Search Documents

By K J. Davey, J T. Woodcock

Australian steelmakers produce up to 30 000 t/yr of electric arc furnace (EAF) dust. Current disposal techniques include sending EAF dust to landfill, stockpiling, and paying zinc smelters or registered waste removalists/processors to take the dust. Many of the complex overseas pyrometallurgical and hydrometallurgical treatment routes cited in the literature are not considered economic. Governmental, environmental and social pressures on producers to consider more sustainable disposal options are mounting, and there is now a strong push to consider recovering potentially valuable or recyclable components, such as zinc and iron units, from EAF dust. As well, there remain strong economic drivers for producers to find lower cost disposal solutions. Characterisation studies undertaken at CSIRO Minerals have revealed important physical differences in the nature of the zinc- and iron-bearing phases contained in domestic EAF dusts. These differences have been exploited using simple and cheap mineral processing techniques such as water washing, wet cycloning and wet magnetic separation. This has allowed a significant upgrade in the zinc content of EAF dust to be achieved, together with a reduction in the levels of key smelter penalty elements, such as chlorides and fluorides. The zinc-rich portion of the dust is now a more attractive smelter feed while the iron-rich part of the dust could potentially be briquetted or pelletised with a reductant and recycled to recover iron, and thus close the loop on dust processing. The basis of the separations tested together with laboratory results from several Australian dust samples are presented and discussed in this paper.

Jan 1, 2006

By A Scrase, J Brereton

The Latrobe Valley is located approximately 150 kms east of Melbourne. Within a very small area there are 3 large brown coalmines and associated power stations, 3 large towns, and numerous smaller towns in the vicinity. The mines have been generating power for Melbourne and surrounds for the last 100 years, with two of the mines being owned and operated by the Victorian Government (State Electricity Commission of Victoria) prior to privatisation in the 1990s. All three mines were privatised with the expectation that the mine voids would be filled with water to become pit lakes, as the final landform/rehabilitation solution (Hazelwood Mine Fire Inquiry, Teague and Catford, 2016). It could be argued that until relatively recently, this was largely expected, by government and industry, to be the rehabilitation solution for managing the two key risks associated with the sites:  The geotechnical stability of the mine pits.  The prevention of fire – through covering coal batters with water. Transitioning away from mining economies requires collaborative, regional, innovative thinking with a multitude of stakeholders, from a wide range of government departments, industry, First Nations people and broader community. Closure planning and rehabilitation activities require a range of skills and experience, such as, closure planning, various scientific and engineering disciplines (pit water quality modelling, geochemical modelling, cover design, landform design, contaminated site etc), civil engineering, demolition etc. Some of these skills are similar, such as financial modelling, stakeholder engagement, contract and project management. But the majority are different to those required during the operational phase of a mine. These closure skills can also be lacking within government, with Departments more familiar with monitoring and compliance activities associated with operational facilities. Some key aspects that appear to be critical to planned successful closure are:  Collaborative regional and localised planning, with industry, government, community, First Nations and other industry, business leaders and entrepreneurs all involved in providing a smooth transition away from mining.  Well-defined and known regulatory pathways to achieve mine licence relinquishment assists in encouraging investment.  Appropriately skilled and experienced government and industry personnel.  Mining companies, who are committed to closure planning and provisioning from the earliest point in project planning.  Mine employees who are appropriately skilled and experienced in mine closure planning and implementation with access to all the relevant technical expertise required for the project. Areas like the Ruhr Valley in Germany provide good some examples of smooth processes that facilitate mine economies transition into new economies (World Resources Institute (WRI), 2021).

Aug 2, 2023

By T R. Anderson, A R. Butler

Haymont (2012) notes that in parts of Australia significant areas of mining disturbance cannot be relinquished. In Queensland it has been estimated that by 2010, just 0.3 per cent 507 ha of mining disturbance had been rehabilitated to the regulator’s satisfaction (Short, 2015).One reason for this poor record is the presence of inappropriate, unachievable or unmeasurable rehabilitation targets (Glenn et al, 2014; Butler, Anderson and Sexton, 2015). In the authors’ experience in Queensland many mature operations have licence conditions that hinder the achievement of sustainable outcomes or prevent successful validation of rehabilitation success. This creates a lack of certainty for industry and a lack of confidence in the community that the sector can deliver good rehabilitation outcomes (Short, 2015).This extended abstract presents a framework approach that has been applied at two contrasting operations. Without the changes presented, the goal of progressive rehabilitation certification, reduction in financial assurance (FA) and a path to surrender at these sites would have been impossible. The framework can be adapted for use across different bioregions and commodities.CITATION:Butler, A R and Anderson, T R, 2016. Reassessing rehabilitation objectives and targets for mature mining operations in Queensland, in Proceedings Life-of-Mine 2016 Conference, pp 139–141 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By W R. Adamson

Cerro Vanguardia SA (CVSA), property of AngloGold Ashanti, mines gold and silver from a system of vetiforme orebodies located in the south of the Argentine Patagonia, in the Province of Santa Cruz.Surface mining techniques are applied to develop a series of narrow pits with an average waste to ore ratio of 26:1. This quite unique constraint brings into focus the need to maximise inter-ramp and final wall angles, leading to a strong need to optimise wall control drilling and blasting in order to reduce back-break damage to an absolute minimum.The paper describes a program of applied investigation and design modification implemented during?2008?and?2009 in?two?separate pits of Cerro Vanguardia. Three distinct yet complementary damage mechanisms were identified and observed during the field components of the work; vibration induced strain fracturing, surface cratering around blasthole collars and quasi-static loading and unloading of the surrounding rock mass as a consequence of poorly controlled confinement.With these mechanisms identified, a measurement, modelling and modification campaign was conducted in order to reduce the incidence of each source of damage. Interactive design analysis and modelling, near-field vibration measurement, video capture and the application of electronic initiation technology were supported by seed wave modelling and topographic evaluation of the achieved results.Results point to the usefulness of simulation techniques for determining optimum delay timing to reduce vibration impact, while the visualisation of explosive energy distribution produced by drilling and explosive loading decisions assists in reducing the probability of over-confinement.This paper presents relevant aspects of the two fieldwork campaigns:1) describing the application of the techniques, and2) summarising the results obtained.

Nov 8, 2011

By V A. Chanturia, T N. Matveeva, V V. Getman, A Yu Karkeshkina

The development and application of new effective environmentally friendly reagents for the flotation of thin and ultrathin mineral components is an urgent task. The analysis of the nomenclature of chemicals, including flotation reagents and flocculants, showed that water-soluble polymers (WSP) might be used in flotation separation of fine grinding products containing non-ferrous and precious metals. Water-soluble polymers that are responsive to temperature changes are the most attractive as reagents during flotation. These are the thermo-responsive polymers or thermomorphic polymers. The presence of nitrogen and oxygen atoms in the polymer molecule contributes to the formation of a coordination bond with non-ferrous and precious metals. A research conducted at the ICEMR RAS within the framework of the scientific school of Academician of the Russian Academy of Sciences Chanturia helped to develop a method of flotation of finely ground mineral particles containing valuable components using modified thermomorphic polymers. The paper focuses on the experimental study of poly (vinyl caprolactam) (PVC) as a flotation reagent for gold recovery from finely ground mineral products. PVC is a ready-made water-soluble thermosensitive polymer that does not require complex synthesis. PVC has a high ability to form complexes in an aqueous environment when heated. According to experimental data, the polymer interacts with gold nanoparticles, contributing to the extraction of gold from fine mineral products and the tailings that makes it perspective as an additional flotation agent for the processing of gold-containing ores.

Aug 24, 2022

By M Ma, W J. Bruckard, C Gontijo, R Holmes

Vale is the largest iron ore producer in the world. Since the 1970s, Vale has been using reverse cationic flotation to remove siliceous impurities from its iron ores. Whilst this flotation process has operated effectively for many years, it suffers from the problems of high reagent costs and high metal loss.In 2010, CSIRO investigated the use of a reverse anionic flotation process for Vale iron ore. Batch laboratory flotation studies conducted on Vale samples showed significantly reduced reagent costs and improved recovery of iron. In this work, the flotation behaviour of the different impurities in the Vale iron ore sample using reverse cationic and reverse anionic flotation processes is compared. Detailed flotation responses are presented and the merits of the two different flotation schemes are discussed.CITATION:Ma, M, Bruckard, W J, Holmes, R and Gontijo, C, 2013. Impurity removal in the reverse flotation of iron ore, in Proceedings Iron Ore 2013 , pp 427-430 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By X Z. Sun, N Jiang, J H. Zhao, C X. Wang, L Y. Bai

In backfill grouting for underground coalmines, the filling materials strengthen the caving rock and support the overlying strata to reduce surface subsidence. The broken roof strata fail and collapse during mining operations without appropriate supporting measures being taken. It is difficult to perform continuous backfill mining on the working face of such roofs using the existing mining technology. Therefore, in order to solve the above problems, fly ash and mine water are considered as filling materials, and flow characteristics of fly-ash slurry are investigated through laboratory experiments and theoretical analyses. Laws governing the diffusion of fly-ash slurry in the void of caving rock masses and in the void between a caving rock mass and a basic roof are obtained and verified. Based on the results obtained from the above analyses and field conditions at the Zhaoguan coalmine, Shandong Province, China, a cave backfill grouting system of the hauling pipeline is developed and successfully tested at the 1703 working face. The results demonstrate that a filling rate of 43.46 per cent is achieved, and the surface subsidence coefficient of the grouting process is found to be 0.475. Compared to the total caving method, the proposed system is found to achieve a reduction rate of 40.63 per cent. This effectively helps in lowering the value of the surface subsidence coefficient. Fly ash and mine water, considered as primary materials in this study, also play a significant role in improving the air quality and water environment.

Nov 29, 2022

By M Ogle

"Booster fans are relatively rare in Australian coal mines. However, as mines become progressivelydeeper it is likely that such fans will be increasingly adopted as a method to sustain or improve the ventilation of underground workings. The reasons why booster fans may be an att ractive alternative include: increased cost of sinking additional ventilation shafts with greater seam depths; environmental objections to shaft sinking projects; and increasing urbanisation and surface constraints limiting availability of potential ventilation shaft sites. As Tahmoor Colliery movedinto its northern lease the ventilation constraints became the limiting factor on production. Thelimitations of the old workings meant that the existing ventilation system would be inadequateto sustain the required production. Extensive ventilation modelling was carried out to evaluatevarious potential solutions and the recommended option was the installation of a booster fanor fans, to gain underground access to an already approved shaft site in the northern lease.Proposals were sought from recognised fan manufacturers and various alternative arrangements were tendered. Ultimately the choice was between one large centrifugal fan and a set (three or four) of smaller æauxiliary-likeÆ fans in parallel. The successful tender was for a single centrifugal, an arrangement very similar to the booster fans that have been operating eff ectively at Westcliff Colliery for a number of years. This paper describes the current ventilation network, evaluation of the ventilation options, the fan selection process, and the project status to date."

Jun 1, 2012

By Amos QG

The Paddington I and proposed Paddington II Pits are both located in what is, by Eastern Goldfields standards, a large tonnage-low grade orebody. The Pits have been designed to supply ore to a substantial Treatment Plant at the designed rate of 875,000 tpa. (This throughput is currently being increased to 1,200,000 tpa).Generally the orebody lends itself to large tonnage mining techniques, relying on only a relatively small amount of sampling. The surface enrichment zone and depleted zone are reasonably complex and require more intensive grade control and sampling techniques as typically utilised in many surface mines in the Eastern Goldfields, although as experience and understanding of the nature of the orebody was gained, less sampling became necessary.

Jan 1, 1986

By Singh BN, Chakravarty PK, Chatterjee LM

Indian blast furnaces operate with coke gener- ally containing 24 to 28% ash compared to 10-15% ash in coke in most other parts of the world. The operating problems are further aggravated by the high alumina content and the adverse alumina to silica ratio in the ore. The above factors not only increase the coke rate but, at the same time, increase the flush slag volume, make the bosh slag highly limey and thereby viscous, and produce a flush slag containing 24 to 26% alumina. Relative- ly low flame temperatures (RAFT) make conditions more difficult. The high basicity of the bosh slag limits the maximum flush slag basicity to around 1.0, beyond which the burden movement is adversely affected by the viscosity of the bosh slag: This effect is partly controlled by operating blast furnaces with high MgO in the flush slag (around.10%), which also improves the desulphurizing power of slag. Steps are underway in some plants to inject lime through theòtuyeres to control the bosh slag basicity and also to neutralise the large quantity of silica which is released at the tuyere level from the coke ash, so that the silicon content of the hot metal can also be controlled. High bosh slag basicity coupled with the characteristics of iron ore/aggolmerates, widens the softening-melting zone and alters the shape of the softening-melting zone. This leads to operat- ing difficulties and poor hot metal quality. This paper discusses the above aspects of Indian blast furnace operation and steps being taken to surmount some of the above difficulties.

Jan 1, 1981

By N Dube, K L. Sandvik, C Mutevhe

Trojan Nickel Mine is the largest producer of Ni, Cu and Co in Zimbabwe. The mine has operated a nickel flotation concentrator and base metal refinery continuously since 1969, creating 28 million tonnes of sulfide bearing tailings, five million tonnes of permanent waste rock and about seven million tonnes of smelter slag. Exposure of the sulfide bearing minerals renders them susceptible to oxidation in the presence of water and oxygen, resulting in acidic solutions with elevated concentrations of total dissolved solids, sulfate, metals and residual flotation chemicals in various waters draining from the mine site. These pollutants pose a direct threat to the environment and human health, and understanding their deportment and behaviour in the various waste streams is essential in the mineÆs environmental objectives to prevent or minimise adverse impacts arising from its operations. A geochemical assessment of the pollutants was carried out to compute a mass balance between the major sources of pollution and the distribution and fate of pollutants in waste streams from the mine site. Waste rock, tailings, surface water, ground water and sediments were sampled, tested and analysed. Mineral composition and water chemistry data show that geochemical reactions are responsible for the release of pollutants from waste rock, tailings and plant spills. Drainage from the mine area is near neutral due to buffering by magnesium carbonates in the fine fraction of the tailings. The natural wetlands that exist downstream of the waste rock and tailings dams are effective in reducing metal loadings to water courses. However, solutes and heavy metals are occasionally released to surface and ground water, when their concentrations peak during the dry season. The results demonstrate the necessity to understand the natural chemical processes that characterise the distribution of pollutants in nature and how such knowledge can be used to develop cost effective methods to remediate pollution in the natural environment.

Jan 1, 2006

By M Gwynne

McArthur River Mine is located approximately 50 km south-east of the NT township of Borroloola and approximately 120 km from the Gulf of Carpentaria. The mine hosts a series of layered shallow dipping tabular orebodies, with current reserves of approximately 22 Mt, grading 13.6 per cent zinc, 6.3 per cent lead and 65 g/t silver. Owing to economic considerations, the lower most orebody (No 2 orebody) has been selected for initial mine production. Following the completion of the No 2 orebody, mining will transfer to the lower grade and metallurgically more complex No 4 orebody. The mine employs a total of 235 people throughout the underground and surface areas. The majority of the workforce work a fly-in/fly-out, seven-day- on/seven- day- off roster with 12-hour shifts. Presently, a further 18 contractors are involved in trial mining areas. An apparent dip room and pillar technique has been selected as the primary mining method. Officially opened in September 1995, the current production rate of 1.2 Mt per annum will eventually escalate to 1.5 Mt per annum. Though most production is achieved through the use of conventional loaders, trucks and jumbos, the recent development of methods utilising scrapers, hand held machines and modified jumbos has produced encouraging results in steeper dipping areas of the mine. Initial production has been hindered by several factors including extensive and largely unpredictable faulting, worse than expected ground conditions and difficulties with some mining equipment. Compounded by the relatively thin 3 m ore seam, initial mining resulted in high dilution and poor production. This paper describes the development of unique planning and production systems that were evolved in order to overcome these problems and achieve the targeted production rates and head grade.

Jan 1, 1998

By Plamer D. J, Newman O. M G

The Effluent Treatment System at Pasminco Metals - EZ (PMEZ) was commissioned in December, 1991 and has operated satisfactorily, ensuring that aqueous discharges from PMEZ comply with the Tasmanian Environment Protection Act. The system treats both spills and run-off from the Zinc Plant, and acidic liquor generated in the gas cleaning section of the Sulphuric Acid Plant. The spills and run-off from the Zinc Plant are collected in a large catchment pond. The pond liquor, after partial neutralisation with sodium hydroxide to pH 4, and removal of suspended solids, is preferentially recycled to the Zinc Plant, for example, for washing of residues. Liquor which cannot be recycled, is treated in the Lime Neutralisation Section. The other input to the Lime Neutralisation Section is the acidic liquor from the Sulphuric Acid Plant from which mercury has been removed by contact with aluminium pellets in a fluidised column. In the Lime Neutralisation Section, the liquors are blended and neutralised to pH 10 by the addition of slaked lime. The heavy metals and most of the fluorine are precipitated. The precipitated solids are removed in a thickener with part of the thickener underflow being filtered. Most of the thickener underflow is recycled to generate solids that settle rapidly and filter well. The filter cake is returned to the Zinc Plant for the recovery of contained heavy metals while the thickener overflow is discharged to the Derwent River.

Jan 1, 1993

By S S Solomons

In 1991 the uranium spot market price dropped to approximately US$7/Ib U308, a historical low in real terms and the short-term outlook for the industry in the next five years was grim. At this time the Ranger operation was producing uranium concentrate at its design capacity of approximately 3 000 tonnes/year. The loss of two major long-term contracts owing to price and reduced power utility demand due to excess inventories meant that the company could not match production to sales. Continuance at this production level would have resulted in a rapid buildup of product inventory and the tie-up of significant cash reserves. After analysing various options, an innovative operating strategy was devised such that production and sales were approximately balanced without a significant impact on the unit production cost or a long term effect on the plant or operation. A campaign mining/milling operation commenced and approximately 40 per cent of the workforce were retrenched. Multi-skilling of all employees was a critical aspect of ensuring a successful outcome. This paper examines the strategy and reports on the success of the operation two years after the restructuring exercise was effected in November 1991.

Jan 1, 1994

By T B. T Nguyen, L Matthews, D O’Dea, T Honeyands, T Harvey

Productivity and fuel consumption of the blast furnace is driven by the quality of the iron ore sinter, which in turn is related to the sinter mineralogy. The sintering conditions including temperature and gas composition have a significant influence on the formation of melt and finally the mineralogy of the sinter. In this work, analogue sinter tablets were produced from iron ore fines in a laboratory furnace with tightly controlled temperature profile and oxygen partial pressure in the gas. The mineralogy of the sinters was analysed using reflected light microscopy. The results showed that increasing thermal enclosed area (area enclosed by heating and cooling curve above a reference temperature) reduces primary hematite and platy silico-ferrite of calcium and aluminium (SFCA) contents. This is attributed to increasing melt formation, leading to greater assimilation of the iron ore particles. Lower magnetite was found for tablets with greater median pore size, which is thought to be due to greater oxidation of magnetite to hematite during cooling in air. It was also found that higher alumina content was found to result in more SFCA formation under the same heating/cooling conditions, whereas tablets with higher goethite had higher assimilation and produced more secondary hematite on cooling. Finally, it is necessary to relate the enclosed area to the temperature at which the melt formation becomes significant which strongly depends on chemical composition of the ore studied.

Nov 8, 2021

The Porgera gold mine has made significant progress with the successful installation of a JK FrothCam image analysis system. The system is used to measure and control froth velocity on the scavenger circuit which has brought significant economical and operational benefits. The froth velocity signal, determined by analysis of the camera, is transmitted to the PLC that manipulates flotation cell airflow rate and cell level controllers to maintain a target froth velocity of 130 mm per second. Following on from a three-week trial installation in June 2000, a permanent installation was commissioned on the scavenger Outokumpu (OK150) tank cells. Further work is in progress on the rougher Wemco cells. This paper describes the evaluation of FrothCam Technology and its subsequent installation.

Jan 1, 2003

By C Katonga

Mindola mine is currently the deepest mine in the Zambian copper belt. Stoping is currently active to 1330 m below surface with long range plans indicating future production from 1590 m level. The orebody is tabular and dips between 55o to vertical. The thickness varies from 8 to 14 m. The vertical crater retreat method of mining was first introduced at Mindola mine in the late-1980s following several trials that helped define the design criteria for its application. Over the last ten years the method has been continually modified to improve safety and maximise ore production. For example, due to the weakness of some rock units within the orebody formation and the instability of the hanging wall, the last VCR slices are usually between 8 - 10 m thick, and efforts are being made to strictly apply shrinkage method in order to reduce dilution. Recent advances in mining technology in the areas of equipment, blasting techniques, rock mechanics and materials handling have been employed to increase the overall productivity of the mine. Large down-the-hole machines capable of drilling 165 mm diameter blast holes, up to 80 m long are used in stoping. Each stope produces up to 20 000 tonnes of ore per month and can last for three months. Heavy systematic ground support of VCR development has significantly enhanced safety for mining crews and equipment. Crater mining has not only improved productivity and enhanced safety, but also overcome various problems associated with conventional sublevel open stoping previously employed at the mine. This paper discusses the technical and operational aspects of vertical crater retreat mining at Mindola mine during the last ten years. The changes in mining method are often accompanied by changes in mine design, blast design, mining equipment, ground support and operating practices.

Jan 1, 2000

By Y H. Zhu, X X. Tang, Y C. Yin, M L. Xing

Based on the stiffness theory, the stiffness difference and energy supply of surrounding rocks are important inducing factors for strain burst. However, due to the lack of multi-level low stiffness testing machine, there are few experimental studies on rock failure mechanisms under the influence of loading stiffness. This paper introduced a self-developed rock testing system with changeable stiffness. The main testing machine of this system is a combined structure of inner and outer frame. The change in the loading stiffness is achieved by using a stiffness servo control system to control the energy accumulation in the inner frame. The tests of the sandstone specimens under three different loading stiffnesses in the testing system showed that the loading stiffness did not significantly affect either the uniaxial compressive strength or the Young’s modulus of the rock. However, the post-peak stress-strain curve of the rock became smoother and steeper when the loading stiffness was decreased, and the stress drop rate increased. It is shown that the stress drop rate had a power function correlation with the loading stiffness. After the peak load, the inner frame of the testing system rebounded several times at high speeds. The magnitude of the instantaneous rebound speed and the rebound duration increased with the decrease of loading stiffness. Both the mean rebound velocity and the total rebound deformation had power function correlations with the loading stiffness. The loading stiffness has limited effect on the energy storage and energy dissipation characteristics of the specimen, while the released energy of the testing machine increases as the loading stiffness decreases, which is the key factor affecting the failure mode of the specimen. According to the test results, a rock burst mechanical model considering the stiffness is established, and the energy supply mechanism of rock burst is quantitatively explained.

Nov 29, 2022

By L Nagy, K P. Juhasz

The authors were engaged to optimise a traditional rebar cage reinforced concrete segmental lining by means of finite element analysis (FEA) using macro synthetic fibres for the Shanghai metro extension. The aim of this study was to reduce or entirely replace the original steel reinforcement of the segmental lining, in order to make the precast production process faster and more economic. The outer diameter of the tunnel was 6200 mm, the thickness of the segments was 350 mm.The numerical calculations were performed by Atena Finite Element software, which is based on the combination of Menétrey-William and Rankine failure surfaces on the compression and tension sides respectively. The effect of the macro synthetic fibres was modelled as tension stiffening on the tension surface.A one-to-one full scale model of an assembled tunnel ring using the original reinforcement cages was tested at Tongji University in Shanghai, July 2013. The ring was tested to differing load levels where load and displacement were measured until failure. The author’s first step was to calculate the real displacement characteristics of the original reinforced concrete (RC) ring, then calculate the numerically modelled version, so as to compare them. The material parameters of the concrete and rebar used had been determined through basic material tests conducted at the Tongji University. (Bi, Liu and Wang, in press).The numerical modelling undertaken has shown good correlation with the full-scale physical test results. Optimisation of the lining reinforcement was achieved through the addition of fibres, resulting in a substantial reduction of the steel rebar cages. Several results have been computed with the numerical model using different dosages of macro synthetic fibres, showing that the mass of steel reinforcement could be reduced by 50 and 75 per cent respectively.CITATION:Juhasz, K P, Nagy, L and Winterberg, R, 2014. Full-round numerical modelling of a macro synthetic fibre reinforced tunnel boring machine tunnel in the Shanghai Metro extension, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 477–484 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By B C Tanda, E A. Oraby, J J. Eksteen

"Base metal and precious metal deposits are well known for their significant geometallurgical variation throughout the volume of the proven resource. At the metallurgical level, the plant normally processes an upper oxidised layer, a transition zone and a sulfide zone, often leading to different processing techniques for the different zones. A novel processing approach is presented whereby alkaline leaching with glycine is used to leach base and precious metals, using a copper-gold ore deposit as a case study. Glycine is a cheap, non-toxic, non-volatile, highly water-soluble crystalline solid produced industrially in bulk quantities. As a chelating ligand it forms a number of stable glycinate complexes with Ni, Co, Cu, platinum group metals (PGMs), Au, Ag, Zn, Pb, Hg and Cd, with broad stability regions over an extended temperature-pH-Eh range, allowing dissolution of these metals in the neutral and alkaline regions (pH 7–13). It has been shown that this lixiviant system can leach the metals from their oxide, oxy-halide, basic sulfate, carbonate, native and various sulfide forms, including refractory sulfides such as chalcopyrite. Extraction of the metals from their soluble glycinates is easily achieved using a range of solvent extraction and precipitation processes, and the glycine remains stable in aqueous solution for recycle and reuse. Minerals bearing metals in Groups 1 to 8 of the periodic table are normally unaltered. This technology therefore provides a highly selective leaching environment for the extraction of numerous scarce metals of economic interest, with minimal interaction with gangue minerals, whilst using environmentally benign reagents. Problematic leach residues such as jarosites, elemental sulfur and silica gels are averted through this processing approach. This technology allows hydrometallurgical processing that is much less domain-sensitive in the geometallurgical sense, and utilises essentially the same key reagents for the whole deposit.CITATION:Eksteen, J J, Oraby, E A and Tanda, B C, 2016. Developing Robust Hydrometallurgical Processes to Recover Metals from Deposits with Large Geometallurgical Variation, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 15–20 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016