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By P. J. F. Fourie

The purpose and frequency of comprehensive performance testing and the types of tests to be included are discussed. The results obtained from a series of such tests are reviewed.

Jan 1, 1980

By A. Mainza

It is common practice in the mineral processing industry to use hydrocyclones for particle classification. However, classification in the UG2 platinum circuits using the hydrocyclone poses major challenges due to the differences in density between silica and chromite, the two major components of this ore. Silica,-the PGM carrying component, has an average density of 2.7 and the barren chromite component has an average density of 4.5. When conventional and flat bottom cyclone are used there is a misplacement of particles due to differences in density leading to inefficiencies in the classification by size. As a result of the density effect, coarse silica reports to the overflow, resulting in loss of recovery, and fine chromite reports to the underflow, resulting in loss of milling capacity and unnecessary production of fine chromite. A classifier based on a different concept was required in the classification of UG2platinum ore. The three-product cyclone, which is a hydrocyclone with two concentric vortex finders to produce three distinct products, has been tested in the UG2 ore application and indications are that misplacement of particles due to differences in the component densities can be minimized through the use of this unit. Industrial and pilot plant trials were conducted and indications are that the three-product cyclone can be installed to selectively produce a middlings stream that can be screened using Pansep screens to provide a screen oversize, which is predominantly coarse silica that can be preferentially reground to recover the PGM values contained in the coarse silica.

Jan 1, 2004

By R. L. Castro

Currently, in several caving operations, the spacing between the drawpoints is determined by consulting Laubscher's design guide (Laubscher 1994, 2000), a methodology based on the gravity flow characteristics of the caved rock. Laubscher's methodology is based upon the height of interaction between adjacent flow zones, but does not allow calculation of primary recovery for a given layout. In this paper the authors present a technical and economic methodology based on the flow that occurs near the drawpoint and the associated development costs to estimate the optimal spacing. The flow model at the drawpoint was validated at the El Teniente mine, which extracts coarse caved rock. To validate the flow model, small-scale simulations using drawpoint clusters were conducted and results compared to extracted grades, marker recovery, and drill holes to determine ore remnants that are part of the production control programme at the mine. The results indicate that primary recovery depends on the height of interaction, which varies with the friction angle of the caved rock and the spacing between adjacent drawpoints. Primary recovery estimations indicate values from 85 per cent to 97 per cent depending on the drawpoint spacing used. Extrapolations were then conducted to estimate the primary recovery for different drawpoint configurations planned to be used in the New Mine Level of the mine. The results indicate that the optimal drawpoint spacing is 32 m x 20 m with a through length of 18 m. The methodology developed may be used to estimate optimal drawpoint spacing for block caving mines under different metal prices and mine cost conditions.

Jan 1, 2012

By A. J. Jager, N. C. Joughin

The effects of extensive solid-waste packing as a support medium are described. It is shown that the waste packing resulted in excellent hangingwall conditions with only minor deleterious effects.

Jan 1, 1979

By George Kayesa

[ ] A multiple-bench slope failure occurred at Letlhakane mine on 14th July 2005. No injuries or damage to equipment was suffered and mining production was not affected. Slope failure was preceded by the precursors of tension crack formation, crack widening and extension as well as slope monitoring targets movement. It was predicted that slope failure was imminent using the Geomos slope monitoring system, though the timing was not certain. The area to be affected by the slope failure was also known before hand as was the slope failure mode. As a result, measures were taken to avoid exposing personnel and mining equipment to the slope failure risk. This paper discusses how the prediction of the slope failure of 14th July 2005 using the Geomos slope monitoring system resulted into avoiding potentially fatal injury, damage to mining equipment and loss of mining production.

Jan 1, 2006

By C. van Loggerenbergt, P. E. Ventert

A strong incentive exists for the coal-preparation engineer to improve plant efficiency by modifying circuits and upgrading process equipment, since these result in lower production costs and more valuable plant products. At the Grootegeluk Coal Mine, it was found that the overall plant efficiency could be improved by modifications to the dense-medium circuits, the installation of additional process equipment for the recovery of fine coal, and improvement of the fine-material processing circuit. Apart from these modifications, there is still potential to increase the plant efficiency, particularly in the utilization of plant waste, the recovery of slimes, and even the improvement of cycloning performance as a result of new cyclone design. This paper points to the potential wealth locked up in existing coal-preparation plants, and shows how the coal-preparation engineer, with new technology at his disposal, can unlock this wealth.

Jan 1, 1992

By R. C. J. Goode, W. S. Rapson, W. R. Lawrie, L. W. P. Van Der Bosch

W. R. Lawrie (Member): As all the Institute members present are aware, the Ninth Commonwealth Mining and Metallurgical Congress was held in Great Britain from 3rd to 24th May, 1969. The Congress opened in London and the first week was devoted to technical sessions. Several receptions and other forms of entertainment were held in the evenings. The Congress was attended by some 1 200 delegates, many of whom were accompanied by their wives. As can be imagined a large organisation was needed to cater for all the whims of these delegates, to arrange accommodation and to provide transport for the technical trips, for the receptions and for the sight-seeing tours. Papers presented at the technical sessions proved of great interest. It was stimulating to hear of the developments taking place in the various branches of mining and metallurgy. The discussions which developed between men from so many different countries were thought provoking, led to new friendships and most of us made valuable contacts for the future. There were 141 papers presented in the one week. They were given in four separate halls with two, three and sometimes four papers coming up for discussion in each of the three sessions per day in each hall. Among the more interesting subjects were those concerning off-shore drilling and the facilities for production of petroleum and natural gas. Beach mining at Consolidated Diamond Mines drew a large audience. Automation, mechanization and other technical developments were well described and we were brought up to date with modern techniques of mineral prospecting. There was general discussion on the future of the mineral industries together with comments on the consumption and price trends of these metals and minerals. The future of uranium, of vital interest to us in South Africa, came in for much debate. During the first week, besides attending the technical sessions and seeing some of the sights of London, we were royally entertained. There was a banquet, attended by some I 400 people, where we were welcomed by Princess Alexandra, a reception by H.M. Government in the Banqueting House, and we were entertained at the House of Lords on a terrace overlooking the bustling and rather muddy river Thames. Then there was the visit to the Glyndebourne Opera. It is only in London that at 3 o'clock of an afternoon, nearly 1 000 people all togged up in dress suits and long dresses and carrying packets of sandwiches for supper could arrive at a station to catch a train, and not even cause a stir of interest or a raised eyebrow! This is the way we travelled 60 miles to the opera from London. Surely there can be no more picturesque or romantic a setting for an opera than this large 400-year old red brick manor house nestling in the green valleys of the unspoilt Sussex countryside. It was a glorious evening and though we returned somewhat late and tired, not one of us would have missed this experience. After the first week in London there was a choice of tours of one week to London and the Home Counties, Cornwall, a Geological tour to Scotland, South Wales, and North England. These were followed by further one week tours to Yorkshire and Lancashire, Scotland, West Country and Midlands, a Geological tour of Wales, and a Mining and Geological tour to Jurassic Iron Mines. We then returned to London for the final session and closing banquet. Post-congress tours were arranged to Europe and to Ireland. It was a wonderful Congress, a great experience, we made many friends and may there be many more congresses! . L. W. P. van den Bosch (Member): Much has already been said in appreciation of the excellent organisation and arrangements made for the delegates who attended this Congress. This report is confined to a brief discussion of the personal impressions gained from the papers presented and the technical visits attended. The papers covered a wide variety of subjects ranging from highly theoretical observations to practical descriptions of operations. There were three main themes, VIZ: 1. The attention given to research and its forceful application to practical operation. 2. A steady development in mechanization and automation leading to savings in manpower. 3. Improvization, modernization and adaptation of exisitng facilities. Thoughts on these themes can best be illustrated by comments on some of the industries visited. COAL The National Coal Board (N.C.B.) has been most progressive and all of us have heard of the Bevercotes Colliery with its completely automatic mining and coal handling equipment. This was not, unfortunately, on show but there is no doubt that this is one of the greatest advances in coal mining leading towards continuous production. Coal in Britain is fighting for its life against oil, North Sea gas, imported gases and nuclear power. Output is dropping, the less efficient collieries are closing down and efficiencies are steadily rising as the following tabulation indicates: In 1931: 1 million men produced 300 million tons of coal In 1947: 0.7 million men produced 230 million tons of coal In 1968: 0.4 million men produced 160 million tons of coal

By B. S. Xakalashe, M. I. Khama, Q. G. Reynolds

The carbonaceous reduction of manganese ore is an energy-intensive process that releases large amounts of pollutant gases. In an attempt to circumvent the greenhouse gas emissions, this research investigates hydrogen as an alternative reductant. The reduction of manganese ore with hydrogen results in the structural changes in the intermediate products, which might limit the diffusion of the reactant gases through the pores. Computational fluid dynamics (CFD) models capture the structural changes and predict the rate controlling mechanism and this is key in designing the prereduction reactors. The current work uses CFD models to predict the degree of reduction in a shaft furnace under hydrogen reducing conditions. Manganese ore is described as a collection of scalar and tensor fields such as thermal conductivity of the porous medium, density, and viscous resistance. The results indicate that advection contributes significantly towards the overall transport of hydrogen to the reaction sites. Porosity of the final product was found to be higher than porosity of the raw material.

Mar 4, 2025

It is widely accepted that the type of grinding media has an impact on the grinding chemistry and subsequent flotation behaviour of the sulphide minerals being separated. There are countless laboratory investigations demonstrating that inert grinding media produces more oxidizing pulp potentials, reduced levels of grinding media corrosion products, and superior concentrate grades and valuable metal recoveries. However, taking these results to industrial scale has proved difficult. This paper provides details of the protocol developed and used during a high-chrome grinding media plant trial. It describes the test regime employed to measure changes in pulp chemistry as well as concentrate grades and recoveries to produce a statistically meaningful result. The work also highlighted the need for close cooperation between the metallurgists on site and the researchers conducting the trial. To demonstrate the protocol, data gathered during a plant trail in a PGM concentrate will be presented describing the changes in pulp chemistry and metallurgical response observed.

Jan 1, 2012

By E. E. Almási, G. Mucsi, G. Rákhely, Á. Rácz, B. Csőke, Zs. Pap, K. Bohács, N. Halyag

Wet stirred media milling is a widely applied grinding process in the field of mineral processing to produce <10 μm ground materials. In this paper, the results of wet stirred media milling of different Ti, Fe and Cu-oxide and phosphate minerals are presented. During the experimental work, grinding of ilmenite, vivianite, hematite and cuprite was carried out in a continuous operation wet stirred media mill. During the experiments, the particle size distribution and specific surface area of the ground materials were determined after a certain grinding time, as well as measuring the specific grinding energy, thereby determining the grinding kinetics of the different minerals. The measurement results showed the differences and similarities in the grindability of the individual minerals. Nano particulate vivianite, hematite and ilmenite was successfully manufactured in a stirred media mill; however cuprite was characterised as the coarsest final product for the same grinding circumstances. Keywords: Wet stirred media mill, cuprite, vivianite, ilmenite, hematite

Jan 1, 2020

By W. A. Lenhardt

During the past five years, several research projects on the causes of mining induced seismicity have been carried out by the Rockburst Research Department at Western Deep levels Limited. This paper summarizes the results of these investigations. Several types of mining-induced seismic events are addressed, and models of their mechanisms are presented. It is shown that most of the seismicity results from mining in geologically disturbed areas, and ways and means are discussed to reduce the seismic potential. Stabilizing pillars, for instance, have been introduced to reduce stresses at the stope face and to alleviate the facebursting problem. Facebursts still occur in areas of very low stresses, and pillars became the source of very large seismic events (M >3). At this stage, the understanding gained of pillar-associated events allows a review of current mining practices. Further, it makes possible an examination of the efficiency of measures to alleviate the effects of various seismically prone situations.

Jan 1, 1992

By P. J. Kinver

This paper deals with the development of the cut-and-fill mining method at the Broken Hill orebody of Black Mountain Mineral Development Company (Pty) Limited, at Aggeneys in the north-western Cape Province of South Africa. Lead, copper, zinc, and silver are produced. Production started in January 1976, being confined to blasthole production methods in the upper, steeply dipping areas of the orebody. This blasthole reserve is 70 per cent depleted, and pillar extraction is in progress. The balance of the production tonnage, 60 kt per month, is produced from three cut-and-fill stopes situated in the flatter-dipping areas of the orebody. The cut-and-fill mining method at Black Mountain is a result of research and planning activities that included the use of modelling, laboratory tests, mathematical analyses, in situ tests, and experience gained from other mining operations. These investigations and the resulting developed methods and designs are summarized in the paper.

Jan 1, 1985

By A. Ball

This paper addresses the need for a unifying model that will permit the selection and design of optimum materials for a given wear situation. With this objective in view, the characteristics of the various forms of abrasive, adhesive, and erosive wear are described in terms of localized stress, strain, strain rate, and frictional heating. The measured performance of a variety of metallic, ceramic, and polymeric materials and coated or surface treated materials are described briefly. These results were obtained under conditions of dry-particle abrasion, abrasion in conjunction with corrosion, cavitation erosion in liquids, erosion by particles in low- and high-velocity gas streams, and erosion by particles in a liquid stream. Electron microscopy was used extensively, together with microhardness profiles, in the determination of the modes of material detachment and the underlying deformations and structural changes. As a result of the experimental work, a model based upon a critical strain to microfracture is presented. The microstructural features and materials properties that determine wear resistance are discussed.

Jan 1, 1986

By M. J. Gouws, T. P. Knoetze

The spontaneous combustion of coal and the explosion of coal dust are two phenomena that were identified by the South African mining industry as requiring investigation. Research contracts were awarded to the G.P. Badenhorst Research Facility of the CSIR and the Department of Mining Engineering of the university of the Witwatersrand by the now defunct National Energy Council. Both projects entailed tests on numerous coal samples in specially designed apparatus. Since the completion of the project, attempts have been made to predict experimental results without incurring the cost of performing experiments. This paper describes predictive indices, based on routine laboratory tests, that were developed by the different research teams for their particular projects. A comparison of the results obtained by applying the spontaneous combustion liability index and the explosibility index to common coal samples indicates that, in general, propensity to spontaneous combustion and explosibility exhibit an inverse relationship. A brief overview is given of some major South African coal-mine disasters.

Jan 1, 1995

By T. Feroze, B. Genc

"The ventilation of underground coal mines plays an important role in minimizing the risk of methane and coal dust explosions. The ability of ventilation, with the use of line brattices (LBs), to remove methane and coal dust in empty headings is dependent on the amount of air leaving the LB and entering the heading. The quantity of this air depends on the associated system variables, namely heading dimensions, settings of the LB, and velocity of air in the last through road (LTR). However, the exact effect of these system variables on the flow rate at the exit of the LB in an empty heading is not known. The installation of LBs in South African coal mines is generally carried out based on experience. This can result in overor under-ventilation and may increase the cost of providing ventilation or cause accidents, respectively. In this paper, using computational fluid dynamics (CFD), the air flow rate at the exit of the LB in an empty heading was estimated using full-scale three-dimensional models. The CFD model used was validated using experimental results Firstly, the settings of these three system variables were varied, the flow rates at the exit of the LB were measured, and finally the results were used to calculate the effect of each system variable. The outcome is a mathematical formula that can be used to estimate air flow rate at the exit of the LB in empty headings for any practical scenario.This paper will help the coal mining sector in South Africa by providing estimation models based on scientific reasoning for the installation of LBs, and will also serve academia as part of the curriculum towards educating future mining engineers."

Jan 1, 2016

By C. Chongo, F. X. Paquot, C. Ngulube

"Over the last six years, the Kansanshi copper-gold mine has continued to process significant quantities of complex transitional mixed ores. Initially, the ore treated came predominantly from accumulated stockpiles. Subsequently, the feed source shifted primarily to freshly mined ore that generally showed less tarnish with better flotation kinetics, but with the downside of lower concentrate grades. A number of changes were made to improve the efficiency of the rougher circuit and quality of concentrate produced. These changes were as a result of initial mineralogical studies and laboratory flotation test work that were discussed at length in a previous paper1. Salient among the recommendations adopted as a result of previous work were increased circuit capacity and a modified configuration to increase the residence time and the number of sulphidization stages. These modifications were completed and commissioned in 2011. This, however, resulted in significantly low rougher concentrate grades and a below-specification final concentrate product. This was due primarily to higher mass pulls from the extended rougher bank with multiple concentrate discharge streams, and which necessitated an enlarged cleaning capability. The extra cleaning capacity came on stream in 2014. Of note was the development of a recovery model, based on the strong correlation between the total copper and acid-soluble copper ratio, as a tool for monitoring plant performance. IntroductionThe Kansanshi mine, the largest copper mine in Africa, is 80% owned by Kansanshi Mining plc, a subsidiary of First Quantum Minerals. The remaining 20% is owned by the state through the parastatal Zambia Consolidated Copper Mines Ltd (ZCCM). The mine is located approximately 10 km north of the town of Solwezi and 180 km to the northwest of the Copperbelt town of Chingola. The mine has been in commercial operation since 2005."

Jan 1, 2016

By H. M. Krieg, M. J. Ungerer, C. G. C. E. van Sittert, D. J. van der Westhuizen

"The transition metals tantalum (Ta) and niobium (Nb) are of significant importance, for example in the nuclear energy sector where they are used as cladding materials, as well as in capacitors and specialized materials. For these applications a high-purity metal is needed. The separation of Ta and Nb is always a challenge since they are found together in nature and have similar chemical and physical properties, resulting in costly and laborious separation processes. A technology that has been used successfully for the separation of these metals entails solvent extraction (SX)1. While separation was achieved in a previous SX study using a sulphuric acid (H2SO4) medium with the extractants diiso-octyl phosphinic acid (PA) and di-(2-ethylhexyl) phosphoric acid (D2EHPA), due to the absence of speciation data for Ta and Nb it is not clear how the separation occurred.One method that might be suitable for determining the speciation of a reaction is molecular modelling. Calculations based on the densityfunctional theory (DFT) are now used not only for light elements and small molecules, but also metal complexes, heavy metals, and especially metal separation in SX2. In this study the aqueous phase used during SX was investigated by studying periodic systems of Ta, as a metal and in salt form, when it is in contact with H2O and H2SO4. The results were used to predict the reaction mechanism occurring during SX. Results showed that (i) in a 1:1 acid-water ratio, the deprotonation of H2SO4 was endothermic, (ii) in a 1:5 ratio deprotonation was exothermic forming HSO4 -, and (iii) in a 1:10 ratio double deprotonation occurred to form SO42- exothermically."

Jan 1, 2017

By I. D. Wood

The geostatistical methods given for the estimation of low-ash coal reserves take into account the geological structure of the seam, and consequently give far more reliable results than have been obtained in the past. Confidence limits are given for all the estimates.

Jan 1, 1979

By M. Tang, X. Tong

"SynopsisSlime coating is one of the most common ways for serpentines to contaminate metallic mineral concentrates during traditional flotation of coarse sulphide particles. This could pose quite a complicated and challenging problem in the case of some types of low-grade and finely disseminated Cu-Ni ores bearing high serpentine contents. This is the case for the copper and nickel sulphides from the Yunnan Mine, China. Previous batch flotation tests of this ore resulted in satisfactory recoveries of 86.92% Cu, 54.92% Ni, and 74.73% Pt+Pd, and concentrate grades of 4.02% Cu, 3.24% Ni, and 76.61 g/t Pt+Pd. However, the MgO content in these concentrates was more than 19%. In the current study, microflotation tests and settling rate tests were introduced to investigate the effects of a combination of strong collectors (a 2:1 weight ratio of butyl xanthate and butyl ammonium dithophosphate) on entrainment of serpentines in metallic mineral concentrate, as well as visual observations of the concentrates in suspension using still photography. All test results indicated the presence of serpentines entrapped in the hydrophobic flocs that resulted from these collectors, even with the use of effective gangue depressants. These strong collectors are used to flocculate the ultra-fine sulphides by forming loose and ‘fluffy’ hydrophobic flocs. However, these hydrophobic flocs may also be able to load or entrap some serpentine slimes into the concentrate, and this entrained serpentine could be harder to remove by using depressants or intensified conditioning than serpentine slime coating on the particle surfaces.IntroductionSerpentine minerals, which have the generalized composition (Mg,Fe)3Si2O5(OH)4, can be easy to crush and grind due to their convoluted and bent layered structures. These serpentines can hinder the enrichment of some metallic minerals and dilute their concentrates by entrainment during flotation. The resulting high pulp viscosities, slime coatings, and high content of dissolved ions adversely affect the flotation recoveries of copper and nickel sulphides, and high levels of MgO entrained in the concentrates lead to heavy penalties from smelters. Since the quality of nickel flotation concentrate depends heavily on its MgO content (generally less than 6–7% for No.1 or 2 grade nickel concentrate according to the standard requirement from National Nonferrous Industry), reducing the entrainment of serpentine during flotation is becoming more and more pressing. Previous research has focused on the collectors and depressants that are commonly used in copper-nickel flotation, as well as their interaction mechanisms."

Jan 1, 2015

By G. Dhakal, J. -I. Kodama, K. Neaupane, T. Yoneda

ABSTRACT Durability tests and evaluation of sub-zero temperature effects to some argillaceous clastic rocks were carried out. Welded tuff, limestone, sandstone and schist samples collected from different parts of Japan were tested and results are presented. Schist and dolomite from Ganesh Himal area along the higher Himalayas of Nepal were also tested, and the results are compared. The slaking tests were performed on all samples in pure water. The results reveal that the slaking index of schist from Japan is lower than that of schist from Nepal. Regarding carbonate rocks, the slaking index of limestone from Japan is higher than that of dolomite from Nepal. A tendency of decrease in slake durability with an increase in porosity is also observed. Freezing and thawing experiments conducted on welded tuff and schist reveal that crack initiates earlier but extends slower in schist than in welded tuff. It is also observed from the freeze-thaw experiment that the welded tuff deteriorates and wears faster than the schist. However, sandstone remains relatively intact for a long run of freeze-thaw cycles. Zusammenfassung Beständigkeitstests sowie die Bewertung der Auswirkungen von Minusgraden auf Tonschiefer Trümmergestein wurden durchgeführt. Dabei wurden geschweißter Tuff, Kalkstein, Sandstein und Schiefer aus verschiedenen Gebieten Japans sowie Schiefer und Dolomitgestein aus dem Ganesh Himal Gebiet, dem höheren Himalaya Nepals, untersucht und die Resultate verglichen. Für alle diese Gesteine wurden Slaking-Tests in reinem Wasser vorgenommen. Die Resultate zeigen, dass das Slaking von Schiefer aus Japan höher als das von Schiefer aus Nepal war, wohingegen bei kalkhaltigem Gestein das Slaking von Kalkstein aus Japan niedriger als das von Dolomitgestein aus Nepal ausfiel. Es wurde dabei auch eine Tendenz zur Löschbeständigkeitsverringerung bei gleichzeitig erhöhter Porosität beobachtet. Gefrier- und Tautests an geschweißtem Tuff und japanischem Schiefer zeigten, dass Risse in Schiefer schneller auftraten, aber sich langsamer ausweiteten als in geschweißtem Tuff. Bei Gefrier- und Tautests wurde ebenfalls beobachtet, dass geschweißter Tuff schneller verfällt und verschleißt als Schiefer. Sandstein hingegen blieb über lange Tau- und Gefrierzyklen intakt Résumé Des tests de solidités et l’évaluation de l’effet des températures en dessous de zéro sur les rocs argileux ont été effectués. Les rocs d’origine volcanique (cendre), les rocs calcaires, sableux et les schistes de différentes régions du Japon, ont été étudiés. Les schistes et les dolomites de la région de Ganesh Himal le long du haut Himalaya (Népal) ont été étudiés et comparés à ceux du Japon. Les tests de désintégration sur les rocs ont été effectués dans l’eau pure. Les résultats montrent que l’index de désintégration des schistes du Japon est inférieur aux schistes du Népal. En ce qui concerne les rocs carbonyles, l’index de désintégration des rocs calcaires du Japon est supérieur à ceux des dolomites du Népal. Une décroissance de la résistance à la durabilité est observée avec une plus grande porosité des rocs. Les tests de congélation-décongelation sur les schistes et les rocs d’origine volcanique (cendre) du Japon montrent une apparition précoce des fissures mais l’expansion des fissures est plus rapide dans les rocs volcaniques. Des tests similaires montrent que les rocs volcaniques (cendre) se désagrégent plus rapidement que les schistes. Cependant, les rocs sableux restent intacts après plusieurs cycles de congélation-décongélation.

Jan 1, 2003