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By G. L. C. Young

The first full-scale Reichert cone concentrating plant to be erected at a large South African gold mine was at President Steyn Gold Mining Company, Welkom. ThiR plant was installed as a part of the runof-mine mill extension of 150000 t per month that was commissioned in 1976-1977.

Jan 1, 1982

By M. Bryson, J. Taguta

The Prieska deposit, mined between 1971 and 1991, is one of the world’s top thirty volcanogenic massive sulphide (VMS) base metal deposits. The Prieska Copper Mine in the Northern Cape Province was closed by Anglovaal when underground mining had extended to depths which did not allow for safe and economic extraction of the deposit at the time. The mine has a recorded historical production of over 1 Mt of zinc and 430 k tonnes of copper from 46.8 Mt of milled sulphide ore, achieving life-ofmine metal recoveries of 85% for copper and 84% for zinc into high quality concentrates (refer ORN ASX release 15 Nov 2019). Orion Minerals Ltd is currently investigating the feasibility of developing a new mine in the footprint of the historical Prieska Copper Mine, using the extensive remaining infrastructure, with the intent of extracting the unmined zinc-copper mineralisation from the Prieska deposit. This paper reports results on the flowsheet development philosophy on the hypogene ore, and challenges encountered in the process. This study initially failed to replicate historic copper and zinc recoveries employing the historic production flowsheet and reagent conditions unmodified on bench scale, as the copper and zinc were co-floating. Flowsheet modifications were therefore made to improve differential flotation and recovery, resulting in achieving comparable saleable products and recoveries from processing the hypogene ore on bench scale. Flotation variability test work on the hypogene ore focused on the use of the original flotation procedure and reagent suite using a sodium cyanide-zinc sulphate depressant system on the copper circuit, and it generated a saleable copper product of 20-26% Cu grade at 80-86% recovery. The zinc circuit generated a saleable zinc product grading at 48-55% Zn at 80-94% recoveries. Some zinc losses were due to the deportment of some zinc in sauconite. It is recommended that further test work may further improve the copper grades and recoveries. Keywords: Prieska, flotation, hypogene ore, flowsheet development, sulphide flotation, reagents

Jan 1, 2020

1. Book reviews Underwater tools, by Donald J. Hackman and Don W. Candy. Columbus (D.S.A.), Battelle Press, 1981. 152 pp. $32,95. Reviewer: B. Schmitz Uranium exploration case histories. Proceedings of Advisory Group Meeting Vienna, IAEA, 1981. Price: Austrian schillings 630. Reviewer: E. C. Kostlin Jet cutting technology, a review and bibliography, edited by Robin Brown. Published by BHRA Fluid Engineering, Cranfield, Bedford MK430AJ, England. Reviewer: D. O'Beirne 2. New Books Proceedings, Twelfth Congress of the Council of Mining and Metallurgical Institutions, by H. W. Glen (editor.) Johannesburg, The South African Institute of Mining and Metallurgy, 1982. 2 vols., 1060 pp. R78,85 (air-mail RI53,85). Amborite. Johannesburg, De Beers Industrial Diamond Division (P.O. Box 916), 1982. 6 pp. Free of charge. 3. New Journal BHRA Fluid Engineering has announced its new journal World Ports and Harbour Abstracts and the associated newsletter World Ports and Harbour News, which are issued from January 1983. The Abstracts is published bi-monthly and costs £60 in the V.K. and E.E.C., and £72 elsewhere. 4. Mintek reports Report 2134D On-line analysis, by X-ray diffraction, of fluorsparcontaining slurries. (First published 30th Sep., 1981.) Report 2135D A preliminary on-line analysis, by X-ray diffraction, of pyrite-containing slurries. (First published 30th Sep., 1981.) Report M28 The measurement of flow velocity distribution in fluids. Report M34 The determination, by atomic-absorption spectrophotometryusing electrothermal atomization, of platinum,palladium, rhodium, ruthenium, and iridium. Report M45 Two computer programmes for the calculation of massand heat balances in the production of high-carbon ferromanganese. Report M50 The development of an on-line gold analyser. Report M54 Major amounts of mercury in native gold from upper Witwatersrand sediments. Report M55 A new robust method for the treatment of analytical data. Report M57 The hydrometallurgical treatment of liquors generated by the leaching of a low-grade matte. Awards for inventions For inventing devices of exceptional value to the mining industry, two mining men were presented with awards in Johannesburg on 25th November, 1982, under the Chamber of Mines' Ideas and Suggestions Scheme. Mr W. W. Malan, President of the Chamber of Mines, made the presentations.

Jan 1, 1983

By J. Petersen, H. Naderi, M. H. Nikzad, M. Karimi

In this research, the thermodynamic study of sodium persulfate (Na2S2O8) solution in the presence and absence of H2SO4 and Fe3(SO4)3 was done. Eh-pH and equilibrium distribution diagrams were constructed using Outotec HSC Chemistry Software and the main stable ionic species were determined. Also, the mean activity coefficient and Pitzer model coefficients were evaluated. Effects of system composition, sodium persulfate concentration and temperature were investigated. According to the results, HS2O7 -, HS2O8 -, S5O3 2-, S4O3 2-, S3O3 2-, HS- and NaSO4 - are the main stable species in these three systems. Increasing of sodium persulfate concentration resulted in disappearing of SO4 2- and the appearance of NaSO4 -. The main effect of increasing the temperature from 25 to 75oC, is changing the stability regions of HS2O7 -, NaSO4 -, SO4 2- and S2-. From equilibrium studies, it was concluded that at 25 and 50oC, increasing the persulfate concentration results in a 55-60% decrease for HS2O7 - and an 20- 30% increase for HS2O8 -. At 75oC, HS2O8 - becomes the main species and its percentage decreases with increasing the persulfate concentration. Keywords: Thermodynamic, sodium persulfate, activity coefficient

Jan 1, 2020

By H. C. de Wet

The predevelopment and preparation of a total infrastructure in a deep level mining environment, prior to the shaft system being commissioned has major advantages. This paper intends to indicate these advantages and outline an understanding of the disadvantages. These benefits can be classified in three basic groups: the financial and timing advantages, a knowledge of the ore body and the development of required technology to meet the design parameters. The required technology in many aspects was still to be developed prior to successful application. Stemming from the technological evolution are some secondary advantages which will be described in each of the groups. Safety and health considerations and some practicalities made some of the new technology redundant prior to the actual application. In each case the actual achievements and the anticipated benefits will be indicated to allow the reader to distinguish clearly between planned and actual achieved advantages.

Jan 1, 1997

By M. D. Mwema

Copper oxide ores deposits in the Katanga province of the Democratic Republic of Congo (DRC) contain at variable level cobalt oxide minerals. In contrast to copper oxide minerals which readily dissolve in the sulphuric acid solution, the cobalt oxide bearings are difficult to dissolve, especially if cobalt is present in the third oxidation state (Co2O3). This species become soluble after reduction of Co+3in Co+2. In practice, the use of reducing agent is therefore necessary in order to transform the insoluble minerals into soluble cobalt sulphate species. The following reducing agents are currently used at the Shituru plant: ferrous ions, which are present in leach solutions, pulverised copper or sodium meta bisulphite (MBS). Due to the high consumption of reducing agents (0,8 t MBS/t of solubilized Co; 1,2 t Cu/t-Co), cobalt production is expensive. The use of sulphur dioxide as reducing agent was then investigated in order to reduce operating cost. This reagent also presents the advantage of sulphuric acid production during the leaching process. It has been added in the leaching vessel (tank). From the laboratory and industrial tests, selective leaching of cobalt (78%) has been performed. The cobalt leaching kinetic depend on sulphur dioxide dosage. Dissolution of copper, iron and manganese remained very low. No emanation of SO2 gas was observed during the process.

Jan 1, 2002

By P J. Grobler

The current commodity boom is depleting the ore bodies at a rate not seen in the past. As the existing ore bodies get depleted, only the more inferior bodies are left for exploitation. This places an emphasis on beneficiation to upgrade the lower grade ore to high-grade feedstock for downstream processes. This paper discusses the role of dense medium separation in this quest for high-grade feedstock for the future. It covers the production and utilization of ferrosilicon and gives a future perspective of the technology. It concludes about the way ahead and the challenges facing the processing fraternity and mining industry.

Jan 1, 2006

By M. Z. Emad, Y. Majeed, G. Rehman

Massive deposits of rock salt are mined in the Salt Range area of Pakistan. The main export products of rock salt include salt lamps, blocks, and tiles, while local consumption includes the chemical industry and domestic use. The profitable production of salt for value addition depends on the quality, size, and shape of the block. Salt processing for value addition is easier when very few cracks are present in the blocks. The current salt mining practice involves drilling and blasting, which introduces undesired fractures in the material. This paper focuses on the extraction of rock salt blocks by applying conventional cuboidshaped block mining methods used in quarries. The techniques include wedges and feathers, expansion chemicals, and blasting with low-yield explosives. Experimental work involved both laboratory-scale and in-situ field testing. Laboratory experiments assisted with the determination of splitting force, loaddeformation curves, and other rock mechanics parameters. Regression analysis proposes a relationship for the estimation of radial strain from the load in the case of the wedges and feathers method. The splitting force obtained from the laboratory tests was used to confirm the accuracy of the already published empirical relationship. The results of the laboratory as well as in-situ tests showed that the wedges and feathers technique is the most suitable method for mining rock salt blocks of the desired size, shape, while minimizing cracking.

Mar 2, 2022

By M. B. Algeo

Discussion of the above paper M. B. ALGEO The management and staff of Buffelsfontein Gold Mining Company Limited are to be congratulated on the excellent performances described in the paper presented by Mr Christos. In this day and age, with the current economic and labour situation, the mining industry is being constantly pressed to increase the productivity of ever-diminishing quanta of resources. Stress in rock The ISRM Symposium, 1976 is to be held in Sydney from 9th to 13th August, 1976. It is being organized by The Australian Geo. mechanics Society as a regional symposium of the International Society for Rock Mechanics. Thermal analysis The First European Symposium on Thermal Analysis will be held at the University of Salford on 20th to 24th September, 1976.

Jan 12, 1975

By F. T. Cawood

The new mineral royalty regime for South Africa was signed into law in November 2008, with its main objective being to compensate the State for the depletion of public minerals through a royalty charge payable from 1 March 2010. The aims of this paper are to establish the potential impact of mining royalties on State revenues, industry affordability, and explore whether the dual formula system is likely to encourage miners to become refiners. It also measures the royalty dispensation against economists? tax standards in an attempt to make a judgement on the ?equity? of the new system. This paper argues that most stakeholders should be comfortable with most of the requirements of the Act for most of the time. However, the new regime is unlikely to motivate miners to become refiners, as the benefit of the reduced rate on refined minerals appears to be insufficient to justify the additional costs to refine the mineral resource to the prescribed states of beneficiation.

Jan 1, 2011

By M. Royker

Gold has been demonstrated as a possible catalyst for oxidation reactions. Some evidence for a possible promotion effect of platinum has also been recorded. The influence of platinum as promoter for Au/?-Al2O3 prepared via anionic ion-exchange for the oxidation of glycerol was investigated in a batch reactor at 60°C. It is inferred that the addition of platinum reduces the catalytic activity and the rate of deactivation, resulting in an overall higher final conversion of glycerol with increasing platinum loading. The addition of platinum to the catalyst favours the formation of the desired product, glyceric acid.

Jan 1, 2012

By D. Mesa, J. Karvonenb, A. López, P. R. Brito-Parada, R. Grau, D. Davoise

The froth zone in flotation cells plays an important role in determining metallurgical performance. This is even more critical as cell sizes increase, since larger bursting surface areas can easily result in poor froth transport and even stagnant froth zones, which are detrimental to recovery. Generating additional overflowing lip length by adding internal launders and reducing surface area (while also directing the froth to the overflow) by adding crowders are well established design strategies to enhance froth mobility. However, comparative experimental studies of froth zone design modifications at industrial scale are scarce and often lack detailed froth characterisation. In this work, we present the results of two experimental campaigns that were carried out at Atalaya’s Riotinto concentrator in order to determine the effect of a new froth zone design on the flotation performance of a TankCell® e300 cell that operates as the first cell of the rougher bank. These campaigns provided a unique opportunity to assess froth phase phenomena and metallurgical performance before and after changes in design. The original cell design had an internal peripherical launder and a froth cone, while the new concentrate launder technology adds a centre launder and an adjustable froth crowder to the existing launder design. The new concentrate launder arrangement reduces significantly the froth area as well as the froth transport requirements, aiming to improve froth recovery and, consequently, enhance flotation performance, allowing copper recoveries in the TankCell® e300 cell to increase dramatically. In addition, radial profiles of froth height and froth velocity at the surface were determined, which provide valuable insight into the effect of design changes on froth stability and mobility. Keywords: Flotation performance, enhanced recovery, launder, crowder, froth stability

Jan 1, 2020

By J. A. Taylor, R. J. Fowell

Abstract: The amount of published literature pertaining to the field of rock mechanics has increased markedly in recent years. Whilst computer applications aid our understanding of the mechanisms of pillar instability, the applications do not take into account the effect of time; thus the determined pillar factor of safety has limited meaning. A more realistic approach would be to consider pillar stability in terms of time to failure. However such an approach would require a reasonable estimate of the in-situ pillar mass strength and a validated methodology linking the time to failure with in-situ pillar mass strength and the geometric layout of the working. Résumé: Le volume de bibliographie au sujet de la mécanique des roches a augmenté considérablement ces derniêres années. Alors que des modeles informatiques aident a la compréhension des mécanismes d'instabilité de pilliers, ces modèles ne prennent pas en compte les effets du temps; ainsi, la determination du coefficient de surete du pillier a un sens limité. Une approche plus réaliste devrait considérer la stabilité du pillier en fonction du temps de défaillance. Cependant une telle approche exigerait une estimation raisonnable de la resistance du massif rocheux du pillier ainsi qu'une méthodologie qui lie le temps de défaillance avec la résistance in-situ du massif rocheux du pillier et la géometrie de l'excavation souterraine. Zusammenfassung: Die Anzahl der Veröffentlichungen auf dem Gebiet der Felsmechanik ist in jüngster Zeit sehr gestiegen. Computerprogramme sind wertvoll um den Mechanismus der Pfeilerunbeständigkeit zu verstehen, aber sie vernachlässigen den Zeiteffekt. Daher haben die errechneten Sicherheitsfaktoren der Pfeiler nur begrenzte Bedeutung. Eine realistischere Bewertung wäre, die Stabilität der Pfeiler auf Grund der Zeit bis zum Verfall zu beurteilen. So ein Verfahren würde eine Schätzung der in-situ Gebirgsfestigkeit und eine validierte Methologie, die die Zeit zum Verfall in Abhängigkeit der in-situ Pfeilerfestigkeit und der geometrischen Auslage der Grube zusammenbringt, brauchen.

Jan 1, 2003

By A. M. Neale

Kriel Colliery has experienced some sub-standard blast results on the overburden. Blast results are considered poor when the fragmentation is too big, back break into the new highwall, capping is experienced and/or excess overburden material is thrown into the void. Poor blasting leads to lower productivity, equipment breakdowns, and poor drilling and blasting results on the adjacent blast, contamination of coal or loss of coal. A simulation was developed in Microsoft Excel to model blasting results while changing various parameters. From the simulation results, it could be seen that a change of blast design could be beneficial. As an example, smaller drilling patterns were simulated (10 m x10 m to 8 m x8 m, and 8 m x8 m to 7 m x7 m in Pit 5 and Pit 6 respectively) in combination with changes in explosives (P700 emulsion vs. ANFO) and drill bit diameter (311 mm vs. 251 mm). The results show that each of the options has a specific scenario that will be most beneficial to the mine. These results are quite specific and subject to variable inputs. The purpose of the example is to demonstrate how the simulation can be used as a tool to asses blast design variations.

Jan 1, 2010

By D. Malovichko

Seismic events and pillar failures observed in two platinum mines in the Rustenburg area, South Africa, were investigated. We studied the sources of approximately 300 largest seismic events recorded in 2009. Moment tensors of these events were estimated from amplitudes and polarities of P- and S-waves. The inverted mechanisms contain isotropic implosive components in many instances. Analyses of uncertainty of the moment tensor solutions confirmed the significance of the implosive component in general. Several documented cases of pillar failure were considered in detail. For each of these a seismic moment tensor was calculated from an elastic stress model assuming an instant removal of a failed pillar. The geometries and magnitudes of the theoretical seismic moment tensors are in agreement with the observed (i.e. inverted from seismic data). The results indicate that either pillar failure or fracturing in the proximity of the reef (within a fraction of the dominant wavelength of seismic waves) are responsible for a significant portion of the large events recorded in these mines.

Jan 1, 2012

By H. J. Ilgner

The paper reviews the results to date of an integrated research programme currently being conducted by CSIR Mining Technology, aimed at impacting significantly on concentrated mining with face advance rates of up to 20 times faster than presently achieved. Consideration is given to the interplay between innovative technologies for continuous non-explosive mining or rock comminution underground and lateral hydraulic transportation in cross cuts, haulages and eventually hydro hoisting. Novel technologies for underground comminution of reef and development waste and an innovative pumping system suitable for the hydraulic transportation of coarse comminuted rock are reviewed. Emphasis is placed on South African gold mine reef and waste samples comminuted by electric shock wave comminution technology. The innovative TORE® pump system appears to be well suited for the successful hydraulic transportation of rock, produced by electric shock wave comminution, at solids concentrations between 45 % and 67 % by mass.

Jan 1, 1997

By J. Y. Foley, K. Eden, A. E. Grosz, C. J. Giles, J. E. Grosz

"Portions of the Icy Cape placer Au district have been described and exploited since the early 1900s. Industrial studies of Au-bearing garnetrich intervals established a 3.5 million troy ounce resource in the western half of the district. This estimate is not compliant with CIM and SME definition standards for Mineral Resources and Mineral Reserves. We note high variability in the textures of sediments and their heavy mineral (HM) content and composition in the district, probably as a function of the depositional environment. Sediments are medium- to fine-grained sands with a valuable HM assemblage that averages 26.0% in a range of 1.1– 72.6%. Valuable heavy minerals (VHMs) garnet, magnetite, ilmenite, rutile, and zircon, but excluding Au, average 7.9% in a range of 1.0–37.6% of the HM assemblage. Trace quantities of uraninite, thorite, monazite, xenotime, and others are noted. Garnets have an average Y content of 726 ppm with a range of 0–2150 ppm. Energy-dispersive X-ray fluorescence confirms compositions commensurate with Ca, Al, and Mg silicates. We provide empirical analytical data and note high variability in the textures, HM content, and compositions as a probable function of depositional environment. Icy Cape District land and resources are owned by the Alaska Mental Health Trust Authority and managed by the Trust Land Office (TLO). IntroductionThe Icy Cape Heavy Minerals (HM) District in Alaska subtends more than 200 km2 fronting the Pacific Ocean and backing to the foot of the Robinson Mountains at about 1700 m above sea level. We classify the district into geomorphic provinces; the eastern region as deltaic (Figure 1) and the western region as coastal plain (Figure 2), based on geomorphologic expressions. The coastal plain is entirely built up of unconsolidated outwash sediments and ancient beach sand deposits."

Jan 1, 2017

By A. P. Cook

Gas samples were taken from a wide range of target areas on dumps arising from coal mining activities. Some of the dumps had largely burned out, some were still burning, some were in the process of rehabilitation, and on others rehabilitation was essentially complete. It was found that rehabilitation was very effective in reducing emissions to tolerable levels. Even incomplete rehabilitation reduced the CO2 emissions to less than about 1 kg/m2/a, whereas some unrehabilitated areas showed emissions of over 100 kg/m2/a. Some areas where there was active combustion taking place were also sampled, and they showed as much as 7 000 kg/m2/a, but the areas concerned were very small and their total contribution accordingly low. Analyses were also made for SOx, NOx, NH3, and CH4, but these were generally (and unexpectedly) at very low levels. The mines sampled represented 53 per cent of all surface coal mining activity. Accordingly the estimated total emissions were scaled up, to arrive at estimates of 1950 000 ± 350 000 t/a C02, 2040 ± 580 t/a SOx, 306 ± 85t/a NOx, and 31 ± 9 t/a NH3 for all surface mines. Methane was detected only from burning coal, and due to the difficulty in sampling, no reliable estimate could be made of these methane emissions.

Jan 1, 2012

By van der Merwem J. N.

"Coal pillars are prone to scaling over time, and are progressively reduced in size and consequently subjected to increased load and reduced strength. The effective factor of safety therefore reduces. Databases of failed and stable pillars cannot, therefore, be regarded as definitive.More than a decade has passed since the first attempt to predict the lifespan of pillars. This paper presents a review based on the new database and pillar strength equations. The methodology for the analysis is based on the fact that pillars scale. The ultimate safety factor (defined as the ratio between strength and load at the time of failure) is derived, followed by an estimate of the rate of pillar scaling, which results in an estimate of the expected time of failure.It is suggested that the predicted lifespan should not be used as an absolute indicator of expected pillar life, but rather as an index – the pillar life index (PLI) – to complement the safety factor and related probability of failure when evaluating pillar stability. A pillar with a predicted lifespan of less than 500 years would be regarded as being in danger of imminent collapse, while a lifespan of at least 1 000 years should be required for long-term purposes.The differences between this analysis and that published in 2003 constitute a strong case for regular reviews of all the empirically based stability indicators, namely the safety factor, probability of failure, and the PLI. Reviews at 10 year intervals appear to be required.The constants in the proposed method are valid only for the Witbank No. 1, 2 and 4 seams and the Highveld No. 2 and 4 seams.IntroductionIt is well known that over time, coal pillars are prone to scaling, and thus are progressively reduced in size and consequently subjected to increased load and reduced strength. The effective factor of safety therefore reduces and it is quite possible for failure to occur after a long time interval. In fact, scrutiny of the database of failed pillars indicates that failure occurred after periods ranging from 2 to 49 years, and not immediately after mining.The factor of safety for pillars at the time of failure is not the same as that immediately after mining. The concept of the safety factor is based on the pillar strength obtained by statistical analysis of pillar dimensions immediately, or within a month after mining, when the surveys are conducted. Strictly speaking, the safety factor as commonly used is valid only immediately after mining, and it continues to reduce thereafter. The ideal situation would be to base analyses of pillar strength on pillar dimensions at the time of failure, but that is simply not possible because the real dimensions cannot be measured at that time."

Jan 1, 2016

By J J. McEwan

Silver tarnishes readily in common atmospheres and is accelerated in humid atmospheres. Tarnish is the formation of silver sulphide on the surface of silver when it is exposed to a wide range of sulphur-containing atmospheres. Tarnish is unattractive and highly undesirable, and can be removed either with a silver polish or a chemical dip. Dips are generally only recommended when heavy black tarnish cannot be removed with a polish, and care must be taken during cleaning because these can contain aggressive chemicals and give off hazardous and unpleasant smelling fumes. Polishes work best for large areas of plain undecorated silver, and form part of a regular cleaning programme. Some polishes contain chemicals that inhibit tarnishing, but these generally only have a short life. Several methods have been developed to reduce tarnish formation on Silver; these include alloying, surface treatment, and coatings. The authors evaluated a range of self-assembled monolayer (SAM) surface treatments and coatings in earlier research. Four treatments/coatings increased the time to noticeable tarnish by more than ten fold, and the results were reported at the International Corrosion Congress (ICC) in 2005, and at the Mint Directors Conference (MDC) in 2006. SAM treatment using 95% 1-hexadecanethiol (C16H34S) was found to give good anti-tarnish performance and showed potential for the commercial treatment of Sterling silver. Therefore research was performed to optimise the methods of application of this type of coating to provide an easier, faster, and more-user friendly technique to provide an anti-tarnish treatment. Keywords: silver, tarnish resistant coatings.

Jan 1, 2006