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By Peverett N. F

The purpose of filtration in a gold reco- very plant is to separate the gold bearing liquid from the solids in the slurry. Some of the gold is inevitably lost due to incomplete separation. An investigation recently completed by the authors has brought to light a method of reducing such losses. In this investigation, the filtration pro- cess was represented by a steady-state mathema- tical model which took account of 14 indepen- dent variables and three parameters. One of the filters in the plant at West Driefontein Gold Mine in South Africa was isolated from the rest and fully instrumented. A computerized data acquisition system was installed close to the filter, and the data obtained from it served to test the model. Using the model together with an optimizing program, the optimum operating point for the filter as a function of throughput was found, and a control strategy developed to minimize the total gold losses in the filter plant.

Jan 1, 1977

By V Rajakumar, S Trang

Titanium has the potential to become the third wave of light metals used in high volume applications, following on from aluminium and magnesium. These light metals have functional attributes that can meet many of the goals needed for societyÆs transition to sustainable development. CSIRO has initiated a Light Metals Flagship to focus additional R&D efforts in support of the light metals industry. The vision of the Light Metal Flagship is for Australia to lead the Light Metals Age by reducing the costs and environmental impacts through innovative technologies for these metals. Life cycle principles will be used to identify novel technology pathways for metal production and product manufacture that are more energy efficient, less capital intensive and incorporating eco-efficient material flow chains.Under the auspices of the Light Metal Flagship, a Life Cycle Assessment (LCA) of titanium metal production was carried out with mineral sands mining of ilmenite as the starting point. Upgrading of the ilmenite to synthetic rutile by the Becher process and titanium metal production by the conventional Kroll process were the processing routes considered. Two alternative processes for titanium metal production, the FFC Cambridge process involving direct electrochemical deoxygenation of titanium dioxide, and a plasma process for producing titanium powder from titanium tetrachloride were also examined using LCA methodology and compared to the Kroll process. The environmental impacts included in the LCA were greenhouse gas emissions (Global Warming Potential, GWP) and acid rain gas emissions (Acidification Potential, AP). The Gross Energy Requirement (GER) of each process was also determined.These results for titanium, along with those from previous LCA studies by CSIRO on aluminium, magnesium, steel and stainless steel production, were used to show that despite the relatively large amounts of primary energy required for the production of these light metals, their special properties (eg corrosion resistance, strength and light weight) mean that these metals offer potential GER and GWP reductions compared to other competing materials in a number of applications, when viewed on a life cycle basis. Two applications considered in the paper are the lightweighting of motor vehicles and chemical plant equipment manufacture.

Jan 1, 2004

Mineral sands are different to almost any other commodity; however, it shares similarities with other commodity types, such as the importance of quality constraints of iron ore and coal or the importance of physical properties of diamonds. The mineral sands industry consists of two principal product streams; titanium dioxide minerals û in the form of rutile, ilmenite and leucoxene, and zircon. The principal valuable heavy minerals (VHM) include ilmenite, leucoxene, rutile and zircon. Variations of other titanium minerals occur between the end members of ilmenite and rutile, including pseudo rutile and anatase. Most mineral sands deposits are found in unconsolidated fossil shorelines several hundreds of metres to tens of kilometres and occasionally hundreds of kilometres inland from the present coastline. Mineral sands orebodies essentially fall into two categories based on the mode of deposition: alluvial or aeolian. Alluvial deposits are further split into marine beach placers (or strandlines) and lacustrine heavy mineral (HM) accumulations. Exploration for mineral sands involves the positive identification of key criteria leading to the focus of exploratory surface sampling, augering and drilling. Assaying is primarily focused around determining the percentage of HM contained within a given sample. Other results of interest include clay fines, sand and oversize. Metallurgical/mineralogical assessment is often undertaken via laboratory scale bench tests that replicate the wet concentration and dry mill processing routes. The most critical component in resource assessment for mineral sands is about quantifying HM grade, then mineralogical assemblage and then quality of those mineral species. This will determine whether a mineral sand final product is marketable or not. Mining of mineral sands is conducted either wet or dry. Wet methods are generally preferred for large tonnage, unconsolidated and low clay orebodies. Where ground conditions are hard and orebodies are small, high grade and discontinuous, dry mining techniques are generally employed. Concentration of mineral sands from the primary ore is carried out in two sections; wet, utilising sizing and gravity differentiation between HM, VHM, clay and quartz, and dry, exploiting the magnetic, electrostatic and to a lesser extent specific gravity (SG) properties of the minerals of interest. Mineral sands exploration, mining and processing faces the same operating challenges as the rest of the resource sector. Added to this are the issues that are unique to mineral sands and to which the industry devotes considerable resources to developing solutions.

Jan 1, 2009

The estimate of an ore reserve is a vital statement made about a mineral occurrence by an evaluator. It is important that such a statement communicate reality to all groups involved in a mining project, be they technical, financial, company directors, Stock Exchanges or the public. Ore reserve statements should state both resources and recoverable ore reserves. Resources may be important in very long term considerations, (because mining, metallurgical technology and economics change with time) but recoverable reserves are todays reality. The important factors contributing to recoverable reserves (in a general sense) are geology, mining method (and its impact on dilution and ore loss), metallurgical recovery, costs and commodity prices. These all need to be reflected in the ore reserve statement. In this paper recoverable ore reserve concepts across a wide range of orebodies are considered and discussed with respect to geology, mining method and ore reserve calculation procedures.

Jan 1, 1987

By D Mukendi-Ngalula, G Hearn

Beach sand minerals from the volcanic rock structures of the Drakensberg, Kwazulu-Natal, (South Africa) have been processed. Screening, flotation, spiral concentration and magnetic separation methods were used either separately or successively in an attempt to concentrate monazite minerals. Products thereof and those from a long time (up to 72 hours) microwaves treatment of the finally produced ilmenite-bearing minerals have been studied using the M÷ssbauer effect spectroscopy. The 57Fe M÷ssbauer effect spectroscopy has demonstrated its versatility and power in monitoring the ilmenite internal reduction mechanism and products and, in characterising the iron-bearing phases contained in different products from the beach sand minerals processing. Microwaves heating of ilmenite for up to 38 hours reduced internally the Fe3+ from the ilmeniteÆs structure. A more prolonged microwaves heating (up to 72 hours) re-oxidised the mineral. 61 per cent natural ilmenite recovery was obtained in the floating products of a spiral concentrated -212+106 ¦m screened and beach sand minerals fraction. A preferential concentration of hematite with a 62 per cent recovery was found in the sinking products while the combination of screening-spiral separation-magnetic separation and flotation yielded a floating product with the highest ilmenite and the highest hematite abundanceÆs (71 per cent, 19 per cent respectively). A natural ilmenite containing 87 per cent ilmenite and 13 per cent hematite could be produced and extracted from the sinking products of the flotation process collected subsequently to the spiral concentration and the initial screening.

Jan 1, 2000

By D K. Miller, L W. Armstrong

In April 2006, Orica Quarry Services undertook an investigation to determine the likely vibration and frequency response of three water storage tanks to quarry blasting, immediately adjacent to the tanks. Of the three tanks that were studied, two are relatively tall with a æwineglassÆ shape; one is constructed of steel (4 ML storage capacity) while the other is constructed of concrete (2 ML storage capacity). The third is a ground-embedded concrete tank that is relatively squat and broad in shape (38 ML storage capacity). A vibration limit of 25 mm/s and an acceleration limit of 0.16 g were imposed on the tanks. However, this report shows that this acceleration limit, whilst having relevance to low frequency earthquake motions, is quite inappropriate for the high frequency blast vibrations that are typical in a quarry blasting environment. The investigation involved firing 11 single blastholes of known charge weights and distances from the tanks, and measuring the tank vibration response using blast monitors placed on and around each tank. Analysis of the data collected from the cement tanks showed resonant responses over a broad range of frequencies, with dominant and lesser responses in vertical and lateral motion recorded at 9.8 Hz, 12 Hz, 16.8 Hz, 17 Hz, 31.3 Hz and 38.1 Hz. Unfortunately, most of the data collected on the steel tank was corrupted by noise due to electrical sources and/or mechanical sources such as the water agitator inside the tank. Advanced Monte Carlo vibration models were then constructed using the single blasthole information. Knowing the resonant frequencies enabled the modelling of electronic delay sequences for the reduction of resonant vibrations. Ultimately programmable and accurate electronic delay detonators were deemed essential to allow blasting in relatively close proximity to the tanks while avoiding resonant frequencies. Three blast designs were modelled, ranging in maximum instantaneous charge (MIC) from 4 kg to 22 kg, and 60 holes to 160 holes. The modelling showed that two of the designs (using small charge weights) could be used no closer than 71 m from the storage tanks. This is based on a 90 per cent confidence level of achieving vibration levels within the 0.16 g acceleration limit, even though the velocity levels predicted to be generated at this distance were significantly less than the 25 mm/s limit. The third design incorporated larger charge weights and could be used for blasting at distances no closer than 220 m from the tanks. The present work, conducted in an operating quarry, demonstrates the usefulness of Monte Carlo waveform superposition techniques for the control and reduction of ground vibration (either velocity or acceleration) under restrictive environmental constraints. However, a discussion is also presented to demonstrate that it is somewhat restrictive to impose an acceleration limit based on the motion produced by low frequency earthquakes rather than the motion produced by high frequency blast vibrations.

Jan 1, 2007

The Electrolytic Refining and Smelting Company of Australia Limited (ER&S) operates a copper smelting and refining plant and is situated close to the heart of the highly industrialised area of Port Kembla. In March, 1982 the Company entered into an undertaking with the State Pollution Control Commission (SPCC) to monitor ambient levels of sulphur dioxide (S02) gases present in the atmosphere in the surrounding urban area. Despite the use of a 200 metre high stack for dispersal of the smelter waste gas stream at ER&S, two local suburbs, Warrawong and Primbee were experiencing on occasions high ambient concentrations of S02 resulting in discomfort to local residents. In late March 1982, ER&S installed a highly advanced S02 monitoring system to continuously monitor the levels at Warrawong. The system was extended to include S02 monitoring at Primbee in November 1982, and further extended in June 1983, to include an input of meteorological data. Initially the system was designed to monitor and react to high concentrations of S02 at either of the two monitoring stations. Currently however, refinement is taking place to allow a predictive nature to be built into the system such that it not only reacts to an adverse situation but can predict weather patterns likely to cause high concentrations and thus avoid these events. The entire system is still undergoing a growth and development period, however the results obtained to date are pleasing to both the Company and the SPCC.

Jan 1, 1984

By Seymour C. A

Peak Downs Mine, a five million tonnes a year coking coal operation, strip mines a, series of Permian coal seams. Seam thickness ranges from 0.5m to 5.0m, and seams consist of multiple coal plies with intermediate shale and mudstone partings. Four 47m3 draglines strip overburden to a cover depth of up to 60m. Coal loading is by 12m3 shovels and 14m3 to 18m3 front-end loaders. Parting removal takes place where the layer of shale and mudstone between seams exceeds 0.3m in thickness. Parting has been removed by a wide variety of earthmoving equipment in order to evaluate the problem and to select the optimum method from an operational and economic standpoint. Multi-seam stripping of the thicker seams is accomplished by working draglines from spoil- pile benches. Coal seams thinner than lm are recovered by dragline and stacked in the pit for later loading.

Jan 1, 1974

The MIMDAS geophysical data acquisition system developed and tested by the former MIM Exploration Pty Ltd (MIMEX) is now commercially available worldwide through Geophysical Resources and Services Pty Ltd (GRS). The system implements several new features in its design that give it significant advantages over conventional systems and allows for new approaches to electrical exploration. In particular, the achievable signal to noise levels permit exploration to depths once thought beyond the range of electrical exploration. The flexible multi-channel configuration lends itself to truly 3D surveys in the style of modern seismic techniques. Each of these aspects is illustrated with a number of case histories from both Australia and South America.

Jan 1, 2004

The high maintenance of load-haul-dumps (LHDs) and front end loaders in hard rock affects mine planning with reduced availability and productivity. Intensive study of maintenance costs and availability of machines related to machine age and life provide the basis for planning from available operational alternatives.Derived programmes and experiences have led to the beginnings of unmanned operation and automation through reduction of manual diesel units and spreading electrification and use of radio. But electrification has obvious layout limitations. This approach to the present has resulted in better utilisation, costs and safety and the computerised monitoring and control provides continuous awareness of machine and work conditions with the promise of future improvements.

Jan 1, 1991

By M Norbert, P Mok

The mainline running tunnels for Legacy Way comprise of two-lane tunnel boring machines (TBM) driven tunnels. The length of the TBM tunnel section is approximately 4.2 km. The TBMs employed are double shield TBMs. Typical support to the segment ring while advancing a double shield TBM comprises of filling the excavated annulus between the ground and the segmental lining by injecting pea gravel, followed with primary grouting to fill between the pea gravel some distance behind the excavated face. The methodology adopted for the Legacy Way project, however, did not follow this typical approach, instead, two component grouting of the annulus was carried out.Where the annulus is typically filled with pea gravel, support is provided to the segment ring very close to the end of the tail shield, whereas in the case of two component grout this is not practical as the risk of grouting in the tail shield is high. The staging of the two component grout injection, the grout early age strength properties become key issues in ensuring that the segment ring leaving the TBM tail shield is stable and can support the necessary external loads.Two-component grout is a grout with two components, cementitious grout (component A) and accelerator (component B), commonly adopted for earth pressure balance (EPB) TBM. The grout reaches its thixotropic state in a matter of seconds providing initial support for the segment rings. Manual injection of two component grout to fill the bore annulus was carried out in stages leaving a portion of the segment rings unsupported. Ring stability during TBM advance was provided by a combination of ram thrust and the segment circumferential joint shear connectors.This paper outlines the design considerations such as rock load derivation by probabilistic analysis carried out utilising the software JBlock, 3D finite element analyses using the software Strand7 for ring stability and the testing and back analysis of the shear connector load bearing behaviour. In particular, the actual available capacity of the shear connectors against their published capacity by supplier was discussed.CITATION:Mok, P and Norbert, M, 2014. Tunnel boring machine excavation stability – double shield tunnel boring machine advance with partially grouted annulus, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 51–62 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

The capacity of chlorine based solutions to rapidly and effectively dissolve coarse gold in oxide ores is well established. The inherent advantages of chlorine are high dissolution rates (10 - 100 times those of cyanide), and low cost. The high dissolution rates mean that coarse or poorly liberated gold may be dissolved over relatively short periods and hence ore particle size may cease to be such a critical factor. The cost of size reduction to allow adequate gold liberation in order to achieve an adequate gold recovery is less of a consideration when using chlorine than in traditional plant or heap leaching cyanide-based treatment systems.Because chlorine based solutions capable of dissolving gold evolve an unpleasant vapour phase with the potential for significant chlorine losses into the atmosphere, traditional heap leaching with active solutions being sprayed onto prepared heaps is not possible. The ore must be covered and the solution may be introduced beneath that cover through prepared injection `wells' and recovered through production 'wells'. The pit is flooded with active solution beneath an overburden or cover with the solution migrating from the injection 'wells' to the production 'wells' over a period of around five - ten days.

Jan 1, 1992

By He F, Zhu D

How to monitor and control the support and surrounding strata system on a longwall face effectively is one of the major research problems in ground control. Based on observations on movements of the support and surrounding strata of face No. 2703 of Dongpang colliery, the relationship between the downtime related to support and surrounding strata and other influential factors is analysed systematically in this paper. Monitoring indices and control measures are then determined by taking corresponding downtime as an objective function. When the monitoring method, developed from the above findings, was used on face No. 2703, the downtime due to support and surrounding strata was remarkably reduced, and the face advanced Normally.

Jan 1, 1992

By Johnson G. D

The typical management systems used to address the issue of operating risk centre around technologies that identify, analyse and evaluate the risk factors. These logical systems such as HAZOPs, Fault Tree Analyses, etc rely heavily on technical considerations and process flow analysis. However, several research projects, across industries and countries have clearly shown that up to 80 per cent `operating risk' is determined by the actions of workers, supervisors and managers. Yet, most of the focus of risk management is on technical and procedural issues. This suggests that a significant imbalance exists in our management systems and that industries are unlikely to show significant improvement on current levels of safety performance. Effective risk management must include the intangible element of the organisation psychology towards risk. A practical and theoretically sound approach had been researched and developed in and for the mining industry. This paper describes the approach and methodologies applied at the Cosmo Howley Gold Mine in the Northern Territory, where an inclusive approach to managing financial and operating risk was followed. The Cosmo Howley Mine showed a dramatic reduction in lost time injuries and improvements in financial indices - providing conclusive evidence of the link between management effectiveness, safety and productivity. This `triangle' has often been the subject of speculation and theory. It is demonstrated in this paper how the management team of Cosmo Howley focused their practices and systems on the improvement of organisational dynamics, ensured tangible and clear focus on parameters of costs and safety and how the improvement process was managed. It is concluded that the improvement process did not require a `major re-engineering' of the organisation. The organisation culture changes that occurred were incremental, planned and effective. It entailed the implementation of sound risk management methodologies, and ensured that a significant emphasis was placed on an aspect that is defined as `organisational dynamics'.

Jan 1, 1994

Gold mine production in South America was 247.3 tonnes in 1995 up from 156.4 tonnes ten years earlier in 1986. This represents a 58 per cent increase and amounted to 11 per cent of total world gold mine production. The major countries involved in order of production, were: Brazil (67.4 tonnes), Peru (51.5 tonnes),. Chile (48.5 tonnes), Colombia (24.1 tonnes), Venezuela (17.1 tonnes), Bolivia (16.0 tonnes), Ecuador (9.6 tonnes), Guyana (8.8 tonnes), French Guiana (3.3 tonnes) and Argentina (one tonne). The most dramatic increase was reported in Peru where production increased from 10.9 tonnes in 1986 to 51.5 tonnes in 1995, heavily influenced by the production from Minera Yanacocha which began operations in 1993 and produced 17.2 tonnes in 1995.With the reformation of the mining laws and the introduction of investment incentives in all the South American countries in recent years, dozens of major and junior mining companies began flocking into the area in the early-1990s to conduct exploration. A recent study undertaken in Brazil shows that an average of $240 million per year will be expended in this country during the period 1993 - 2010. Twenty-five per cent of this expenditure is expected to be made on gold exploration. Similar figures for Peru are $220 million total per year with 50 per cent for gold; $170 million per year in Argentina with 25 per cent for gold and $120 million ner year in Chile also with 25 Der cent for gold.

Jan 1, 1997

By B Hou

The Eucla Basin in southern Australia is emerging as an important global source of zircon from heavy mineral sands. Understanding the geological evolution of the basin and movement of heavy minerals down peripheral paleovalleys and along paleocoastlines is essential to effectively refine exploration strategies for heavy minerals in the basin. Integration of geoscientific datasets in a Geographic Information System (GIS) environment has proved to be effective in reconstructing depositional environments along the Cenozoic basin margin and in tracing the buried paleorivers that once drained broad areas of the Archean-Paleoproterozoic Yilgarn and Gawler cratons, the dominantly Mesoproterozoic Musgrave and Albany-Fraser Provinces, and the Neoproterozoic-Early Paleozoic Officer Basin. Sea level highstands during the late Middle Eocene (39 - 36 Ma) are associated with formation of the Ooldea coastal barrier complex and the zircon-rich heavy mineral deposits at Jacinth, Ambrosia and Tripitaka. More extensive transgression during the Late Eocene (36 - 34 Ma) built the complex Barton shorelines that host the Cyclone deposit and the extensive ilmenite-dominated occurrences of the Barton West prospect. Multi-generation reworking of the source sands is indicated by the high proportion of deposits that are zircon-rich relative to titanium minerals. The age distribution of zircon grains in heavy mineral concentrates from the Ooldea and Barton barrier systems points to the Musgrave Province as the predominant ultimate zircon source. Paleorivers discharging along the northern basin margin presumably carried a sediment load that was then redistributed by easterly longshore drift to build the extensive coastal sand deposits along the northern and eastern basin margin. The south-eastern extension of these deposits was reworked during Miocene-Pliocene (15 - 2 Ma) times into a series of regressive strandlines that show angular discordance with the Eocene coastlines. This discordance is consistent with evidence for long-wavelength tilting of the Australian continent from Middle Miocene times, as the continent drifted toward a dynamic topographic low induced by convective mantle processes associated with the South East Asia subduction systems. The Dromedary and Gulliver’s deposits probably formed at this time. Ongoing research is focused on the geological features of the basin that influence heavy mineral transport, concentration and preservation, and the processes leading to deposits with high zircon content.

Oct 5, 2011

By McDonough RJ

Mechanical agitation is the preferred system for Carbon-in-Pulp processes. Agitator design requires an understanding of the relationships between energy, shear and flow and the nature of shear rates and shear stress distribution in an agitated tank. Laser techniques are useful when studying these phenomena. The alternatives are open impeller agitation or draft tube circulation. Each has advantages and disadvantages but both require careful choice of impeller and system geometry. Overall the draft tube circulator is the more attractive in many cases. Open impeller agitators are designed in accordance with established procedures for mineral slurries taking due account of shear effects in tanks containing carbon. Preferred tank proportions are 1:1. Circulator design methods were developed in the alumina industry before being applied to CIP processes. Optimum draft tube diameter is critical to power requirements. The overall system must be designed as an axial flow pump operating in a closed circuit. Such a system exhibits quite characteristic behaviour which requires an impeller of varying pitch angle and aerofoil section for best stability and efficiency.' Tank height may be 2 or more times diameter. Resuspension of settled solids can be assisted by a series of slots in the draft tube. These slots have the secondary effect of stabilizing hydraulic behaviour and reducing installed power requirements.

Jan 1, 1982

By J Zhang, L Klemettinen, A Jokilaakso, J Biswas, J Partinen, H O’Brien, A Klemettinen

Waste lithium-ion batteries (LIBs) are important secondary sources of many valuable materials, including Critical Raw Materials (CRMs) defined by the European Union (EU): lithium, cobalt, manganese, and graphite. Additionally, LIBs typically contain nickel and copper, which are classified as Strategic Raw Materials for EU since 2023. In recent years, great effort has been made to develop efficient recycling processes for waste LIBs. Pyrometallurgical processes have been essential in industrial production of metals for many decades. These technologies are relatively mature, with high adaptability for different raw materials. Pyrometallurgical treatment in LIB recycling typically involves the use of smelting processes, in which waste batteries are heated above their melting points and metals are separated through a reduction reaction in the liquid phase. Through this recycling route, cobalt, copper, and nickel can be efficiently recovered in the form of a metal alloy, whereas lithium and manganese are lost in the slag phase. The goal of this work was to increase the recoveries of valuable battery metals through a combination of hydro- and pyrometallurgical unit operations. First, industrial Li-ion battery scrap underwent a selective sulfation roasting stage, where the aim was to transform LiCoO2 and Mn-oxides into Li, Co and Mn sulfates. After roasting, the battery scrap was leached in distilled water with a solid to liquid ratio of 100 g/L at 60°C and recovered 95 per cent of Li, 61 per cent of Mn and 35 per cent of Co. After leaching, the solid leach residue was mixed with industrial Ni-slag and biochar, followed by reduction at 1350°C in argon atmosphere. The high-temperature smelting experiments were conducted as a function of time (5–60 mins) to investigate the reduction behaviour of battery metals. The results show that Co and Ni from the slag and leach residue can be efficiently recovered in the slag cleaning stage.

Jun 19, 2024

By J E. Everett, K Jupp, T J. Howard

Simulation modelling is a practice commonly used in the mining industry to evaluate alternative process designs. Such modelling is typically undertaken as an optimisation study to increase the efficiencies, productivity and product quality of operating mines. In this situation, real short-term grade variability data of extracted ore are available from production records as input data into the simulation.There is also a need for simulation modelling to be performed before mines are approved for construction to clarify the grade variability characteristics that can be expected from the operating mine and assist in the optimisation of the process design. In this situation no historical short-term grade variability data are available. To achieve meaningful and reliable results from a simulation it is necessary to have input data for the ore to be extracted from the pits, representative of the short-term grade variability that would be expected for the operating mine.This paper describes an example of a path taken to generate realistic input data.A method described as composite cut-off criterion was used to distinguish ore from waste, which gave substantially greater recovered tonnage at target grade compared to the conventional quadrant cut-off grade criteria.The only data available for the project was resource model data in the form of kriged block models, which are known to underestimate true ore grade variability. To achieve realistic results from the simulation it was essential to increase this variability while maintaining the accurate average grades. Areas of certain deposits that were modelled using both kriging and conditional simulation estimation techniques were quantitatively compared to establish the comparative variance and the kriged data was modified to match the conditionally simulated variance.A realistic mining model was generated via a process of discretisation and regularisation of the resource blocks. Quantitative assessment demonstrated that this method adequately compensated for ore dilution and that adjustment for ore loss was not required due to an ore skin surrounding the edge blocks.The conditioned data was then used to generate a schedule of daily mine extraction, considering grade variability, tonnage, equipment constraints and extensive blended-in-blended-out precrusher stockpiles to feed into the process design simulations.For the precrusher stockpiles a number of alternative allocation criteria were examined for ore being extracted from the pits to identify the best method in achieving reduced variability through the daily scheduling system. The study concluded that a single analyte separation criterion produced acceptable variability with minimal complexity.The blending efficiency of manually stacked and reclaimed precrusher stockpiles was studied to determine a realistic blending efficiency within the pile. A recommended method of building and reclaiming was determined to give maximum blending efficiency.Finally, the data was used as input into process design simulation models; simulation from crusher feed to shiploading demonstrating that control of shipment grade variability was achievable and that the conditioning of the data delivered realistic results.CITATION:Jupp, K, Howard, T J and Everett, J E, 2013. Generating synthetic data for simulation modelling in iron ore, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 231-238 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By R C. A Minnitt

The two methods for calibrating the parameters K and (alpha) for use in Gy’s equation for the fundamental sampling error (FSE), the duplicate sampling analysis (DSA) and the segregation fractionalised analysis (SFA) are described in detail. A case study using identical broken reef material from a Witwatersrand-type orebody is calibrated using the DSA and SFA methods and the results are compared. Classically, the form of Gy’s equation for the FSE raises the nominal size of fragments given by dN to a power of 3. Gy’s formula is a theoretical formula applicable in the case when fragments are randomly collected one by one, which is obviously never the case. This is because the fragment shape factor (f) and the granulometric factor (g) were introduced to take care of this anomaly. More recent formulae, such as those suggested by François-Bongarçon and Lyman, are empirically based formula. A later modification of Gy’s formula raises dN to the power ? (alpha), the latter term being calibrated with the coefficient K in the DSA and SFA methods. The preferred value of ? (alpha) for low-grade gold ores used by sampling practitioners in the mining industry is 1.5. A review of calibration experiments for low-grade gold ores using the DSA and SFA methods has produced values of K that vary between 70 and 170 and values of alpha in the range 0.97 to 1.30. The average value for alpha is found to be 1, rather than 3 as originally proposed in the classic form of Gy’s equation or the industry preference for 1.5. It is suggested that for low-grade gold bearing ores, the equation for the FSE should raise dN to a power of 1. Such an equation for the variance of the combined FSE plus the grouping and segregation error, now referred to as the short-term component of the quality fluctuation error (QFE1), greatly simplifies the characterisation of gold ores, which now only requires the calibration of K for a given mass and established fragment size. The implications for the heterogeneity test from the generalised equation are that provided the fragments have been screened to within a narrow size range, any particular size will return a value for K that is acceptable for use in the sampling nomogram.CITATION:Minnitt, R C A, 2017. A generalised form of Gy’s equation for gold ores – empirical evidence, in Proceedings Eighth World Conference on Sampling and Blending , pp 331–350 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017