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By H. M. Park

Risk is a major factor in all mining activities, arising from many internal and external variables. The authors? research has resulted in a systematic method for the quantification of risk in mining projects (Park, 2012), and this research is being presented in a series of papers. The first paper (Park and Nelson, 2013a) identified the variables associated with risk in mining projects, and their effects and was published in the October issue of Mining Engineering magazine. The second (Park and Nelson, 2013b) discussed methods of assessing the overall risk associated with those variables (published at www.me.smenet.org), and presented a statistical model based on a survey of 31 experts. This paper will present an evaluation of the statistical model, using data from previous mining investment decisions in which the authors have been involved.

Oct 1, 2013

By A. Lashgari

Surface coal mining in the Appalachian region consumes a significant amount of energy in the form of diesel fuel and blasting agents. emission of oxides of nitrogen (Nox) from these sources represents an environmental challenge to the mining industry. this paper presents the results of research work related to determination of Nox emission of mining equipment and blasting agents, which is part of a broader industrial project conducted by the Appalachian research Initiative for environmental research (ArIeS). Data for this project are collected from an operating surface coal mine in West Virginia. the research work presented here may be used by mining professionals to aid in quantifying Nox emission and determine strategies for reducing its overall environmental impact.

Oct 1, 2013

By Carlos Sánchez Romero

El presente texto describe la aplicación de la implementación de herramientas hidroinformáticas para la gestión de recursos hídricos mineros en la empresa Southern. El trabajo comprende el funcionamiento de redes de estaciones meteorológicas y limnigráfícas, los sistemas SCADA para el control de la distribución de agua, así como la integración de la información dentro de un sistema de información geográfica.

Oct 1, 2013

By J. Little

It is common practice for underground mine plans to be created sequentially, where results from one planning process form the input data for another. While this is practical for manual methods, computerized optimization techniques should consider an integrated approach to creating the global mine plan. This is because optimizing an individual mine planning process, such as stope layouts, introduces a likelihood of increasing costs or decreasing revenues associated with other areas, such as production scheduling, as harmful decisions must be balanced. Considering the interaction and influence that individual underground mine planning processes have on each other during optimization will provide more profitable results than if these are ignored. Optimization techniques for stope layouts and production scheduling are reviewed. An integer programming model is proposed that allows for either integrated or isolated optimization. Both approaches are separately applied to a block model. The results demonstrate the model?s ability to produce optimal long-term sublevel stoping mine plans and the benefits of using an integrated approach. Keywords underground mine optimization, stope layouts, underground production scheduling, integer programming, mathematical programming application.

Oct 1, 2013

By H. M. Park

Risk is a major factor in all mining activities, arising from many internal and external variables. The authors? research has resulted in a systematic method for the quantification of risk in mining projects (Park, 2012). This is the second part of a three-part series. The first part was published in the October 2013 issue of Minining Engineering magazine and can be found here at www.me.smenet.org. This paper discusses methods of assessing the overall risk associated with those variables, and presents a statistical model based on a survey of 31 experts. The third paper, to be publised at www.me.smenet.org on Oct. 14, presents an evaluation of the statistical model, using data from previous mining investment decisions in which the authors have been involved.

Oct 1, 2013

By H. M. Park

Risk is a major factor in all mining activities, arising from many internal and external variables. The authors? research has resulted in a systematic method for the quantification of risk in mining projects (Park, 2012). This research will be presented in a series of papers, this one and two more that will be published on Mining Engineering?s web site, www.me.smenet.com. This paper identifies the variables associated with risk in mining projects, and their effects. The second paper discusses methods of assessing the overall risk associated with those variables, and presents a statistical model based on a survey of 31 experts. The third paper presents an evaluation of the statistical model, using data from previous mining investment decisions in which the authors have been involved. There are several major competing entities, including BHP Billiton, Rio Tinto, Anglo American, Xstrata, Freeport-McMoRan, Chinese government- run companies and Japanese trading companies, that have large foreign holdings, controlling deposits in most of the world?s established and productive mining districts. In general, the mining industry considers the United States, Canada, Australia and the European countries to have good mining investment environments, but because the major companies have already achieved market dominance in those countries, large investments are required there. Newcomers seeking to enter the industry, either as producing companies or as investing partners, often have difficulty breaking into these established markets. Thus newcomers are increasingly turning to new areas like South America and Africa, which are relatively less developed. The competition among businesses to secure a share of the new market is intense, but there are still good investment opportunities. However, because most of the countries in these areas are not well developed, several additional risks are associated with participation in mining projects in those areas.

Oct 1, 2013

By José Luis Vitteri

Dado que se generan largas colas de los camiones mineros en los puntos de carga, es necesario revisar las causas principales que la originan. Entre estas tenemos: el desconocimiento de la variabilidad y sus efectos nocivos y la aceptación de que el mínimo costo de operación se obtiene con la mayor utilización de la excavadora. En este sentido, el presente texto describe el manejo de la variabilidad en los procesos de carguío y transporte con equipos pesados a través del estudio de sus causas, de forma que la única manera correcta de reducir el perjuicio de la variabilidad en el transporte, es manipulando la frecuencia inicial de los camiones.

Oct 1, 2013

By Mike Preston

Attrition scrubbers may not be glamorous, but they are an important and sometimes neglected step in mineral processing. Optimal attritioning will significantly improve the results and efficiencies of subsequent processing steps and can lead to reduced costs and improved product yields. Why is attrition scrubbing used? Attrition means to wear away a surface, typically by friction or abrasion. An attrition scrubber does exactly this, using impellers to force particles against each other, causing intense scrubbing, grinding, abrasion and polishing. This process is not a new concept. It has long been used in the glass industry to remove surface contaminants from silica. But it is also widely used in many areas of mineral processing and other applications including soil remediation and plastics recycling. In mineral separation, for example, the scrubbers help improve yield and efficiencies by preparing feed materials for downstream processes such as flotation, magnetic or electrostatic separation. Inefficient scrubbing can lead to coatings remaining on valuable minerals and decreased yields, as the covered minerals cannot be processed efficiently or are mistaken as waste contaminates and removed. In the example of flotation separation, pre-flotation conditioning uses attrition scrubbers to provide better recovery of minerals while using fewer chemicals. If surface contaminants remain on the mineral, yield is reduced, as the unwanted coating acts as a barrier to the reactants, which make it unfloatable and, therefore, unrecoverable.

Oct 1, 2013

By Ihor Kunasz

The high lithium demand forecasted for some high tech applications and batteries for electric and hybrid-electric vehicles, in particular, has sparked increased exploration for lithium, particularly for lithium- and potassium-bearing brine deposits. The latter have generally followed the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) NI 43-101 guidelines on resource reporting, formulated for hard rock deposits (metals and industrial minerals). While a number of the requirements can be appropriately applied to brines, brines are fluids and require a specific analysis leading to a distinct set of reporting requirements. Brines cannot be considered industrial minerals because the various elements occur as ions in a dynamic fluid, rather than being chemically bonded in a solid. Although chemicals are produced from brines, brines have no relation to industrial mineral deposits. This article analyzes the recently released (Nov. 1, 2012) document CIM Best Practice Guidelines for Resource and Reserve Estimation for Lithium Brines, in light of the practical knowledge available from existing brine operations. It recommends modifications to the guidelines, which, if applied in their present format, will result in overstating resources and reserves and mislead potential investors. The CIM Best Practice Guidelines for Resource and Reserve Estimation for Lithium Brines document is generally descriptive and does not fully address the methodology for brine resource or reserve definition. Lithium and other elements (potassium, magnesium) are contained in a fluid, the hydrologic characterization of which should be the principal focus of a brine exploration program. The fundamental requirement in defining lithium brine resources and reserves in a salar is the identification and definition of those formations ? the aquifers ? that will yield brine in a usable quantity to a well, because brines can only be extracted by pumping wells. Fine-grained sediments will never, as required in the summary Table 1, have ?reasonable prospects of economic extraction,? cannot be considered and, therefore, need not be tested. However, the guidelines recommend the collection of solid samples and a high-core recovery for laboratory testing of various sediments instead of focusing on the brine.

Oct 1, 2013

By M Sciortino, J Korczak, J Muinonen, A St-Jean

The Dumont deposit is a large (1179 Mt reserve), low-grade (0.27 per cent nickel) nickel sulfide project located in the Abitibi region 25 km west of Amos, Quebec. Royal Nickel Corporation (RNC) acquired the project in 2007 and has since taken the deposit through to feasibility. The disseminated nickel sulfide and alloy mineralisation is hosted within the serpentinised dunite subzone of the Dumont Sill; a differentiated, pervasively serpentinised, ultramafic sill of komatiitic affinity. Pentlandite ((Ni,Fe)9S8), heazlewoodite (Ni3S2) and awaruite (Ni2.5Fe) are the dominant nickel-bearing metallic phases and can be recovered by conventional methods (flotation, magnetic separation). Non-recoverable nickel is also present within serpentine and olivine of the silicate matrix.A detailed mineralogical program including 1420 QEMSCAN« samples and 4400 electron microprobe points was undertaken to increase the understanding of the nickel deportment in the various recoverable and non-recoverable phases in a spatial context across the deposit. A total of 105 metallurgical tests have been performed under a standard procedure which have linked the mineralogy to metallurgical performance. This has allowed the creation and modelling of geometallurgical domains on a block-by-block basis to understand the recovery variation and metallurgical performance throughout the deposit. Understanding the spatial variability of Ni deportment in recoverable and non-recoverable phases through mineralogy is the key to understanding metallurgical performance, thus unlocking the value of the Dumont deposit and other large tonnage low-grade ultramafic nickel deposits.CITATION:Sciortino, M, Muinonen, J, Korczak, J and St-Jean, A, 2013. Geometallurgical modelling of the Dumont Deposit, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 93-100 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By C Moorhead, J Jones

A common problem in the mining industry is that company geologists can operate in relative isolation to the rest of the company (Jones and Moorhead, 2011). This may result in poor knowledge transfer and often priority conflicts with geology, operations and project departments. This problem is amplified by the acquisition of mineralogy capabilities and other metallurgical (met) test work undertaken by many companies in order to solve for complex orebody problems. Met data is often not located and viewed in 3D space so that geologists and engineers can create and work with geometallurgical (geomet) models (Bye, 2006). Visualisation of data in an interactive graphical 3D model provides a bridge enabling met professionals to collaborate with engineers and geologists to provide a common understanding of the relevance of geomet data.In recognition of this problem, Newcrest has undertaken an effective collaboration strategy to improve internal and external engagement through the use of large visualisation displays (Jones, 2009). The displays are underpinned by IT systems and information management practices that recognise the needs of underlying disciplines. Today it is generally understood within Newcrest that this is required to improve decision-making, deliver faster cycle times and improve governance.Collaboration in companies has been generally associated with the introduction of new IT functions (IBM, 2008). However, the science and engineering process that are used to structure modern IT-based collaboration systems and practices are now known to be simplistic compared to the long-standing practices associated with collaboration and knowledge management in disciplines such as geology and mining.CITATION:Jones, J and Moorhead, C, 2013. Geometallurgical communication as a distributed information system, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 133-138 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By R Castroviejo, E Pirard, L PTrez-Barnuevo

Process mineralogy provides the mineralogical information required by geometallurgists to address the inherent variation of geological data. The successful beneficiation of ores mostly depends on the ability of mineral processing to be efficiently adapted to the ore characteristics, liberation being one of the most relevant mineralogical parameters. The liberation characteristics of ores are intimately related to mineral texture. Therefore, the characterisation of liberation necessarily requires the identification and quantification of those textural features with a major bearing on mineral liberation. From this point of view, grain size, bonding between mineral grains and intergrowth types are considered the most influential textural attributes. While the quantification of grain size is a usual output of automated current technologies, information about grain boundaries and intergrowth types is usually descriptive and difficult to quantify to be included in the geometallurgical model.Aiming at the systematic and quantitative analysis of the intergrowth type within mineral particles, a new methodology based on digital image analysis has been developed. In this work, the ability of this methodology to achieve a more complete characterisation of liberation is explored by the analysis of chalcopyrite in the rougher concentrate of the Kansanshi copper-gold mine (Zambia). Results obtained show that the method provides valuable textural information to achieve a better understanding of mineral behaviour during concentration processes. The potential of this method is enhanced by the fact that it provides data unavailable using current technologies. This opens up new perspectives to the quantitative analysis of mineral processing performance based on textural attributes.CITATION:PTrez-Barnuevo, L, Castroviejo, R and Pirard, E, 2013. New perspectives on quantitative textural analysis, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 191-198 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By M Flanagan, T Sua, B Wright, T Carroll, B Van Dijken

"BHP Billiton (BHPB) West Australian Iron Ore (WAIO) conducts an extensive geometallurgy (geomet) program for its iron ore deposits in the Pilbara. The geomet program provides accurate information to infrastructure engineers, resource geologists, mine planning engineers and the technical marketing team on the performance characteristics of iron ores. Performance metrics include production planning, such as lump/fine splits, processing capability such as the level of ultra-fine iron ore and ironmaking blast furnace properties including tumble index (TI) and reduction disintegration index (RDI). Prior to the introduction of the current geomet program in WAIO, basic geometallurgical information was provided at the deposit level, such as deposit lump percentage and head grade chemistry. As the business value of geometallurgy was realised during the growth period of WAIO, the geomet process was reviewed and formalised into five steps: geomet drill planning laboratory measurement data management algorithm development block estimation.The geomet laboratory process produces simulated iron ore products from drill core, which are then subjected to physical geometallurgy test work. With the large amount of geometallurgy data collected, extensive databases are utilised to collate and organise the data to improve its usability within the business. Algorithms are created from the data to predict important geomet variables and a block estimation method is used to estimate geometallurgical properties into resource models. The predicted geometallurgy data is regularly reviewed at the different steps against plant and shipping data to allow refinement of the geometallurgy algorithms. It is also recognised that geomet data can be used to optimise the operations in existing processing hubs for improved production rate. In addition, future geomet programs will focus on generating data from all available drill core programs, not just dedicated geomet drill holes, and will incorporate new types of data, such as hyper-spectral information, for improved geometallurgical estimation.CITATION:Wright, B, Carroll, T, Flanagan, M, Sua, T and Van Dijken, B, 2013. BHP Billiton West Australian iron ore geometallurgy - past, present and future, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013, pp 105-110 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 29, 2013

By D J. Bradshaw, B Lottermoser, A Parbhakar-Fox

"Best practice for acid rock drainage (ARD) risk assessment still relies solely on the geochemical properties of sulfidic rocks and mineral processing products, despite the fact that a rockÆs tendency to produce acid also depends on mineralogy and texture. Consequently, there are a plethora of geochemical tests routinely utilised by the mining industry to predict ARD formation. Due to limitations associated with these tests and their relatively high costs, analysis of recommended best practice sample numbers is rarely achieved, reducing the accuracy of waste management plans. Our research addressed this through examining the application of geometallurgical data for predicting acid formation, and led to the identification of potential environmental geometallurgy indicators.Samples obtained from an iron-oxide copper gold deposit were subjected to the geochemistry-mineralogy-texture (GMT) approach, an improved methodology for classifying acid forming potential. GMT results were compared against geometallurgical and assay data sets to evaluate: relative carbonate content measurements (measured by HyLogger) and identify how these could be used to calculate effective acid neutralising capacity mineral hardness (measured by EQUOtip) to determine application of this data for calculating lag-time to acid formation opportunities to automate the acid rock drainage index (ARDI) using classified images produced by a GEOTEK logger and automated microscopy.Links between the GMT approach and geometallurgical data sets were identified. Classified mineralogy data has application at stage one, HyLogger and EQUOtip at stage two and computer-based ARDI evaluations of classified images at stage three. Through such integration, ARD characterisation costs can be reduced, with value added to geometallurgical data sets. Furthermore, deposit-wide ARD domaining is possible, and acquisition of total-orebody knowledge more likely. Through adoption of this environmental geometallurgy approach, a better informed waste management plan can be formulated, allowing for best practice ARD sampling in a more cost-effective manner.CITATION:Parbhakar-Fox, A, Lottermoser, B and Bradshaw, D J, 2013. Cost-effective means for identifying acid rock drainage risks - integration of the geochemistry-mineralogy-texture approach and geometallurgical techniques, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013, pp 143-154 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 29, 2013

By J Stiefenhofer

"*This is an abstract only*Construction of geological models for kimberlites has historically largely been based on visual volcanic textures and features, with chemical data only collected on an ad-hoc basis depending on the level of perceived complexity observed in the geological data. The focus of this paper is a high-level view of the impact an initial absence (or lack) of relevant chemical data had on two kimberlite resource models as well as how the magnitude of the problem increased once the resource estimation process commenced (Stiefenhofer, 2013). The impact of ignoring chemical data on a project assessment where micro-diamond estimation techniques are employed, is also discussed. Resource estimates based on micro-diamond data are critically dependent on the use of the correct geological model since stationarity of the size frequency distribution is key to the generation of correct grade estimates. A multilevel approach is advocated where the volcanological/visual model is verified using chemical data and both are in turn verified by the diamond data.CITATION:Stiefenhofer, J, 2013. The use of chemical and metallurgical parameters to enhance the economic value of kimberlite resource models, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013, pp 101-104 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 29, 2013

By N L. Turner, D J. Robinson, A J. McFarlane, N M. Chapman, L L. Kuhar, R L. Meakin, R Martin

A number of geometallurgical tests have been developed within the AMIRA P843A Geometallurgical Mapping and Mine Modelling (GeMIII) project, an interdisciplinary collaborative research project involving four research groups and over 20 global mineral companies. Researchers at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) have been focusing on the development of predictive hydrometallurgical indices for the GeMIII project via rapid, small-scale, cost-effective tests and protocols for comparative ranking of attributes relevant to leach performance. One of the focus areas has been the development of a leaching scheme for determination of the mineralogical deportment of copper in a large number of samples for geometallurgical applications.Various leaching schemes have been used over the last 20 years to identify the mineralogical deportment of copper. Typically, weak sulfuric acid and cyanide are used to target copper oxides and æsecondaryÆ copper sulfide minerals, covellite, chalcocite and bornite, respectively. Residual copper is assigned to chalcopyrite and/or bornite. Adaptations of this scheme have included the use of a weak organic acid to target oxides or ferric sulfate to target secondary copper sulfides. Testing of the weak acid/cyanide scheme in the GeMIII project using head and residue QEMSCAN mineralogical data analysed with a statistically reliable comparison method indicated that the inferred mineralogical deportment from various leaches could differ markedly from the theoretical or assumed value. Based on this initial work, test development and leach tests on samples from multiple sites has resulted in the development of a scheme to target copper oxides, chalcocite, covellite, bornite and chalcopyrite. This paper presents results from leach tests conducted on a large sample suite from two pits in a Cu-Au ore deposit with results calibrated using mineral liberation analyser (MLA) mineralogical analysis. This study has assisted in the development of a protocol for determining the mineralogical deportment of copper in a large number of samples for geometallurgical applications.CITATION:Kuhar, L L, McFarlane, A J, Chapman, N M, Meakin, R L, Martin, R, Turner, N L and Robinson, D J, 2013. Calibration and testing of a geometallurgical leaching protocol for determining copper mineralogical deportment, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 177-186 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By G McCullough, B Mutsaers, J Jessop

"*This is an abstract only* Geometallurgical initiatives have demonstrated considerable value to operations that have trialled them. However, it is extremely difficult for these initiatives to become properly embedded into the operations and for that value to be realised on an ongoing basis.This paper will explore some of the historical reasons why this is the case. Some of these reasons include the limited tools available to manage an integrated operation. These, in turn, have resulted from poor communications infrastructure, inadequate sensor capability and the way technical mining software has evolved over the last 30 years.This paper will then investigate how the evolution of technology in recent years can help overcome these constraints and compare progress with similar industries.CITATION:McCullough, G, Mutsaers, B and Jessop, J, 2013. Obstacles to embedding geometallurgy decision-making into operations and how to increase maturity of this critical capability, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013, pp 139-140 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 29, 2013

By M S. Powell

In this paper it is argued that we are entering a new mining era, based on considerably more challenging orebodies as we rapidly expand minerals production by exploiting previously uneconomic deposits. Rapidly increasing production costs cannot be sustained by continually increasing commodity prices, as illustrated by the recent downturn in the industry.Driven by reduction in grade, requiring the processing of 50 to 100 per cent more ore to recover the same amount of metal, often accompanied by finer grain structure - necessitating a finer product size and more challenging recovery - the productivity of the mining industry is dropping in real terms. The author suggests that tweaking current technologies and relying on economies of scale will not turn the industry around, but rather a switch to considerably more efficient processing is required.It is imperative to utilise the properties of the orebody, especially in terms of variability, in revolutionising our processing techniques. Our new mantra may be æselective mass mining with flexible processingÆ. This paper explores how this may be implemented using current technology and equipment in order to change the cost profile of the new mining industry. Orebody knowledge, based on the underlying process drivers, rather than proxies, is required. These properties and their variability will need to be propagated into the orebody through utilising the geological data rather than smoothing block averages, which destroys information on variability.Novel flexible circuit designs are presented that can respond to a wide variability in ore properties and throughput requirements in order to slash processing costs and energy utilisation, while enhancing overall recovery. The success of these circuits will be based on an ability to predict at both design stage and in everyday processing the variable ore properties, which is dependent upon reliable orebody knowledge that caries variability and underlying processing properties.CITATION:Powell, M S, 2013. Utilising orebody knowledge to improve comminution circuit design and energy utilisation, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 27-36 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By S Khosrowshahi, A Weeks, W J. Shaw

"To provide an indication of expected performance of the mine and mill, feasibility studies should include an assessment of the expected day-to-day variability in process plant feed. Attempts to do this based on conventional resource models will be flawed as such studies fail to consider and account for the in-built smoothing (averaging) of input data.This can lead to one of two situations: an expensive, over-engineered process plant that can cope with every possible situation, or operational strategies that fail to manage the natural variability within the orebody and the impact of day-to-day operational decision-making.In both cases the value of the project diminishes through excessive capital costs or reduced throughput or recovery during operations.Unlike conventional estimation techniques, the geostatistical method of conditional simulation can reproduce the inherent variability of the deposit. Once a valid model has been developed, it is possible to analyse the model using a transfer function that simulates the proposed mining processes and provides a representation of the likely variation of mill feed characteristics at any time scale.The case study demonstrates how the proposed mining strategy would result in mill feed being considerably more variable than expected, resulting in poor recovery, low throughput and potential breaches of environmental conditions. Mitigation measures included budgeting for additional mining equipment to enable greater flexibility during mining and revised stockpiling and crusher feed strategies.Awareness of the benefits of modelling the variability of geometallurgical parameters will increase the use of this approach in producing more realistic financial models of expected mine performance at the design stage.CITATION:Shaw, W J, Khosrowshahi, S and Weeks, A, 2013. Modelling geometallurgical variability - a case study in managing risk, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013, pp 247-252 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 29, 2013

By I Swane, R Rait, A Robertson

Geochemical assessment of mine waste materials prior to commencement of a proposed mining operation is a fundamental component of mine feasibility studies and the regulatory approvals process. Static and kinetic geochemical test methodologies are widely used to predict the geochemical nature of mine waste materials and to develop strategies for managing potentially æhostileÆ materials. These data can also be integrated with data from other fundamental studies such as hydrogeology to predict specific environmental outcomes and potential impacts at mine closure and post-closure.A case study is presented for a proposed open pit gold mine in Mongolia, which illustrates how geochemical, hydrogeological and groundwater quality data can be used as part of a geochemical modelling process to predict the final pit lake water quality over time. A series of static and kinetic test geochemical test programs were completed and acquired data integrated with hydrogeological and groundwater quality data provided by the proponent. A widely used geochemical modelling program (PHREEQC) was used to develop the geochemical model and predict water chemistry in the pit void after mine closure. Sensitivity analyses were completed to explore the effects on the model output of groundwater to leachate water ratio, pit wall rock type and climate.Modelling has indicated that pit void water should be pH circum-neutral at mine closure and should remain within Mongolian and World Bank water quality guideline limits under the modelled simulation most likely to occur in the field. Final void water salinity is expected to increase eight fold over 14 years after end of mine life due to a continuous flux of salts (particularly sulfate salts) into the pit lake whilst the pit lake volume will remain relatively constant due to evaporation and a slow recharge rate. Dissolved metal and sulfate salt concentrations in pit water are also predicted to increase over time and could be moderately elevated compared to applied water quality guideline values. Some of the metal concentrations, however, may be lower as these would be expected to precipitate at circum-neutral pH and greater. Recommended additional assessment work on the project when mining commences includes determining the magnitude of adsorption and co-precipitation of metals occurring in the pit void water/sludge system.CITATION:Robertson, A, Rait, R and Swane, I, 2013. Geochemical assessment of mine waste materials and prediction of final pit lake water quality at a proposed gold mine in Mongolia, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 165-170 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013