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By G. B. Dukes

Scaling of rockpasses was problematic at Tau Lekoa Mine prior to production commencing in 1991. High horizontal stress levels relative to the host rock mass strength have been instrumental in causing the observed scaling. Scaling has been more pronounced in the deeper rockpasses and these are monitored regularly. Rehabilitation of one of the reef passes and one of the waste passes was required in the period 1999 to 2001. This paper describes the extent of the problems experienced to date as well as the rehabilitation completed.

Jan 1, 2006

By E. M. W. Skinner

Various models of near-surface kimberlite pipe emplacement have been proposed over the years. These include a top-down, phreatomagmatic model, a bottom-up, embryonic pipe model and three top-down explosive dyke models. AU of these models consider kimberlites as essentially the same rock type. However, different kimberlites have different pipe shapes and contain different rock types with very specific mineral assemblages and textures and therefore are likely to have been emplaced by different processes. Some authors have considered local geological differences as the principal reason for the contrasting geology but others argue that, while geological differences might contribute locally the petrographic peculiarities of particular kimberlites may be due mainly to inherent compositional differences specifically in the ratios of juvenile CO2 and H2O.

Jan 1, 2010

By J. A. Cruise

With the end of the official apartheid legislation in the early 1990s, South Africa was heralded as a non-racial country. However, racial awareness has been reintroduced into the country with the Affirmative Action and Black Economic Empowerment legislation. Gender and racial transformation are the current order of the day. All organizations are required to reflect in their make-up the demographics of the population as soon as possible. Scorecard shave been drawn up to measure the rate of transformation for gender and race in organizations. The mining industry in South Africa has been in the forefront of this transformation legislation and scorecards. This paper seeks to show the effect of gender and racial transformation on mining engineering education and professionalism by analysing the changing demographics of graduating mining students at both the South African universities offering a degree in mining engineering, the professional registration of mining engineers with the Engineering Council of South Africa (ECSA), and the membership of the Southern African Institute of Mining and Metallurgy (SAIMM), the vocational institute for mining engineers. It also demonstrates the absurdity of gender and racial quotas based solely on the demographics of the current population of the country. This paper shows the degree to which mining engineering has transformed in both gender and race.

Jan 1, 2011

By M. Olalde, I. Watson

"The consequences of ineffective mine closure in South Africa are evident from the number of abandoned mines and operations on extended care-and-maintenance, the on-selling of mines to less well-resourced companies to close, and increasing illegal mining activities. However, the data to substantiate these observations and provide insight into the underlying issues has not been available. Through the Promotion of Access to Information Act, a list of mine closure certificates applied for between 2011 and 2016 and a list of certificates granted over the same period for all nine regions of South Africa was obtained. From the analysis of this data, we show that the mine closure system as implemented in South Africa is largely ineffective. Although closure certificates are being granted, these are for prospecting sites and small-scale mines, which have a relatively small environmental impact. No large mines of any environmental significance were relinquished over the period under review, with very few applying for closure certificates. Furthermore, the issuing of closure certificates varies significantly between regional offices, with the success rate for applications being generally low and issuing of certificates taking an extended period. IntroductionThere are a number of concerns with the mine closure process as practiced in South Africa, and these have largely been laid at the door of government. Alberts et al. (2017) stress that the legislation generally conforms to international best practice. However, the system is ‘complex and unwieldy’, involving various pieces of legislation and different government departments with overlapping requirements and different interpretations of the law. A further area of concern is the capacity and competence of government to implement legislation. The ‘shortage of relevant mine closure skills and knowledge within the regulator’ was identified by van Druten and Bekker (2017) as a key contributor to unsuccessful closure. Lack of capacity and resources within the regulator has also been highlighted by Botham, Kelso, and Annegarn (2011) and Milaras, McKay, and Ahmed (2014). A recent study of the mineral application process by Corruption Watch (2017) indicates that positions in the regulator have been frozen for many years, leading to a shortage of staff, and that unqualified individuals have been appointed. There is also the perceived reluctance of government to grant closure in order to limit transfer of the liability to the state and delay the inevitable job losses."

Jul 1, 2019

By D. Almond

Low-grade, complex mineral deposits have resulted in the need for complicated large-throughput processing plants delivering increased productivity, reliability, and utilization, together with reducing operational costs. Complex mineralogy has resulted in complicated process flow sheets designed to recover minerals as efficiently as possible. In addition, the remote location of many minerals-processing plants, continuously rising energy costs, and fierce competition pose significant challenges to the modern mine, compounded by a global scarcity of qualified and experienced operational personnel. Over the last decade the Internet and automation technologies have undergone major advancements. Automation technologies, solutions, and concepts that existed, but were considered risky or unreliable prior to the year 2000, have now gained acceptance and matured. Furthermore, new technologies and different collaboration schemes have appeared, offering innovative solutions to the mining industry to address many of the challenges described. These advancements in reliable remote systems that access technology through the Internet provide significant opportunity to support mining operations, enhance process performance, provide engineering services, and proactively anticipate and execute maintenance services. This paper references a global survey of automation trends in the mining industry and the potential for an intelligent collaborative environment using automation technologies to exploit opportunities in operating the plant of the future, increasing effectiveness, and reducing operational costs. A variety of possibilities are described, including asset management solutions, remote access capabilities, performance monitoring solutions, advanced process control technologies, and the formation of an intelligent collaborative environment. A real example where this technology is used to support the operation and maintenance at a cement plant in Egypt is given to underpin the concepts described in this paper.

Jan 1, 2012

By J. A. Beukes, M. Marais

TICOR South Africa is a new titanium feed stock producer. In the Ticor South Africa plant the ilmenite feed to the smelter plant is roasted to enhance its magnetic properties. This allows for the magnetic separation of chromite from the ilmenite. The magnetization reaction relies on partial oxidation with both under- and over-oxidation causing insufficient magnetization. To subject the roaster plant feed material to the required physical conditions a circulating fluid bed (CFB) roaster is used. This paper describes the development of a laboratory model that will aid in the control of the CFB roaster.

Jan 1, 2003

By J. A. Cruise

From 27th to 29th September, The South African Institute of Mining and Metallurgy held a Colloquium on Equipment Alternatives in Underground Mining in Johannesburg. The Colloquium, which was highly successful, was held concurrently with the 1988 Electra Mining Exhibition. Particle characterization The Fourth European Symposium on Particle Characterization is to be held in Nirnberg, West Germany, from 19th to 21st April, 1989.

Jan 1, 1988

By M. Hermanus

1. INTRODUCTION It gives me great pleasure to extend my warmest greetings to everyone attending the 30th International Conference of Safety in Mines Research Institutes. I would also like to bid a special welcome to all of the international delegates who have travelled to Johannesburg to take part in what surely be a most rewarding session of deliberations. As you come together over next four days, you will have a wonderful opportunity to exchange ideas and information on strategies and practices for the implementation of sustainable patterns of development. The objectives of this meeting are both timely and far-reaching, as countries around the globe work towards the sustainable use of the world resources. Each of you brings a high level of expertise to these deliberations. I know that you will make the most of this opportunity to address the challenges and opportunities to highlight the most innovative and technologically efficient methods of social protection in order to ensure an increase in the quality of life, health, safety and living environment for the peoples of the Africa. Our country, although endowed with an immense and diverse array of mineral deposits, is perhaps best known in the mining industry for the fact that it is the world’s biggest producer of gold. Although South African gold production has declined over the past years and the industry faces serious problems, it is a myth that the South African industry is moribund. There is a new energy coursing through the South African producers which will ensure their powerful presence for many years to come, based not only on their domestic production but also and probably increasingly on their external operations. Africa features prominently in the latter category.

Jan 1, 2003

Experimental studies on viscosity of titanium bearing slags have been reviewed and the assessed data were used in extending the capability of the structurally related viscosity model for silicate melts, developed by the present authors. Experimental data on ternary and higher order systems containing CaO, MgO, MnO, FeO, Al2O3, TiO2, Ti2O3, SiO2were assessed and used. The newly extended viscosity model represented the viscosity behaviour over broad temperature and composition ranges. The structural role played by TiO2and Ti2O3in silicate network structure is discussed with respect to their effect on viscosity of melts. Keywords: viscosity model, TiOx containing silicate melts, silicate network structure.

Jan 1, 2004

By N. Simpson

Low carbon 11.5% chromium stainless steels are finding increasing use in industry as square or rectangular tubing material for the construction of structures by welding. During processing, resistively welded circular pipes are bent into square or rectangular shapes. During this process longitudinal cracks can sometimes develop atone of the inner corners of the section. An investigation has shown that the processing of round into square tubing with very sharp corners can cause excessive cold working at the inner corners of the squared tube. This, together with the high tensile residual stresses and a susceptible microstructure due to the presence of grain boundary carbides, can result in brittle cleavage cracking. Measures that can be used to reduce the problem are described.

Jan 1, 2003

Recent studies on the physico-chemical properties of molten slags and oxide solid solutions of interest are reviewed. The review covers redox and phase equilibria in slags, viscosity, diffusivity, electrical conductivity, kinetics of interfacial reactions between slags and CO-CO2, interfacial properties and phenomena. Some highlights from ongoing work on modelling phase diagrams, component activity, viscosity and electrical conductivity of multi component slags will be presented and results compared with published experimental data on slags with or without suspended solid phases.

Jan 1, 2004

By F. M. G. Egerton

Mechanisation of mining operations is not a new concept in the world of mining. Machinery has been developed, manufactured and used for many decades in massive orebodies and coal mines, both locally and abroad. Because of their size and the huge tonnages available, massive ore bodies lend themselves very easily to mechanisation. However, little progress in mechanisation has been made in narrow tabular orebodies in South Africa. The equipment available for narrow tabular orebodies requires excavations of a size that introduce large volumes of waste dilution. Nevertheless, it is essential for South African miners to experiment with mechanisation and to find a solution to the problem. This address looks at current conventional mining methods and compares them to bord-and-pillar type mining methods. Off-reef mechanisation is also touched on. It then looks at different hybridised mining methods that are being used, i.e. a mixture of conventional mining and mechanisation. It finally looks at future prospects for mechanisation in narrow tabular orebodies.

Jan 1, 2004

By M. D. Dolan

In this study, the development of a new method for investigating the diffusion of metal cations in multi-component slag systems, using microprobe analysis is discussed. This method allows the analysis of the diffusion of multiple species within a single system. This project has focused on the diffusion characteristics of manganese, iron, calcium and silicon in silicate slags, in order to simulate industrial steel and ferromanganese production. The diffusion behaviour of transition metals is of particular interest because of the effects of their variable valence. This study identified the variation in diffusivity of slag components with changes in composition and temperature of multi-component slag systems. The molecular structure of the experimental calcium-aluminosilicate slags was investigated to determine the chemical and physical properties that influence diffusion behaviour. This experimental data was used to develop predictive models for diffusivity. These models enable the estimation of the diffusivity of many slag components in complex slags, over a range of compositions.

Jan 1, 2004

By J. A. Bakken, M. Tangstad, P. A. Eidem

In the submerged arc production of ferromanganese, sillicomanganese and ferrochromium, the coke bed characteristics play an important role. The basic mechanisms of electric current conduction in the coke be dare not yet fully understood, but important parameters are the material resistivity of coke and the contact resistance between the coke particles. Preliminary tests indicate that the contact resistance is of great importance to the bulk resistance of the coke bed. An apparatus measuring the material resistivity and contact resistance of carbon materials has been developed. Both graphite and industrial coke have been tested. The material resistivity tests were performed on single particles to ensure that the effects of pores and cracks were included and the contact resistances were excluded. Two geometries were tested to obtain the contribution of the contact resistance to the total resistance of two connecting particles. The tests were performed in an inert atmosphere at temperatures and current levels found in industrial submerged arc furnaces. The results show that the method has a satisfactory reproducibility. It was found that the contact resistance is about 10 times higher than the resistance of the material when two particles are in perfect contact and that the resistivity of SSAB coke is more than 10 times higher than that of the graphite at room temperature, but with increasing temperature the difference decreases. For SSAB coke the general trend is that both the resistivity and the contact resistance decrease with increasing temperature.

Jan 1, 2007

To the members of The South African Institute of Mining and Metallurgy We have audited the annual financial statements of The South African Institute of Mining and Metallurgy set out on pages 357 to 366 for the year ended 30 June 2002. These financial statements are the responsibility of the Institute?s Council. Our responsibility is to express an opinion on these financial statements based on our audit. Scope We have conducted our audit in accordance with statements of South African Auditing Standards. Those standards require that we plan and perform the audit to obtain reasonable assurance that the financial statements are free of material misstatement. An audit includes: ?examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, ?assessing the accounting principles used and significant estimates made by management, and ?evaluating the overall financial statement presentation. Audit opinion In our opinion, the financial statements fairly present, in all material respects, the financial position of the Institute at 30 June 2002 and the results of its operations and cash flows for the year then ended in accordance with South African Statements of Generally Accepted Accounting Practice. Auditors 26 July 2002 Council?s approval of the annual financial statements The annual financial statements for the year ended 30 June 2002 set out on page 357 to 366 wereapproved by the Council on 26 July 2002 and are signed on its behalf by:

Jan 1, 2002

By D. M. MacHunter, T. Lawson, D. K. Henderson

The development and commercialization of new generation high tension electrostatic separators has provided a basis for simplifying mineral separation plant circuitry. The inclusion of new design features including insulated plate electrodes that have resulted insignificantly improved separation efficiencies in electrostatic separators are described. The increase in separation efficiency has resulted in a reduction in the number of treatment stages required to produce final high grade mineral products. Comparative performance data on different feed types are presented. A comparison between mineral separation plant flowsheets using both conventional and new generation high tension electrostatic separation technology is presented. A 55% reduction in the number of installed electrostatic separators and a 36% reduction in plant area was achieved through the use of this new electrostatic separation technology.

Jan 1, 2003

It is well known that the electrochemical precipitation of metals from aqueous solutions is conducted by the electrochemical standard potential scale. This scale indicates the order of nobility of different metals. Consequently, the standard potential scale shows the nocivity of metals when they are present as impurities in aqueous solutions containing metals. In the hydrometallurgy of cobalt, nickel and zinc are co-deposited during cobalt electrodeposition. Nickel has almost the same chemical, physical and electro-chemical properties as cobalt. Furthermore, the electrochemical potential of nickel is relatively higher than that of cobalt. For this reason nickel is preferentially reduced at the cathode in the presence of cobalt. The presence of small amounts of zinc in solution leads to contamination of cobalt electrowon. In spite of its lower electrochemical potential in comparison to cobalt, zinc is reduced on the cathode because of its higher hydrogen-overvoltage. But, in the hydrometallurgy of zinc, small amounts of cobalt present solution will contaminate the zinc reduced at the cathode. This is easily explained by the fact that cobalt is more electropositive than zinc. The co-deposition mechanism of sulphur at the cathode is not yet well understood. Great attention has to be paid to the mechanism of co-deposition of sulphur during cobalt electrolysis. This work aimed to investigate the influence of some parameters on the co-deposition of nickel, zinc and sulphur during cobalt electrowinning. The following parameters have been investigated: Co2+concentration in the electrolyte, current density and ammonium sulphate (NH4)2SO4additions. It has been established that important nickel, zinc and sulphur co-deposition takes place at relatively low Co2+ concentration in solution. The behaviour of these elements with regard to the cathodic phenomena has been established.

Jan 1, 2005

By Z. Zhang, R. G. Reddy

Experimental and thermodynamic modelling studies on the structure of alkali borate melts and properties are discussed. A thermodynamic structure model for alkali borate melts is developed to describe the distribution of structural groups in the alkali borate melts as a function of composition. A qualitative interpretation for the boron anomaly in viscosity has been proposed, which regards the boron anomaly as a manifestation of the various antithetical effects caused by the introduction of alkali oxide into boric oxide. It has been found that the viscosity of alkali borate melts increases or decreases according to the changes in rigidity and spatial connectivity of the glass network structure, which is the function of temperature and composition. These concepts with some key examples are discussed in relation to their usefulness and practicality in industrial slags. Keywords: alkali borate melts; structural model; activities; structural groups; viscosity;

Jan 1, 2004

By J. F. Curtis

In the synopsis, the author concludes that ?high levels of seismicity do not coincide with high rockburst rates?. Implicit to an appreciation of this statement is the necessity of a common understanding of what is understood by the terms: ?high level of seismicity? and ?high rockburst rates?. With respect to the former term there is no difficulty in that the level of seismicity is traditionally measured in terms of the Richter Scale. The latter term however presents a problem in that the author defines it as a particular sort of seismic event?viz: ?Rockburst? is understood as a seismic event that causes damage to an underground excavation with subsequent injury, loss of material/equipment or production shifts? (p. 322). No scale is given of the amount of: ?excavation damage ?level of injury ?material/equipment loss ?production shifts lost whether separate or cumulative, for a particular seismic event to be classified as a rockburst. A further difficulty arises in that in common usage the words ?rockburst?, ?seismic event? and ?earthquake? are all used to describe the same event.

Jan 1, 1999

The 102nd Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Gold Room, Transvaal Automobile Club, 60 5th Street, Lower Houghton, Johannesburg on Wednesday, 18th August, 1999. Obituaries The President announced the death, during the year, of the following members: Honorary Life Fellows and Past Presidents D.D. Howat Life Fellows O. Deane, J.S. van Zijl Fellow A.A. Hejja Retired Fellows A.L. Forder, C.B. Parker, A.C. Petersen, F.W.J. Ross Members J.S. Stanko, D.H. Gray Retired Member P.K. Bredell Retired Associate I.S. van Eyssen In memory of the deceased and in sympathy with the bereaved, all rose and observed a moment of silence.

Jan 1, 1999