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By K. G. Lomberg

The density used to covert volume to tons is critical in determining the real in-situ tonnage of Mineral Resources. However, the methods used to determine density and the use of different technical terms are seen to be inconsistent throughout the industry. Probably the best discussion addressing the determination of density was presented by Lipton (2001). This paper does not try to replicate this excellent work, but rather to review current industry practice and present a comparison of the approach to density in public reporting. Some of the technical terms used in reporting and the common methods applied are also discussed.

Sep 1, 2021

By S. Shi, X. Xia, F. Xuesai, Z. Shen, D. Han

The hydrodynamic characteristics of a mechanical flotation cell’s transportation zone have significant impact on its metallurgical performance, especially on coarse particles recovery efficiency. However, how to define and adjust the transportation zone was seldom investigated by researchers. In this paper a method will be introduced to define the boundary of the transportation zone by PIV measurement. It is found that the transportation zone can be extended upwards by enlarging the entire rotor-stator assembly from the bottom of tank and increasing the jet angle of the impeller. Two control methods have been validated in industry tests on KYF-160m3 and KYF-320m3 air-forced mechanical flotation cells. The result shows coarse particles recovery are both improved distinctly. It is suggested that enlarging the top transport boundary is able to helpful to reduce the floating distance of bubbleparticle aggregates, which contribute to improve coarse particle recovery in large flotation cells. Key Words: Flotation cell; Transportation zone; Coarse particles flotation

Jan 1, 2020

By M. Weir, J. R. Cutland, L A. J. Pronk van Hoogeveen

"A computer system for the design of open pits to mine stratiform orebodies has been developed for use at Nchanga Consolidated Copper Mines, Ltd. The particular requirements of such a system, for example, the accuracy of representation of geological detail and the ability to follow footwalls, arc described in this paper, together with the methods that have been adopted to satisfy them.A modified version of the Open Pit Design Program of Rio Tinto Zinc Consultants, Ltd. is incorporated in the system and the geological data are converted into a form usable by the computer by means of a pencil follower. Some of the uses which have been made of the system are described, with reference to the long- and medium-term planning of the Nchanga Open Pit, the major producing pit at Chingola Division."

Jan 1, 2014

By L. Makua, K. Langa, Ndlovu. S., C. Saguru

"Global demand for the three platinum group metals (PGMs) Pt, Pd, and Rh has been steadily growing due to their widespread use in emission control, industrial catalysis, and numerous other applications. The primary supply of PGMs is currently the mining industry. However, legislative, operational, and environmental challenges faced by many mining operations result in erratic supply patterns and deficits for these three metals. Naturally, recycling scrap material to recover Pt, Pd, and Rh has therefore aroused research interest in the scientific and engineering communities. Given that the majority of the global demand for these three metals is driven by emission control devices, autocatalytic converters are therefore a significant source of already processed and beneficiated PGMs for recycling.Although pyrometallurgical processes dominate the recycling industry, hydrometallurgical processes may offer certain advantages, chief among these being lower emissions and reduced energy consumption. In this investigation, scrap converter material was leached in acidic chloride media and the leach liquor subjected to solvent extraction and cloud point extraction (CPE) to recover the PGMs. The recoveries for Pt and Pd using Alamine 308® dissolved in kerosene with decanol as a modifier were 95% and 81%, respectively. The maximum recoveries using CPE after complexation with 2-mercaptobenzothiazole (2-MBT) in the presence of Triton X-100 and tin (II) chloride dihydrate as a reductant were 97% for Pd, 96% for Pt, and 91% for Rh. This demonstrates that CPE, although relatively new, may have some potential as a breakthrough PGM recovery technology. IntroductionPlatinum group metals (PGMs) have found a wide variety of applications in different industries due to their chemical, catalytic, and physical properties. PGMs are essential in automobile emission abatement, petroleum refining, and the pharmaceutical and electrical industries (Carabias-Martinez et al., 2000). However, the abundance of PGMs in the Earth’s crust is low and their primary sources are fast depleting (Crundwell et al., 2011).The high demand for PGMs, together with social, economic, environmental, and political aspects related to their production, has led to concerns about their future supply. This has resulted in renewed interest in recycling end-of-life material. PGM supply from recycling has doubled over the last decade, and currently contributes 22% to global supply (Johnson Matthey, 2016). This is in part due to the environmental, social, and operational challenges associated with mining of PGMs. For example, labour unrest, energy cuts, declining commodity prices, and declining ore grades have collectively made the mining landscape economically challenging (KPMG, 2015). On the other hand, the high content of PGMs in secondary sources makes their recovery from the increasing quantities of waste products important from a resource conservation viewpoint. Moreover, PGMs obtained through recycling have been demonstrated to have a 1% environmental cost from a life-cycle perspective, whereas PGMs obtained from mining contribute the remaining 99% of environmental cost (Bossi and Gediga, 2017). Sustainable resource recovery and the economic incentive of recycling have therefore been major drivers to justify investment in PGM recycling. The autocatalytic converter industry accounts for about 70% of the global consumption of these metals (Johnson Matthey, 2016) and therefore recycling spent converters has become a major source of Pt, Pd, and Rh (Figure 1)."

May 1, 2019

By Y. Makola, M. Kilumba, S. Mwaba, P. Ilunga, F. Banze, B. Nel, P. Kyoni, N. Mautsa, R. Nkomba, G. Ilu

Kamoto Copper Company is a copper cobalt mining company established in Lualaba Province of Democratic Republic of Congo under a Joint Venture between Glencore PLC and Gecamines (the state-owned mining company). Operations consist of underground and open pit mines, a concentrator producing sulfide concentrate and oxide ores milled slurry, and a hydrometallurgy plant producing copper cathode and cobalt hydroxides from concentrate and ores. The production capacity is 300 k/a of copper cathode and 35 kt/a of cobalt hydroxide. Since Q4 2020, the Luilu hydrometallurgy plant has experienced operational instabilities due to increase in proportion of dolomite in the ore mined and fed to the plant. This was diagnosed by the significant increase in calcium grade in ore and acid consumption, continuous foaming, and overflow of tanks with subsequent adverse impact on equipment availability due to corrosion caused by acidic spills, structure integrity, and safety concerns around the acidic slurry spills. Production was adversely impact due above equipment availability and often throughput restriction to mitigate the foaming and overflows. A high gangue-acid-consuming ore management programme was developed with the aim of mitigating these impacts. The programme included: (i) use of defoamer agent in leach to stop foaming and overflow, (ii) design of a mechanical solution to leach foaming and overflow, and (iii) froth flotation for copper and cobalt minerals separation from dolomite. Only option (i) is presented in this paper. Through laboratory testwork, pilot-plant testing, plant trial, and full plant implementation, Kamoto Copper successfully implemented a defoamer agent (Kemfoam X9980) dosing at leach, resulting in significant reduction in foaming and overflow of leach reactors and countercurrent decantation thickeners. The optimum defoamer dose rate obtained was 20 mg/L. Since then, the Luilu recovered its operational stability, the corrosion of critical equipment ceased, and availability improved as the acidic leach slurry spills ceased. The constraint on throughput due to leach foaming was addressed and the frequency of sliming events in the thickeners was significantly reduced as the foaming on the supernatant surface ceased, with subsequent significant reduction in interfacial crud in solvent extraction.

Jan 1, 2023

By T. Nghipulile, M. Moys, M. Bwalya, H. Simonsen

The quest for efficiency in comminution is an ongoing concern as comminution usually constitutes a major cost component in the metal production industry. Such improvements can be made by circuit optimization or development of more efficient equipment. A novel crusher, known as the rotary offset crusher (ROC), promises to deliver in this space. The ROC was invented in 2002 by Michael Hunt, Henry Simonsen, and Ian Sinclair, but failed to garner enough support to progress to production. The original design concept was recently rekindled, and a laboratory version of the crusher has been built and commissioned at the University of the Witwatersrand. The crusher is simple in design, with two cylindrical discs that are parallel to each other, and, as the name implies, there is an offset between the vertical axes of the discs. The top disc has a conical section on its lower face, and this creates a crushing zone between the opposite faces of the two spinning discs. Centrifugal motion transports particles through the crushing zone. Batch experiments have been conducted with quartz at various crusher settings (discs offset, rotational speed, and vertical exit gap) for various feed size distributions. The indications so far suggest that the disc speed is a key factor affecting the performance. Size reduction ratios as high as 11 were recorded from experiments with quartz at a speed of 830 r/min.

Jan 1, 2021

By NIM REPORTS

Notices CONFRRENCE ON COMPUTRRS IN ENGINEERING The above Conference, which is being organized by the Electrical and Electronics Board of the Institution of Engineer!!, Australia, ill to be held in Sydney on 16th and 17th May, 1974. It is being planned in conjunction with the Sixth Australian Computer Conference and will be held during the week immediately preceding the latter. NIM REPORTS Report No. 1495 A method for the determination of ekmental sulphur on the surface of sulphide minerals. Report No. 1500 The chromatographic separation and determination of nobk metals in matte-leach residues. Report No. 1505 The production of the refractory aluminium saicates, with special refererence to South Africa. Report No. 1517 Computer-controlled flotation plants in Canada and Finland. Report No. 1526 Heat of solution as a control of aqueous-ammonia concentration. Report No. 1529 South African costs of equipment for the metallurgical industry (197).

Jan 9, 1973

"Chairman: Professor H. S. SICHEL Rapporteur: Miss M. I. WATSONPapers:Unrolling of Copperbelt orebodies by J. H. E. Perry and V. H. WiikAn exploration model for tabular orebodies by G. S. Koch and R. F. LinkHarmonic analysis of copper and gold occurrences in the Arbitibi area of the Canadian Shield by F. P. Agterberg and A. G. FabbriMathematical models of orebodies by M. J. Newton and A. G. Royle Estimation of lateritic-type orebodies by A. JournelIn his presentation Mr Wiik said that unrolling could be regarded as a reversal of the natural process of folding, so that the aim of an unrolling procedure would be the reconstruction of original pre-tectonic conditions. While simply formulated, this aim might not always be achieved. The geometrical relationship between points on the deformed surface and corresponding points on the original surface is process-dependent, and a true reconstruction could be achieved only if the deformation history were known in detail.In this computer unrolling procedure all these complexities were ignored. Referring to one particular marker horizon, Mr Wiik said that it was assumed in the procedure that this marker was deposited as a horizontal stratum and that it had subsequently been deformed by simple flexure-type folding.The procedure allowed the geologist to incorporate his knowledge and conception of the deposit through repeated re-contouring with dummy points. This 'manumatic' aspect of the procedure had proved invaluable, not only in resolving specific unrolling problems but also in making the system more acceptable to the geologists in general.Unrolling served towards removing what might be termed `tectonic noise' superimposed on the primary distribution patterns for regionalized variables such as metal content and orebody thickness. From this point of view, variograms derived on the basis of unrolled-plan co-ordinates should be more meaningful in terms of depositional environment than are variograms calculated from a normal map projection.Mr M. M. Oosterveld remarked that it appeared from the paper that there were problems in applying the unrolling technique to ore reserve calculation, and asked whether there were not other methods that might be used for that purpose.Mr Wiik replied that at present unrolling played only a minor role in practical ore reserve estimation within Roan Consolidated Mines, Limited. The techniques currently in use differed from one orebody to another, but in general they involved projection onto a vertical longitudinal section or a horizontal plan, with subsequent grid interpolation by means of a standard computer contouring package."

Jan 1, 2014

By S. J. van Wyk, A. S. H. Haagner

Land rehabilitation transcends the mere establishment of vegetation across disturbed landscapes; it should be conceptualised as a specialised ecological reconstruction process. This process necessitates a long-term perspective on the success of land repurposing. It requires a continuum of inputs specified and managed by a dedicated and qualified custodian to ensure the sustained economic viability and ecological sustainability of the land. Based on the authors’ combined experience and field observations over more than five decades, they advocate for an urgent shift away from traditional land rehabilitation practices toward a paradigm centred on land capability reconstruction and active stewardship. The prevailing rehabilitation culture has overly simplified the process to a mere revegetation exercise, which is fundamentally incompatible with the comprehensive requirements for sustainable land capability. While the regulatory framework provides valuable guidance for obtaining a mine’s social license to operate, a paradigm reset is essential. Mining companies must prioritise rehabilitation quality, set achievable sustainability goals, and establish clear pathways and milestones to meet relinquishment criteria. Currently, the status quo view—a model reliant on outsourced contracting and agricultural approaches—is that mine rehabilitation is a one-time intervention rather than a complex, systemic, and long-term process. This perspective presents significant challenges, as the success of ecological interventions can only be accurately assessed over extended timeframes, often spanning decades. Shortsighted rehabilitation specifications, coupled with practitioners operating within agricultural decision frameworks, frequently overlook the necessity for integrated rehabilitation expertise and the scientific foundation essential for designing and implementing effective ecological outcomes. A lack of long-term monitoring information impedes the required adaptive management of rehabilitated systems and, therefore, delays the transition towards final land use. This short approach costs the mining industry millions annually, often without recognising the inadequacies in long-term liability mitigation and the substandard ecological success achieved. The disconnect between procurement processes, the qualifications of service providers, and the unclear pathways to relinquishment can impede successful rehabilitation outcomes, frequently undermining progress toward sustainability milestones. Unless there is a fundamental reset of the land rehabilitation culture, pursuing sustainability will remain an elusive and perhaps impossible objective. Consequently, mining companies may hesitate to fully commit to sustainable land rehabilitation practices, as the prospects for relinquishment and final closure remain uncertain at best.

Apr 25, 2025

By P. J. D. Lloyd, Jill Urban, M. R. Urban

The adsorption of gold from cyanide solutions onto constituents of the reef, and its role in reducing the efficiency of the gold-recovery process by M. R. URBAN. M.Sc. (Chem. Eng.) Rand (Visitor). JILL URBAN. B.Sc. (Chem. Eng.) Rand (Visitor) and P. J. D. LLOYD. Ph.D. (Cape Town) (Fellow) Evidence for the adsorption or re-precipitation of gold from cyanide solutions onto gangue minerals of the Witwatersrand reefs has been gathered over a number of years by various investigators. The evidence from tests using radioactive tracers is conclusive and indicates thlt adsorption contributes about 0,1 g/t to the total gold loss from conventional reduction works. The loss is a function of the alkalinity and cyanide concentration of the solution, and it appears to be affected by the extent of time between milling and cyanidation. The heavy minerals appear to be the strongest adsorbers, and the clay minerals somewhat less strong adsorbers. A sensitive qualitative test based on thin-layer chromatography permits the extent of adsorption and desorption to be readily determined.

By A. J. S. Benade, N. B. Strydom, W. H. Van Der Walt

The performance of the improved microclimate suit by N. B. STRYDOM M.Sc., Ph.D. (Illinois) (Fellow), A. J. S. BENADE, B.Sc. (Potch.) (Visitor), and W. H. VAN DERWALT, M.Sc. (Potch.) (Visitor) An assessment has been made of a new improved microclimate jacket when worn by men working for four hours in a hot environment (wet-bulb temperature of 33,9°C and an air speed of 0,4 m/s) and at work rates of 35 Wand 70W. At the lower rate of work in heat, the use of microclimate suits maintained the rectal temperatures of the men at almost the same level as when they worked without that protection at normal room temperature (20°C). At the greater rate of work without protection, the men's rectal temperatures rose to 40°C within two to three hours, so that they could not complete four hours of work. When they wore microclimate suits, they easily completed four hours of work, and their rectal temperatures were lower than when they worked at the lower rate without protection.

Jan 8, 1975

Book reviews Fiftieth Annual Report (1971) of the Safety in Mines Research Establishment, published by H. M. Stationery Office, London on behalf of the Department of Trade and Industry. Advances in extractive metallurgy and refining. This excellent volume, published by the Institution of Mining and Metallurgy, contains all the thirty papers presented at the International Symposium held in London in October, 1971. Electric Melting Practice by A. G. E. Robiette, Charles Griffin and Co. 412 pp. In recent years the application of electric furnaces to melting processes has expanded to such an extent that it has become a topic in its own right, quite distinct from the related subject of electric smelting which is still limited, for the most part, to those areas where inexpensive electrical power is available. Optimum use of manpower by A. J. van Zyl. The sixties represented one of the longest periods of sustained economic growth South Africa has experienced. At the same time it caused a certain amount of inflation and an acute manpower shortage.

Sedimentary Ores-Ancient and Modern (Revised), edited by C. H. James. Proceedings of the 15th Inter-University Geological Congress. University of Leicester, December, 1967. Special Publication No.1, Department of Geology, University of Leicester, February, 1969. Obtainable from: Leicester University Bookshop, May's Walk, Leicester LE 17 RD. Price: 42s. Postage and packing, 3s. 6d. This volume should be of interest to economic geologists and students in this field. A number of illustrated papers on the genesis of ores in sediments are presented; the authors include experts such as Prof G. C. Amstutz, Dr K. C. Dunham, Prof D. Williams and W. G. GarIick. The papers deal mainly with sulphide deposits, but the late Prof J. H. Taylor's contribution concerns ores of iron and manganese. Brief references to the Witwatersrand ores represent the only discussion of South African deposits. With the notable exception of W. G. Garlick's paper on Zambian copper deposits, the Abstracts given are inadequate, necessitating thorough reading of the papers to extract the important matter.

By J. O. Jensen

A method is described for the determination of cyanide in gold slurries, based on amperometry. The measured current is proportional to the concentration of cyanide, and is not effected by pH or by the concentration of oxygen in solution. It is also unaffected by other ions that may be present in gold-leaching solutions, including sulphide, thiocyanate, and thiosulphate. The current depends on the temperature, and an activation energy of 17,9 kJ/mol was determined Since the current is controlled by the mass transfer of cyanide to the anode, it depends on the conditions of agitation. In tests on an operational gold plant, slurry was pumped directly from the top of the leaching tank, through the measuring cell and back into the tank. The results indicate that the instrument is a promising alternative to the instruments currently available. The readings from the instrument remained in calibration for at least two days, showing that the instrument would need to be re-calibrated by the operating staff at regular periods.

Jan 1, 1994

By A. N. Brown

This title of is not that originally chosen for the Colloquium, which was 'A high gold price'. Such a title would have been unfortunate because it would have related the Colloquium only to the high gold price of the past two years, which reached the dizzy peak of 850 dollars per ounce in January 1980. The chosen title is, of course, the right one because it places the whole problem in the right perspective. It relates to a situation that has occurred many times before. Over the course of the past century, the gold price has periodically been inhibited from rising, so that it has undergone a succession of stepwise increments. With each increase, the relationship of the working cost to the gold price alters, and gives rise to a jump in ore reserves. Award for CMI fuelling technique Consolidated Metallurgical Industries Limited - the Lydenburg-based ferrochromium producer in the J.C.I. group - was one of the five recipients of the 1981 National Productivity Institute annual award.

Jan 1, 1981

Book review HOEK, E., and BRAY, J. Rockslope engineering. London, The Institution of Mining and Metallurgy, 1974. £5. NIM reports Report no. 1625 The determination of uranium and thorium by the use of delayed neutrons. Report no. 1626 Formation constants of zinc chlorocomplexes in perchlorate medium. Report no. 1629 The thermodynamics of the formation of complexes of silver with some substituted pyridines. Report no. 1630 An electrochemical investigation of the dissolution of copper, nickel, and copper-nickel alloys in ammonium carbonate solutions. Report no. 1640 A semi-automatic titrimeter for cyanide analyses. Report no. 1644 Prospects for the recovery of minerals from the sea. 1974 A.S. & T.S. National Award Professor D. C. Midgley, President of the Associated Scientific and Technical Societies of South Africa, today announced the winner of the 1974 A.S. & T.S. National Award. 1974 G.W. en T.V. Nasionale Toekenning Professor D. C. Midgley, President van die Geassosieerde Wetenskaplike en Tegniese Verenigings van Suid- Afrika het vandag die wenner van die 1974 G.W. & T.V. Nasionale Toekenning aangekondig.

Jan 9, 1974

By P. R. Jochens, A. A. Hejja

The effect of the reactivity of lime on desulphurization efficiency in the basic oxygen furnace by A. A. HEJJA,D. D. HOWAT, andP.R.jOCHENS Published in the Journal March 1973. DISCUSSION R. E. Leyman* The authors discuss in detail the effects of transport and storage at the steel plant on the reactivity of lime as measured by the DIN Reactivity Test. They attribute the deterioration in reactivity to the absorption of water vapour and carbon dioxide, but make no mention of the possible role of atmospheric sulphur dioxide in this respect. The significance of the mineralogical and surface characteristics of gold grains in the recovery process by C. E FEATHER and G. M. KOEN Published in the Journal February 1973. AUTHORS' REPLY TO DISCUSSION (Published in the Journal July 1973) H. P. Carlisle Mr Carlisle's questions and observations will be dealt with in the same order as they were raised. 1. How were the mass percentages of the grains determined from the sizes measured in polished section?

Jan 3, 1973

By A. J. S. Benade, N. B. Strydom, W. H. Van Der Walt

The influence of two weeks of microclimate cooling on the state of heat acclimatization by N. B. STRYDOM, M.Sc., Ph.D. (Illinois) (Fellow), A. J. S. BENADE, M.Sc. (Potch.) (Visitor), and W. H. VAN DER WALT, B.Sc. (Potch.) (Visitor) Five volunteer Black subjects were acclimatized according to the climatic-room acclimatization procedure, and their states of heat acclimatization were determined by the usual heat-stress test. The subjects thereafter wore pre-frozen jackets in a somewhat higher environmental temperature (33,9/35,6 °C). stepping at the same rate as before for four hours a day for fourteen days. The heat-stress test was repeated and followed by a similar test at the higher environmental temperature. It was found that fourteen days of microclimate cooling in a very hot environment had no adverse effect on the degree of heat acclimatization. The sweat rates during microclimate cooling remained high, even though no sweating is possible beneath the pre-frozen ice-jacket. which indicates that there is an increase in sweat rate from the areas of exposed skin.

Jan 7, 1975

By D. D. Howat, J. van der Colf

This paper is the first in a series of three dealing with this subject and also with the rate of oxygen removal from the slags in the presence of solid carbon and with the physicochemical properties of the reduced slags. For selected members of the system, the melting temperatures and primary crystallization products were determined. as were the viscosity and the electrical resistivity of the corresponding melts. All the experiments were conducted in a neutral atmosphere. Where determined, the primary phase was found to be either perovskite or magnesium aluminium titanate. The composition variable exerting the most pronounced influence on viscosity or resistivity was found to be the basicity expressed as the mass ratio (CaO + MgO)jSiO,. The ratio CaOjMgO became important only at Iow basi<:ity values. Although generally there is a direct proportionality between log (viscosity) and log (resistivity), slags h&apos;lving either a very high silica content or a very high titania content have anomalously Iow electrical resistance.

Jan 1, 1979

By J. W. Wilson, P. C. Graham

Raise-boring experiences in the gold mines of the Anglo American Corporation Group by J. W. Wilson M.Sc., M.I.M.M., F.S.A.I.M.M., M.A.I.M.E. and P. C. Graham M.Sc. (Eng.) Gold mining is being carried out at ever-increasing depths in South Africa. For reasons of safety and human comfort, it is becoming imperative for raises to be developed by means other than conventional drilling and blasting. Raise-boring is an attractive alternative method. Initial raise-boring experiences in South African gold mines showed disappointingly high costs due to the abrasivity and difficulty of drilling Witwatersrand quartzites. Consequently, a research and development project was instigated with the objective of making raise-boring an economically viable technique in hard abrasive rock. A Robbins 61R raise-borer was made available to the Research and Development team and a number of raises have been drilled. During these trials two advances in cutter design were tested. This paper presents the results obtained, including drilling costs, and provides details of the equipment used.