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By M. U. Ozbay

The stability of pillars is analysed on the assumption that pillars shed load in a stable manner if the slope the strata load-deformation relation is steeper than that of pillars in the post-peak regime. Concepts of local stiffness, mine structural stiffness, and critical stiffness are discussed. Procedures are described for the determination of strata stiffness for various pillar layouts by use of the available boundary-element computer programs. The postpeak stiffness of pillars is assessed from the available data relating to the post-peak load-deformation relationship and width-to-height ratio. Stability analyses are carried out by the contrasting of strata stiffness with post-peak pillar stiffness. It is shown that the strata stiffness becomes unacceptably small for a stable yield-pillar layout when the span exceeds about 5 times the depth. The strata stiffness is found to increase, thereby increasing the stability, as the span-to-depth ratio, number of pillars, and percentage extraction are decreased. It is also found that the stability in a yield pillar becomes difficult to achieve when al the pillars in a layout are in the descending part their post-peak load-deformation curve

Jan 1, 1989

By L. Marais, S. Denoon-Stevens, J. Cloete

"Historically, mining companies worldwide provided housing and developed towns to accommodate their employees. At the end of the 1980s this approach became less prevalent and attempts were made to mitigate the effects of mine development and mine closure on communities living near the mines. Permanent settlement in mining towns urgently needed to be minimized. Since the advent of democracy, South African policy has moved in the opposite direction, shifting the emphasis to creating integrated communities and encouraging home ownership. Despite this policy shift, however, mines continue to influence local housing conditions. One direct outcome has been the development of informal settlements. We surveyed 260 informal settlement households in Postmasburg, a small and remotely located town in the Northern Cape Province of South Africa. We found that because they employ contract workers and thus arouse expectations of employment, the mines here contribute extensively to the development of informal settlements. But local factors also contribute, and the functional role of informal settlements as a form of housing that supports mobility should not be underestimated. We also found that both municipal and mining company policies for informal settlements were inadequate. Finally, we found that low-income informal settlers not associated with mine employment suffered the highest levels of social disruption.IntroductionA mine generates demand for labour, which in turn generates demand for housing. When settlements spring up near a mine this often means poor housing conditions. In South Africa in the 1960s and 1970s mining companies invested heavily in company towns or mining settlements, but they have become increasingly hesitant to do so, for three reasons. First, declining resource prices in the mid-1980s and the 1990s compelled them to focus on core business interests and reduce the costs of peripheral activities such as housing (Bryceson and MacKinnon, 2013); second, at the turn of the 20th century they were often accused of taking over the role of local government (IIED, 2002) and consequently became hesitant to invest in developing mining towns; and third, changing labour regimes also curbed their investment in such towns (Haslam McKenzie, 2010). Increasingly, the companies began to endorse block-roster shifts, and outsourcing also became more common in the early 1990s. Block-roster shifts in Australia (together with improved technology) have meant that miners do not need to settle near the mines but can fly in and fly out and have their urban houses as their stable homes. This has had serious negative implications for housing in remote towns in Australia, particularly worker camps, large-scale renting out of available accommodation, and ‘hot-bedding’."

Oct 1, 2018

The Institute was founded in 1894 as the Chemical and Metallurgical Society of South Africa. In 1904 it was reconstituted as the Chemical Metallurgical and Mining Society of South Africa and in 1956 it became the South African Institute of Mining and Metallurgy. The objects of the Institute are to advance the science and practice of mining and metallurgy, to afford opportunities for the interchange and recording of knowledge of mining and metallurgy and to ensure high standards of professional conduct and competence. Membership benefits include monthly issues of the Journal of the Institute, General Meetings at which papers are read, symposia, excursions to mining and industrial concerns and the use of club facilities at Kelvin House. Technical journals received on an exchange basis are available to members at the Johannesburg Public Library. The current membership of the Institute is over 1 600. Membership applications are accepted from suitably qualified persons and the requirements for entrance to the various grades of membership are summarised below. Fellows shall not be less than 30 years of age, shall be university graduates in pure or applied science or shall produce evidence to the satisfaction of the Council that they have successfully completed a co-ordinated course of study in pure or applied science of at least three years' duration at an approved university or institution deemed by the Council to be of equivalent status. Members shall have been employed in senior technical positions in important mining or metallurgical undertakings for at least five years or they shall have practised as mining or metallurgical consultants for at least five years. They shall be practising their profession at the time of application. Entrance fee R10,00, Annual subscription R20,00. Letters of designation: F.S.A.I.M.M. Members shall be not less than 25 years of age and shall be university graduates in pure or applied science, or shall have successfully completed co-ordinated courses of study in pure or applied science of at least three years' duration. They shall have been engaged in work of an approved technical character in the mining or metallurgical industries, of which not less than two years shall have been in positions of responsibility. A candidate shall be practising his profession at the time of his application. Entrance fee R8,00, Annual subscription R18,00. Letters of designation: M.S.A.I.M.M. Associates shall be not less than twenty-five years of age, and shall have been engaged in positions of responsibility in, or associated with, the mining or metallurgical industries for periods of not less than three years. If, however, the candidate for admission to the higher grade of Associate, is at the time of his application, already a Student, he need satisfy the Council only that he is, at the time of his application, engaged in a position of responsibility in or associated with the mining or metallurgical industries. In all cases the applicants shall satisfy the Council that they are fit and proper persons to become Associates. Entrance fee R8,00, Annual subscription R18,00. Graduates shall be not less than 21 years of age and shall be university graduates in pure or applied science, or have completed co-ordinated courses of study in pure or applied science of at least three years' duration at an approved university or institution. They shall not remain Graduate members after attaining the age of 30 years without the permission of Council. Entrance fee R2,00, Annual subscription R12,00. Students shall be persons not less than 18 years of age who are being educated or trained in a manner approved by the Councils to occupy a technical position in or associated with the mining or metallurgical industries and who, furthermore, shall not have attained the qualification required for a higher grade of membership. They may remain Students until they have obtained the necessary qualifications for transfer to a higher grade of membership, but not after the end of the Institute's financial year in which they attain the age of 28 (twenty-eight) years. They shall then transfer to a higher grade to retain membership of the Institute. The Council may relax the provisions of this clause in such cases as it considers appropriate. Entrance fee nil; Annual subscription R5,00. Other. The Council has the power to elect to the grade of Fellow or Member, candidates who may not fulfil all the requirements for entrance to these grades but whose status, professional achievements and practical experience in mining or metallurgy justify such election. Applications. Requests for membership application form should be addressed on the attached form to the Secretaries South African Institute of Mining and Metallurgy, P.O. Box 61019, Marshalltown, Transvaal.

Report M48 Tracer tests on furnaces at M etalloys Limited. Report M52 A high-speed, multi-input serial-interfacing system for a computer with simultaneous back-1lP recording on magnetic tape. Report M53 The development of an automatic sample-changer and control instrumentation for isotope-source neutron-activation analysis. Report M69 The determination, by X-ray-fluorescence spectrometry,of tin and tungsten in ores, concentrates, and residues of scheelite, wolframite, and cassiterite. Report M77 Analysis of the results of a marked-ball test in relation to theories of ball wear in rotary mills.

Jan 1, 1983

By G. J. G. Juby

The Chamber of Mines Research Organization has been evaluating three membrane-desalination processes for use within the South African mining industry. These processes are electrodialysis reversal (EDR), tubular reverse osmosis (IRO), and slurry precipitation and recycle reverse osmosis (SPARRO). The evaluation of EDR and TRO is complete, and the operating costs (1988) associated with each process are expected to be about 50 cents per kilolitre for a plant of 50 l/s (4 Ml/d) installed capacity. The SPARRO process is still being evaluated. Pilot plant results, water Qualities, and expected capital costs are presented where appropriate.

Jan 1, 1992

By S. K. Kawatra

Feasibility studies of the on-stream analysis of lead in mineral slurries by S. K. KAWATRA. P. Eng. (Canada). Ph.D. (Australia). M.Sc. (India) (Visitor) Instruments for the measurement of lead in mineral slurries by the use of isotopes can be based on the absorption of Iow-energy gamma rays, backscattering of beta particles, or X-ray fluorescence. The merits of each method are discussed, and the reasons for the selection of the beta-backscattering technique are given. A system using this technique has been designed, constructed, and tested on samples of concentrates from an industrial concentrator.

Jan 8, 1976

By K. C. Wilson

Recent experiments and analyses have provided greater understanding of friction losses for the size distribution of the particles forming the slurry. Wilson and Sellgren (2001), Wilson et al. (2006) and Sellgren and Wilson(2006) have proposed a multi-component model consisting of carrier fluid and pseudo-homogeneous, heterogeneous and fully stratified solids. The technique presented here was found to estimate friction losses well when compared to reported experimental results with pipelines with diameters mainly from 0.2 to 0.5 m for various mixtures of fine sand to coarse gravel and products from mineral processing and phosphate mining.

Jan 1, 2007

By H. Wagner

The paper points out that bord-and-pillar mining is the most important method of coal extraction in South African underground coal mines, and advocates that pillar design procedures should be refined to make more rational allowance for the differences in strength properties between various coal seams and roof and floor strata. However, any deviations from well-established design procedures must be based on sound engineering principles and reliable data on the strength properties of the seams and strata concerned. Recent information indicates that practices for the protection of surface structures against underground mining should be revised.

Jan 1, 1980

By H. H. McGregor

SYNOPSIS Changes in the national productivity (gross national product per head of the population) have been assessed in order to derive a target figure for the required annual increase. The conclusion reached IS compared with the targets of the economic development programme of the Republic. Productivity and management structure in the gold mining industry is then analyzed together with investment in plant, machinery and equipment for rock handling purposes. The conclusion is drawn that productivity improvement does not appear to have accorded with the massive expenditures in plant and equipment, and in augmented management. The productivity of the manufacturing and construction sectors of the economy has been examined. The principal difficulty is that the main avenue of approach is the value of product divided by the total labour force. This introduces inflationary questions, and the use of a suitable deflator becomes of prime importance. Severa1 different methods of assessing the productivity improvement in the industrial sector have been used with what is regarded as a comparatively high degree of compatibility. Improvements in productivity in the manufacturing industry up to 1966 appear, from the information available, to have substantially exceeded comparable figures for the mining industry. There is however evidence that thereafter productivity of the manufacturing industry has not maintained this satisfactory rate of increase. If the economy is to achieve the planned rate of expansion, there is no doubt that greater attention to this aspect will be required in the future than has been accorded to it in the past.

By C. J. Badenhorst

Occupational illnesses and diseases tend to be chronic and are generally characterized by temporary or permanent physical dysfunction. With the exception of some symptoms, they are not generally visible. Therefore, safety overrides health in mining because occupational ailments take years to develop and management observes less physical trauma, if they witness anything at all. Occupational health issues need to be addressed systematically, encompassing all aspects of the interaction of employees within the work environment. Risk assessment is central to the management of occupational health. This should not be seen as a complex process and may involve little more than simply considering the consequences of one?s actions before starting work. Competent risk assessment provides the starting point and defines the scope of further action. The objectives and final use of an occupational health risk assessment determine the process and the method by which it is carried out. The occupational health risk assessment is therefore a systematic procedure to identify potential health hazards, evaluate the extent of exposure subjectively and/or objectively, and to establish the need for, and effectiveness of existing control measures. Furthermore, it facilitates the drafting of occupational exposure monitoring, medical surveillance and occupational health education programmes. Various models for conducting occupational health risk assessment provide step-by-step guidance for the identification and assessment of significant occupational health hazards and assist in producing suitable and significant occupational health risk assessments. The paper gives an overview of an occupational health risk assessment model based on the basic principles of occupational health and the legislative requirements, which will simplify the occupational health risk assessment process and ensure a sound base for the development of all other occupational health systems.

Jan 1, 2004

By Hannweg L. A.

In a first for the diamond industry, Koffiefontein Mine in the Free State, South Africa, opted for the front cave mining method to extract a 90 metre high block of kimberlite ore. Block caving, because of its high initial capital requirements, resulting in a negative internal rate of return (IRR),was ruled out as a feasible mining method for Koffiefontein Mine. Front caving is essentially a combination of the traditional block cave and sub-level cave mining methods, but uses two or more levels of retreating drawpoints. Two extraction levels, in the case of Koffiefontein Mine, are spaced 12 m apart vertically, with the upper 478 m level (48Level) acting as the undercut/extraction level, and the lower 490 m level (49 Level) as the extraction level. Caving is achieved by undercutting a small column of ore, which is then drawn, on both the 48 and 49 Levels, until the planned extraction percentage is achieved. The next column of ore is then mined by advancing the undercut (48 Level), and the process is repeated until the entire ore block is depleted to the contact. Caving-by-gravity techniques of mining rely on closely controlled draw of the caved ore to ensure proper caving action and to minimize the dilution of ore with waste material from the open pit. This paper discusses the need for, and implementation of, a draw control system at Koffiefontein Mine — a computerized production management system, and a draw control system based on linear programming, to allow control over the draw rate and mining sequence — a major factor in all production planning to optimize production efficiency, ore recovery and cave management. Keywords: Draw control, Koffiefontein Mine, Front cave, Caving

Sep 1, 2001

By R. D. Hancock

The complex responsible for the poisoning of anion-exchange resins is identified as the anionic cobaltic penta¬cyanide mono aquo species. It is shown that, at high concentration, this species polymerizes in solutions of pH less than 9. A mechanism for poisoning is presented that involves adsorption of anionic cobalt cyanide by a normal ion-exchange process, followed by polymerization within the resin matrix to form complexes that are too large to diffuse readily through the resin pores. The effects of resin structure and functionality on the extent of cobalt poisoning are examined, and the effect of cobalt poisoning on the kinetics and equilibrium loading of uranium is discussed.

Jan 1, 1979

The First International Symposium on Seismicity in Mines, organized by the South African National Group on Rock Mechanics in collaboration with the South African Institute of Mining and Metallurgy, was held in Randburg (near Johannesburg) from 13th to 17th September, 1982. It was the first attempt to provide an international forum for the consideration of seismic problems specifically affecting mines or associated with mining. Numerical mathematics The South African Society for Numerical Mathematics and the Computer Science Department of the University of Natal are organizing the Ninth Symposium on Numerical Mathematics to be held in Durban from 18th to 20th July, 1983.

Jan 1, 1983

By H. T. Kaiser, P. De Waal

The Alusaf aluminium smelter at Richards Bay by H. T. KAISER, B.Sc. (Pta), M.B.L. (Unisa) (Visitor) and P. DE WAAL, B.Sc., B.lng. (Mech.) (Stell.) (Visitor) A description is given of the aluminium smelter at Richards Bay, which operates on the Hall-Heroult electrolysis principle. The annual output of metal (average 99,7 per cent aluminium) is approximately 7S 000 tons. Since its commissioning in 1971, the plant has fulfilled South Africa's total demand for low-alloy rolling slabs, extrusion billets, remelt ingots, and electrical conductor rod. The plant layout allows for sufficient expansion of its capacity to meet longterm increases in demand.

Jan 7, 1977

By R. K. Brummer

The support of stopes and tunnels in South African gold mines subject to rockburst damage requires special attention. The interaction of a seismic wave with either a stope or a tunnel is subject to a number of variables, namely the distance from the source of the event, the ground velocity, the orientation of the excavation with respect to the direction of the seismic wave, and the geology and fracturing around the excavation. This paper discusses these factors in relation to the support requirements in stopes and tunnels. The need for the integration of hydraulic props with stope support and the use of yielding anchors for tunnel support are emphasized.

Jan 1, 1988

By B. K. Loveday

A Colloquium on 'Control and Simulation in the Minerals Industry' was held at the Holiday Inn, Milner Park, on 20th September, 1984, in conjunction with the Electra Mining Exhibition. A total of 170 persons attended the very full morning programme, which began with an opening address by the President, The South African Institute of Mining and Metallurgy, Mr l.D. Austin. He outlined the reasons why computers were being used to an ever-increasing extent for control and simulation in the minerals industry. The computer was even used to check, among other things, the validity of the signals it was receiving by mass-balance calculations.

Jan 1, 1985

Caving is the lowest cost underground mining method provided that the draw point spacing, draw point size, and ore-handling facilities are designed to suit the caved material, and that the draw point horizon can be maintained for the life of the draw. In the near future, several open-pit mines that produce more than 50 kt per day will have to examine the feasibility of converting to low-cost, large-scale underground operations. Several other large scale, low-grade underground operations will experience major changes in their mining environments as large dropdowns are implemented These changes demand a more realistic approach to mine planning than in the past, where existing operations have been projected to increased depths with little consideration of the change in mining environment that will occur. As economics force the consideration of underground mining of large, competent ore bodies by low-cost methods, the role of cave mining will have to be defined In the past, caving was generally considered for rockmasses that cave and fragment readily. The ability to define cavability and fragmentation, the availability of large, robust load-haul-dump units, a better understanding of draw-control requirements, improved drilling equipment for secondary blasting, and reliable cost data have shown that competent orebodies with coarse fragmentation can be exploited by cave mining at a much lower cost than by drill-and blast methods.

Jan 1, 1994

By M. Kilfoil

Many minerals processing operations result in crushed rock being mixed with a liquid. Sometimes, the rock particles have to be dried before the next process begins and there may be a considerable distance between the equipment carrying out these processes. Bateman Engineered Technologies (BET) developed, patented and commercialized a method of simultaneous pneumatic conveying and drying. A joint project to assist with optimizing the process is under-way. Part of it is a numerical simulation of the process. The simulation is done using a dedicated program written in MATLAB, (commercial software which is widely used in engineering). It accounts for heat and mass transfer as well as particle transport. The main part of the program consists of a loop containing a series of equations which are evaluated sequentially. During any particular iteration, the properties are changed one at a time. Since the properties are changing relatively slowly, this method gives good results. The outputs of the simulation are consistent with the operational experience of BET’s engineers. The output is very comprehensive and all numerical. Since the program is currently being used for research purposes, flexibility is very important. Thus the output is converted into a spreadsheet file. Variations in the output quantities are displayed graphically using MS Excel. Some simulation could have been done using computational fluid dynamics (CFD) software. The advantages and disadvantages (technical, financial and skills requirements) of the two approaches for this particular type of simulation are compared briefly. Keywords: Pneumatic conveying, Heat and mass transfer, Computer model

Jan 1, 2003

By F. L. D. Cloete, A. K. Haines, T. D. Sampson, T. H. Tunley, W. A. M. te Riele

The recovery of zinc from pickle liquors by ion exchange A. K. HAINES. Ph.D. (Visitor) T. H. TUNLEY. B.Sc;.(Chem.Eng.)(Visitor), W. A. M. TE RIELE. pr, Eng.. Ph. D. (Visitor), F. L. D. CLOETE. M.Sc. (Chem..Eng.)(Visitor), and T. P. SAMPSON. Pr. Eng.. BSc, (Chem.Eng,). B. Econ. (Visitor) Picklers and galvanizers in and around Johannesburg are encountering an ever-increasing problem in disposing of spent liquors from their hydrochloric acid pickling baths. Particularly troublesome is the zinc-contaminated liquor that is produced as a result of the clean-up of rejects from the galvanizing operation. Because of the volatility of zinc chloride. this liquor presents difficulties when processed in a conventional pyrohydrolysis acid-recovery unit. The paper describes the Metsep Process. developed by the National Institute for Metallurgy and Woodall-Duckham S.A. (Pty) Ltd. which involves the use of continuous ion exchange for the separation of the zinc from the pickle liquor. and the use of liquid-liquid extraction for the conversion of zinc chloride eluate to salable zinc sulphate. A description of laboratory and pilot-plant tests is given. and the approach used in the design of a full-scale continuous- ionexchange plant is outlined.

Jan 11, 1973

Mintek now offers a service for the accurate measurement and analysis of air pollution in South Africa. 'The deteriorating air quality and general degradation of the environments in industrialized and urban regions of South Africa have been of concern for more than a decade', says Mintek's Dr Johann Engelbrecht. 'The accompanying effect on health, visibility, and damage to property and the environment have prompted the public, authorities, and industry to take appropriate action. A recent study conducted by the Medical Research Council on schoolchildren in the Vaal Triangle, clearly demonstrated the relationship between the deficient quality of the air in that area, and the resultant respiratory diseases.

Jan 1, 1996