Search Documents

By A. Angelov, U. Peukerd, S. Gaydardzhieve, A. Stefanov, K. Grossman, V. Stoilov

Flotation concentrate originating from the Asarel-Medet porphyry copper mining and processing complex in Bulgaria has been subjected to regrinding using a Ro-Star mill; the effects of which on the downstream metallurgical behaviour are discussed. Particularly the effect on the liberation degree was studied through an optical microscopy and MLA-SEM automated mineralogy. On the other hand, copper selective flotation of the reground bulk concentrate was realised to evaluate the anticipated metallurgical improvement. Process parameters such as involvement of prior hydrocycloning and variation of collector dosage have been evaluated. Within a two-minute residence time inside the Ro-Star mill, an improved liberation degree of the copper bearing minerals has been observed. As a consequence, enhanced copper recovery and selectivity against pyrite was noted. It has been found that in order to guarantee efficient flotation of the resulting ultrafine particles, a modified flotation regime (i.e. changing collector suite and dosages) should be followed. Keywords: RoStar Mill, liberation, flotation recovery, ultrafine particles

Jan 1, 2020

By M. Pötsch, W. Schubert, A. Goricki

Geological and geotechnical data are essential for the design of tunnels. To determine the rock mass behavior and the support of a planned tunnel excavation a consistent method for rock mass characterization and excavation and support determination has been developed. Probabilistic data processing with analytical methods is used for the quantification of the procedure and allows an evaluation of the applicability and the technical risk of different excavation and support methods. The sensitivity of the procedure on selected input parameters is highlighted in a parametric study. Finally an application of the procedure illustrates the use of the described method of probabilistic excavation and support determination for tunnels. Des données géologiques et géotechniques sont décisives pour la planification d’un tunnel. Pour la détermination du comportement des strates, le choix du soutènement et de la méthode de progression une description compréhensible de la montagne a été développée. À l'aide d'un traitement de données probabiliste, la procédure proposée est transposée quantitative sur une base de méthodes analytiques. De cette manière l'évaluation des méthodes de construction et la détermination du risque technique deviennent possibles. La sensitivité de la procédure de différents paramètres d'entrée est représentée dans une étude de paramètre. Pour finir, l'application de la procédure décrite est montrée à l’aide d'un cas pratique. Geologische und geotechnische Daten sind entscheidend für die Planung von Tunnels. Für die Ermittlung des Gebirgsverhaltens und der Festlegung von Ausbruch und Stützung wurde ein nachvollziehbarer Ablauf der Gebirgsbeschreibung entwickelt. Mit Hilfe von probabilistischer Datenverarbeitung auf Grundlage analytischer Methoden wird die vorgeschlagene Prozedur quantiativ umgesetzt. Dadurch werden die Bewertung von Baumethoden und die Ermittlung des technischen Risikos ermöglicht. Die Sensitivität des Verfahrens von einzelnen Eingangsparametern wird in einer Parameterstudie dargestellt. Abschließend wird anhand eines Beispiels die Anwendung des beschriebenen Verfahrens gezeigt.

Jan 1, 2003

By D. B. Paterson

In view of decreasing head grades, the relatively high gold price, and recent developments in metal evaluation, an exercise was initiated to determine the extent of gold concentration, the mode of occurrence, and the areas of concentration within the run-of-mine milling circuits of Randfontein Estates Gold Mining Company (Witwatersrand) Limited. The total gold content of three of the thirteen run-of-mine mils in the Group was measured as a typical lock-up of approximately 200 kg per mil. The majority of this gold was concentrated either behind the grid-type body liners or within the pockets of the body liners. This paper is an account of the experimental procedure and the results obtained, and highlights possible means of limiting gold lock-up in future.

Jan 1, 1988

By N. F. Dawson

Recovery of a chromite concentrate from UG2 flotation tailings streams, of a grade suitable for further pyrometallurgical treatment for the production of ferrochrome, has certain specific challenges not only by virtue of the decoupled nature of the primary PGM recovery process and secondary gravity based chromite recovery circuits, but also because of intrinsic variations in the nature of the ore and its mineral composition. Variability in the ore, together with upstream process dynamics, creates a challenging environment in which to achieve optimal recovery of a gravity concentrate with accurate grade control. This paper examines certain inter-relational aspects between the ore gangue and chromite mineral types, the influence of the primary PGM extraction circuit and secondary chromite extraction activity as applied specifically to UG2 ore against a background of actual plant experiences and circuit configurations applied in order achieve a suitable quality of chromite concentrate.

Jan 1, 2010

By V. Yahorava

Efficient recovery of precious metals from process solutions is essential for improving process economics. Traditionally, precious metals are relatively effectively recovered from waste streams via precipitation or cementation. However, these approaches have a number of drawbacks, including poor water balance, creation of environmentally unfriendly waste streams, and losses of precious metals. Ion exchange technology is an alternative for the recovery of precious metals from waste or low-grade streams. This technology allows the recovery of the precious metals to extremely low levels (micrograms per litre) with relatively high upgrade ratios from the solution onto the resin without major water balance concerns, while the impact on the environment could be minimized or avoided. Research was conducted on the recovery of platinum group metals and gold from different low-grade and waste streams from one of the precious metals refineries in South Africa by means of ion exchange. Various functionalities and matrices (granular and fibrous) of ion exchange materials were evaluated. The results from these studies indicated that in some cases ion exchange could be very effective for the recovery of precious metals, and that the PGM concentration could be reduced to < 1 mg/L. The upgrading ratios of the various PGMs onto the specific fibres were relatively high for the specific streams evaluated, which might in some cases justify incineration of the loaded material instead of stripping and recycling the adsorbent. The cost of direct incineration for one of the waste streams tested would be less than 1% of the value of the PGMs recovered. However, the adsorbent has to be carefully selected and the process design optimized for each specific stream.

Jan 1, 2014

This volume, which was advertised in the December, 1968, issue of the Journal at a pre-publication price of £4, is edited by W. Ryan of Warren Spring Laboratory and published by the Institute of Mining and Metallurgy, London. It is an up-to-date review of the operations of some 50 or so companies whose activities embrace the extraction and refinement of metals in the United Kingdom. Thirty-four metals are discussed, ranging from aluminium to zirconium and also there are chapters on ferro-alloys, non-ferrous alloys, high purity metals and metalloids, the platinum group metals and the rare earths. The sources of the various metals are given, followed generally by a brief description of the primary recovery process. Thereafter the operations of specific companies that deal in a particular metal are described in some detail. Certain metals such as barium, bismuth, gallium, thallium and zirconium are perforce covered very briefly as their commercial application is limited but in other cases, especially aluminium, copper lead and zinc, fairly detailed descriptions and illustrations are provided. This publication should be of considerable value to students as it presents modern procedures with regard to the refining and uses of the particular metals under review. This information may not be available from text books which in any case tend towards obsolescence. The book should also prove a valuable addition to the bookshelves of practising metallurgists providing, as it does, a schedule of most of the metallurgical companies operating in the United Kingdom. The quality of the paper and binding, the clarity of printing and illustrations and the arrangement of the subject matter are excellent and are subjects for which the editor and publishers are to be commended. R.J.A.

By L. Xingwana

"The purpose of this study is to understand how ore loss and dilution affect the mine call factor, with the aim of subsequently improving the quality of ore mined and fed to the mill. It was necessary to know the relationship between ore mined and delivered for processing in order for the mine to operate efficiently. A review of the literature suggested the mine-to-mill integration approach as a standard intervention to address declining mine call factors. A case study was undertaken at a gold mine in the Free State on the influence of the fragment size distribution on ‘free gold’, the effect of ore loss and dilution on the mill efficiency, and time tracking of ore movement from source to the plant. The study revealed that fragmentation, underground accumulation of ore, and dilution have a significant influence on the mine call factor and mine output. It was difficult to quantify the total ore loss due to the time lag between mining and milling, which is extremely variable, when estimating the mine process inventory. However, it was possible to estimate the total dilution with some degree of precision by analysing the daily blast and head grades. It is therefore recommended that mines accept that some gold loss and dilution will always occur during blasting and transport of broken ore, and this loss must be minimized.IntroductionThe mining of high gold grades is obviously very beneficial for the economic viability of an operation, but optimum recovery of the product is required to maximize profits (Chapman and Bindoff, 2010, p. 13). Although integrating these two requirements is very difficult, due to the various activities occurring between mining and processing, it is indispensable. The main driver of this integration is the impact that different ore types and characteristics have on head grade. According to Isokangas et al. (2012, p. 871), mining and processing operations involve a series of well-defined sequential stages that are complementary in an efficiently operating mine, with the performance of one operation affecting that of another. An attempt to optimize each function separately without considering the whole extraction process will not result in the optimum efficiency of the entire mine. Several researchers have developed a proven methodology for revealing these inefficiencies (Dance et al., 2006, p. 1)."

Jan 1, 2016

By G. Sahasrabudh, G. DeIulii, K. P. Galvin

A novel agglomeration process has been developed, utilising a concentrated water in oil emulsion as a binder. The binder is typically 95 wt% water, the remainder being an organic phase containing kerosene and the emulsifier— sorbitan mono oleate (SMO) in equal mass portions. The binder can selectively agglomerate hydrophobic particles in less than 7 seconds. The agglomeration has proven to be highly effective in recovering any particle of virtually any size, provided the particle is hydrophobic. The approach has previously been applied to coal, magnetite and silica. In the paper, sodium isobutyl xanthate (SIBX) and its much longer chain version, potassium tetradecyl xanthate (C14X), were used separately as collectors to selectively agglomerate chalcopyrite from the ore. Xanthates attach to metal sulphides, thus hydrophobising sulphide mineral particles. Chalcopyrite is a sulphide mineral; however, it hydrolyses quickly in the presence of water. Ethylenediaminetetraacetic acid (EDTA) was used to remove the oxide layer formed at the surface of the mineral particles after wet grinding, leaving behind a freshly generated metal sulphide surface. After the EDTA treatment, the ore particles were quickly conditioned at an optimised pH as well as collector concentration and agglomerated. The agglomeration achieved a copper recovery of 75% within 7 seconds, consistent with the recovery achieved by flotation over much longer time scales. Keywords: Chalcopyrite, agglomeration, froth flotation, interfacial chemistry, X-ray fluorescence, selective hydrophobisation

Jan 1, 2020

By C. H. Wyndham, N. B. Strydom

INTRODUCTION Acclimatization of the labour force to heat is an integral aspect of gold mining in South Africa. A recent survey revealed that about 250,000 Bantu mine workers require to be acclimatized to heat each year. Until 1965 men were acclimatized by means of one of the Chamber of Mines methods (introduced by the Human Sciences Laboratory in 1953). This type of acclimatization was carried out underground where men shovelled rock in hot stopes under careful supervision. However, it has become increasingly difficult in the last few years for mines to provide underground the conditions of work and environmental heat required for adequate acclimatization to heat. In examining an alternative to acclimatization in underground hot stopes, the Human Sciences Laboratory carried out a trial in 1965 of acclimatization in an air-conditioned climatic room on the surface of a mine. The new procedures developed from this trial have been so successful that there are today 26 climatic rooms on different mines. These rooms have been built following a design proposed by Mr Hodgson of the National Mechanical Engineering Research Institute1. Approximately 85 per cent of the total number of men being acclimatized each year are put through the new procedures in these climatic rooms. This paper gives an account of the problems which arose and how they were solved, the inter-relationship between physical conditioning and climatic room acclimatization, the prodecures developed for elimination of labourers with low maximum oxygen intakes, and the advantages of climatic room acclimatization. CLIMATIC ROOMS The majority of the climatic rooms (twenty) have been built on the surface, but a number (six) of mines preferred to establish their acclimatization centres underground in order to decrease the initial costs involved in the construction of such facilities. These underground climatic rooms are usually located near shaft stations in redundant haulages and they can accommodate from 200 to 400 labourers, thus eliminating the need for multiple acclimatization shifts. Figs. 1-4 illustrate various aspects of a surface climatic room. PROBLEMS WHICH AROSE IN INTRODUCING CLIMATIC ROOM ACCLIMATISATION There were four main problems which arose in connection with the introduction of the new method. These were: (i) The type and rate of work to be used. (ii) The air conditions required to obtain optimum acclimatization. (iii) The duration of exposure to heat each day and the total number of days of acclimatization. (iv) The methods of cooling labourers with high body temperatures. Shovelling rock would have been the desirable type of physical work to employ, but the air-conditioned space required to accommodate large numbers of men and the difficulty in standardizing the work rate in shovelling led to the decision to employ instead the work procedure used by the Human Sciences Laboratory in acclimatizing men in the Laboratory. This is the lifting of the body weight against gravity when men step on and off a bench. It has the advantage that large numbers of men can work physically at the required rate in a relatively small space (120 men can be accommodated in an area of 70 ft by 21 ft) and the cost of construction and ventilation of the climatic rooms is thereby reduced. Also the work rate can be standardized by varying the height of the stepping benches in relation to the individuals&apos; body weights. The next problem was the air condition to be used in the climatic rooms. The Laboratory&apos;s research experience in acclimatization led it to choose an air temperature of 89°F (with the air almost saturated with water vapour) and an average velocity of air movement of 100 fpm. This air condition was combined with a work rate of 1,560 ft lb/min (oxygen consumption 1.0 litre/min) on day 1, and the work rate was increased gradually over the period of acclimatization to reach a work rate of 3,120 ft lb/min (oxygen consumption 1.6 litres/min) on day 9.

The imbalance between the coal resources contained in thin seams (1,5 m or less) and the production from them is outlined. It is suggested that an Increase In the exploitation of thin coal seams is necessary, and that drum-type continuous miners can produce a substantial amount of any increase. Continuous miners are employed in a number of mining methods including bord-and-pillar, pillar extraction (stooping), rib-pillar extraction, and shortwalling. These techniques of mining are evaluated with respect to production rates and the cost of extraction for South African conditions included in these evaluations are the types of equipment used to transport coal from the mining machine to the section conveyor belt. Computer simulation techniques are used to generate the required production levels, and interpretations are made of other results from the computer modelling. For thin, coal seams, bord-and-pillar mining utilizing continuous haulage is apparently the most productive and cost-effective of all the methods using the continuous miner. The relative efficiencies of the other techniques of mining and of coal-transportation vehicles are also outlined.

Jan 1, 1984

By N. C. Joughin

A simplified economic model is derived for the financial return from a new gold mining project. The model is used to analyze the effects of changes in the mining rate, capital costs, working costs, value of the reef and the stoping width. The most effective avenues for improving the return from a new project are indicated. It is shown that those technological innovations which would improve the return significantly, and therefore make it possible to open more mines, are the use of smaller mines, means for improving the mining rate to capital costs ratio for smaller mines, planning and control of mines by computer simulation, an improved mine valuation procedure and means for mining at a decreased stope tramming width.

Jan 1, 2014

By Turgay Gurun

"Digital simulation can be used as an analytical tool to optimize the design of crushing plants without need for large-scale experimental programs.General mathematical description of a crushing operation permits the simulation of a crushing plant flowsheet under various operating conditions. The process model encompasses multistage open- and closed-circuit crushing of hard and soft rock. Crushing balances are analyzed in the light of crusher and screen performance and a comparison of different closed-circuit arrangements is made in terms of process and layout criteria.The simulation model allows comparison of process alternatives to be made in terms of equipment selection and capital and operating cost estimation. It thus provides the pertinent practical information to maximize plant efficiency, and to minimize expenditures in such items as equipment, structures, power consumption, and so on."

Jan 1, 2014

By M. M. Oosterveld

"In South West Africa diamonds are mined from ancient beach deposits by the Consolidated Diamond Mines of South West Africa, Limited.To improve the control of mining production, a computer is used for the calculation of statistically more accurate and homogeneous ore blocks. Geological and sampling information has been digitized and stored on magnetic files.The figures derived for each block entail the calculation of the diamond size frequency distribution, the diamond density distribution and the ore reserve by using the density distribution.The diamond size frequency distribution is used for estimating the revenue in an ore block.A description is given of how a linear programming system can be used for production planning."

Jan 1, 2014

By K. Shame, H. H. Thiele

South Africa holds approximately 70% of the world’s total chrome reserves. Chromium is an important raw material for the production of stainless steel and ferrochrome alloys. Over the years, China’s ferrochrome market has been dependent on chrome ore imports from South Africa. In 2018, China imported about 75% of its chrome ore from South Africa. With the low platinum price and the rising demand for stainless steel, a growing demand to evaluate new beneficiation technologies for fine chromite was identified. Gravity separation of fine chromite (<75 μm) is inefficient, due to the limitations of the technology to upgrade fine particle size distributions. Potential for the recovery of chromite, specifically fines (<75μm), lost to UG2 PGM flotation tails, but also from MG and LG6 spiral circuit tailings exist. Flotation of podiform chromite ores from India and Kazhkhstan is successful in generating saleable product grade, following acid or alkaline flotation routes. Application to South African stratiform chromite is being evaluated, with the emphasis on evaluating reagent type, optimising dosages and the effect of pH in optimising flotation performance. Flotation can unlock additional value from chromite tailings material. The effect of ore characteristics such as gangue mineralogy, particle size distribution and headgrade are reported. The performance in terms of product quality and yield are evaluated and compared. The impact of this paper will not only prolong life of mine and increase revenue but will also alleviate environmental burdens associated with tailings dams. Keywords: Chromite, flotation, fine material, performance optimisation

Jan 1, 2020

By S. Chatterjee, F. Suparno, A. Paithankar

Estimating reserves and quantifying resources stand as pivotal and intricate endeavours within the realm of coal mining operations. Intricate geological formations compound the challenges in resource estimation, thereby complicating reserve calculations. The uncertainties tied to geological attributes of coal, encompassing parameters like tonnage and coal quality, wield significant sway over resource and reserve computations within coal mines. This research delves into the domain of geological uncertainties, with a specific focus on calorific value, aiming to numerically characterise resources and reserves within an open-pit coal mine situated in Indonesia. To quantify resources, the coal seam geometry underwent simulation via a multipoint geostatistical technique known as single normal equation simulation. A geologically established coal seam served as the training image for generating 20 equiprobable coal models. To simulate CV, 50 realisations were generated for each simulated coal seam, utilising sequential Gaussian simulation. Deviations of the simulated coal seams ranged from -0.07% to 5.48% in comparison to the training image. The CV simulation yielded an average value of 5,920.29 kcal/kg, accompanied by a standard deviation of 586.54 kcal/kg. However, the average CV spanned from 5,305.26 kcal/kg to 6,526.55 kcal/kg across diverse simulations. For reserve calculation within the context of geological uncertainties, an algorithm rooted in maximum flow graph theory was employed to construct the ultimate pit for the coal mine. Within this final pit, the average stripping ratio was 1.62, coupled with a CV value of 6,019.66 kcal/kg. When juxtaposed with the deterministic model, the findings underscore that the stochastic ultimate pit delineates a more expansive excavation, accompanied by a heightened undiscounted cash flow.

Oct 2, 2025

By T. Szendrei and S. Tose

Historical approaches to the problem of flyrock based on correlation studies and regression analysis, including artificial neural networks and similar techniques, are inherently incapable of addressing two core issues – root causes of flyrock and projection velocity. A further shortcoming of correlation techniques is that they give no information on the influence of rock size and shape on the flight distance. The scaled depth of burial model for crater blasting in the collar zone and bench face does not specifically address the question of flyrock velocity. A third approach, based on flight trajectory calculations, often neglects the very significant effects of air resistance on the trajectory. Some trajectory models incorporate air resistance but use an implausible fragment velocity model that cannot propel sizeable rocks to distances much beyond 150 m. Nonetheless, trajectory calculation incorporating the effects of air drag affords the most promising approach to the prediction of flyrock range. A unique and insightful feature of the proposed realistic flight modelling is that it collapses all suspected causes of flyrock, many of which are not well understood, to just a single parameter – the launch velocity. This indicates that the root causes of flyrock lie in the mechanisms of momentum transfer to broken rock and suggests new avenues of study.

Dec 13, 2022

By S. Purushotham, Y. R. Murthy, M. Narasimha, S. K. Tripathy, M. Kumar

Spiral concentrators are gravity-based separators widely used to beneficiate coal, heavy minerals and beach sand. It consists of a helicoid trough that spirals downward in the helical configuration around an axial column. The particle segregation takes place based on size and density under the influence of gravity as the particles spiral down within the thin water layer. In the last century, most design modifications of this equipment were based on trial and error based lab-scale experimentations and empirical approach. The use of Computational Fluid Dynamics (CFD) has gained interest in the past two decades to understand the underlying flow physics in the spiral concentrators. In this paper, we used CFD to model the fluid flow and investigate the particle segregation inside a conventional LD9 spiral concentrator. Firstly, the Volume of Fluid model was used to resolve the liquid-air interface. The liquid depth and flow field predictions for varying flowrates were validated against the experimental literature data. One-way coupled VOF-LPT model was then used to describe the particle dynamics in the spiral flow field assuming dilute particulate flow. Moderate dense particulate flow (20 vol.%) was then modelled using the Algebraic Slip Mixture (ASM) model. Four particle-phases representing particles of different sizes of dual-density were simulated, and the component particle segregation was analysed. Keywords: Spiral concentrator, two-phase flow, multiphase, discrete phase model, ASM model

Jan 1, 2020

By N. de Koker, Y Jooste, J. Gerber

This paper presents a novel application of the boundary element method for numerical modelling of the seismic activity and hazard that is associated with the shaft pillar extraction at Bambanani mine in South Africa. In the numerical model, the tabular mining excavations are represented by displacement discontinuity elements, and to accommodate crush, shear, and fault slip seismic events, the numerical model is populated with additional displacement discontinuity elements that represent modelled crush- and shear-type failures in the rockmass. Crush-type failures are evaluated by applying the limit equilibrium method and a Hoek-Brown strength criterion, and shear-type failures are evaluated by applying a Coulomb-friction strength criteria to Ortleppshear and geological features. In this paper, the modelling results are presented as time history analyses of modelled potency from 1 January 2010 to 30 June 2022 and normalised exceedance rates for different mining periods using an upper-truncated power law. The normalised exceedance rates of seismic events that have moment magnitude Mw ≥ 1.0 are lowest for the initial mining period (26 events per year) and highest for the final mining period (218 events per year). The relative errors of the modelled potency and normalised exceedance rates are typically less than 10% or 15%, which suggests that the modelling methodology is appropriate for medium- and longer-term forecasting of seismic activity and hazard, as presented in this paper. Shorter-term forecasting is not considered in this paper.

Nov 24, 2025

By S. M. H. Ahmadi, K. Barani, F. Moradpouri, R. Ghaedrahmati

As exploration is time-consuming, costly, and risky, determination of the erosion surface of a metalliferous deposit before geophysical surveying and exploration drilling might be very helpful. Geochemical haloes can be used to determine whether the erosion surface is supra-ore or sub-ore and thus reduce the risk of exploration operations. The aim of this investigation is to determine the erosion surface of the North ROK porphyry deposit (NRPD) in northwestern British Columbia in Canada using linear productivity (LP), which is the content of an element defining the halo multiplied by the width of the halo. A total of 2045 soil samples from the B horizon were analysed using ICP-MS for 36 elements, including Cu, Mo, Pb, Zn, Au, As, Ag, Ni, Co, Fe, and Mn. The data-set was snalysed to obtain the statistical parameters and the elements Cu, Mo, Pb, and Zn were chosen to calculate the linear productivity and the total linear productivity. These four elements were modelled using probability plots to identify and separate subpopulations in terms of anomalous haloes and background, including the threshold values of each subpopulation. The results of the probability plot modelling and thresholds values were then used to map the distribution of each element in a GIS to calculate the linear productivity. The total linear productivity indicated that the erosion surface is supra-ore. Finally, a 3D orebody model of the Cu, Mo, Pb, and Zn distributions was constructed using borehole data and used to validate the results.

Feb 6, 2023

By J. A. Kinnaird, B. J. Youlton, K. L. Youlton

Methods for treating and processing refractory gold ores are well established. However, what is less well understood is how the formation of the gold-bearing deposits affects gold processing and extraction. In order to evaluate the effect of ore genesis on gold extraction a number of South African gold deposits were studied. These included complex Pilgrim’s Rest samples as well as refractory Fairview, Barbrook, and Consolidated Murchison samples. We found the refractory nature of gold ores is controlled by a limited number of well-understood mineralogical factors. Solid solution gold is linked to low temperature and pressure conditions in fine-grained sedimentary lithologies, while reactive pyrrhotite can form from hydrothermal fluids associated with mafic magmatic rocks. These formational controls can be used to identify and avoid complex deposits at a desktop study phase, or address and reduce complications further along the pipeline using early mineralogical studies.

Jun 1, 2021