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By W. Mbhalati

"Conzal Mine was not meeting production targets in 2013, and it was established that this was caused by the inability of the load haul dump machines (LHDs) to tram the required tonnages. An investigation of the LHD productivity was therefore conducted to identify the inhibiting factors. This was accomplished by carrying out a literature review on LHD operations to gain in-depth knowledge and conducting observations in the working environment. The relevant information and data on the LHD type used at Conzal was also acquired.The major inhibitor was found to be excessively long tramming distances in all the sections of the mine. The one-way tramming distances were all significantly greater than the 90 m set in the mine’s code of practice (COP), with the Main Shafts section having the longest average one-way tramming distance of 260 m. The other inhibitor was LHD utilization, which in 2013 was only 47% against a target of 70%. Simulation of the LHD operation, taking these two factors into account, showed that production could be increased by more than 100%. As a result, it was recommended that conveyor belts should be extended regularly in order to keep tramming distances within the recommended one-way distance of 90 m. In addition, utilization can be improved by minimizing employee absenteeism as well as by modifying the travelling routes such that LHDs do not encounter unnecessary delays.Paper written on project work carried out in partial fulfilment of BSc. (Mining Engineering)"

Jan 1, 2015

By N. Sacks, N. B. S. Magagula, I. Botef

"Low-pressure cold gas dynamic spraying was used to deposit WC-4wt%Ni and WC-4wt%Ni-1wt%Mo coatings onto mild steel. Dense coatings with very low porosities were produced. No decarburization occurred during deposition and no deleterious phases were formed. The coatings were subjected to standardized material characterization tests, as well as slurry abrasion testing to assess their wear behaviour. The wear tests were conducted in synthetic minewater-silica slurries, while distilled watersilica slurries were used as a control. The hardness of the coatings, 512HV0.3 and 458HV0.3 for WC-4wt%Ni and WC-4wt%Ni-1wt%Mo respectively, are comparable to those achieved using high-temperature coating processes. The abrasion wear rates for both coatings were less than 5 mg/min and 10 mg/min in the distilled water-silica and synthetic mine water-silica slurries respectively. The approximately 50% increase in wear rate in the synthetic minewater slurry is attributed to a synergistic corrosive wear mechanism. The predominant wear mechanisms were identified as binder smearing and delamination, with carbide grain fracture and pull-out. IntroductionSlurry abrasion is a common phenomenon in mining operations, particularly in pipelines transporting, for example, sand-water slurries. This type of wear can cause pipeline fracture, shortened operational lifetimes, and impede pipeline efficiency. To reduce or limit abrasion, thermally sprayed tungsten-carbide-based coatings are often used as pipe linings (Kanchan et al., 2010). This is due to their attractive mechanical properties, which include high wear resistance, stiffness, hardness, compressive strength, and tensile strength. These properties are provided by the coating microstructure and composition, which is a blend of hard, wear-resistant tungsten carbide (WC) particles embedded in a fracture-tough metallic binder phase (Brookes, 1997). Cobalt (Co) is the most commonly used binder due to its excellent wetting of the WC phase and moderate mechanical properties; however, its application is limited to non-corrosive environments as it has a low corrosion and oxidation resistance (Andren, 2001). Nickel (Ni) may also be used as a binder, and has been shown to have superior oxidation and corrosion resistance, but in some applications may not have the required mechanical properties (Kim et al., 2006)."

Jan 1, 2016

By C. K. Chabedi

"This paper discusses the difficulties associated with the potential exploitation of the deep multi-seam resources east of the Daarby fault in the Waterberg coalfield. The resources occur at a depth greater than 250 m and the thickness of the coal is roughly 110 m, but the top 50 m comprises coal intercalated with shale and the bottom 60 m contains five seams with sandstone and shale partings. Various factors affecting multiple seam mining at these great depths are discussed with reference to lessons learned from local and international experience on multi-seam mining. Field geological and geotechnical data was utilized to assess the stability of the roof of the seams. There is no specific rock mass rating for the Waterberg area, therefore approximate coal mine roof rating (CMRR) values were used to propose appropriate support strategies. Analysis of Multiple Seam Stability (AMSS) was used to analyse the strength of the parting or interburden between the various seams, the mining sequence, and the interaction between the various seams.The research indicated that it is possible to mine seams with a low CMRR at high mining rates using longwall mining, although support for gateroads is expected to be expensive, time-consuming and onerous to install, and will impact gateroad development rates. It will not be possible to simultaneously mine zones in close proximity and failure of the interburden is predicted, thus dangerous mining conditions are anticipated. However, it will be possible to mine just two of the eleven zones using longwall mining. IntroductionThis paper discusses the difficulties associated with the potential exploitation of the deep multi-seam resources east of the Daarby fault in the Waterberg coalfield using bord and pillar and longwall mining. Figure 1 illustrates the location of the Waterberg coalfield relative to other coalfields in South Africa, while Figure 2 shows the areas containing deep and shallow resources. The Waterberg resources are expected to contribute to South Africa’s future energy requirements, and are currently exploited at the Grootegeluk open pit mine. Grootegeluk produces coal mainly for a power station, with the higher quality product supplied as metallurgical coal. The deposit is technically unique and challenging, being a multi-seam coal deposit with a total of 12 seams over a thickness of 110 m as shown in Figure 3, including Zone 5. There is currently limited knowledge on the multi-seam mining of the deep Waterberg resources. Multi-seam mining utilizing the bord and pillar method has been practised in South Africa before, but at a depth of less than 100 m in the Witbank coalfields. Multi-seam mining in thin seams has also been performed in the Natal coalfields at a depth of less than 160 m, but mostly using bord and pillar mining and secondary mining (partial pillar extraction)."

Jan 1, 2016

By C. N. Harman, N. S. S. Rama Rao

Production of Ferro-alloys through submerged electric arc furnace involves use of electric power as one of the major inputs. Hence the production by this power intensive process can be made economically more competitive if the specific power requirement for smelting each ton of the product is brought down. This becomes all the more necessary where the power cost is comparatively high, like in India. Since the day FACOR started production of Ferro Chrome in 1968, briquetted chromite fines along with lumpy ores were used as feed. Subsequently the increase in the proportion of briquettes and reduction in lumpy ore helped in increasing the use of chromite fines and also brought down the specific power requirement. Meantime FACOR had been closely watching the technical development of use of sintered pellets in Outokumpu and SRC Processes which need still lower specific power. But the high capital requirement for a pelletisation plant kept FACOR from introducing pellets feed to their Ferro chrome furnaces. So this was postponed to be adopted in future. In February 2004 in the ?1st Ferro-Alloys India?, a paper [1] was presented by Dr. Amit Chatterjee. In the questions period after the presentation of the paper there came up a discussion in which it was revealed that with the Indian high grade chrome ores it was not possible to make sufficiently strong pellets, unless a larger percentage of bentonite is used as binder. This is because the Indian high grade Chrome ores have different mineralogy of gangue content compared to low grade ores in Finland and South Africa. Higher usage of bentonite gives rise to higher slag volume and this would result in increased specific power. Since FACOR had plans to go in future for sintered pellets feed, this gave rise to a doubt on success of pelletisation for Indian high-grade chrome ores. This prompted FACOR to take up experimental production of sintered chromite pellets and use of the same in one of their existing furnaces for production of high carbon Ferro chrome. The results are encouraging and are summarized in the paper.

Jan 1, 2007

By P. S. Piper

In the 1960s it was suggested that the volume of stope convergence, and hence the rockburst hazard, could be reduced by the emplacement of backfill. Recent advances have facilitated the placement of large quantities of backfill underground, and a reassessment of its potential benefits as part of a regional support strategy is now timely. In this paper the principal criteria of effectiveness of backfill are taken to be its impact on face energy release rate (ERR) and average pillar stress (APS) levels, and maximization of acceptable ore extraction ratios. The possible effects of backfill on excess shear stresses (thought to modulate large seismic events) are also briefly reviewed. Analytic solutions describing backfill properties and their impact on ERR and APS in certain idealized geometries are also presented, and compared with the results of an extensive suite of computer simulations, in which parameter sensitivities are explored. Results indicate that a regional support strategy is required at depths exceeding 2 km in order to maintain acceptable levels of ERR, and backfill ribs can on their own fulfil this role at depths less than 3,3 km. At greater depths use of stabilizing pillars becomes imperative, but here too supplementary backfill ribs can reduce ERR and APS levels and permit significant increases in ore extraction ratios.

Jan 1, 1988

The relationships between backfill-transportation parameters (solids concentration, velocity, and pipe diameter) and the wear rate of backfill-transportation pipelines is well understood. However, the degree of wear experienced by a pipeline depends not only on the transportation parameters, but also on the characteristics of the solids making up the backfill, i.e. the particle-size distribution, hardness, shape, and sharpness of the particles. Therefore, unless data corresponding to the specific wear rate of the solids are available, the determination of the wear rate for pipes transporting an uncharacterized backfill is largely guesswork. This paper describes an evaluation of particle characteristics with special reference to particle sharpness so that pipe wear rates can be correlated with solids of different size distributions and sharpnesses.

Jan 1, 1993

By J. Szlazak, A. Tor, M. Borowski, N. Szlazak, D. Obracaj

This article presents the analysis of ventilation systems used in dead-end headings, while being drilled, in coal mines. Special emphasis is put on methane and dust hazard. Mathematical model for distribution of methane concentration in a heading is given as well. This model takes into consideration sources of methane emission and change in air flow rate due to leaks in a duct line. Solving equations presented in this article enabled giving dependencies describing distribution of concentration along the heading. On the basis of these dependencies there is a possibility of determining places with higher methane concentration and ways of combating this hazard. Determining the distribution of methane concentration in dead-end headings ventilated by a separate ventilation system is of great importance as far as work safety conditions are concerned. The information obtained may be of use when finding proper places for installing methane sensors. Three kinds of separate ventilation systems were distinguished: forcing, exhaust and overlap. The development in construction of fans and spare parts of a duct line enables using both forcing and exhaust ventilation systems in headings developed by continuous miners, with length above 1000 m, in the conditions of methane, temperature and health-detriment dust hazards.

Jan 1, 2003

By A. C. Legg, M. T. Malema

Keywords: Pyrometallurgy, flash, smelting, furnace, nickel, copper, Botswana BCL Limited operates the only Flash Smelting Furnace on the African continent, at Selebi-Phikwe, situated in north-eastern Botswana. The furnace was commissioned in 1973 and produces a high-grade sulphide matte containing nickel, copper and cobalt, which is shipped to refineries in Zimbabwe and Norway for further processing. This paper outlines the recent process improvements and plant expansions that have resulted in a capacity increase from 40 000 to 60 000 tons per annum of metal production.

Jan 1, 2006

By D. A. Viljoent

Historical Background The Empire Council of Mining and Metallurgical Institutions was formed during the early 1920s to foster the holding of British Empire Conferences, and today is representative of the following Institutes: Australasian Institute of Mining and Metallurgy Canadian Institute of Mining and Metallurgy Geological Society of South Africa Institute of Petroleum Institution of Metallurgists Institution of Mining and Metallurgy Institution of Mining Engineers Metals Society Mining, Geological and Metallurgical Institute of India South African Institute of Mining and Metallurgy South Wales Institute of Engineers. The first public suggestion for the formation of a Council that would link mining institutions in various parts of the British Empire came from Mr Frank Merricks, who, as President of the Institution of Mining and Metallurgy, was speaking at the annual dinner of the IMM in 1921.

Jan 1, 1981

By R. G. Jurd

This paper considers the introduction of large-scale longwall mining into South African coal mining, instead of the conventional mechanized bord-and-plllar mining that is widely practised at present. The two methods are compared, and longwall mining is found to have the advantage in several respects in some seams. The most cogent reasons for the introduction of the longwall method In some seams are associated with safety strata control and increased labour costs.

Jan 1, 1978

By T. Gerritsen, R. C. Delgado, J. Janzen, E. R. Veloza

The paper describes the components of an Integrated Furnace Control system for covered-arc (shielded arc) smelting with results from the recently started 75 MW Cerro Matoso Line 2 Furnace. The paper starts with a review of the mechanisms of power and feed input and heat losses in the shielded-arc smelting process, and describes how the details of the control system are tailored to the process. The control modules of a covered-arc smelting furnace are described including measured results and screen captures. This paper focuses on Integrated Furnace Controls tailored to shielded-arc smelting, but similar approaches have been recently applied to other furnace processes including immersed-arc smelting.

Jan 1, 2004

The Annual General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 26th August, 1970, at 4.15 p.m. Mr. J. K. E. Douglas (President) was in the Chair. There were also present sixty-three Fellows, thirty-five Members, one Graduate, eight Associates, five Students and nineteen Visitors, making a total of one hundred and thirty-two. The President declared the meeting open at 4.20 p.m. OBITUARIES The President: 'It is my sad duty to announce the deaths of the following members of the Institute. Dr J. A. Papenfus, Fellow, who joined the Institute in 1942 and passed away on the 28th of May, 1970. Mr D. G. Beadle, Fellow, who joined the Institute in 1946 and passed away on the 17th of June, 1970. Gentlemen, Derek Beadle was very well known in this Institute. His papers on dust will be remembered and, at the time of his untimely death, he was one of our assistant editors. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, I would ask you to rise and observe a few moments' silence.' MINUTES The President: 'May we confirm the minutes of the General Meeting held on 15th April, 1970, as published in the July, 1970, issue of the Journal'. Agreed. WELCOME TO VISITORS The President: 'Ladies and Gentlemen, we are honoured this afternoon by the presence of many distinguished guests and I extend to you all a most cordial welcome. We are happy to have with us Dr A. A. von Maltitz, President of the Chamber of Mines of South Africa, who is also Honorary President of this Institute. We also have one of our Honorary Vice- Presidents, Mr T. L. Gibbs, the Government Mining Engineer; Mr D. E. Hamm, President, Institution of Certificated Mechanical and Electrical Engineers, S.A.; Mr S. C. M. Naude, Director, Witwatersrand Technical College; Mr I. R. G. Stephen, Senior Vice-President, The S.A. Institute of Electrical Engineers; Mr G. M. Tompkins, President, The S.A. Institution of Mechanical Engineers; Professor P. B. Ackermann, President of the Geological Society of S.A.; Mr A. S. Robinson, Vice-President of the S.A. Institute of Civil Engineers; Professor W. Mare, President of the Institute of Land Surveyors of the Transvaal; Mr B. D. Charlton, President of the S.A. Institute of Assayers and Analysts; Mr R. Hemp, The President, The Mine Ventilation Society of S.A.; Mr L. J. Prince, The President, The S.A. Association of Mine Managers; Mr J. Botha, The President, The S.A. Institute of Foundrymen; Mr G. Niterl, The President, The Institute of Welding; Mr M. R. Gericke, President, S.A. Council of Professional Engineers; Mr N. A. Honnet, Chairman, Orange Free State Branch; Mr P. R. C. Cooke, Chairman. The South African Chemical Institute (S. Tvl' Section). Gentlemen, we are very honoured indeed, to have these distinguished gentlemen with us this afternoon, as our honoured guests. We are also pleased to have with us, one of our Honorary Fellows, Mr F. G. Hill, and several Past-Presidents. I also extend a very warm welcome to all our lady guests and to all our other visitors.' MEMBERSHIP The President: 'I have pleasure in announcing that the names of the following candidates, having been published in accordance with By-Law 5.2.2, Council has elected them to membership in the following grades: NEW APPLICATIONS Fellows: Herbert Dalton-Brown, Stephen William Morel. Members: Clive Lester Workman-Davies, Basil James Russell Botha. Students: Timothy Nigel Watson, John William Hairbottle. I wish to welcome the new members to the Institute and to congratulate those members who have been transferred to a higher grade.' ANNUAL REPORTOFTHE COUNCILAND ACCOUNTS FOR THE YEAR ENDED 30th JUNE, 1970 The President: 'I now have pleasure in presenting to you, the Annual Report and Statement of Accounts for the year ended June, 1970. These have been handed to you this afternoon and, as is customary, I propose they be taken as read. Before moving their adoption, however, I would like to refer to some of the salient features, leaving as is usual, the task of dealing with the finances, to our Honorary Treasurer. It is encouraging that membership has continued to grow, and now stands at 1,613, an increase of 61 over last year's total. Your Council, however, is aware that there are still people in our mining and metallurgical industries, who could qualify for membership, but who have not yet joined the Institute. A drive to increase membership was accordingly organised, and members of Council were given the responsibility for campaigning in sections of industry, and for publicising the objectives and advantages of belonging to the Institute. Up to now there has not been much reaction to this campaign, but I hope we will see results in the coming year. At the same time, Council has recognised the need for change in the conduct of the Institute's affairs in order to meet the changing needs of our membership. Our members, both mining and metallurgical, are in the first place, geographically more widely dispersed than they used to be, and secondly, with the growth of the metallurgical industry, their technical interests are now more diversified. The Institute must cope with these changing needs if we are to continue to perform a useful function. The

Project evaluation is completed through individual studies covering technical and financial aspects of the mine to market. These studies are completed at various levels of detail depending on where the project evaluation is in the project's life cycle. The competency of the studies varies in relation to the quality of data, level of the skills employed, control, management and reporting structure. The focus of this paper is managing elements of the study, looking at the cost of opportunity to influence the project, against the value added. Selection of the study manager and study teams is central to getting an integrated project evaluation addressing the correct issues completed on time. Retention of key personnel can reduce rework which, in turn, can reduce time and cost impacts. It is important to have a work breakdown structure at the outset so that the study teams have a common numbering and naming system that will integrate areas, equipment, budgets estimates and accounts. Having set up the evaluation groups and provided training in the study procedures, understanding the scope and schedule are vital elements in producing a project evaluation that addresses the opportunities and the risks of the final project. Arriving at an accurate capital budget requires integration of the research controlled through common systems. Project evaluation process must also address how the project is to be delivered.

Jan 1, 2007

By H. P. Kritzinger, T. C. Kingsle

"Rotary kilns are used for a variety of mineral processing operations. Hatch makes use of a kiln model developed from first principles to evaluate designs for its clients. This tool has been applied to a variety of pyrometallurgical applications, including ferrovanadium, nickel carbonate, nickel laterite, iron ore reduction, and spodumene (lithium) production.This paper illustrates the application of numerical optimization techniques in combination with the kiln model in the interrogation of a generic iron ore reduction process. The fundamental modelling concepts are explained, followed by a description of the optimization approach. The results show how the combination of the two methods, with modern computing power, can generate a large number of viable design and operating candidates."

Jan 1, 2015

Often plant performance suffers as a result of poor control. Poor control leads to low mill throughputs, poor classification and less than satisfactory concentrate grades and overall recoveries. By using the appropriate control tools, substantial gains in plant performance can be made. Mintek?s MillStar and FloatStar controllers have been implemented at various sites across the world. The MillStar controller incorporates leading technology that controls process units from the mill feed through to the flotation feed. Typical results show that milling circuit throughput is increased by 6-10 % and the final product grind size is tightly controlled, thereby enhancing flotation performance. The FloatStar controller is aimed at stabilising and optimising flotation circuits. Through improved level control alone, recovery improvements of up to 1 % have been achieved. Furthermore, by using on-line grade analysers, the controller stabilises final concentrate grades, whilst maximising flotation recovery.

Jan 1, 2005

By N. D. L. Burger, S. Thorley

In engineering design of operators? compartments, in underground mining equipment, ergonomics principles are often neglected or not given the full recognition they deserve. This paper defines ergonomics, applies it to machinery in an underground mining environment, and describes the ergonomics analysis undertaken during the design phase of an EJC extra low-profile mining loader. Encompassing the design of the operator?s compartment of this new loader, this paper illustrates the importance of ergonomic principles within the collective design process ensuring that it is fully integrated into the design approach. An ultimate aim of this study is to ensure that all future designs follow this route to guarantee not only the outcome of a highly efficient, cost effective and productive machine but that it is also takes the human factor into account, not only in maintenance but also in operation. Maximizing comfort will have the ultimate outcome of actually increasing productivity beyond expectations.

Jan 1, 2004

By W. F. Lorch

Growing use of deionised water in surface coating techniques by w. F. LORCH Production engineers in the metal plating, paint, plastics-coating and printed circuit industries are increasingly aware of the cost of sub-standard or blemished items which have been poorly processed. An area where quality control can quickly produce higher efficiencies is in the choice of suitably purified water for making up solutions, for rinse baths and 'drag-out' baths, for cleansing lines and electrophoresis tasks, for maintaining electrolyte density and hence consistency, and for facilitating the recovery of valuable minerals. The author of this article examines the general problems of using nonpurified water, and shows how purified water has become accepted by the principal surface coating industries to improve processes and effect economies.

By M. I. Brittan

SYNOPSIS The key reactions of the copper segregation process have been studied with a view to establishing the kinetics of the system. The investigation was carried out using two refractory copper ores from the Zambian Copperbelt in a small-scale, fluidized bed, chloridization reactor. The rate of chloridization of the copper in the ores is compared with the rate of volatilization of the cuprous chloride produced and with the rate of reduction of the cuprous chloride to form segregated metallic copper. In conjunction with available data on the rate of production of hydrogen chloride in a segregation system and with due regard to the conditions applicable in a TORCO reactor, it is concluded that the chloridization reaction is the major rate limiting step of the process. Factors influencing the rate of this extraction step and aspects of its mechanism are examined. The findings have confirmed the validity of the existing theory of segregation and provide insight as to the viability of the system of reactions involved in the copper segregation phenomenon. Experimental results which relate to observations made in the course of TORCO plant operation and segregation studies are discussed.

By D. F. Malan, D. Ile

This study explores the use of backfill in hard rock bord-and-pillar mines to increase the pillar strength and extraction ratio at depth. The use of backfill will also minimize the requirement for tailings storage on surface and the risk of environmental damage. A literature survey indicated that backfill is extensively used in coal mines, but rarely in hard rock bord-and-pillar mines. To simulate the effect of backfill confinement on pillar strength, an extension of the limit equilibrium model is proposed. Numerical modelling of an actual platinum mine layout is used to illustrate the beneficial effect of backfill on pillar stability at greater depths. The magnitude of confinement exerted by the backfill on the pillar sidewalls is unknown, however, and this needs to be quantified using experimental backfill mining sections equipped with suitable instrumentation.

May 3, 2023

By J. P. F. Charpin

The transport of large boulders in a furrow from a mining area to a nearby pond was considered. The furrow is filled with a mixture of water and soil particles flowing down to the pond at high velocity. Due to operating constraints, the slope of the furrow is reduced progressively. A relationship is derived, relating the slope of the furrow and the composition of the fluid to the maximum size and shape of the transported boulders. The characteristics of the boulders carried all the way down to the pond may then be determined.

Jan 1, 2007