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This paper explores options worthy of consideration in the management of S02 produced from the gold roasting operations at Kalgoorlie. Some of the options have relevance to other sources of SO2 in the region, eminating from nickel smelting operations. The paper considers the following options: 1. Capture of SO2 within the roaster where sulphur-containing reaction products are mixed with the calcine. 2. Processes in which the sulphur-containing products are bled separately from the stack for further treatment or for dumping as a waste. These include: Seawater-based scrubbing of SO2; Sulphuric acid manufacture as a feedstock for fertiliser production or for leaching of bauxite; its use as Caro's acid: and the production of value-added sulphur-containing reagents eg liquid S02 and sulphonic acid.

Jan 1, 1992

Up to 80 per cent of the copper in a bornite ore can be quickly leached with percolating acidified ferric sulphate solutions. The upper limit for rapid copper extraction is set by the conversion of bornite to slowly dissolving chalcopyrite. The dissolution occurs in two stages: a rapid linear initial stage, followed by a slow, non-linear stage. The initial step is largely controlled by the rate of oxidant supply (Fe2(S04)3); temperature is not an important variable during the initial reaction. The second leaching stage is controlled by chemical and physical factors and is temperature dependent. The initial copper leaching rates are insensitive to both the concentration of the ferrous sulphate reaction product, and the sulphuric acid concentration.

Jan 1, 1973

Between, 1980 and 1984, the demand for non- ferrous metals in the free world grew annually by 1.5 per cent for copper, 0.4 per cent for lead, 1.4 per cent for zinc, and 2.5 per cent for nickel. The growth rate decreased substantially compared to the rate experienced before 1980, and was far lower than the GNP growth during the corresponding period. The main reasons for this are considered to be 1. resource-saving efforts by industrialized countries resulting from the first and the second oil crises, 2. saturated demand for durable consumer goods, and 3. substitution of non-ferrous metals by new materials such as optical fibers.

Jan 1, 1986

By M Griffiths

This paper outlines an approach to high solids slurry pipeline design with data generated from a closed pipe-loop test system. The pressure and flow rate data generated is used to develop a pseudo-shear diagram for the purposes of system design. Following this approach enables the design of a full pipe flow system maximising system life and reliability. The alternative free fall system is explained and the disadvantages highlighted.Environmental and social considerations are discussed; mainly water and land use, and how designing for high solids slurry pipeline systems can be used improve these aspects of a mining project.Also discussed is how the use of high solids slurry pipeline systems can help to mitigate the risk associated with surface tailings storage facility failure, with the Bulyanhulu project used as a positive example.

Aug 8, 2011

A series of numerical experiments were performed in order to define the fracture strength of schistose rock during crushing. Fracture strength was shown to decrease as the fabric aligned with the principal axis of loading. One of three types of characteristic stress-strain behaviour are defined by the orientation of the fabric with respect to the applied stress.

Jan 1, 1993

By Wakamatsu DT, Nakahiro Y

This present paper deals with the fundamental study of the separation of fine cassiterite and quartz by liquid-liquid extraction using iso-octane as an oil phase, dodecylamine acetate (DAA) as a collector, and sodium chloride as a depressant. With regard to the distribution of fine cassiterite and quartz between oil and aqueous phases, the effect of DAA has been investigated in terms of pH, DAA and NaCl concentrations, zeta potential, and adsorption density. From the results of the experimental work, a maximum recovery of cassiterite in the oil phase was obtained with pH around 6.0, DAA concentration of 1.0 x 10-5 mole/litre, and NaCl addition of 0.1 mole/litre. In these conditions of liquid-liquid extraction, most of the fine quartz remained in the aqueous phase. Thus it was found that NaCI was an effective depressant for fine quartz under optimum conditions. A series of separation tests by liquid-liquid extraction was then conducted for the mixed samples (6.0 per cent Sn) of cassiterite and quartz. By a single separating process, the per cent of recovery of cassiterite in the oil phase was about 92 per cent with a grade of 27 per cent Sn. The same results could also be obtained by using kerosene in place of iso-octane as the oil phase.

Jan 1, 1993

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 Crosby N. R

The design of mine openings and the assessment of their reserve are processes ihicl, require the routine manipulation of considerable amounts of data. A number of computer programs have been assembled to operate in a mini computer in order to provide some mechanical assistance for these processes. The system responds to plain language commands. which allows mining engineers to compute the reserves for a number of possible mining outlines, on an interactive basis. Methods of numerical analysis were used in preference to statistical or qeostatistical techniques.

Jan 1, 1977

By E J. Y Koh, G J. McLachlan, E Amini, N Beaton

Preconcentration greatly reduces the ore mass input to the processing plant while upgrading the grade. One of the commonly used methods of preconcentration is optical sorting. These methods rely on optical sensors which classify the material stream into “accept-reject” streams. Currently, it is common to use near infrared (NIR) or colour cameras to classify streams based on reflectance or colour thresholds set by experts. The imaging is done through line-scan sensors where the material is scanned on a belt or a chute. Then, a separation apparatus like a diverter gate or air jet is controlled to separate the streams according to the classification made by the algorithm. Separation efficiency is dependent on the classification algorithm. Existing classification algorithms rely on low-level feature discrimination like observing individual pixel values for reflectance or colour hues. This limits discrimination between minerals with low contrast in colour. Human experts perform mineral segmentation using texture, colour distribution and shape, but it is difficult to translate these visual rules to mathematical thresholds. Deep learning methods like Convolutional Neural Networks (CNNs) provide high-level feature discrimination similar to a human expert. Instead of relying on pre-defined features, the CNNs learn complex features from the dataset. CNNs can construct a hierarchy of features based on pixel clusters to learn texture, shapes, and colour spectrums of the mineral grain surface to provide better separation. In this study, a state-of-the-art deep learning instance segmentation method is used to outline boundaries and classify grains from the background (mineral segmentation). The algorithm is trained on images collected from a flotation feed of a gold deposit, where the gold is mechanically locked inside pyrite. This method can process on-line video inputs at 5 frames per second to provide a live grade. The proposed method is inexpensive as it only uses a camera and a desktop computer.

Nov 10, 2020

By B Mil, D P. Adhikary, M S. Craig, P Rutzou

As shallow coal reserves with easier mining conditions are exhausted, future deep coal mining with difficult mining conditions may face significant economic, technical and environmental challenges. Moreover, due to increased coal production capacity with the new generation longwall systems, predicting adverse mining conditions has become more important than ever before. The potential impact of these difficult conditions is an increase in mining risks and costs. Reliable prediction of rock mass deformation, mine stability and mine water inflow is not only essential for improving mine safety and reduction of coal production costs, but it is also important for the assessment and management of the environmental impact of mining. This paper briefly describes an integrated approach to mine groundwater simulation and prediction. Central to this integrated approach is a three-dimensional computer code called COSFLOW, developed by CSIRO of Australia in collaboration with NEDO and JCOAL of Japan to address the pressing issues of mine water management. COSFLOW incorporates unique features that make it ideal for the simulation of coal mining and examining the interaction between rock fracture, aquifer interference and water flow. This paper also presents an example of an application of the integrated approach and COSFLOW in water inflow prediction at Springvale Mine in New South Wales.

Jan 1, 2006

By T Christopher

The Campamento Au/Ag deposit, discovered by Linear Gold in 2004, is located in Chiapas State, southern Mexico. The deposit is hosted by a sequence of Pleistocene-Pliocene andesitic volcanic rocks that have been intruded by a feldspar-phyric porphyry complex. Measured and indicated resources are 852 000 oz Au and 3.46 million ounces Ag with inferred resources of 374 000 ounces Au and 920 000 oz Ag. Resources were estimated at a 1.0 g/t Au equivalent cut-off. This is an ABSTRACT only. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By L C. Thompson

BioLix is the term for a new class of biologically-derived lixiviants for precious metals (gold and silver) recovery. BioLix can be used as an alternative to cyanide on virgin and spent ores. The BioLix process is based on inducing microbial enzymatic reactions that generate organo-lixiviant chemicals. The bioprocess involves a two-stage culture strategy. First, specialty microorganisms are cultured to generate a high biomass. Then, a food-grade quality amendment is introduced that forces the microorganisms to produce the organo-lixiviant. The second-stage culture is applied to the ore where the microbial/lixiviant system acts on mineral surfaces to extract precious metals. The process operates at ambient temperatures and near neutral pH. This paper will examine the BioLix process through an extensive laboratory development and demonstration project. Laboratory development consisted of identifying and isolating specialty microorganisms and inducing agents for the production of the organo-lixiviant solutions. A demonstration was performed on low-grade and high-grade oxidised ore from the Buffalo Valley mine in Nevada, USA. Results indicate that the BioLix process was comparable to cyanide in terms of gold recovery and operated at near neutral pH and ambient temperatures. Applications for the BioLix process will be discussed including spent-ore re-leaching, cyanide replacement for virgin ore, and in situ mining.

Jan 1, 2004

By Bogie I, White P. J

Active geothermal systems occur widely in Sumatra and in the Taupo Volcanic Zone (TVZ) of New Zealand. There are also many occurrences of epithermal gold mineralisation in Sumatra, some of which are economic. Minor sub-economic occurrences of gold have been reported in the TVZ but none have yet been mined. There are both similarities and differences in the nature of the active geothermal systems and mineral deposits in Sumatra and New Zealand, which can be systematically related to the tectonic setting. The thicker crust and consequent predominance of silicic volcanism in New Zealand leads to hydrothermal. systems which are little eroded and with limited lateral outflows. The systems in Sumatra are of mixed character, with some of the characteristics of those in andesitic island arcs such as Java or the Philippines, eg a higher proportion of systems with identifiable acid magmatic volatiles, a greater potential for deep erosion and lateral outflows than in New Zealand; but modified by the more oblique component of subduction and thickened crust so that some are localised in volcano-tectonic depressions and consequently have high piezometric levels of primary hydrothermal fluid. The unusual occurrence of calcic zeolites in veins associated with gold mineralisation in Sumatra is thought to be indicative of "satellite" boiling zones along de-gassed hydrothermal outflows.

Jan 1, 1995

The Telfer Underground sublevel cave (SLC) Operation is located approximately 850 m below surface. The cave was designed to propagate through an old decline which was initially used to monitor the cave. There was a requirement to install air blast plugs at two locations in the old decline in order to isolate any potential air-blasts from the active workings in the event of the rock mass collapsing into the cavity. There was a further requirement for an air-blast plug in another section of the mine where there was a risk of the cave intersecting an old workshop and providing an air-blast pathway through an abandoned incline. The design criteria for the plugs was that they should withstand the design air blast loading, be free draining, cost effective and easily constructed with the mining expertise available on site. A plug consisting of grouted mullock was considered robust and least challenging to construct. For the purpose of estimation of maximum air pressure on plugs, it is supposed as a worst case that the rock above a cave falls as an airtight piston onto the top of a muck pile, forcing air into it and also mine workings intersected by the cave. Airflow through the muck pile is governed by Ergun's equation for turbulent flow. In a time-stepping integration scheme, transient air pressures and velocities are calculated according to equations of thermodynamics, in the cave and at intervals along intersected drives by means of a finite difference spatial discretisation. The ability of plugs to withstand computed pressures is assessed by finite element elastoplastic analysis. This paper outlines the rationale for potential air blast loading, calculation of transient air pressures, plug design and analysis of plug behaviour. The plug construction method is also discussed.

Nov 25, 2010

By G Haywood

This paper presents the evolution of the planning, scheduling and mining practices at the Yilgarn Star underground. The paper will concentrate on the principals of æjust in timeÆ and the impact of such practices on mine planning and scheduling and subsequent development and production. The principals of æjust in timeÆ were developed to minimise the impact of creep and time dependent failure of the ground in the ore and hangingwall zones. These zones are characterised by altered schistose material with inherent weak rock strengths compounded, at depth, by the maximum principal stress of the virgin stress field approaching the UCS of the rock mass. Yilgarn Star underground has and continues to develop the æjust in timeÆ methodology to ensure the continued viability of the mine. The mine continues to use longhole open stoping mining methods to ensure high levels of productivity with minimal dilution and at an acceptable cost of production.

Jan 1, 2002

The dielectric properties of practically all oxide and sulphide ore minerals are such that they heat rapidly when irradiated with microwaves particularly at the standard frequency of 2450 MHz. The presence of carbon or low rank coal mixed with the minerals still further enhances the heating rate. Amongst the patented technologies being investigated are: (i) the direct reduction of oxides with or without carbon included in the pellets or briquettes; (ii) microwave precursor heating of composites ahead of smelt reduction; (iii) microwave smelting of ore or concentrate mixtures with carbon, sometimes assisted with oxygen. Microwaves appear to stimulate endothermic reduction reactions as readily as they do exothermic oxidation reactions. Being a method of achieving "bulk" heating, composites or columns of ore-char blends rapidly heat throughout rather than from the outside inwards as in conventional heating. The microwaves of themselves do not generate any gas - the only gases to be cleaned are the products of reaction in the composites or blends, plus the products of oxygen smelting. In the case of sulphide composites, depending on the quantity and type of low rank coal or char present, sulphur may be eliminated, and collected, in the elemental form. Furthermore, reactions seem to take place at lower temperatures than in conventional smelting but no doubt at the "points" where actual reactions are taking place the atomic or molecular vibrations are such as to satisfy the laws of thermodynamics. Examples are given of the production of unusual products of smelting sulphide concentrates and also the alloys produced from refractory minerals such as chromite and ilmenite. The techniques have been used to produce products with as wide a range of melting points as relatively pure tin and tungsten-molybdenum alloys. Special equipment is being designed and evaluated for these new fields of pyrometallurgy.

Jan 1, 1989

By Travis G. A

The Mons Cupri Cu-Pb-Zn deposit is situated within a complex Archaean volcanic sequence dominated by rhyolitic fragmental rocks. This sequence is underlain by a 150 m group of rhyolitic ash flow tuffs with minor conglomerate and sandstone, and is overlain by approximately 180 m of dacite and andesite flows. The Mons Cupri sequence itself consists of several elongate or circular rhyolite domes, flanked by rhyolitic fragmental rocks ranging up to 400 m in thickness away from the domes. The lithology of clasts (typically 1 cm to 1.5 m in size) provides strong evidence that the flanking fragmental unit was derived by explosive eruptions associated with the rhyolite domes. An approximately 15 m thick shale horizon, bleached and silicified at its base, overlies both the rhyolite domes and the frag- mental unit. A south-dipping chloritic pipe-like body, with near-surface dimensions of 1,000 by 250 m and narrowing at depth to produce a cone-shaped cross section, lies within the rhyolitic frag- mental rocks about 250 m north of the largest rhyolite'dome in the Mons Cupri vicinity. Its east west elongation parallels that of the rhyolite dome. Ghost fragments indicate that the material in this fissure is a severely chloritized derivative of the rhyolitic frag- mental unit. The chloritic pipe is overlain

Jan 1, 1973

Tertiary laterite is extensively developed in the Darling Range area, but there is doubt that. the high relief areas along the Darling Scarp have been peneplaned. Three distinct laterite types are distinguished which are termed transported, introduced and residual laterites to avoid ambiguity. Transported laterites are recemented (primarily) lateritic materials and introduced laterites are chemical deposits of bog iron type. Residual laterites are formed in situ from the host material which can be either decomposed bedrock or detrital' clay, and the two varieties formed from these sources are termed residual A and residual B laterites. The genetic requirements for residual laterite formation are (1) host material, (2) porosity and permeability, (3) rainfall, (4) temperature, (5) relief and drainage, (6) vege- tation and (7) time. Previous theories on the origin of laterite appear to be inadequate and incompatible with field observations. Field investigations and drilling in the Darling Range area disclosed lenticular section and thickest laterite development on slopes and thin or oc- casionally no laterite development on crests. Lateritisation is considered a surface feature and the end product of the chemical weathering cycle. The relief and rain-water acting on a kaolinitic host material are con- sidered the major contributing factors in the

Jan 1, 1973

By J H. Zietsman

The transition to more sustainable metal production is receiving much attention at present, and the iron and steel industry is at the centre of the conversation. New, more environmentally friendly production technologies, such as direct reduced iron (DRI) smelting furnaces, need to be developed in a short period of time. This necessitates increased use of computational modelling that incorporates more accurate material descriptions. The combination of large-scale multiphysics models of high-temperature processes with CALPHAD material descriptions leads to infeasible computation times. This can be resolved with the previously reported RapidThermo framework, which has been demonstrated to make equilibrium calculations orders of magnitude faster, within controllable limits of accuracy. In this paper, we explain how further material properties, which are important to modelling hightemperature reactors, can be added to the RapidThermo framework. This can improve the accuracy and usefulness of process and multiphysics models in the development of new technologies, which can significantly accelerate development cycles.

Aug 21, 2024

By Sandvik

Fine grinding in an air-swept ball mill working in closed circuit with a forced vortex air classifier has been investigated first in continuous laboratory and then in industrial scale. Results from the laboratory circuit have shown significant influence of mill load (powder filling) on the capacity of the circuit. In laboratory scale the mill load was measured and controlled by a weighing platform placed under the complete mill set-up. The mill load of the industrial air-swept ball mill has till now been controlled by measuring the power consumption of the mill motor. Thus, it was necessary to operate far from the range of optimal mill filling. To improve the circuit performance, alternative ways of mill load measurement were investigated. An important factor was investment cost, as many fine grinding mills operate in relatively small circuits that do not wan-ant large investment. In this case the task was accomplished by using a piezoelectric strain transducer, which detected strain changes in the mill shell. It was installed in the midpoint of the shell, where the highest deformation was obtained. As the transducer was on the top position, it indicated compression, and on the bottom position it measured tension. By taking the difference between the readings, it was possible to calculate total strain variations, directly proportional to the mill load. The signal from the transducer was sent to a control room via a cordless infrared communication system, employing a microprocessor control card, which could further regulate other operating parameters of the circuit according to the software model. The installation required very low investment cost and provided simplicity of application as well as stability and reliability of characteristics under severe industrial condition. The measurement system made it possible to optimise the mill load and thus increase the production from 3.2 to 3.7 dh (15 per cent), and stabilise the circuit operation.

Jan 1, 1995