phd research proposal
DESCRIPTION
The overall objectives for the project.TRANSCRIPT
HYDROGEOCHEMISTRY OF SALTWATER TAILINGS DEPOSITS –
IMPLICATIONS FOR RELEASE OF CONTAMINANTS TO THE WATER COLUMN
1 PROPOSAL OBJECTIVE
The overall objective for the project is to investigate the environmental consequences
(element leaching and reaction rates) of shoreline and submarine mine tailings deposits from
a geochemical-hydrogeochemical perspective using two different cases: 1) the old tailings of
the Råna Mine (“Nikkel og Olivin A/S”, now closed) in Ballangen municipality, and 2) tailings
material from the Nussir Mine located in Kvalsund municipality, where underwater tailing
disposal is planned for Nussir and Ulveryggen deposit in Repparfjorden.
2 SCOPE OF WORK
The proposed research will be a combination of fieldwork on shoreline tailings deposits
(Råna Mine), experimental laboratory work (Råna and Nussir), and modeling studies. The
experiments will be carried out on bulk tailing materials as well as single sulfide minerals,
reacting with model pore water (both fresh- and sea water). Reaction rate investigations of
separate sulfide minerals (pyrite, pyrrhotite, bornite, chalcopyrite, sphalerite and galena) in
saline systems will be performed to support the studies of reaction rate evaluations of tailings
material.
The scope of fieldwork will be based on tailings cross-section estimation – unsaturated zone
thickness and water table fluctuation, and include installation of monitoring/nested wells,
measuring of physicochemical and hydraulic parameters, analysis of chemical components, and
collection of solid samples and water samples for laboratory analysis and experiments.
Laboratory studies will comprise both batch and column tests. For the shoreline case in
Råna, both unsaturated/saturated conditions will be investigated, using both fresh and salt
water. Conditions simulating the fresh-salt water interface will also be applied. Specially
designed experiments will be applied to simulate discharge to the sea column for the
underwater planned tailings for the Nussir Mine.
The experimental program will be carried out in the laboratories of Kjeøy Research
& Education Center (KREC). Some parts will be complemented at Department of Geosciences,
UiO and Department of Mineralogy, Petrography and Geochemistry, AGH University of
Science and Technology in Krakow. Geochemical modeling should help indicate equilibrium
state for internal tailings conditions using modeling programs such as PhreeqC, (USGS),
Geochemical Workbench (Aqueous Solutions LLC) or Flowtran (Lichtner, 2000). Data
acquired from the experiments, computing models, and field analysis, will be used in order to
understand the hydrogeochemical processes in the tailings.
3 INTRODUCTION
The sub-sea/deep sea tailings deposition method is applied only in a few countries: Norway,
Papua New Guinea, Philippines, Chile and Turkey (Skei, 2011). It is a controversial method
for disposing of mine tailings material. The tailings will cover a larger part of the sea bottom,
where deposited; and the finer particles may be transported further in the water for longer
distances and affect flora, fauna, and fish resources. Hazardous chemicals used during
processing or flocculation may leach into the water and affect the receiving environment. The
minerals deposited may dissolve and also influence the receiving environment (Walder, in
prep.). The oxidation and dissolution of sulfide minerals in seawater is likely higher than in
fresh water due to the corrosion effect of chloride. Many deep fjords with high thresholds have
anoxic bottom water, protecting the sulfides, but the planned disposal site in Repparfjord has
oxic bottom conditions. The seawater on the other hand is alkaline with buffering capacity
(Stumm and Morgan, 1996).
The focus of this PhD project is the behavior of disposed tailings material in contact with
seawater and fresh, as well as, the interaction in the groundwater boundary between fresh and
seawater aquifers. What are the main hydro-geochemical processes under shoreline and sub-
sea-tailings conditions controlling the release rate of heavy metals, their interaction and
binding to tailing material, and the discharge from tailings to the water column.
3.1 RÅNA MINE
The Råna mining district is located approximately 20 km south of Narvik. A few deposits
exist in this zone. The Bruvann Deposit was mined from 1989 until 2002 from an open pit and
underground. The extraction processing plant was located near the mine entrance,
approximately 400 m above sea level.
A massive sulfide deposit, Bjørkåsen Mine, located 3 km further south, was exploited
between 1917 and 1964. Waste from Bjørkåsen was discharged onto the tidal flat in the inner
part of the arm of the Ballangen fjord. A large portion of the tailings from the Råna Mine was
deposited on top of the material from the Bjørkåsen Mine. Tailings were also disposed on east
side of Arneselva River, and smaller amounts were also deposited at the Fornes peninsula.
3.1.1 GEOLOGY OF RÅNA
Råna is a synorogenic mafic-ultramafic intrusion. The intrusion was emplaced during the
Caledonian orogeny and is situated in the Upper Allochton, of the Narvik Nappe Complex
(NNC). The intrusion covers an area of approximately 70 km2. Caledonian sulfidic
metasedimentary rocks are well known in the NNC. The Råna Intrusion is located in proximity
of several former sulfide mines. The presence of sulfidic country rock is highly important and
of ore genetic importance for the Råna Intrusion.
The Råna intrusion has the shape of an inverted cone with its axis plunging to the north-
northwest. The exposed part of the intrusion forms a nearly concentric shape with
a peripheral zone of gabbro-norite containing bands and lenses of ultramafics, i.e. peridotite
and pyroxenite.
The majority of the exposed ultramafics in the northern part of the intrusion are mineralized
to a variable extent. Disseminated sulfides, occurring interstitial to the mafic silicate matrix, by
far, dominate the mineralization scheme. More erratic mineralized zones with accumulation of
semi-massive sulfides are often found in relationship with assimilated country rock.
Mineralization includes minor massive sulfide veins, massive to semi-massive sulfide
breccias and basal disseminated sulfide mineralizations in ultramafic cumulate rocks. Sulfide
mineralization consists predominantly of pyrrhotite, pentlandite, chalcopyrite and lesser
amounts of pyrite. The geological environment and the encountered mineralization are
regarded as good indicators for larger ore-potential.
3.1.2 RÅNA MINE WASTE DISPOSAL
The tailings are located close to the Ballangen fjord at the shoreline/tidal flats, and are built
with watertight dams (fig. 1) at Ballangsleira and Fornes. Waste rocks were deposited in the
open pit area. The tailings ponds were reclaimed, according to the closure plan, with 10 – 20
cm of soil, while in fact, the cover is in many places even thinner than this.
Fornes and Ballangsleira tailings deposit were decommissioned in 2001. Discharge water
from the mine and from the deposit is elevated in nickel, arsenic and iron according to
Klif/SFT (Segalstad et al., 2008). This is caused by sulfide oxidation under the soil cover.
Nickel concentration is relatively high in water leach analyses from Fornes, as well (Segalstad
et al., 2008). However, the tailings were assumed (in the mine permit) not to generate acid
conditions from sulfide oxidation. Soil pH is in the range 6 – 8, likely due to the high content
of olivine (Iversen, 2001). The results from Segalstad et al. (2008), however, indicate there is
a potential for low pH generation in the tailings material in the Fornes deposition site.
The receiving environment, the Ballangen Fjord, has increased in nickel and arsenic
concentrations (Iversen, 2007). The sources to this contamination are poorly understood
(Segalstad et al., 2008).
Sources of pollution are drainage from waste rock and a nickel-containing moraine, which
previously covered the outcrop of the ore body, in addition to water from the mine. The
moraine was removed in 1989-1990. Studies carried out in 2004-2007 concluded that the
moraine dump is the main source of pollution in the area (Iversen, 2007). Most of the water
from the mining area discharges into the Arneselva River. A minor seepage from the moraine
dump is, however, running into the Skjelelven, a creek north of the Arneselva River. The
Arneselva River was probably heavily loaded with nickel from natural sources prior to mining
operations (Iversen, 2007). Removal and transport of a nickel-containing moraine previously
covering the outgoing ore body area is a probable explanation for the observed increase in
nickel concentrations in the Arneselva River during the mining period. From 2002, the nickel
loading from the area has been decreasing (Iversen, 2007).
Fig. 1. Outline map of tailing disposal (avinet.no).
3.1.3 CHEMICAL REACTIONS IN TAILING DEPOSIT
Olivine and clino-pyroxene are the main minerals with smaller amounts of pyrrhotite,
pyrite, nickel sulfides and calcite, in the tailings material from Råna. The sequential extraction
data indicate that the amount of calcite is very small or absent in the analyzed material from the
Fornes tailings pond (Segalstad et. al, 2008). Magnesium is high in the water leach, indicating
that olivine is weathering in the system (personal communication – Walder, 2012). Pyrrhotite
oxidation and acid generation is offset by olivine weathering with consumption of hydrogen
ions, according to the following chemical reaction:
2 FeMgSiO4 + 4 H+ + 0.5 O2 + 5 H2O = 2 Mg
2+ + 2 H4SiO4(aq) + 2 Fe(OH)3
The high pH and pyrrhotite oxidation indicate that olivine neutralization is as rapid as the
pyrrhotite sulfide oxidation.
Although the pH is neutral, nickel is mobile due to its poor sorption on metal hydroxides
and the high solubility of nickel oxide; while copper and cobalt are more likely to be sorbed in
the precipitating iron hydroxides. It is, therefore, expected that unknown quantities of nickel
leach from the tailings into the fjord.
3.1.4 NUSSIR MINE
NUSSIR ASA was established in 2005 to develop the Nussir and Ulverygen copper deposits
in Kvalsund municipality in Finnmark County, near Hammerfest. The Nussir mineralization
area was discovered in the late 1970's, but to this date, remains to be one of Norway's major
undeveloped copper deposits. Further exploration of the ore has yielded valuable amounts of
gold, silver, platinum and palladium in addition to its significant copper deposits (Nussir
ASA).
The company aims at commencing mining operations on the ore deposit at Nussir and
Ulveryggen simultaneously, with a common processing plant for copper ore at Repparfjord.
3.1.5 NUSSIR GEOLOGY
In the northern district of the Repparfjord-Komagfjord window, supracrustal and intrusive
rocks of Early Proterozoic age are unconformably overlain by a thin sequence of Vendian
sediments. Both of these units are overthrust by allochthonous rocks of lavas, tuffs and
sediments of the Raipas Supergroup and intrusions of the Raudfjell Suite, regionally
metamorphosed at greenschist facies during the polyphase Svecokarelian Orogeny, about 1840
Ma. The approximately 8 km thick supracrustal sequence is divided into four groups and
eleven formations on a lithostratigraphic basis (Pharaoh et al., 1983).
The Nussir copper-mineralization occurs in a dolomite layer at the southern slope of Nussir
by Repparfjorden, Kvalsund in Finnmark. The mineralized layer is 2-3,5 m wide and can be
traced in outcrops, local Cu-mineralized blocks and smaller contaminated fields over
a distance of 8 km along the east-west strike direction, commonly dipping 50-60° to the north.
On the southwestern side of Nussir, the strike turns partly north-south. The easternmost
registered outcrops are situated about 1,7 km northwest of the industrial plant at the southern
end of Repparfjorden (Pharaoh et al., 1983).
Main ore minerals are fine-grained, disseminated chalcosite and bornite, commonly
occurring in fine-grained bituminous schist layers and small quartz-bearing fractures. The
dolomite occurs at the top of a 2-3000 m sequence of coarse conglomerates and sandstones
(Saltvann Group); the hanging wall to the north comprises carbonaceous siltstones, jasper and
further mafic sediments and basalts (Pharaoh et al., 1983).
3.1.6 NUSSIR SUB-SEA TAILING DEPOSITION
Waste material has previously been deposited in the shallower part of the fjord (shoreline
deposition). Nussir plans to deposit the tailings in the fjord at approximately 90 m depth.
The outlet will provide around 25.000 to 50.000 tons of copper concentrate per year,
generating approximately 2.007.500 tailings a year for sub-sea disposal. Ore will be processed
in a froth flotation plant using up to 600 kg/day of frothing agents sodium isopropyl xanthat
and methyl isobutyl carbinol; and pH modified using lime (CaO) (fig. 2). The tailings will be
pumped to a thickener and treated with a flocculation agent (Magnafloc 10) in order to recycle
water for processing and reduce the amount of total tailings generated.
Disposal of tailings in Repparfjord was previously conducted in the shallower waters from
1972 to 1978; however, a sub-sea tailings disposal facility would be placed further out in the
fjord, down to a depth of 90 meters, with a threshold depth of 50 to 60 meters.
Nussir plans to mix cold seawater into the tailings before it is pumped to the deposition area.
Mixed with cold seawater, the tailings fall to the bottom instead of rising up and mixing with
the sea. This limits the spread of fine particles and also the spread of the deposit itself.
Fig. 2. Submarine tailings placement in a Norwegian Fjord (modified from Walder, in prep.).
4 EXPERIMENTAL PART RESEARCH
This research proposal describes how data from the field investigation and laboratory
experiments will be obtained to evaluate acid/neutral rock drainage generation in seawater, and
where there may be interaction between seawater and fresh water. The field investigation will
include: geophysical data collection to evaluate thicknesses of the Råna tailings and salinity
variations in the groundwater; setting wells for water quality analysis, obtaining solid samples
for laboratory experiments; and running reaction rate experiments on pure sulfide minerals in
salt water and fresh water.
Under normal conditions, fresh water flows from inland aquifers and recharge areas to
coastal discharge areas to the sea. In general, groundwater flows from areas with higher
groundwater levels (hydraulic head) to areas with lower groundwater levels. This natural
movement of fresh water towards the sea prevents salt water from entering freshwater coastal
aquifers (Barlow, 2003).
Fig. 3. Tailing groundwater section.
Due to the tidal variation of 2-3 meters, there will be some fluctuation within the tailings;
and in a transition zone, the tailings will interact with both seawater and salt water. There are
also most likely seasonal fluctuations due to winter freezing with no recharge, melting during
the spring season, and rain and high recharge in the summer and fall. The storms also bring in
salt via aerosol also affecting the chloride content of the recharging surface water. These
processes are to be tested both in the field and in the laboratory.
Due to different unsaturated and saturated salt water and fresh water zones occurring in
tailings (fig. 3) as a result of groundwater flow and obvious rainwater infiltration, as well as,
possible interaction with river water; experiments will be conducted to evaluate different
potential reaction model.
4.1 FIELD ANALYSIS
Electrical geophysical prospecting methods detect the surface effects produced by electric
current flow in the ground. Using electrical methods, one may measure potentials, currents, and
electromagnetic fields that occur naturally or are introduced artificially in the ground. In
addition, the measurements can be made in a variety of ways to determine a variety of results.
There is much greater variety of electrical and electromagnetic techniques available than in the
other prospecting methods, where only a single field of force or anomalous property is used.
Basically, however, it is the enormous variation in electrical resistivity found in different rocks,
minerals and groundwater that make these techniques possible (Reynolds, 2005).
A resistivity survey measures the electrical resistance to a current induced into the ground.
The electrical resistance of sediment or rock depends on many factors such as salinity of pore
water, particle size, porosity, density, mineral and chemical composition, and moisture level.
Resistivity data can reveal something about these factors and the geological composition of the
area being measured.
A well sampling plan will be designed after the geophysical data has been obtained. Nested
wells will be installed for monitoring of groundwater level fluctuations and for water quality
analysis. Depth of wells should be such that water from saturated zones can be obtained and
water tables of fresh water and seawater can be measured.
Physicochemical parameters such as pH, Eh, conductivity, temperature, dissolved oxygen
will be measured immediately after sampling, as possible changes, or additional reactions may
occur due to transport and storage conditions. Additionally, impermanent elements (for
example, easily oxidized Fe2+
) will also be determined in water samples immediately upon
collection.
Tailings material will be collected during drilling from different depths in enough amounts
for mineralogical, geochemical analysis and column experiments. Setting of pumps will allow
for water sampling. For next the step of the research investigation, it may be necessary to
collect water from the river partly surrounding the tailings disposal.
Data from the drilling will be used for the development an internal tailing depositional
model. As a result, it will be possible to draw cross-sections and estimate thicknesses of the
unsaturated and saturated zones as well as different material layers. Measurements of water
table position in well in time allow for assessment of water table fluctuation in shoreline
deposit.
4.2 RÅNA TAILINGS EXPERIMENT
Chemical reactions in the infiltration zone and transition zone (1 and 2 in fig. 3) can be
evaluated by column kinetic tests (CEN/TR 16363:2012), where tailings material is rinsed by
seawater, salt water (NaCl+Na2CO3), and distilled water (rainwater) (fig. 4). Variations in
volumes of infiltrating water will also be tested to evaluate the geochemical processes.
Leachate will be analyzed for physicochemical parameters and chemical composition.
Afterwards, the leachate will be reacted with river water (for first case: seawater) and seawater
(for second case: rainwater) (fig. 4). Product solution will be reanalyzed and potential
precipitation analyzed. Solid analysis will be performed on the material prior to the
experiments and after the experiments have ended. Hydraulic parameters, soil permeability,
grain size, surface area, porosity, hydraulic conductivity, and soil-water characteristic curves of
the solid material will also be determined.
Fig. 4. Draft of column experiment.
The chemical situation inside fresh and seawater saturated zones (3 and 4 in fig. 3) can be
illustrated by tailing material mixed with seawater, fresh water, and sea/fresh water in
appropriate ratios (fig. 5). These solutions will be continuously shaken or rolled. The solutions
will be sampled from the bottles periodically and analyzed for physicochemical parameters and
chemical composition. These results will be compared with geochemical modeling.
Fig. 5. Draft of bottle experiment.
4.3 NUSSIR TAILING LEACH TEST EXPERIMENT
The bottom water in fjords is commonly oxidized with strong water currents. Therefore, for
simulating the reactions taking place between tailings material and seawater, special columns
will be prepared. The bottoms will be covered by waste material from Nussir or the
Ulveryggen processing plant; the rest of column will be filled with seawater and NaCl solution.
The NaCl solution with pH ~8.5 set by Na2CO3 will be simulating seawater. It will be used
for avoiding of uncontrolled reaction material with not indicated component of seawater.
The walls of each column will contain 4 holes with installed pipes (2 for inflow and 2 for
outflow), drilled slightly above the surface of the material. Pipes will be fastened to a
peristaltic pump, which will circulate water above the tailings surface and to collectors (sample
cups), that allow for easy sampling (fig. 6).
Additional pipes, directly connecting the collectors and columns will constitute a safety
system for removing excess water from the collectors due to over pressure caused by
imperfections in the peristaltic pump construction (fig. 6).
Samples collected during fixed time intervals will be analyzed for pH, redox potential,
conductivity (salinity), dissolved oxygen, temperature and chemical composition. Results will
indicate reaction rates and any contamination potential from tailings disposal in saline
environments.
Fig. 6. Scheme of sub-sea tailing deposition leach test model (modified
from Walder, in prep.).
4.4 SULFIDE REACTION RATES IN SEAWATER
The overall oxidation process of iron sulfides, represented by the most common sulfide
mineral, pyrite, may be expressed as follows:
FeS2(s) + 15/4 O2+ 7/2 H2O →Fe(OH)3(s) + 4H++ 2SO4
2-
The oxidation of other metal-sulfide minerals may be described by similar overall reactions.
However, it should be noted that not all of the sulfides would generate stable metal
oxy/hydroxides or generate acidity under natural conditions (e.g. galena, sphalerite).
The reaction rates of sulfide minerals in oxidizing conditions are well investigated. Reaction
rates of sulfide minerals in saline systems are less known. The previously described
experiments are looking at bulk material, where many geochemical reactions may take place
(e.g secondary mineral precipitations, silicate mineral dissolution and hydrogen ion
consumptions). This makes it difficult to evaluate the sulfide mineral oxidation rates in other
settings.
Therefore, reaction rate experiments will be performed with single sulfide minerals:
pyrrhotite, pyrite, sphalerite, galena, chalcopyrite, bornite and Ni-sulfides. These experiments
will use approximately 10 gram of sample in each reaction vessel with 1-2 liter solution.
Different salinities will be used for each mineral; and the experiments will run between 60-90
days depending upon the results obtained during the experiments.
x8
4.5 CHEMICAL AND MINERALOGICAL ANALYSIS
Analysis will be performed on samples of water and tailings collected from drill holes and
laboratory experiments. Chemical and mineralogical analysis will be carried out.
Chemical analysis is the most important characterization analysis that will be used. Fresh
water and seawater will be analyzed for chemical composition, primarily As, Ni, Fe, Zn, Pb,
Cd, Cu and Ag, together with major anions and cations concentration; and changes in
composition over time during the experiments. Analysis will be carried out using Ion
Chromatography and Atomic Absorption Spectroscopy (at Kjeøy Research & Education
Center); and Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) and Mass
Spectrometry (ICP-MS) (at AGH University of Science and Technology in Krakow and
University of Oslo).
All waste material used in this study will be analyzed for major and trace element
concentrations using Sequential Chemical Extraction (SGS Labs, Ontario, Canada) in order to
check mineral evolution during the experiments. The Acid-Base Accounting (ABA) (SGS
Labs, Ontario, Canada) procedure will measure the acid- and alkaline-producing potential of
tailing material in order to determine if the waste material will produce acid and subsequently
leach metals.
Mineralogical analysis is a way of identifying the mineral phases together with
quantification of mineral concentration. This will be carried out by Powder XRD Diffraction,
supported by Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS
(AGH University of Science and Technology Krakow / IG University of Oslo), Transmission
Electron Microscopy (TEM), Resonance Raman (RR) Spectroscopy (at AGH University of
Science and Technology in Krakow), and by Mineral Liberation Analysis (MLA) or
Quantitative Evaluation of Minerals (QEM-SCAN) (at SGS Labs).
5 CONCLUSION
The proposed research will give a greater understanding of the mineral leaching issues
related to sulfide containing tailings material deposited or to be deposited in sub-sea or
shoreline from a pure mineral perspective; and from tailings material from a proposed mine
and a closed mining operation. There will be a minimum of three scientific publications as a
result of this research.
6 RESEARCH AND PUBLISHING PLAN
The detailed research/study plan is given in the PhD application form, the project is planned to
start March 2013.
2013
Progress reports both on the Råna case (field work, tailing characteristics, initial batch and
column experperiments) and Nussir case (leachate tests and tailing material characteristics).
Paper 1 The Nussir work will be presented at the SweMin conference in Luleå, with
manuscript draft ready in the fall.
2014
Paper 2 Experimental work and characteristics of the Råna tailing material. Manuscript
draft (end spring semester)
Paper 3 Hydrogeological and geochemical characteristics of the Råna shoreline tailings
(November).
2015
Paper 4 Shoreline and sub-sea tailings comparison based on modeling studies
(September).
7 BIBLIOGRAPHY
Barlow P. M., 2003. Groundwater in Freshwater-Saltwater Environments of the Atlantic
Coast. U.S. Geological Survey Circular: 1262.
Iversen E. R., 2001. Environmental effects connected to tailings disposal at the Nikkel og
Olivin nickel mine. Norwegian Institute for Water Research, ISBN No.: ISBN 82-577-4033-0.
Iversen E. R., 2007. Water Quality and Transport of Pollutants from Mining Area 5 Years
after Mine Closure. Nickel and Olivine Mine (Nikkel og Olivin AS), Ballangen Municipality,
2002-2007. Norwegian Institute for Water Research, ISBN No.: ISBN 82-577-5224-8.
Lichtner P.C., 2000. FLOWTRAN User’s manual. Los Alamos National Laboratory
Document, NM.
Pharaoh T. C., Ramsey D., Øystein J., 1983. Stratigraphy and structure of the northern part
of the Repparfjord - Komagfjord window, Finnmark, Northern Norway. Norges geologiske
undersøkelse; NGU; No.377;1-45 pages.
Reynolds, J.M., 2005. An introduction to Applied and Environmental Geophysics. Wiley,
Chichester, 796 p.
Segalstad T. V., Walder I. F., Nilssen S., 2008. Mining Mitigation in Norway and Future
Improvement Possibilities. 33rd INTERNATIONAL GEOLOGICAL CONGRESS, in Oslo.
Skei J., 2011. Mining industry and tailing disposal. Status, environmental challenges and gaps
of knowledge. The Climate and Pollution Agency (Klif) TA-2715.
Stumm W., Morgan, J.J., 1996. Aquatic chemistry, 3rd ed. J. Wiley and Sons, New-York.
Walder I. F., Sub-sea tailings deposition evaluation guideline. In preparation.
http://www.nussir.no/
http://www.avinet.no/