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By B G. Lottermoser

Field and laboratory data combined with computational modelling have been used to predict the pit water quality for the Highway Reward mine. Open pit mining of the Highway Reward copper-gold deposit has produced a final mining void with a diameter of 600 m and a depth of 280 m. This void will be left to fill with ground and surface water once pumping of pit water ceases. Several leaching tables were constructed to simulate weathering reactions and surface water run-off in the major pit wall units during a 200-day leaching experiment. To date, about three-quarters through the experiment, combined run-off from these cells has reached a pH

Jan 1, 2003

By P Martin, A Somarin, S Bailey

Field-based research was conducted to investigate the performance of field portable X-ray fluorescence (FPXRF) in the analysis of reverse circulation (RC) drill chips in iron ore exploration. For years, FPXRF has been considered unsuitable for iron ore exploration due to the limitations of the elements it is capable of analysing for, in particular its inability to measure light elements (Mg, Al, Si, P, S). With the advent of the use of silicon drift detectors (SDD) in FPXRF, light elements are now measurable elements. However, doubt over the appropriate use of this new technology still exists due to the absence of reliable comparative field data. These doubts concerned the ability of the FPXRF data to correlate strongly with the laboratory assay of the same samples. It was believed that inconsistent grain size and other variables not being controlled would contribute greatly to this perceived unreliability.We tested RC chip samples on-site in the Pilbara, with the portable Thermo Scientific Niton XL3t X-ray fluorescence (XRF) analyser for a range of elements including Fe, Mn, Al, Si and S and then compared the results with laboratory assay data. A strong correlation indicates that the FPXRF results are reliable. Furthermore, to show the effect of simple sample preparation, we also analysed pulps of the same samples in the same way.The correlations were good for all of the elements of interest for the RC chip samples (R2 values between 0.82 and 0.9), and excellent for the pulps (R2 values between 0.89 and 1). The results also showed a direct correlation between sample preparation and improved quality of results with the FPXRF. This indicates that FPXRF can produce data from unprepared RC chips for Al and Si that, when compared with laboratory assays, is reliable for a field application in drilling and grade control. CITATION:Somarin, A, Martin, P and Bailey, S, 2013. Non-destructive analysis of diamond core for light elements using Niton field portable x-ray fluorescence, in Proceedings Iron Ore 2013 , pp 117-230 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By D Adhikary, M Khanal, B Poulsen, H Guo

During longwall mining, the ability to reliably estimate the height of longwall mining-induced fractures is critically important in order to effectively manage mining-induced water inflows and aquifer interference. The extent of mining-induced subsurface deformation, fracture, surface subsidence and aquifer interference is largely controlled by local lithological conditions, mining methods and mine layouts. Therefore for the purpose of quantifying mining impacts it is imperative to incorporate the local geology and mine plan parameters in a mine scale model. Two different numerical models based on 3D continuum (Finite Element Method) and 2D discrete (Discrete element method) domains, respectively, are developed to incorporate the mine site parameters of a study site in Australia. Both the models are calibrated and validated with measured mine data. The continuum numerical modelling method is used to investigate the change in permeability of the overburden strata due to underground extraction considering the full 3D nature of geology and mine layout. The discrete element modelling method is used to simulate the initiation and propagation of fractures, allowing the caving of overburden strata to be represented in a realistic manner, and the permeability enhancement of the strata overlying the goaf to be calculated from first principles. Permeability enhancement in the discrete element model is a direct function of the fractures induced in the deformation/caving process; fracture location, extent, aperture and connectedness. From the numerical modelling under the simulated condition for the mine studied here, it is predicted that the permeability of the caving zone from the goaf to five times the mining height increases by almost six orders of magnitude. In the fracture zone to approximately ten times the mining height, the change in permeability is predicted to be around two to three orders of magnitude. At the height of more than ten times the mining height the magnitude of permeability increased is predicted to be one to two orders of magnitude. CITATION:Khanal, M, Poulsen, B, Adhikary, D and Guo, H, 2018. Modelling of height of connective fractures during longwall mining, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 254–265 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By P R. G Milne

A risk-based approach to optimising pit wall slope angles was trialled in the design of a 60m deep open pit in extremely weathered and distinctly weathered materials in the Kalgoorlie area. The pit used for this approach was Stage 1 of a three-stage open pit project. The Stage 3 pit will require long term stability, as it will contain the portal for a long life underground project. Information from failures induced by steeper wall angles used in the Stage 1 pit would be valuable in predicting and preventing long-term stability issues in Stage 3. In this approach, the pit wall slopes are based not on the normal factors of safety, but on the assessment of the probability of failure and the direct and indirect costs of dealing with the failure when it occurs. In this example, the benefits and risks of adopting steeper wall angles were compared in a series of graphs. These charted the increasing probability of failure and simultaneous decreasing factors of safety with increasing pit wall slope, and the range in the possible volumes of circular failures for increasing wall angles. These were brought together in a graph showing the potential excavation savings (in BCM) and the probable cost of a failure (probability of failure times the probable volume of the failure). The resulting pit design was based on the project Mining EngineerÆs semi-quantitative assessment of where and when a higher risk of failure was acceptable and where it was not acceptable as it may have unduly affected the integrity of haul roads or production. The design incorporated wider than normal berm widths to accommodate anticipated failures and to enable modification of the wall configuration if required. Several re-designs were required during the life of the project in response to aggressively induced failures. It is considered that this risk-based approach provides a practical route to optimal pit design and operation but it requires an experienced, dedicated and efficient mining team for it to be implemented with benefit.

Jan 1, 2003

By G Chitombo, M Ruest

In surface mining, studies of the kinematics of blasted rocks using high speed film/video image analysis have allowed the estimation of the starting time, direction and magnitude of visible movement of fixed sections of the free face. Horizontal displacement versus time plots from discrete targets at the face generally report changes in slope over very small time intervals. These changes indicate step increases in velocity due to the action of explosive gases. In practice, the onset of rock mass movement, different to localised spalling, has been associated with a response time which exceeds the combined times of detonation, propagation and reflection of stress waves. This time is referred to as minimum response or burden movement time. As an engineering index, burden movement time has been used to provide guidelines for the selection of inter-hole and inter-row delay sequences in production blasting. With respect to improving breakage and fragmentation, it has been demonstrated that the delay interval between adjacent explosive charges should be less than the expected burden movement time. Similarly to reduce confinement between rows, delay intervals should exceed the expected burden movement time. The Hybrid Stress Blasting Model (HSBM) is a modelling framework that dynamically links an ideal and non-ideal explosives detonation code to a geomechanical rock model. This blast simulation tool is aimed at analysing the role played by different explosive formulations in fragmenting and/or damaging various rock types under different degrees of confinement. In the current framework, the rock behaviour under extremely high pressures and loading rates is calibrated from shock tests and the role of the explosive in fracture growth is accounted for and assumes a compressible fluid flowing through the explicit fracture network. The model is being developed as part of an international collaborative research project funded by a consortium of companies comprised of explosive and equipment suppliers and major mining houses. As part of the development and validation of the HSBM project, data from literature addressing the kinematics of the rock mass (ie burden displacement, face velocities and response times) has been collated and used to evaluate the current version of the code. A series of numerical experiments have been conducted with the view to: evaluate the response of the rock mass to changes in burden distance given by the impact of both stress waves and radial gas flow pressure;compare the modelling outcomes in terms of displacement, response time and face velocities to documented field observations; andcompare stress induced and stress/gas induced modes in terms of burden displacement outcomes. Results from these experiments have shown that in its current form the model is able to capture the trends observed and measured in practice. This is with respect to the simulation of burden displacement, response time and average face velocities for different geometries and charging conditions. The experiments have served as consistency checks which form part of an ongoing and comprehensive evaluation and validation of the HSBM code also aimed at addressing some of its current limitations.

Jan 1, 2007

The efficient and profit-maximising daily and long-term management of the Vera Nancy resource depends on decisions based upon assay data. This paper examines the range of sample sources, the methods of sample collection, assay techniques and Quality Assurance used by the mine. The orebody has a relatively low nugget effect for a gold mine (around 25 per cent) and this greatly assists in reducing sampling error and producing reliable assay data for production decision-making. Reconciliation between mine and back-calculated mill grades generally sees the mine under-calling mill grades by around four per cent.

Jan 1, 2000

By G Brooks

The control of phosphorus in steelmaking is one of the famous challenges of pyrometallurgy. It is well established that highly basic slags, the presence of FeO in the slag and lower temperatures (less than 1650°C) are favourable for phosphorous removal. The thermodynamics of this reaction have been extensively studied under laboratory conditions and the general trends confirmed through industrial trials. However, in general, phosphorus slag/metal distributions measured in industry are far from equilibrium and quite specific to the oxygen steelmaking technology being used. This variability was quantified by Urban, Weinberg and Cappel (2015), who found that the phosphorus partition ratio measured in plants varied with blowing practice, stirring intensity and even converter life. Some recent kinetic studies by Gu, Dogan and Coley (2017) have shown how the kinetics of these reactions vary with FeO content and dissolved sulfur at the droplet scale. A global kinetic model by Rout et al (2018) provides meaningful predictions of where dephosphorisation occurs in an industrial basic oxygen furnace (BOF) and some recent heat transfer modelling by Madhavan et al (2021, 2022) implies that temperature difference between droplets and slag has a role to play in explaining why equilibrium is not achieved. This paper will review the current state of knowledge and provide suggestions on predicting phosphorous removal for industrial operations and how greater removal could be achieved.

Jun 19, 2024

By T Raynlyn, R J. Holmes, J R. Manuel, A Poliakov, L Lu

The prediction of sintering performance of iron ore fines and the possibility of targeted optimisation of specific sinter properties are very important for both the iron ore industry and related research organisations. Physical pilot-scale sinter runs require large amounts of raw materials and are expensive, so it is critical to target large test work programs with many different sintering parameters effectively. To predict values for sintering performance parameters such as tumble index (TI), low temperature reduction disintegration index (RDI) and productivity, a comprehensive database of pilot-scale sintering experimental results has been established and empirical modeling conducted. Similarly to earlier work, physical, chemical and mineralogical characteristics of the iron ores have been considered. However, in contrast to the previous work where only one textural parameter was taken into account, namely the proportion of dense haematite ore texture, the current model includes the abundances of several different textures which were combined into different textural factors corresponding to different sinter properties. Coefficients for the variables within specific regression equations can provide a better understanding of the effect of the variables on the corresponding sintering performance. The modelling results have also been used for predicting the sintering performance of mixtures that were not part of the database used for establishing the models. Comparison of experimental and modeling results for the verification test data is also reported in this paper.

Jan 1, 2009

By Y Peng, D Wannas

In the fine particle flotation technologies being developed today the fine hydrophilic (gangue) particles are usually well dispersed. These highly dispersed fine particles can be recovered into the flotation froth product by mechanical entrainment. Flocculation of hydrophilic particles caused by polymer depressants could potentially reduce the mechanical entrainment of these particles. This paper reports testwork completed on fine particles of several solids, iron oxide, hydroxylapatite, galena and sphalerite, as well as on a relatively coarse quartz sample (-75+38 ¦m). Dodecylamine was used as a collector for the quartz, and several dispersants and polymer depressants, including sodium silicate, sodium metaphosphate, zinc sulfate, potassium dichromate, corn starch, corn dextrin and carboxymethyl celluloses (with molecular weights of both 700 000 and 80 000) were used as flotation modifiers. The major part of the testwork involved flotation tests in a 200 ml flotation column. Both water and solid recoveries were recorded. The degree of flocculation and dispersion was determined by settling tests in 250 ml graduated cylinders. It was observed that flocculation of the fine hydrophilic particles significantly reduced their mechanical entrainment, while dispersion severely aggravated it. Thus, in the flotation separation of artificial mixtures of the -75+38 ¦m quartz and fine iron oxide or hydroxylapatite, polymer depressants that caused flocculation were found to perform better than the ones that did not cause flocculation.

Jan 1, 2005

By J J. Hanhiniemi, M S. Powell

A ‘Variable Blend and Rates’ model is developed for SAG mills which extends upon the JKSimMet® Variable Rates Model. Similarly, a ‘Variable Blend Residence Constrained Perfect Mixing’ Ball Mill model is also introduced, also extending upon the existing JKSimMet® model. These models are used in conjunction with JKSimMet® while employing external technical programs. The technical model is then used to inform an economic model described elsewhere in Hanhiniemi and Powell (2022), which calculate operating and unit costs based on operating conditions, design, and ore characterisation. The SAG and ball mill models include constraints beyond those in the JKSimMet® models. The SAG model constraints include Size Specific Energy (SSE) verification, charge weight limit, and assessment of the impact of media to ore composition in the charge using the SAG Charge SSE Model developed in this paper. The ball mill model includes residence time, volumetric capacity, and SSE verification constraints. These models are applied to Cortez Gold Mine in the processing of two very different ore types and their blends; ‘Horse Canyon’ which is softer in coarser sizes and competent is fine sizes, and ‘Wenban’ which is competent at coarser sizes but softer in fine sizes than Horse Canyon. Horse Canyon also has a finer run-of-mine size distribution then Wenban. The application of the model at this site included undertaking five surveys at varying blends. The behaviours of the blends and individual components is then studied in the SABC circuit. A nonlinearity is observed with throughputs increasing with blending. The newly developed modelling approach captures these responses. Controlled blending based on ore competence-by-size and size distribution was implemented by the site, which then realised significant improvements in throughput without any capital cost (Ntiamoah et al, 2020). The modelling developed in this paper is then compared to existing practice, and the new method was found to provide improved fidelity and utility. A three-dimensional surface is then developed using the model describing the SAG mill throughput capacity at varying conditions (speed-filling) versus varying blend. The change in throughput as a function of only the changing charge composition is presented. The result is nonlinear, and explanations are provided to describe this behaviour.

Aug 24, 2022

By J Ortiz

In almost all copper mining companies, mine planning is done considering different time frames, leading to long-term (life-of-mine) (LOM), medium-term (first three years) and short-term (first year, monthly, weekly, and up to daily plans). Shorter term plans are usually associated with more abundant information, hence models with lower uncertainty. However, they capture more of the variability found on the geological attributes. In long-term models, usually estimation methods tend to hide this variability, providing smoothed interpretations.Medium and long-term plans consider average values for the parameters and optimisation techniques are applied aimed at maximising the economic profit. Short-term plans, on the other hand, are made to comply with the medium-term promises, maximising the use of the available resources (equipment and processing capacities) and dealing with the variability not characterised in the previous planning stages. This generates an important gap between the short-term and the medium and long-term plans. A case study was made using an important oxide copper mine, where the variability found in the short-term plan has a large impact in the productive process, thus reducing the daily ore grade variability is an important goal. In this paper, this planning issue is addressed by creating medium-term mine plans using mixed integer programming which are compared using the output of a simulation of the daily extraction that is aimed at satisfying the daily constraints of the processing plant, the availability of mining equipment and the variability of ore grade. The result shows the expected gap between these mine planning processes, which suggests correcting some of the parameters used in future medium and long-term plans.

Sep 26, 2011

By Riley S. J

The basic aim of mine planning is to design mine layouts and schedules that achieve optimisation of operations, minimum cost and maximum resource recovery. Successful accomplishment of this aim is facilitated by timely and comprehensive rehabilitation planning commencing at the pre-feasibility stage and continuing until the end of mining. Incorporation of a final landfomt design for waste rock dumps in a mine plan requires a prediction of surface stability, which may be achieved through erosion modelling. Erosion prediction models can be placed in two broad categories: soil loss prediction models eg USLE and CREAMS, and geomorphic models such as SIBERIA. A waste rock dump landform design based on selected slope form and grade and drainage systems should be developed as part of planning. A digital terrain model (DTM) of the landfonn should then be produced which can be modelled for long-term erosional stability using pre-determined parameter values. If acceptable standards of stability are not achieved, the landform should be redesigned and remodelled until the desired result is obtained. The planning process incorporating models requires knowledge of spoil or waste rock properties and model parameter values. This information is site specific and can be obtained from drill cores or costeans at the pre-mining stage and from spoil or waste rock during the mining stage. Realistic model parameter values are critical in post-mining landfonn design and can be obtained by several methods, including rainfall simulation, monitoring, geochemical analyses and grain size analysis.

Jan 1, 1994

By J J. Plumb, P D. Franzmann

A study was conducted to describe the microbiology of the MICCL Monywa chalcocite heap bioleaching operation. Microorganisms were detected in the heap using culture-based techniques and cultureindependent PCR-DGGE analysis of the 16S rRNA gene. The metabolic requirements, temperature and pH optima were determined for selected strains isolated from the heap material. Six strains (BH1-BH6) were enriched and isolated from heap solids and leachate samples. Phylogenetic analysis of the 16S rRNA genes showed that strains BH3 and BH4 were closely related to the acidophilic bacterium Acidithiobacillus caldus and strains BH5 and BH6 were closely related to Leptospirillum ferriphilum. The optimum growth temperature for L. ferriphilum was 41.3¦C and the optimum pH range was 1.1 to 1.5. A new species of Archaea was isolated from the heap samples. Cells of the proposed species, Ferroplasma cyprexacervatum (æcyprusÆ L.n. meaning copper; æexacervoÆ L.v. meaning æto heap upÆ), are non-motile pleomorphic cocci, capable of chemomixotrophic growth with ferrous sulfate and yeast extract. Cells grow anaerobically on ferric iron in the presence of potassium tetrathionate and yeast extract as electron donors. Growth occurs from 14¦C to 63¦C, with an optimum temperature of 55.2¦C. The optimal pH for growth was 1.0 - 1.2. The species was phylogenetically most closely related to Ferroplasma acidiphilum with a 16S rRNA gene sequence similarity of 95 per cent. Molecular analysis of mine samples (16S rRNA PCR-DGGE) detected the above-mentioned cultured strains of microorganisms as well as species of Sulfobacillus and other unknown Proteobacteria. The microbial community of the Myanmar bioleach heaps contained similar levels of diversity to a dump bioleach operation in Chile, but contained greater amounts of biomass than another heap bioleach operation in Australia. The operating parameters of the Myanmar heaps (low pH and moderate temperature) have selected for the growth of moderately thermophilic microorganisms that are more commonly found in extremely low pH acidic mine drainage sites than in heap systems. The novel species of Ferroplasma is thought to be involved in the aerobic and anaerobic cycling of iron within the heap bioleaching environment.

Jan 1, 2004

At many locations in Australia the decommissioning of mining operations will require the disposal of excess water. If the water is contaminated its disposal may be restricted by government guidelines. The timing of water disposal may be critical to the schedule of close-out. The uncertainty of the annual rainfall input to the water storage and disposal system may determine the success or failure of close-out. The uncertainty associated with any outcome can be used to determine the reliability of the system, or inversely its risk. The technique of Monte Carlo simulation, using the uncertainty in annual rainfall, is applied to quantify the risks associated with water disposal as part of the requirements for close-out in two case studies. In both case studies it is assumed that water disposal is via evaporation only. The first case study is the Nabarlek operation, located about 270 km east of Darwin. This project is required to complete the engineering work associated with its close-out by December 1995. The second study investigates the situation of close-out for the Ranger Uranium Mine, about 250 km east of Darwin. It should be noted that the Ranger mine was examined as part of the annual update of its contingency rehabilitation plan and the probability of implementing the plan is extremely small. The probability of success for the Nabarlek case varied from less than ten per cent to greater than 95 per cent depending on the management strategy. Four possible strategies were investigated for the Ranger mine with the chance of success varying between 20 and 95 per cent. The estimation of the evaporation rate and the area allocated to evaporation was critical in both cases. By applying seasonally based evaporation pan coefficients determined on site, rather than an average monthly value of 0.75, the chance of success was improved by up to 35 per cent for Ranger. Simulation modelling is able to provide information on the likely response of mine water management systems and the level of risk. This information is required to efficiently plan and manage the disposal of water for close-out.

Jan 1, 1994

Hidden under picturesque Bemic Lake, in Canada's eastern Manitoba, lies a highly fractionated pegmatite orebody, hosting a unique assemblage of minerals. Accidentally discovered in 1929, the orebody had a brief history as a tin producer, but it is now mined by Tantalum Mining Corporation of Canada, Ltd. (TANCO), for its cesium, lithium, rubidium and tantalum bearing minerals. The mine also has potential for mbidium-feldspar, amblygonite, gallium rich mica, and quartz production. This paper describes the geology of the orebody, and its mining and processing. Selective, concurrent, mining and milling of the various products necessitates a high degree of planning and control, and these aspects are also discussed. The introduction of Quality Control and SPC are discussed, for such are the keys to excellence.

Jan 1, 1989

By M Scoble, E Rubio

The re-engineering of manufacturing production systems has demonstrated the benefits from using production information for optimising processes. This paper explores the techniques and issues in the acquisition and analysis of mine production data for tactical decision making in production control. The use of information and operations management tools is presented in the context of block caving studies, with particular focus on the relationship between secondary breaking and LHD production performance.

Jan 1, 2000

By R Blin, R Walde, R Belli, D Inaudi

A fiber optic distributed sensing system allows the monitoring of parameters useful to determine the short- and long-term behaviour of the structure in response to the external actions, including, eg seismic activities as well as long-term phenomena such as seepage, tunneling, sinkholes, and other geo-structural movements. Monitoring of large retaining structures with such a system provides direct strain/deformation and temperature measurements on the broad interior area with an arrangement of several sensing cable lines, enabling early detection, localisation and sizing of subsurface damages. Measurements are provided every meter along the entire sensing cable, this is particularly important in such cases where the location of defects and damages cannot be predicted. Fiber optic distributed sensing cables are generally available for retrofit installation inside the dam structure using trenches on the downstream face or laid during construction below the geomembrane liner within the bedding sand layer. Mapping the cable route enables exact correlation between a linear coordinate on the cable length and a position in the dam. Cable installation is envisaged to be carried out during further raising of the embankment; additional cable sections are plugged to the previously installed cables and measured with the existing measurement system, requiring only an update of the mapping. The measurement system is placed remotely from the sensing area since a section of sensing cable can be used to link to the sensing area at the storage facility several kilometers away. The system is available for on-line, 24/7 real-time operational data management. Such fiber optic distributed sensing systems allow storage facilities to be monitored with long, accurate, continuous and precise data for geotechnical diagnostic purposes. This contribution will introduce the principles, benefits, and limitations of this technology.

Jul 1, 2021

The Cannington silver lead zinc deposit is located near Mt Isa in North West Queensland. This world class orebody is owned by BHP World Minerals (BHP) and is estimated to contain 45 million tonnes of ore at an average grade of 11 per cent lead, four per cent zinc and 500 grams/tonne silver. At BHPÆs planned 1.5 Mtpa extraction rate, the mine life will exceed 20 years. Construction of the underground mine, which commenced in August 1993, was carried out by Peabody Resources Ltd (Mining Services Division) (PRL) for BHP Minerals Pty Limited (BHP) under contract packages totalling approximately $100 M using several innovative techniques to deliver safety, quality and time related project goals. Client/Contractor Partnering, resulting in harmonious working relationships, a combined commitment to the achievement of an excellent safety record, and a seamless transition from the construction phase to operation of the mine, has been a feature of the project.

Jan 1, 1998

By A K. B Opitz, M Becker, J L. Broadhurst

"One of the key drivers of geometallurgy is to define the ore characteristics and their variability to build a geometallurgical model. The inclusion of waste rock properties and their variability is just as important, given that the generation of acid rock drainage (ARD) poses one of the most significant environmental challenges facing the mining industry. Formed through the oxidation of sulfide minerals in the presence of oxygen and water, ARD generation is exacerbated through the regeneration of lixiviates by naturally occurring iron- and sulfur-oxidising micro-organisms. In order to manage the potential risk of ARD pollution, timely, accurate, reliable and robust characterisation and prediction of the ARD potential of waste material is critical from an early stage in the mining process.This study demonstrates the use of the biokinetic-accelerated weathering test developed at the University of Cape Town to characterise the ARD potentials of gold waste rock samples under microbial conditions. These tests are performed in conjunction with standard characterisation tests to provide an indication of the potential for ARD generation under both chemical and biological conditions. Results provided information regarding the relative rates of acid neutralisation and acid generation, with the contribution of specific minerals to the observed behaviour considered through use of a detailed mineralogical assessment. Overall, the addition of the biokinetic test to the current geometallurgical characterisation and prediction toolbox will allow for relatively rapid assessment of the bulk kinetics of ARD generation.CITATION:Opitz, A K B, Becker, M, Broadhurst, J L, Bradshaw, D J and Harrison, S T L, 2016. The Biokinetic Test as a Geometallurgical Indicator for Acid Rock Drainage Potentials, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 183–192 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By D Judkins N OÆLoughlin

"Basin Minerals Limited commenced exploring for conventional strandline hosted mineral sands (rutile, ilmenite and zircon) deposits in the Murray Basin in April 1997. This has resulted in the discovery of a major mineral sands field in the Douglas Project area, located southwest of Horsham in the Wimmera Region of Western Victoria. After the successful completion of a pre-feasibility study on these deposits in September 2000, the Douglas Project has advanced to bankable final feasibility study. This study should be completed by mid-2002 to allow a decision to commence production in 2003 at an expected rate of in excess of 500 000 tonnes of combined mineral sands products per annum. The field comprises several mineralised strandlines. The main ones of economic interest are from west to east, the four strandlines, Acapulco, Bondi, Bondi East and Echo. These strandlines at August, 2000 contain total Inferred Resources of 443 million tonnes at 4.7 per cent HM at a one per cent HM cut-off; ie 20.8 million tonnes of heavy mineral concentrate which in turn contains 11.3 million tonnes of ilmenite and leucoxene, 1.3 million tonnes of rutile and 1.6 million tonnes of zircon. The heavy mineral concentrate is coarse-grained with mean diameter grain size of the strandline deposits ranging from 130 to 160 microns in size. Major controls on the formation of mineral sands deposits in the Murray Basin are discussed with reference to the main mineral sand bearing, strand plain domains; the Central Strand Plain, the New South Wales Strand Plain and the West Wimmera Strand Plain. The Douglas Project deposits on the West Wimmera Strand Plain domain are characterised by wide zones of mineralisation with high-grade cores (>10 per cent HM), low stripping ratios, and a valuable economic heavy mineral suite comprising 60 to 80 per cent of heavy mineral concentrate. Constituent mineralogy of the heavy mineral concentrate of the overall deposits is; ilmenite (40 to 58 per cent), leucoxene (five to seven per cent), rutile (four to ten per cent) and zircon (four to 14 per cent). The Douglas Project Area appears to be endowed with significantly enhanced levels of heavy minerals compared to other areas of the Murray Basin due to its unique palaeo-geographical position. Long shore drift to the south of the basin has caused large quantities of heavy mineral to be trapped against the palaeo-cliffs and headlands of a rugged palaeo-coastline which includes in a major embayment, the Grampian Mountains, the Black Range and the Glenelg Complex. To the east, major faulting and uplift has brought the fine-grained WIM offshore deposits close to the surface and has resulted in erosional stripping of mineralised strandline deposits. This mineralisation has been recycled and reconcentrated within the younger strandlines to the west within the adjacent Douglas Project Area. These strandlines are thought to be younger than other mineralised strandlines discovered to-date in the Murray Basin. The Project Area strandlines are described; ie their morphology, geology and patterns of mineral distribution. The mineralogy of each of the strandlines is distinctive and variations are noted along strike and section."

Jan 1, 2001