.17 Drilling and Sampling Procedures
All drilling up has been undertaken by Um Alqura RC Exploration Drilling
machine Atlas Copco Explorac 100 plate (17)
Plate(17):Atlas Copco Explorac 100RC Drilling at Zone One
3.17.1 Drilling and Sampling Method
RC samples are collected at 1 m intervals from the base of the RC cyclone with
new plastic bags, which are clearly labeled with the hole number and meter
interval. Drill chips in the bags are geologically logged and the information
recorded on a paper drill log sheets by the attending geologist. The bags are then
sealed. Below is a systematic procedure from the collection at the cyclone to the
laboratory dispatch stage:
56
Each meter sample is collected from the cyclone into a plastic sample
bag measuring30 x 40 cm and weighed at the rig with the weight
recorded on the drill log sheet
The bulk sample is then passed through the integrated riffle splitter
with two sub‐sample ports, one to produce a ~3 kg sub‐sample in a 30
x 40 cm plastic bag.
When a duplicate is required, the bulk bag is passed through the riffle
splitter to produce a ~3 kg duplicate sample.
Samples tags are added to each 3 kg sample from numbered ticket
books, with the hole number and interval clearly written on the ticket
stub for reference
The bulk reject samples are then numbered and left at the drill site in
ordered lines
The riffle splitter is cleaned thoroughly with compressed air prior to
the next sample being split.
All samples (original, archive and duplicate) are then transported to the camp at the
end of the shift, where the archive sample is stored and original and duplicates
prepared for dispatch to the temporary storage facility
Plate (18) RC samples are collected at 1 m intervals from the base of the RC cyclone with new
plastic bags
57
3.17.2 Drill Sample Quality
Sample recovery for the RC samples was estimated based on a 127 mm hole size
and densities of assumed density of 2.5 g/cm Sample recovery for RC samples was generally good, averaging 90%. All RC drilling was conducted in dry conditions
3.17.3 Drill hole Surveying
Drillhole locations were initially set out using a handheld GPS and marked with a
painted rock. Upon completion of the drilling, a cement marker, inscribed with the
drillhole name, was placed at the collar Figure (). After drilling, all collars were
surveyed using differential GPS (DGPS) equipment.
58
Plate (19): All collars were surveyed using differential GPS
The drill rigs were aligned to the design azimuth for each hole using compasses
that were corrected for magnetic declination. A line of pegs, approximately 6 m
long and oriented to the design azimuth, is first pegged adjacent to the planned
hole collar. The drill rig is then brought into position such that the tracks are
approximately parallel to the pegged line. Offset distances from the pegs to the
tracks are then monitored by tape measure during a final adjustment to fine‐tune
the rig’s position. The rig is then regarded as being aligned to the design azimuth
and drilling commences.
59
3.17.4 Geological Logging
RC drill chips were geologically logged at 1 m intervals, recording rock types,
structures, quartz veining type and percentages, sulphide occurrence and
alteration type and intensity. Sample weight, estimated recovery and quality
were also noted during logging Figure (16).
RC drill chip samples were sieved at 1 m intervals to produce a sub ‐sample to act
as a visual reference material. These samples are stored in plastic chip trays as
shown in Figure (20)
Figure (20) Picture showing a 1m interval sieved RC chip sample in a chip tray.
60
Figure (16). Example of an RC geological Log.
61
3.17.5 Sample preparation, analyses and security
All samples collected on the project were subject to quality control procedur
es which ensured the use of industry best practice in respect of handling,
sampling, transport, analysis, storage and documentation of sample materials and
their analytical results.
3.17.6 Sample Submission Procedures
When samples are dispatched to the laboratory, a completed sample submission for
m accompanies the samples. The submission form details the sample number
sequences and also instructs the laboratory on the elements required for analysis
and the analytical methods to be used.
3.17.6 Sample Preparation and Analysis All rock chip samples were crushed to a nominal crush size of 80% passing
<2mm. Samples are weighed before and after crushing.
A single tier splitter was used to produce a split of the original sample for dis
patch to the assay laboratory. Compressed air is used to clean the crusher
and splitter
Laboratory samples were placed in new plastic bags, with the sample ticket i
ncluded, and the sample number written on the outside of the bag. The
plastic bag containing the assay sample is then sealed with a cable tie.
A crusher flushing sample of barren vein quartz was used to clean the
crusher plates after 20 samples and at the end of individual sample batches.
All samples were analyzed for gold by Aqua Regia with lead and AAS finish
in DAL Mining laboratory.
Statements of DAL Analytical Laboratory Services
DAL Analytical Laboratory Services ensures that the laboratory staff is
competent enough to perform the analysis requested.
Use validated methods to achieve accurate and reproducible results with
equipment that is maintained and calibrated to achieve the highest levels of
performance.
Sample preparation
62
Continually monitor the efficiency of crushing and pulverizing to avoid
contamination and ensure that a representative portion of each sample submitted is
prepared .Samples duplicates are created and analyzed for all rock s and drill
samples submitted.
Quality Control and Quality Assurance
DAL Analytical Laboratory Services insert references material, replicates and
blanks into randomly assigned positions with each analytical rack. These QC
samples provide a final verification of the entire analytical process.
63
4. Resources estimation
4.1Introduction
The resource estimate includes data derived from RC drilling supplied by Golden
Ideas Mining. Details of this sampling and assay are described in previous sections
of this report. . Surpac Vision (6.6.2) software was used for data
compilation, domain wire‐framing, coding of composite values and for resource
estimation. The resulting estimates were imported into Surpac Vision for
resource reporting. The estimate was prepared using. Results from 16 boreholes.
The mineralized part of these boreholes were analyzed and used in the resource
estimation. A block model was created in Surpac Vision (6.6.2) software using a
block size with dimensions of 5m x 5m x 5 m.
4.2Models
Many different models were created in this study; one of the most
important models are topographic model since the quality and adequacy of
topographic control have direct affect on the resource estimation model.
Golden Ideas Mining conducted a full topographic survey program using Trimble
Gps an advance and very accurate survey tool.
Topographic model
Plate (21) Trimble Gps
64
65
Figure (17): topographic map
66
4.3 Drilling modeling
Based on the theory of geostatistics and application of Surpac software, a three
dimensional geological model of gold deposit is constructed. The process of
building the database mainly includes exploration information collecting in the
mineralized areas. Geological data include the results of RC drilling, surface pits.
The distribution of lithology and faults was recorded by geological logging
procedures, and then the verified data was imported into Surpac database
module to construct a proper format of three- dimensional geological
database. By using geological database to store geological information, the three-
dimensional geological model had been established more accurately and
comprehensively, which lays a foundation for subsequent resource evaluation. The
collected geological data of 16 drilling boreholes from the research area were
used to establish four basic tables: collar table, survey table, assay table
and lithology tables. Among them, drill hole collar table mainly includes
drill hole collar coordinates, borehole depth, borehole type and trenching
time survey table mainly includes drill hole orientation and inclination
and inclination depth; assay table mainly includes original chip or pulp
sample analysis results (including gold grade information); lithology table
mainly includes information of rock type, stratum, mineral and alteration. After
that, the established geological database is validated by three-dimensional
software, and the DTMs and 3DMs are established in Surpac software based on
proper interpretation methods.
67
Figure (18): Drilling modeling
68
Figure (19):Combination of trenches and drill holes model
69
4.4 Solids Models
70
Figure (20): Different views of geological solid models
71
Solid report
4.5 Sample compositing
Geological statistical analysis of database data and estimation of block model by
sample grade or body weight require that every sample has the same
weighting which means that the entire sample should have the same sampling
lengths. Thus, the analysis results are assured in the reasonable estimation process.
Therefore, before the basic statistical analysis and variance function analysis of
samples, it is necessary to commence samples compositing. There are few
different sample combination methods which include along the sample
direction compositing method, bench compositing method, geological domain
compositing method, ore body internal compositing method and so on. For this
study, the method of compositing along trenching direction with geological region
method is adopted. In the process of sample composition, the influence of the
average lengths of original samples, exploration lines spacing, minimum mining
unit (MMU) and block model size are all considered for determination of final
compositing lengths
72
Figure (21): 1 meter composite length was used
4.6 Basic statistic results of the Gold assay data
Figure (22): a histogram showing the frequency and cumulative frequency of gold grade
73
Figure ( 23): Grade outlier restriction (top cut) used in the study
4.7 Grade outlier restriction (top cut)
Outlier grades were assessed by examining probability plots of the Au
assays Within the domain. Cut off was applied to be16g/t .
Figure (24): Grade outlier restriction histogram
74
Figure (25): cumulative frequency curves after appl lying cut off
4.8 Block model
The block model is essentially a set of specifically sized "blocks" in the
shape of the mineralized orebody. Although the blocks all have the same
size, the characteristics of each block differ. The grade, density, rock type
and confidence are all unique to each block within the entire block model.
Three kinds of block models are found, nearest neighbor polygon, inverse
distance squared and ordinary kriging. The techniques are weighting scheme
which is based on the principle that block content is a linear combination of
the grade data or the sample around the block being estimated. The method
used in this study is inverse distance one. Once a block model is created and all
attributes defined, they must be filled by some estimation method. This is
achieved by estimating and assigning attribute values from sample data which has
X Y Z coordinates and the attribute values of interest.
75
Figure (26): The block model of 5x5x5 m & 2.5x2.5x5 m sub block.
4.9 Block Constraints
This is the engine of the block model. Constraints are the logical combinations of spatial
operators and objects that may be used to control the selection of blocks from which information
may be retrieved and/or into which interpolations may be made. When applying constraints,
Surpac applies a “centroid rule”. Blocks are sub-celled along the edge of the constraint. If the
centroid of the parent or of the sub-block is “inside” a constraint, the entire sub-block or parent
block cell volume is reported, or a value is interpolated.
4.10 Blocks and Attributes
Records in the Block Model are related to blocks. These are cuboid partitions of
the modeled space and are created dynamically according to the operations
performed on the Block Model. Each block contains attributes for each of the
properties to be modeled. The properties or attributes may contain numeric or
character string values. Every block is defined by its geometric centroid and it’s
76
dimensions in each axis. Blocks may be of varying size defined by the user once
the block model is created.
Figure (27): Block model coloured by attribute values
77
4.11 Variogram map
Figure (28):Variogram map
78
79
80
Figure (29): block model showing attribute values
Figure(30):Ordinary kriging (Interpolate block values using kriging with variogram parameters
81
4.12 Classification of mineral resources
82
4.13 Pit optimization
The Pit Optimizer works on a block model of the deposit where each block must
have a net value that represents the economic value that will be returned if that
block is extracted in isolation. The Pit Optimizer then considers each of these
blocks in turn to work out which combinations of blocks should be mined in order
to return the highest possible total value given mining constraints for a particular
sale price. The result is a 3D surface that represents the base / limit of the pit that
maximises the total value of the mine and any further extension of the pit will not
increase the total return
4.14 Pit Slopes
The golden ideas pit is designed for 10 m bench heights based on consideration of
the loading equipment capabilities (mining height and reach), production drill
configuration, and geo-mining conditions. The golden ideas pit is designed for 10 m
bench heights based on consideration of the loading equipment capabilities (mining
height and reach), production drill configuration, and geo-mining conditions. This
may be modified during future detailed planning and equipment selection. Factors
That May Affect the Mineral Reserve Estimate. The following factors may affect
the mineral reserve estimate
* Gold price
* US dollar exchange rates
* Geotechnical assumptions
* Ability of the mining operation to meet the annual production rate
* Mill recoveries
* Capital and operating cost estimates.
83
4.15 Design Parameters
- Open pit parameters are surmised below:
* Bench height of 10 m *Bench slope 70⁰
* Berm width of 5 m
* Ramp width of 15 m * Ramp slope 10⁰
84
Figure(31):bottom view of pit in zone one
85
Figure (32):3D view of final pit design
86
Figure (33): Plane view of final pit design
87
Figure (34):Block model and 3D pit design
88
Figure (35):Block model and plane pit design
89
4.16 Classification of Mineral reserve
Category Ore tons Waste tons Grade g/t Gold content
g
Stripping ratio
Open Pit materials
354,811 2,004,933 3.65 1,295,060 5.6:1
Table (7): Summary of ultimate pit stripping ratio
90
5. Mining methods
5.1 Open Pit Mine Plan
The pit will be mined in open pit with a generally strong and competent rock mass.
Pit slope stability will be controlled by the structural condition of the rock mass
rather than inherent weaknesses. Given the gold grades and proximity to surface,
the deposits will be mined via a conventional truck and excavator open pit mining
method. The deposits will be exploited through one pit approximately50 m deep.
Generally we can say there is scope for larger pits under improved geotechnical or
financial conditions, or an increase undefined mineralization below the base of the
pits.
Gold grade distribution and the results of preliminary mineral processing testing
indicate that ore from this deposit can be processed by conventional leaching
method. The method of material transport evaluated for this study is open pit
mining using excavators and trucks of 18cubic meter capacity.
Waste material from pit will be loaded into the haul trucks and dumped directly to
the waste dumps zone located 300 m south west of the pit opposite to ore dip
direction. Ore production is planned at a nominal rate of 500 tpd, equivalent to
167,500 tons per annum. Mining is planned on a 6 day per week schedule, with
two 8 hours shifts per day, 335 days per annum. Peak ore and waste production is
estimated at 500and 2800 tpd respectively. The average of mine stripping ratio is
5.6:1
91
Figure (36): open pit terminology
5.2 Mine design
The bench design is followed as per bench elevation at 10m interval with 75º slope and2.6m bank width.
10m Bench height
3m bench width
75o Bench face angle
2.6m Bank width
92
Figure (37) bench dimensions
5.3 Mine roads & ramps
Haul roads are designed at 10 % gradient with a width of 12 m on exposed
grids/triangles keeping batter slopes at 57 degrees cut and 36 degrees fill.
Figure (38) mine road and ramps design
93
Road width 15m
ramp gradient 10 degree
Pit total slope 75 degree
5.4. Waste dump design
Proposed area of overburden dumping is chosen to be about 300m south west of mine area. Dump design is made for every stage of the project keeping the dump
deck height as 30m, dump slopes at 28 degrees and berm width as 30 meters for allowing safe transport.
5.5. Mining Equipment
Mine production equipment provided will be 2 excavators (1 m bucket width) and
4 trucks of 18m3 to achieve 167,500 tons of ore per annum 1 motor grader one
dozer and one drilling machine for blasting and grade control purposes.
5.6. Drilling and blasting
Mining by conventional open pit methods of drill and blast followed by load and haul will be employed. Drilling and blasting, when need, will be performed on 5m
benches. Loading of the material will be performed on two 2.5m flitches. The mining fleet as mentioned earlier, will consisting of two hydraulic excavators with
bucket capacity of 1m3, and off highway trucks with 18m3 capacity. Rigid frame
diesel trucks and their mechanical capabilities are well respected, Waste material will be hauled to the one allocated waste rock dump positions to
the west of the pit. Some waste material will be required for infrastructure such as the tailings storage facility and hauling road construction.
As a considerable fraction of the oxidized overburden is considered to be softer than the underlying fresh rock, an estimated 60% of the oxidized material will not
require blasting and will “free-dug”, or ripped with a dozer.
The pit configuration bench height and waste material type anticipated at the
project suit drill rigs capable of drilling drill holes with a diameter of 76 - 109mm.
94
Drill burden, spacing and sub-drill design will be functions of the varying material
types of the deposit in terms of its geometry, geological and grade continuity.
6. Recovery method- Heap leaching process
6.1Introduction
The Golden Ideas heap leach plant design has a nominal 182,000 t
throughput capacity utilizing a primary, secondary crusher and ball mill Figure
() to generate an 80% passing 0.8-1mm product. This material is then fed through
an agglomeration drum where lime and cement are mixed to form
agglomerates for transport by conveyors to the heap leach pads via overland and
grasshopper conveyors and radial stacking system.
Figure (39): Overall Process Flow Diagram
95
Figure (40): Plant Layout
96
A design comprises 8 cells with a 100m length and 50m each width and designed
to receive ore in 7m lifts. A weak cyanide solution will then be introduced to the
heaped cell and gold bearing solution collected on the impermeable plastic liner
under the stacked ore (Figure (41&42).
Figure (41): A design comprises 8 cells with a 100m length and 50m
Gold bearing solution will then be pumped to a 240m3/hr carbon in column circuit
comprising 6 countercurrent carbon contact tanks for adsorption onto carbon
(Figure 42). Loaded carbon is then removed periodically reporting to the elution
circuit for gold recovery and subsequent electro winning and smelting to gold
bullion (Dore). The bullion is then shipped to the Khartoum gold refinery for
refining.
97
6.2 Heap Leaching Operation
The ore will be transported from pit to the heap leaching plant located about 1000
m to the south. The actual reserves estimation is 358,811t with average grade of 3.65 g/t. The actual plant can receive 182,500 tons per annum. The ROM pad will
be used to provide a buffer between the mine and the plant. Separate stockpiles will be constructed to allow blending of different grade types to be carried out
using the front end loader, to ensure that a consistent grade and hardness will be delivered to the plant.
The process is a typical heap leaching operation consists of an open pit mine, a mill to process some or all of the heaped ore, a flat area with an impermeable
foundation where heaps are going to be built plate(22), a barren solution pond containing cyanide solution ready for heap spraying, a pregnant pond containing
cyanide solution draining from the heap area, a building housing a Merrill-Crowe or carbon adsorption process plant for precious metal recovery from the
pregnant solution, a laboratory for the analysis and classification of ore and accounting of “values” in all process streams, maintenance area for repairing trucks, tractors, drills, pumps and other mine equipment and amine administration
building.
98
99
Plate (22): a flat area with an impermeable foundation where heaps plant is going to be built
Ore is hauled from the mine to either the heap leaching area or the milling plant
depending on ore grade and mineralogy. In either case, ore eventually finds its way
into a heap and is sprayed with a weak NaCN solution pumped from the
barren solution pond. The cyanide solution percolates through the heaped ore
becoming “pregnant” with precious metals and drains from the heap into lined run-
off ditches. The pregnant cyanide solution collects in the pregnant solution pond.
Pregnant solution is pumped from the pregnant solution pond into the precious
metal recovery plant which is activated carbon adsorption unit. The now barren
cyanide solution is pumped to a holding basin, where lime and cyanide are added
to repeat the leachingprocess. In the carbon adsorption unit, the activated carbon
100
adsorbs the gold. Gold bearing carbon is chemically treated to release the gold and
is reactivated by heating for future use. The resultant gold bearing strip solution,
more concentrated than the original pregnant cyanide solution, is treated at the
process plant to produce a Dore, or bar of impure gold. The Dore is then sold or
shipped to smelter for refining. Gold can be recovered from its ores by a variety of
methods, including gravity concentration, flotation, and agitated tank leaching.
Methods similar to heap leaching can be employed: dump leaching and vat
leaching (vat leaching isthe treatment of sand or crushed ore in bedded vats with
rapid solution percolation).First typically, heap leaching is chosen for basic
financial reasons for a given situation, it represents the best return on
investment. For small operations or operations in politically unstable areas, it
may be chosen because it represents a more manageable level of capital
investment. areas, it may be chosen because it represents a more
manageable level of capital investment.
6.3 The stages for heap leaching
1. Ground Preparation and pad construction: Here the soil on a slightly sloping ground is compacted and covered by an impermeable pad (can be made of
plastic). 2. Ore stacking: Then the crushed ore is stacked in the form of big heaps.
Amount of fines is decreases as low as possible to improve permeability. 3. Then the leaching agent such as cyanide or acid is sprayed over the heap.
4. As, the reagent passes through the heap; the valuable metals get dissolved in it.
5. The solution containing metal is drained from the heap and collected in a pond and the solution is sent for subsequent process for metal recovery.
6.4 Elution, Carbon Regeneration and Gold Room Operations
The following operations will be carried out in the elution and gold room areas:
Acidwashing of carbon. Optional cold cyanide washes to remove copper and/or zinc from loaded
carbon. Stripping of gold and silver from loaded carbon using the split AARL
method. Electro winning of gold from pregnant solution. Filtration of electro winning sludge.
101
Removal of mercury using a mercury retort. Smelting of retorted products to produce a gold doré.
The elution and gold room areas will operate seven days per week, with the
majority of loaded carbon preparation and stripping occurring during day shift.
6.5Acid Wash
Loaded carbon will be recovered on the loaded carbon recovery screen and
directed to the rubber lined acid wash column. The acid wash column fill
operation will be controlled manually. All other aspects of the acid wash and the
carbon transfer sequence to elution will be automated. Acid washing of the carbon
will commence after carbon transfer is complete.
Dilute hydrochloric acid, 3% w/w HCl, will be prepared prior to use and stored in
the dilute acid make‐ up tank. During acid washing, the dilute solution of
hydrochloric acid will be pumped into the column in an up‐flow direction to
remove contaminants, predominantly carbonates, from the loaded carbon. This
process improves the elution efficiency and has the beneficial effect of reducing
the risk of calcium‐magnesium 'slagging' within the carbon during the regeneration
processAfter the soak period has elapsed, the loaded carbon will be rinsed with
treated water. This rinse water will displace any residual acid from the loaded
carbon.Acid‐washed carbon will be hydraulically transferred to the elution column
for stripping.
6.7 Electrowinning
Soluble gold recovery from pregnant solution will be carried out by electrowinning
onto stainless steel cathodes. The electrowinning circuit will consist of three
electrowinning cells in parallel, each containing a number of cathodes. A
dedicated rectifier, per electrowinning cell, will supply the necessary current to
electroplate the gold onto the cathodeOnce sufficient pregnant solution is
available within one of the two pregnant solution tanks, electrowinning will
be initiated by starting the duty pregnant solution pump. The flow of pregnant
solution to the cells will be evenly split across the electrowinning distribution box
and manual control valves will assist the desired linear velocity to be achieved.
102
During the electrowinning cycle the electrowinning cell discharge will be
continuously returned to the pregnant solution tank via gravity.Once the target
barren solution grades have been achieved, the electrowinning cycle is complete
and barren solution will discharge to the duty pregnant solution tank. Barren
solution from this pregnant solution tank will be returned to the leach circuit via
the barren solution pump, a number of gold room vent fans will be provided to
ensure there is adequate ventilation inside the gold room
6.8 Gold Room
Upon completion of electrowinning, precious metal sludge will be washed off the
cathodes with a high pressure cathode washer. The gold and silver bearing sludge
will gravitate to a sludge hopper, from where it will be pumped to a pressure filter.
Retort product solids will be mixed with a prescribed flux mixture (silica, nitre and
borax), prior to being charged into the diesel fired gold furnaceThe fluxes added
will react with base metal oxides to form a slag, whilst the gold remains as a
molten metalThe molten metal will be poured into moulds to form doré ingots,
which will be cleaned, assayed, stamped and stored in a secure vault ready for
dispatch.
.
103
7. Capital and operating costs The basis of the mining cost estimate using analysis of different factors that may affect mining operation like gold price ,political, social and economic conditions
and also similar mining companies’ costs estimates. This mine is an open pit mine producing 500 tons ore and 2800 tons waste per day(strip ratio is found to be
5.6:1). Rock characteristics for both ore and waste are typical of those of quartz or altered chlorite schist and amphibolites material. Operating conditions, wage
scales, and unit prices are typical for Sudan mining operations. All costs listed are in US$. The key design criteria, operating schedule, equipment, personnel, supply
requirements and costs are listed below:
7.1Direct Capital Costs ‐ Mining
Equipment Number Size Cost $
Hydraulic Shovels 2 1.0 cubic meter
270,000
Front-end Loaders 2 2 cubic meter
285,000
Rear-dump Trucks 4 25 metric ton
520,000
Rotary Drills 2 20.00 cm
110,000
Bulldozers 1 60 kW
650,000
Graders 1 115 kW
185,000
Water Tankers 2 9,500 liter
130,000
Fuel Tankers 2 9,500 liter 130,000
Light Plants 4 8.9 kW
60,000
104
Pickup Trucks 4 680 kg 360,000
Total 2,700,000
Table (8) equipment list
7.2 Capital Cost Estimate – Process Plant and Infrastructure
The cost estimate has been compiled from a variety of sources, including m
etallurgical test work , comminuting modeling, first principle calculations and
vendor quotations .
105
106
Table (9): heap leach plant vendor quotation
107
7 .3 Manpower
Labour rates and overhead costs for workers were based on current country rates.
The labour rates are based on a skill level and consist of a base salary and the
required overhead allowances. Overheads include such items as work permits,
health insurance, social security and production bonuses.
№ Position Quantity SaSlaries/monthly
Salaries/yearly $
1 General manager 1 3,000 36,000
2 administration and finance affairs manger
1 1,000 12,000
3 Cost accountant
1 400 4,800
4 Secretary
1 300 3,600
5 Public relation & security
1 750 9,000
6 Legal advisor
1 1,000 12,000
7 Senior geologist 1 500 6,000
8 Site manager 1 750 9,000
9 Site accountant 1 400 4,800
10 Junior Geologist 2 400 14,400
11 Mine engineer 2 500 12,000
12 Survey engineers 2 500 12,000
13 Processing engineer 3 500 18,000
14 Mine labors 15 200 36,000
15 Factory labors 10 200 24,000
16 Geologist for geoformation database support
1 400 4,800
17 Exploration labors 4 150 7,200
18 Chief of Laboratory and
Sample preparation 1 750 9,000
19 Assay lab technician 1 300 3,600
20 Lab assistant 2 200 4,800
21 Specialist of sample
preparation 2 200 4,800
22 Crusher (sample worker) 4 150 7,200
23 Camp manager 1 750 9,000
24 Technician (all technical systems of camp)
1 250 3,000
25 Cook 2 200 4,800
108
26 Cook assistant 2 150 4,800
27 Logistics Driver 6 150 10,800
28 Cleaner 4 80 3,840
security 2 200 4,800
Total 14,330 296,040 $
Table (10): Labour rates and overhead costs
7.4 Camp / Accommodation
Quotations were solicited from several facility service providers for the
design, construction operation and management of a construction and operations
camp with all necessary facilities, the Turkish company (Precon )for prefabricated
buildings and office containers, was chosen to build Golden Ideas camp. The
quotation wasbased on a number of accommodation units to cover the estimated
peak number of construction workers, operationsemployees and visitors anticipated
on site at peak manning. . Water will be supplied from the River Nile at
Kadabasvillage (Allocated about 30km to east of mine site) by tanker andpower
will be generated by diesel generators.
7.5 Plant Buildings
The following plant buildings have been included in the capital estimate:
Plant warehouse and office. Reagent storage facility.
Plant workshop and office. Main office building. Plant office and control room.
Clinic and emergency response building. Plant security gatehouse.
Light vehicle workshop (shared with processing and other departments). Spare parts warehouse.
7.6 Mine Buildings
The following mine buildings have been included in the capital estimate:
109
Mining office for technical Personnel. Washrooms and ablution block.
Heavy vehicle workshop Tyre bay.
Explosives storage facility.
110
Figure (42) Golden Ideas main camp and office design
111
Main area Cost $ Remarks
Mine equipment 2,700,000
Treatment plant 1,507,103 Including design and civil work
Generator plant 195,000 For camp and. plant
Camp and offices 250,000 Including furniture
Subtotal 4,595,620
Contingency 15% 683,343
Grand Total 5,278,963
Table (11) Capital Estimate Summary
112
7.7 Operating Costs – Mining
open pit mining costs were derived from first principle based on equipment
required and include pit and dump operations, road maintenance, mine supervision
and technical services cost. These costs were then compared with several other
similar operations in Sudan for budget pricing followed by validation against a
more detailed budget estimate. The average open pit operating cost (US$ /t mined)
is shown in Table ( ).
Supplies & Materials $/mt ore 1.0
Equipment Operation $/mt ore 0.3
Salaried Labor $/mt ore 0.5
Drill & blast $/mt ore 0.6
Miscellaneous $/mt ore 0.4
Load and Haul $/mt ore 1.0
Grade Control $/mt ore 0.10
total $/mt ore 3.9
Table (12): average open pit operating cost (US$ /t mined)
7.8 Operating Cost – Plant and Infrastructure
Process plant and infrastructure operating costs have been developed based on a
treatment rate of 182,000 of ore, with the plant operating 24 h/d, 365 d/y with a
91.3% plant utilization, nominally 8,000 h/y.The OPEX has been divided into
multiple cost centers, with fixed and variable costs
The estimate comprises the following major cost centers:
Plant and related infrastructure power. Plant consumables, including mill media and liners, reagents and diesel for
fixed plant equipment and plant mobile equipment. Plant maintenance materials, including mobile equipment parts.
Laboratory. Plant and administration labour.
General and administration costs.
113
Table (13): average operating cost (US$ /t mined)
7.9 Summary costs
Table (14): Summary costs
Item Description Total cost$
Waste tons 1,986,941 6,934,293
Ore tons 354,811 1,383,762
Ore transport per ton 354,811 177,405
Stripping ratio 5.6:1
Ore grade 3.65 g/t
Ore recovery 75%
Gold content before recovery
1,295,060 gm Au
Gold content after
recovery
971,295 gm Au
Process Cost tons 2,050,907$
G&A Cost tons 1,64,433$ 2,703,100
Government Royalty 7%
Gold content after royality 679,906 gram Au
gold price per gram 40$
Selling cost per kilogram 45$ 30.595$
Revenue 38,851,800
Total Costs 11,198,591
Cash Flow 27,653,209
waste mining 3.5$/t
Ore mining 3.9$/t
Ore transport 0.5$/t
Process costs 5.78 $/t
Royalty 7%
G & A cost € 3.0 $/ton
Recovery 75%
Gold price 1300$ ounce
114
Figure (43): Operating Expenses Split
20%
8%
3% 24%
13%
16%
16%
0% Waste tons
Ore tons
Ore transport per ton
Process Cost per ton
G&A Cost per ton
Government Royalty
Government Royalty
Selling cost per kilogram
115
8 -References
Abdulrahman, E.M. (1993), Geochemical and geotectonic controls of
themetallogenic evolution of selected ophiolite complexes from the Sudan.
Berliner GEWISS. Abh. A. 145, 175.
Abdelsalam, M. G. (1993), Tectonic evolution of the late Precambrian
Nakasib Suture and Oko Shear Zone, Red Sea Hills, Sudan. Ph. D. thesis, Univ.
Texas, Dallas.
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