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

In the copper electrorefining process, the dissolution of anodes is significantly reduced or even stopped when the passivation phenomenon occurs. The results of this phenomenon are increasing energy consumption, residual formatting, and voltage levels in the cell. In this study, the electrochemical behaviour of blister copper in the presence of sodium persulfate (PDS) was studied. The electrochemical methods of LPR, Tafel, and Electrochemical Impedance Spectroscopy (EIS) were used. The results showed that the addition of sodium persulfate activates the electrode surface and increases the open circuit potential. In the presence of PDS, the polarisation resistance of the electrode shows an increasing or decreasing tendency, based on the PDS concentration. This tendency is probably due to the formation of surface layers (such as slime layer or copper sulfate) and dissolution of this layer at various concentrations of PDS. The lowest polarisation resistance of 1.8 ohms and the highest corrosion current of 60.6×10-3 and 36.6×10-3 A/cm2 from LPR and Tafel techniques respectively were obtained at the concentration of 40 g/l PDS. Based on the results of potentiodynamic and electrochemical impedance spectroscopy tests, the addition of sodium persulfate to the solution reduces the corrosion resistance, therefore the passivation time of the blister copper anode increases. Keywords: Blister copper, electrorefining, sodium persulfate, anodic passivation

Jan 1, 2020

YEAR 1943-1944 Vol. 44 Page A major change-over in the ventilation of a deep level mine, by F. G. Hill and E. C. Ranson, 27; Discussion 56, 62, 67, 71, 72, 79, 123, 129 131 A note on the quarrying of surface limestone in the Sinai Desert, by V. L. Bosazza.. .. 59 Mining with diamond drills at the Nkana Mine of the Rhokana Corporation, Limited, Northern Rhodesia, by W. A. Odgers and A. G. Stirling, 95; Discussion 117, 121, 122 123 On silicates and dusts from the Witwatersrand gold mines (some preliminary notes), by J. J. Frankel, 169; Discussion .. 178 Presidential Address-Review of the rock pressure problem, by C. Biccard Jeppe, 3; Discussion 11,15 17 The chemistry, production and application of plastics, by P. N. Lategan, 138; Discussion 151 153 YEAR 1944-1945 Vol. 45 Page A microtechnique for the size-grading of mine dust, by S. R. Rabson, 34; Discussion 49, 50, 52 55 Activated carbon for regenerating used lubricating oil, by F. J. Tromp and J. J. Matthee 90 A contribution to the study of the production of zeolites, by C. C. le Grange and A. J. Petrick 235 A laboratory method for the determination of the suitability of South African coal and coal blends for the manufacture of metallurgical coke, by R. F. J. Teichmann .. .. 202 Copper containing cements for self-sanitising surfaces, by R. S. Young and H. L. Talbot 156 Notes on some sulphide minerals from the Far East Rand, by E. Mendelssohn, 84; Discussion, 88 89 Presidential Address-A review of underground support on the Witwatersrand with its Bearing on the Problem of ultradeep mining, by P. J. Louis Bok, 3; Discussion, 24, 25 27 Scientific management with particular application to a Witwatersrand gold mine, by J. S. Ford, 63; Discussion, 77, 80, 82 83 Some aspects of rock-drilling practice (the Witwatersrand gold field), by C. J. Irving, 163; Discussion, 185, 190 *197 Temperature measurements in a mine on the Witwatersrand with an electrical resistance thermometer, by O. Weiss, 127; Discussion, 136 137 The measurement of the geo-thermic gradient by means of the clinical thermometer, by R. A. H. Flugge-de Smidt, 105; Discussion, 136 137 The micro-chemical determination of free and combined silica in mine dust, by S. R. Rabson, 43; Discussion, 49, 50, 52 55 The oxidation of pyrites associated with South African coals, by R. F. J. Teichmann 141 YEAR 1945-1946 Vol. 46 Page Air cooling plant, No. 4 Shaft, City Deep, Limited. A review of layout and results achieved, by H. W. Unwin, A. Malcolm and R. E. Campbell Pitt, 66; Discussion, 100, 102, 103, 106, 110 115 A preliminary note on the Waterberg coal field as a possible source of coking coal, by P. E. Hall 124

By W. J. Cruise

This paper reports on a test that was conducted underground in a mine for two years on the following: pipes coated with paint, fusion-bonded powder, metal, or impregnated tape; and aluminium, stainless-steel, 3CR12, and plastic pipes. It was found that the degree of corrosivity and mechanical damage increases substantially from the shaft of a mine towards the stope. Thus, the range of coatings that can be used successfully is fairly large in the shaft and haulageways, but corrosion-resistant materials, especially corrosion-resistant steels, need to be used close to the stope. A study of the relative costs involved showed the costs of pipes of low-carbon steel and unplasticized polyvinyl chloride to be lowest, and those of epoxy-coated steel pipes to be highest.

Jan 1, 1985

By J J. Pretorius, G M. Hoffmann

Utilisation of lower-grade (<60 per cent Fe) resources, not utilised in the current products, is crucial to ensure optimal resource utilisation and maintaining/improving future profit margins by reclassifying low-grade material to ore. The purpose of the Sishen Expansion Project (?SEP?) is therefore to investigate the technical and financial viability of producing up to an additional 10 Mtpa of new products at Sishen from material currently classified as low-grade materials. Jigging technology has progressed to a point where Sishen?s 50 to 60 per cent Fe run of mine (?ROM?) material, once considered as waste, can be beneficiated to produce a saleable 64 per cent Fe product. This has been confirmed through appropriate beneficiation testwork. Consequently, Sishen can now produce saleable product from material not currently included in the resource definition, increasing the resource base of the mine significantly and ensuring higher resource utilisation. Mine Planning utilised the geological models to produce detail planning schedules, reflecting the current and SEP plants separately, optimised to comply with product specifications of both the current and SEP plants and to confirm the viability of the low-grade resources identified as SEP feed material. The SEP products specifications have been derived by optimally matching iron ore market requirements with the revised resource base. A 64.0 per cent Fe lump product and a 63.5 per cent Fe fine product are the optimal SEP products. The SEP plant will be able to produce 10Mtpa at an average yield of 60 per cent and a lump to fine ratio of 62 to 38. The plant consists of five major sections namely crushing, material preparation, beneficiation, final product handling and quality control services. Maximum integration with the current Sishen plant was considered. Kumba currently has an agreement with Transnet to rail up to 23.5 Mtpa through the Sishen Saldanha Iron Ore Export Channel (?IOEC?). Transnet and Sishen Iron Ore Company have signed a Definitive Agreement that deals with the expansion of IOEC?s capacity, which increases Kumba?s entitlement from 23.5Mtpa to 35.0Mtpa. The detailed enviro-legal impact assessments for the SEP indicated that the project has low enviro-legal risk as a result of it being a brownfields project incorporated into the current Sishen operations.

Jan 1, 2006

By J. C. Steinhobel

Answers to questions raised at the Symposium on Trackless Mining in Metal Mines Questions by J. O. Steinhobel (1) When rubber-tyred equipment is used for the delivery of stores and items of equipment, how is heavy material-pipes, rails, timber support, ventilation columns, etc.-dealt with? Termination of Membership In accordance with By-Law 7.6.1. of the Constitution of the Institute, the names of the undermentioned members have been removed from the membership register.

Jan 9, 1973

By S. Z. Shkundin

An evaluation of the accuracy of tachometric and hot-wire anemometers in mine workings and gas-media ducts is given. The acoustic means of gas flow rates measurement is considered with particular reference to the equations of acoustic waves propagation in aerodynamic fields. The paper defines how it is possible to minimize the error of integrating acoustic anemometers.

Sep 1, 2001

By T. A. Claasen

Exceptionally low yields in the coking-coal fields of the Soutpansberg area in the northern Transvaal, are taxing the skill and ingenuity of preparation engineers. The coals are highly intergrown, and a series of crushing and washing steps may be required to extract the maximum usable tonnage. In addition, novel preparation techniques may have to be employed. This paper, which is a case study of work recently undertaken, gives a general account of raw coal properties, emphasizing those related to maximum recoveries, and outlines the steps involved in the design of appropriate flow sheets based on laboratory studies.

Jan 1, 1980

By J. Levin

The Bond standard grindability test provides a Work Index that is widely used to estimate the energy required for grinding, but the test cannot be applied to fine materials such as plant tailings and middlings. For such materials, a comparative grinding test must be used in which a reference material from an operating plant is ground in a laboratory mill to determine the &apos;equivalent&apos; energy consumption per revolution of the laboratory mill. As the Bond grindability test mill and its operating conditions are specified, its equivalent energy consumption per revolution should be a constant, here designated as B. Once B has been determined, the mill can be used to estimate the grindability of fine materials without the need for reference materials. A value of B can be calculated from any Bond grindability test, and 245 tests that were conducted at Mintek were examined to determine its value. A wide range of values was found, but most of them were grouped around 198 x 10- 7 kWh/rev, which is taken as the best estimate of B that is available at present. Values of B that are not close to this figure are obtained from materials for which the Bond grindability test gives misleading or &apos;spurious&apos; Work Indexes. These spurious Work Indexes lead to the apparent departure of B from its true value. Some limitations of the Bond grindability test arise from its use of a mill without litters and of screening, instead of classification, to close the circuit.

Jan 1, 1989

By P. K. Van Manen

Anglo Platinum?s Polokwane Smelter is situated outside Polokwane, in the Limpopo Province in South Africa. A single 168 MVA six-in-line rectangular furnace smelts dry concentrates containing platinum group metals (PGMs). Furnace energy consumption since commissioning is presented, showing that energy efficiency improves as capacity utilization increases. An energy balance for the furnace is outlined, indicating the measured or calculated energy losses from the hearth and side-wall cooling, the copper coolers, the upper furnace walls and roof, and the energy losses in off-gas, matte, and slag. From the energy balance, the potential to improve energy efficiency by controlling the slag temperature, the slag level, and the off-gas volume is derived. Furthermore, the impact on the energy balance of different concentrate types is discussed, as well as the potential impact of replacing all upper waffle coolers by plate cooler panels.

Jan 1, 2009

By P Clive Hart

DRA - BACKGROUND [MULTI MINERAL DESIGN & BUILD COMPANY FOUNDED 1984 ENGINEERING FOCUSED CORE ENGINEERING DISCIPLINES INCLUDE: ?PROCESS ?MECHANICAL ?E&I CONTROL PRIVATE COMPANY, INDEPENDENT & INTERNATIONAL]

Jan 1, 2006

By B. P. Gilbertson

In her wonderful book, &apos;The Guns of August&apos;, historian Barbara Tuchman tells us that the French war plan for 1914 was dedicated entirely to an offensive strategy, not a defensive one. Plan 17, as it was called, concentrated everything on a French advance to the Rhine, leaving the French left virtually unguarded. This strategy could only be justified by the fixed belief that the Germans could not deploy sufficient manpower to extend their invasion around through western Belgium and the low provinces; and this in turn was based on the belief that the Germans would never use reserve troops in the front line. Al evidence to the contrary was ignored. But when the war came, the Germans followed Count Von Schlieffen&apos;s plan; they did use reserves in the front line and they did come the long way around on the west. The result- as you know-was a protracted war, with fearful consequences for the rest of our century.

Jan 1, 1994

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 M. Akyüzlü

The equilibrium between carbon-saturated Fe-Cr-Si-C alloys and SiO2-CaO-MgO-A2O3-CrO2-FeOy slags was studied under atmospheres of argon and carbon monoxide at temperatures of 1500 and 1600°C. The equilibrium distribution of chromium, silicon, and iron between the slag and the metal phases was determined for different compositions of both phases under different atmospheres and temperatures. It is shown that silicon transfer from the slag to the metal increases with increasing temperature, decreasing carbon monoxide partial pressure, decreasing carbon content of the metal, increasing chromium-to-iron ratio of the metal, increasing silica content of the slag, and decreasing lime-to-alumina ratio of the slag. Some activity calculations were made for the experiments conducted at 1600OC in a carbon monoxide atmosphere. It is also shown that a decrease in the iron content and an increase in the slag basicity decrease the chromium content of the slag. A major proportion of the chromium present in the slag was found to be in the divalent state under the highly reducing conditions prevailing in the experiments. The chromous capacities of these slags were calculated and were found to decrease with increasing basicity.

Jan 1, 1992

By M. Reuter

This paper gives an overview of some criteria for the selection of processes for the recovery of lead and zinc from various raw materials and/or intermediate products. A glossary of possible processes and process variants, is presented and discussed, as well as the way in which these are interlinked. Recent developments in metallurgical process synthesis are also discussed, and the results produced by an eco-techno-.economic synthesis procedure for process routes in zinc metallurgy are given briefly. The way in which such a synthesis can complement a life-cycle assessment (LCA) of zinc-producing technologies is also described.

Jan 1, 1997

A dual rate kinetic model consisting of differential equations is used to describe the kinetics of the adsorption of gold cyanide on activated carbon. The partial differential equation describing the material balance in the liquid phase is written for the special case of a fixed bed system. It is shown that an isotherm for the case of a closed system is required to yield accurate simulations of the equilibrium in a column of activated carbon. Whereas the equilibrium loading of gold cyanide is influenced by the free access of oxygen to the system, the traditional open batch stirred tank experiments, which are used to estimate parameters for the calculation of breakthrough curves for organic solutes, cannot be used here. The program solves this model at incremental heights in the column at a specific future point in time. Runge-Kutta and backwards- difference methods are used in the numerical solution. A Von Neumann method is used to show that the solution is stable. Kinetic parameters can be estimated either from batch experiments or from short column runs. In the latter method the column should not be long enough to contain the concentration wavefront for the system of interest. Results obtained from bench scale continuous column experiments were used to verify the computer model. Pure gold solutions as well as real leach liquor were used in both short column and countercurrent moving bed experiments.

Jan 1, 1987

By Nareetsile S., J. Kabwe

In the past few years Orapa and Letlhakane Mines have investigated various new technologies to enhance and improve production. The goal has been to improve productivity, reduce operating costs and make the mines more profitable The advent of Global Positioning Systems (GPS) in the early ’80s brought about the realization of this concept. Orapa and Letlhakane Mines started using GPS in 1999 and it is now used atLetlhakane mine for surveying, vehicle tracking and dispatching and for floor control system. Orapa Mine uses GPS in surveying, floor control and drill navigation. It will also be used for vehicle tracking and dispatching in mid-2001 following the installation of a fleet management and control system. The introduction of GPS at both Orapa and Letlhakane mines have improved productivity and reduced operating costs in the areas of drilling, topographic survey and floor control. In vehicle tracking and dispatching GPS has allowed for real-time information management for timeous decision-making which optimized fleet run time hours.

Sep 1, 2001

By R. J. Mostert

The role of hardenability in the development of high-strength low-alloy (HSLA) steels is discussed. The applicability of the superhardenability treatment. a steel making technique for increased hardenability, to HSLA steels is indicated, and the literature on this treatment is reviewed. Several low-carbon superhardenability HSLA steels were designed by use of published superhardenability multiplying factors. It was found that the hardenability of these low-carbon steels can be increased to the same extent as that of medium-carbon steels. The mechanical properties as determined in normalized bars indicate that the superhardenability treatment can be used successfully in the production of low-carbon hot-rolled HSLA steels.

Jan 1, 1984

By C. Musingwini, T. C. Sebutsoe

"The primary objective of any mining business unit is to make profit by extracting, processing, and selling minerals from a particular mineral deposit. It is important to optimize extraction of the mineral resource given time, capital, and space constraints. Mineral extraction is often associated with uncertainty due to variable technical and human factors. Technical factors such as grade distribution, ground conditions, and equipment reliability influence the performance of a mining production system (MPS). The performance of the MPS is also impacted by human factors such as employee skills, health, and attendance. Uncertainty associated with technical and human factors often leads to actual output differing from what was planned. Therefore an in-depth analysis of the significant causes of deviations from the planned outcomes is relevant.In this paper we investigate the empirical relationships between inputs and outputs in a MPS in order to assist management in directing efforts at key production drivers. Once a MPS has been empirically characterized, more effort and resources can be focused on the key decision-making variables (DMVs) in order to meet the planned outcomes.For a typical underground, tabular, narrow-reef conventional drill-andblast platinum mine the face advance, face length mined, number of teams, team efficiencies, and team size have a statistically significant relationship with the centares (m²) produced, which is a key performance indicator (KPI). The production function derived in this study can be used to align the physical, technical, and human factors together to predict the optimal output level. The most significant production lever of the MPS is the face advance. IntroductionA mining production system (MPS) is a result of an iterative process of design, planning, and optimization of mining input variables and decision-making variables (DMVs). The MPS exists within the mineral extraction link of the complete mining value chain. It represents the stage where mining companies have the opportunity, through production, to start generating returns on the investments undertaken. Returns on shareholders’ investments can be realized at this stage."

Jan 1, 2017

By H. M. Friede, R. H. Steel

Tin mining and smelting in the Transvaal during the Iron Age by H. M. FRIEDE*. Ph.D. and R. H. STEEL* (Visitors) This paper reviews the historical, archaeological, and metallurgical evidence on Iron Age tin mining and tin smelting in Southern Africa. The results of the analysis of twenty samples of tin ore, tin slag, and tin ingots found associated with Iron Age materials in the Transvaal (mostly in the Rooiberg area) are reported and discussed. The types of ingots preserved in local collections are described. A small experimental tin-smelting furnace was constructed and worked according to traditional African Iron Age technology. Qualitative and quantitative results of this experiment are reported.

Jan 7, 1976

By A. H. Mokken, G. K. I. Blendulf, G. J. C. Young

A study of the arrangements for pulp discharge on pebble mills, and their influence on mill performance by A. H. MOKKEN, B.Sc. (Eng.) (Rand) (Fellow), G. K. I. BLENDULF, M.Sc. (Stockholm) (Member), and G. J. C. YOUNG, B.Sc. (London) (Member) Although used for many years in the gold-mining industry, the conventional pan lifter at the discharge end of a pebble mill has hindered attempts at optimization of speed of rotation and pulp flow. A theoretical approach to flow patterns in pan lifters has pointed to limitations in the capacity of these lifters, with capacity decreasing as speed of rotation is increased. Complete elimination of the pan lifter by the adoption of peripheral or end discharge has resulted in a marked increase in pulp flow and an improvement in power utilization. Assays of the gold content of pulp discharged after a mill stoppage from mills fitted with pan lifters show values well in excess of the current milled grade, which indicates an accumulation of gold particles in the mill and, therefore, a longer retention period. The same could apply to other heavy minerals and metals present in the ore feed or worn off mill linings and metallic grinding media. Examples are osmiridium, fine iron and iron alloys, and copper and sulphide minerals. This phenomenon is attributed to the higher specific gravities of these metals and minerals, causing them to migrate towards the mill shell, from which position they are not readily removed by the lifters at the discharge end of the mill. The close association of gold particles with iron and sulphide minerals in the crevices of mill liners might be conducive to the formation of coatings on the gold. Assays of samples of milled pulp taken from a mill designed for end discharge show a lower accumulation of gold. The accumulation and nature of these gold particles are being studied at present. With increasing diameters of pebble (or autogenous) mills, peripheral or end discharge appears to be the preferred method of pulp removal.

Jan 5, 1975