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BL0005 20 January 2015
PV3 Metallurgical Testing of Future Ores from --------------
PV3 METALLURGICAL TESTING OF FUTURE ORES FROM
PINTO VALLEY
BL0005
Contents 1.0 INTRODUCTION ................................................................................................... 1
2.0 COMPOSITE CONSTRUCTION ............................................................................... 1
3.0 CHEMICAL CONTENT ........................................................................................... 3
4.0 COMMINUTION TESTING ...................................................................................... 4
5.0 SPECIFIC GRAVITY ............................................................................................. 5
6.0 FLOTATION TESTING ........................................................................................... 7
6.1 ROUGHER FLOTATION TESTING .............................................................................. 7
6.2 CLEANER FLOTATION TESTING .............................................................................. 10
6.3 LOCKED CYCLE FLOTATION TESTS .......................................................................... 12
7.0 CONCLUSIONS AND RECOMMENDATIONS.............................................................. 15
Appendices: APPENDIX A ............................................................................................ CHAIN OF CUSTODY
APPENDIX B ...................................................................................... METALLURGICAL TESTING
APPENDIX C ............................................................................................................ ASSAYS
APPENDIX D ....................................................................................... COMMINUTION TESTING
APPENDIX E ............................................................................................................. SIZINGS
APPENDIX F ........................................................................ MINERALOGY - PHOTOMICROGRAPHS
HELEN JOHNSTON ................................................................... BRADLEY ANGOVE
P. ENG., MAUSIMM(CP) .................................................. P. ENG., MAUSIMM(CP)
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1.0 Introduction
The objective of this Pinto Valley program was to determine the expected metallurgical
performance of potential future ores from the Pinto Valley deposit in comparison to the
mineralization currently processed by the concentrator. Michael Oxciano, Project Engineer for
Capstone Mining, and Ken Major, Consultant to Capstone Mining, together provided the scope
of work and direction for the testing.
About 300 kilograms of drill core and Run-Of-Mine (ROM) ore was received at Base
Metallurgical Laboratories in late November 2014 for testing. Testing included specific gravity
determinations, comminution testing, head assays, batch rougher and cleaner flotation testing
and locked cycle testing. Flotation testing was conducted using a flowsheet developed in the
PV2 metallurgical program. Testing was concluded early January, after which this report was
prepared.
This report summarizes key results from the test program, using data summaries and graphical
displays. Detailed results, such as condition sheets and full sizing distributions, can be found in
the Appendices as follows:
- Appendix A: Chain of Custody
- Appendix B: Metallurgical Testing
- Appendix C: Assays
- Appendix D: Comminution Testing
- Appendix E: Sizings
- Appendix F: Mineralogy - Photomicrographs
2.0 Composite Construction
Appendix A describes the process of sample preparation, whereby 7 composites were
constructed for metallurgical testing according to client instructions. Prior to crushing of the
samples, apparent density was determined using two methods. Specific gravity of the 7
composites was also determined after preparation using a third method.
Table 1 shows the drill core lengths that were combined to construct the composites. Three
composites were constructed for the Eastern Pushback, two for the Northern Pushback, an
Aplite Composite and a ROM Composite. The Run of Mine (ROM) composite was understood
to represent current ore feeding the Pinto Valley concentrator.
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TABLE 1: COMPOSITES
ZONE / Composite Drill Hole ID From - ft To - ft Sample Form Mass - kg
Run of Mine (ROM Composite) Bucket 1 Bulk Rock 25.6
Bucket 2 Bulk Rock 26.8
Eastern Pushback Low-level Length
DDH-12-91 580 590 1/2 HQ Core 11.8 DDH-12-62 310 320 1/2 HQ Core 11.8 DDH-12-175 1330 1340 1/2 HQ Core 12.2 DDH-12-176 1210 1220 1/2 HQ Core 9.4
Eastern Pushback Mid-level
Length
DDH-12-161 630 640 1/2 HQ Core 10.4 DDH-12-156 510 520 1/2 HQ Core 10.4
GTH-12-3 950 960 1/2 HQ Core 9.4 DDH-12-156 25 35 1/2 HQ Core 11.6
Eastern Pushback Upper-level
Length
DDH-11-33 420 430 1/2 HQ Core 11.9 DDH-11-33 390 400 1/2 HQ Core 13.1 DDH-12-156 240 250 1/2 HQ Core 12.3 DDH-12-154 80 90 1/2 HQ Core 11.3
Northern Pushback Low-level
Length
DDH-11-20 440 450 1/2 HQ Core 10.5 GTH-12-8 500 510 1/2 HQ Core 8.4
DDH-12-55 410 420 1/2 HQ Core 11.2 DDH-12-90 640 650 1/2 HQ Core 12.3
Northern Pushback Mid-level
Length
DDH-12-79 50 60 1/2 HQ Core 6.1 DDH-11-15 820 830 1/2 HQ Core 5.2 DDH-11-14 1280 1290 1/2 HQ Core 9.1 DDH-11-15 860 870 1/4 HQ Core 10.1 DDH-12-177 1150 1160 1/2 HQ Core 10.4
Aplite Composite
DDH-13-195 579 584 1/2 HQ Core 5.2 DDH-13-194 382 394 1/2 HQ Core 13.7 DDH-13-194 465 479 1/2 HQ Core 14.8 DDH-13-194 577 583 1/2 HQ Core 7.3
Detailed sample preparation details are located in Appendix A, along with photos and the memorandum from AJAX Limited
regarding sample collection.
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3.0 Chemical Content
Duplicate, representative head cuts were removed from each composite and assayed via a
multi-element ICP scan. Full results are provided in Appendix C. A summary of average results
for key elements are shown in Table 2.
TABLE 2: HEAD ASSAYS
Composite Assay - percent or g/tonne
Cu Mo Fe S
ROM Composite 0.38 42 1.17 0.66
Eastern Pushback Low-level Length 0.29 66 1.46 0.59
Eastern Pushback Mid-level Length 0.30 57 1.24 0.95
Eastern Pushback Upper-level Length 0.32 39 6.13 2.71
Northern Pushback Low-level Length 0.29 54 1.13 0.51
Northern Pushback Mid-level Length 0.26 83 1.56 1.23
Aplite Composite 0.22 154 0.51 0.35
Mo is in g/tonne, all other assays are in percent.
All the future mineralization samples were lower in copper than the ROM composite.
Molybdenum, however, was similar, or in the case of the Aplite Composite, substantially higher
than the ROM composite.
Sulphur contents were higher than that of copper suggesting the presence of pyrite in the
samples. The variable content of sulphur suggests variation in the content of pyrite with the
Eastern Pushback Upper-level Length containing the most, measuring a relatively high ratio of
sulphur to copper at over 8 to 1. At this ratio, aggressive flotation conditions that reject pyrite
will be necessary for production of high grade copper concentrates. Mineralogical assessment
would be required to confirm the presence of pyrite.
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4.0 Comminution Testing
A sub-sample of each composite was removed after crushing each composite to 12.7mm (1/2
inch) for Bond Rod and Bond Ball Mill Work Index Tests. The tests were conducted by ALS
Metallurgy Kamloops. Their full report is provided in Appendix D. A summary of the results is
provided in Table 4.
TABLE 4: BOND ROD AND BALL MILL TEST RESULTS
Sample ID Rod Ball
kWh/tonne kWh/tonne
ROM Composite 12.5 13.6
Eastern Pushback Low-level Length 13.0 14.1
Eastern Pushback Mid-level Length 11.1 13.2
Eastern Pushback Upper-level Length 14.8 17.1
Northern Pushback Low-level Length 13.1 14.5
Northern Pushback Mid-level Length 12.2 13.2
Aplite Composite 12.5 13.1
The Bond Ball Mill Work Index Test was conducted using a closing screen sizing of 300µm,
resulting in a product sizing averaging 241µm K80. At this closing screen sizing, the 7
composites recorded work indices averaging 14.1 kWh/tonne. The Bond Rod Mill Work Index
averaged 12.7 kWh/tonne.
The Bond Ball Mill Work Index results were similar to those in PV2 testing, which measured
14.7 kWh/tonne at the same closing screen size. Notably, the Eastern Pushback Upper-level
Length measured higher indices, both Rod and Ball, than the other composites. Lower
concentrator throughput would be expected for this mineralization if the same primary grind
sizing is required.
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5.0 Specific Gravity
Apparent density and specific gravity measurements were performed on the samples using a
total of three different methods. Apparent density was measured on pieces of drill core or large
rock pieces using a wet-dry and wax dip method. After preparation of the composites, specific
gravity was determined on a pulverized sub-sample of each composite using a methyl hydrate
method. Detailed data for these measurements is located in Appendix B.
Since the wet-dry and wax dip method use a randomly selected piece of drill core, they may be
less representative of the overall composite than the methyl hydrate specific gravity
measurement. Also, density would be expected to be slightly lower than the methyl hydrate
method due to pores in the rock pieces. Photos showing the apparatus for the wet-dry apparent
density measurements, and the pieces selected for apparent density measurements are shown
in Photos 1 to 3.
PHOTOS 1 TO 3: APPARENT DENSITY MEASUREMENTS
The left photo shows the set-up for the wet-dry method. The sample is weighed on the scale then placed into the sieve in the water
which is attached to the base of the scale and weighed again. The middle and right photos show the drill core pieces selected for
apparent density measurements.
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A summary of average results is provided in Table 3.
TABLE 3: DENSITY
Composite Apparent Density SG
Wet-dry Wax Dip Methyl Hydrate
ROM Composite 2.59 N/A 2.59
Eastern Pushback Low-level Length 2.58 2.46 2.63
Eastern Pushback Mid-level Length 2.48 2.53 2.64
Eastern Pushback Upper-level Length 2.75 2.85 2.80
Northern Pushback Low-level Length 2.57 2.61 2.61
Northern Pushback Mid-level Length 2.64 2.57 2.66
Aplite Composite 2.56 N/A 2.63
For all measurements, density measured between 2.39 and 2.89. The differential between the
apparent density and SG measurement was generally low, indicating that the rock has relatively
low porosity.
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6.0 Flotation Testing
For each of the seven composites, a single batch rougher and cleaner flotation test was
conducted using flotation conditions developed in a previous metallurgical testing program.
Following these tests, two blend composites were constructed, one for each the Eastern and
Northern Pushbacks. Locked cycle tests, to determine closed circuit flotation response, were
conducted on these two blend composites. An additional two batch tests were conducted to
evaluate the effect of primary grind sizing.
6.1 Rougher Flotation Testing
A single rougher flotation test was conducted on each of the seven composites at
primary grind sizing of 300µm K80 using the flowsheet developed previously. In addition,
a second test, at a finer primary grind sizing of 250µm K80 was conducted on the ROM
Composite. A summary of the test schematic, conditions and results is provided as
Figure 1.
For all samples, natural hydrophobicity was observed, with significant copper recoveries
from the first roughing stage despite no addition of collector. Sodium Isobutyl Xanthate
(SIBX) and a sodium dialkyl dithiophosphate (Aero 3477 Promoter, understood to be
equivalent to Flottec 2044) collectors were used, similarly to the current Pinto Valley
concentrator. Although collector dosages were reduced compared to that recorded in
the PV2 program, further reductions may still be possible and perhaps necessary to
avoid excessive pyrite flotation.
Compared to the ROM Composite, the composites representing potential future
mineralization recorded lower copper recoveries. This is likely related to the lower head
grade of these composites1.
The finer primary grind sizing of 250µm K80 for the ROM Composite showed a slight
improvement in copper recovery of around 1 to 2 percent at comparable mass recovery.
A more significant improvement in molybdenum recovery of about 7 percent, was
recorded. Slightly faster flotation kinetics were also observed at the finer sizing.
Duplicate tests would be required to confirm the differential in performance, particularly
for molybdenum.
1 This could be due to lower liberation or grain size of the copper sulphides that is often observed for lower grade ores.
FIGURE 1
ROUGHER RESULTS
Flowsheet Schematic
ROM Composite – Copper Performance
ROM Composite – Molybdenum Performance
Rougher Recoveries at 300µm K80
Bulk Rougher
Concentrates
250-300 µm K80
Conditions Summary
Feed
Notes: Aero 3477 is considered to be equivalent to Flottec 2044. They are sodium dialkyl dithiophosphate collectors.
SIBX: Sodium Isobutyl Xanthate
Note: Detailed test results are provided in Appendix B.
Lime Fuel Oil SIBX 3477*
Primary Grind 8.8-9.5 100-400 10 - -
Roughers 9.5-9.9 0-125 - 2 4
StageTotal Addition - g/tonne
pHTail
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80
85
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95
100
0 1 2 3 4 5 6
Co
ppe
r R
eco
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pe
rce
nt
Mass Recovery - percent
T1 250µm K80
T2 300µm K80
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80
85
90
95
100
0 1 2 3 4 5 6
Moly
bde
nu
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eco
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perc
ent
Mass Recovery - percent
T1 250µm K80
T2 300µm K80
0
10
20
30
40
50
60
70
80
90
100
T2 ROMComposite
T3 Low-levelLength
T4 Mid-levelLength
T5 High-levelLength
T6 Low-levelLength
T7 Mid-levelLength
T8Composite
Re
co
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pe
rce
nt
Cu Recovery
Mo Recovery
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6.2 Cleaner Flotation Testing
Like for the rougher tests, a single batch cleaner test was conducted on each of the
seven composites. For the Eastern Pushback (EP) Upper-level Length composite, a
second test was conducted at a finer primary grind sizing and coarser regrind sizing.
Figure 2 shows the test schematic, conditions and a summary of the results from the
batch cleaner tests.
The target regrind sizing was 43µm K80 based on the program conducted in PV2.
However, achieving this target proved challenging due to the range of rougher masses
and low power requirement to achieve this relatively coarse sizing. For all the initial
cleaning tests, a 5 minute regrind time was used. For the ROM, Eastern Pushback (EP)
Low and Mid and Northern Pushback (NP) Mid composites, the regrind sizings were
close to target. But for the EP Upper, NP Low and Aplite composites, the sizings were
finer than target at around 20µm K80.
Despite the regrind sizing being the coarsest for the ROM composite, this composite still
exhibited superior copper performance to all the other samples. For the ROM
Composite, about 88 percent of the copper was recovered to the second cleaner
concentrate which graded about 28 percent copper. This was reportedly in line with that
commonly obtained at the Pinto Valley Concentrator. Higher sulphur to copper ratios in
the feed tended to result in poorer concentrate copper grades; presumably due to pyrite
dilution.
Despite finer regrind sizings, copper recovery for all the other composites averaged 80
percent into the second cleaner concentrates at an average grade of 26 percent copper.
Molybdenum performance was, however, similar to that of the ROM composite. It
appears that concentrate molybdenum grade is somewhat predictable using
molybdenum head grade.
A second test was conducted on the EP Upper composite at a finer primary grind sizing.
In this test, a shorter regrind time of 2 minutes was used but the regrind sizing was too
coarse from this test at 95µm K80. As a result, copper performance of the cleaning
circuit was poor. It is also notable that significantly different rougher performance for
iron and sulphur was observed in the second test, suggesting that the collector dosage
may be too high in the rougher; activating the pyrite.
FIGURE 2
CLEANER RESULTS
Flowsheet Schematic
Eastern Pushback Upper-level Length – Copper Performance Copper Performance – 300µm K80
Cleaner Performance – 300µm K80
250-300 µm K80
Conditions Summary
Feed
Note: Detailed test conditions and results are provided in Appendix B.
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Cop
pe
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pe
rce
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Copper Grade - percent
300µm K80 PG,19µm K80 RG
250µm K80 PG,95µm K80 RG
Bulk Con
Rougher
Tailing
Cleaner
Tailings
Lime Fuel Oil SIBX 3477*
Primary Grind 8.4-9.2 100-400 10 - -
Roughers 9.4-9.5 0-125 - 2 4
Regrind 9.0-10.0 50 10 - -
Cleaners 11.0-11.1 - - 1
Stage pHTotal Addition - g/tonne
50
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80
85
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0 5 10 15 20 25 30 35
Co
pp
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2nd Clnr Con Cu Grade - percent
Other Comps
T9 ROM
Effect of S:Cu Ratio
Regrind
K80 - µm 47 36 36 19 24 40 18
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18-95µm
K80
0
5
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15
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25
30
35
0 1 2 3 4 5 6 7 8 9
2n
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lnr
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c C
u G
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Feed S:Cu Ratio
0
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T9ROM
T10Low
T11Mid
T12Upper
T13Low
T14Mid
T15
Re
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Cu RecoveryMo Recovery2nd Clnr Con Cu Grade - percent
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6.3 Locked Cycle Flotation Tests
Two blends were constructed, according to client instructions, in preparation for locked
cycle tests. For each the Eastern and Northern Pushbacks, a 50:50 ratio of Low and
Mid-level Lengths were combined to construct two blends. Tailings and water collected
from these tests were submitted to ACZ Laboratories for further testing.
At client request, a slightly finer primary grind sizing was used for the locked cycle tests.
For the Eastern Pushback blend, the primary grind sizing was 255µm K80, while the
Northern Pushback sizing was coarser at 281µm K80. Since the same primary grind time
was used, the coarser sizing would be considered to be a result of harder mineralization.
A regrind time of 3 minutes was used, resulting in sizings of 39 and 48µm K80 for the
Eastern and Northern Pushback blends, respectively. This was in line with the target.
Under these conditions, about 85 percent of the copper was recovered in both tests.
However, the concentrates were relatively low grade, at about 20 to 23 percent copper,
despite the inclusion of three dilution cleaning stages. Visual observation indicated
relatively high levels of pyrite in the cleaners that appeared to be activated.
Subsamples of the concentrate from the test on the Eastern Pushback blend, as well as
the first cleaner tailings from both tests were mounted onto slides for inspection under an
optical microscope. It was apparent that most particles of concern (copper sulphides
and pyrite) were liberated, in both the concentrate and the tailing. This suggests that
improved selectivity may be possible by changes to chemical conditions. Options to
reduce pyrite activation may include lower collector dosages or removal of the stronger
collector, SIBX, from the rougher stage, the addition of pyrite depressants, or higher pH
levels. The presence of some binaries suggests further regrinding would also provide
some benefit.
Molybdenum recovery measured about 48 and 62 percent for the Eastern and Northern
Pushback blends, respectively. The concentrates graded about 0.2 and 0.3 percent
molybdenum; which may be sufficient for economic separation of a molybdenum
concentrate.
The finer primary grind sizings for the two tests did appear to slightly improve rougher
recovery for both copper and molybdenum when compared to the rougher tests at
300µm K80.
FIGURE 3
LOCKED CYCLE TESTS
Flowsheet Schematic
Locked Cycle Test Results – Cycle IV+V Summary
255-281 µm K80
Conditions SummaryFeed
Bulk Con
Rougher
Tailing
Cleaner
Tailings
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39-48µm
K80
Lime Fuel Oil SIBX 3477*
Primary Grind 9.5 250-300 10 - -
Roughers 9.5 - 2 4
Regrind 11.0 100 10 - -
Cleaners 11.0 - - 0-1
Stage pHTotal Addition - g/tonne
T17 Bulk Concentrate Cycle V
Note: Detailed test conditions and results are provided in Appendix B.
All full size photomicrographs are located in Appendix F.
T18 1st Cleaner Tailing Cycle V
Product Weight Assay - percent or g/t Distribution - percent
% Cu Mo Fe S Cu Mo Fe S
T17 50:50 Blend of Eastern Pushback Low and Mid-level Lengths
Feed 100.0 0.30 55 1.44 0.85 100 100 100 100
Concentrate 1.3 20.1 2008 34.7 42.6 85.8 47.6 31.4 64.8
Cleaner Tail 6.3 0.25 133 4.74 3.99 5.1 15.2 20.7 29.3
Rougher Tail 92.4 0.030 22 0.74 0.055 9.1 37.1 47.9 6.0
T18 50:50 Blend of Northern Pushback Low and Mid-level Lengths
Feed 100.0 0.30 64 1.40 1.01 100 100 100 100
Concentrate 1.1 22.9 3484 33.7 42.8 85.2 61.9 27.1 47.6
Cleaner Tail 5.9 0.44 189 7.26 8.32 8.6 17.6 30.7 48.7
Rougher Tail 92.9 0.020 14 0.63 0.040 6.1 20.5 42.1 3.7
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7.0 Conclusions and Recommendations
Six samples of potential future mineralization for the Pinto Valley operation were
evaluated in comparison to a ROM composite understood to represent current feed ore
to the Pinto Valley concentrator. The grade of copper in these future ores was lower,
averaging about 0.3 percent copper, compared to the ROM composite. Likely as a
result, copper performance was generally poorer when compared to the ROM
composite.
In a batch cleaner test on the ROM composite, about 88 percent of the copper was
recovered into a copper concentrate grading about 28 percent copper. In comparison,
the samples of potential future mineralization recorded an average copper recovery of
80 percent to a concentrate grading about 26 percent copper under similar conditions.
In locked cycle tests conducted on blend samples from the Eastern and Northern
Pushbacks, copper was about 85 percent recovered to concentrates grading 20 to 23
percent copper. Visual observations during the test and inspection of slides under an
optical microscope indicate that pyrite was diluting the concentrates. Most of this pyrite
appeared to be liberated. Conversely, most of the copper sulphides observed under the
microscope in the first cleaner tailing appeared to be liberated. Further optimization of
collector type and dosage may allow higher grade concentrates to be produced. Other
alternatives to improve selectivity against pyrite might include the addition of pyrite
depressants or further elevation of pH. Further testing would be required for
confirmation. Notably, the presence of some unliberated particles would suggest further
regrinding would assist with performance to a lesser degree.
Molybdenum grades tended be related to molybdenum grades of the feed which varied
from about 40 to 150 g/tonne for the seven composites. Concentrates from the higher
grade mineralization, particularly the
Aplite composite, would be considered sufficiently high in molybdenum to allow for
economic separation of a separate molybdenum concentrate.