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By L. Lorig

"Two types of extreme event, earthquakes and rainfall, potentially affect open pit slope stability. In the case of earthquakes, there are rather well-developed analysis procedures and acceptability criteria. The analysis procedures relate mainly to selection of the dynamic loading either through design earthquakes and/or pseudo-static seismic coefficients. The acceptance criteria are typically expressed in terms of a minimum safety factor in pseudo-static analyses. The acceptance criteria are often promulgated by governments despite the fact that no open pit slope has ever been adversely affected by an earthquake. This paper explains why open pit slopes are seemingly more resistant to dynamic loads than natural landforms, which can experience catastrophic landslides.Extreme rainfall events are much more likely to cause open pit slope problems than earthquakes. Two types of problem are common – slope erosion and slope instability. Slope erosion is often mitigated by appropriate surface water controls. Slope instability due to elevated transient water pressures is more difficult to mitigate. Analysis procedures and acceptability criteria are rare. This paper will discuss the mechanisms for rainfall-induced slope instability, as well as analysis methods. Examples will be discussed and analysis methods are proposed. IntroductionTwo types of extreme event, earthquakes and rainfall, potentially affect open pit slope stability. In the case of earthquakes, there are rather well-developed analysis procedures and acceptability criteria. The analysis procedures relate mainly to selection of the dynamic loading either through design earthquakes and/or pseudo-static seismic coefficients. The acceptance criteria are typically expressed in terms of a minimum safety factor in pseudostatic analyses. The acceptance criteria are often promulgated by governments (e.g., Peru, Chile) despite the fact that no open pit slope has ever been adversely affected by an earthquake. This paper explains why open pit slopes are seemingly more resistant to dynamic loads than natural landforms, which can experience catastrophic landslides.Extreme rainfall events are much more likely to cause open pit slope problems when compared to earthquakes. Two types of problems are common – slope erosion and slope instability. Slope erosion is often mitigated by appropriate surface water controls. Slope instability due to elevated transient water pressures is more difficult to mitigate. Analysis procedures and acceptability criteria are rare, but do exist. In Peru, for example, slopes are required by law to be designed for a 100-year storm."

Jan 1, 2016

By R. Gurung, S. Asokan, Ch. V. G. K. Murty, R. Upadhyay

Tata Steel Limited which is Asia?s first and India?s largest integrated private sector steel company, as part of its vision to grow in related industries is also undertaking the Titania project. The project will involve mining, separation of ilmenite and other valuable minerals from the inland heavy mineral sands deposit in the Indian state of Tamil Nadu. The raw material will be beneficiated to synthetic rutile, titanium dioxide pigment and ultimately to titanium metal. The recently concluded feasibility study revealed that the deposit under consideration has 10.4%of total heavy mineral content and 15.2% slimes of the size below 63 µm, over an average sand thickness of 6.9 metres. The presence of about 15% slimes in ROM sand coupled with scarcity of water at the project site complicates the slimes handling/disposal system, requiring the development of an innovative, efficient and effective system for disposal of slimes. Mineral characteristics of slimes revealed the presence of kaolinite clay, which poses its own challenges in thickening/dewatering of slimes. This paper outlines the detailed studies conducted, including slime characterization, settling and thickening characteristics, and ge-technical studies to arrive at an efficient and effective slime handling/disposal system, with a view to plant saplings on the mined-out reclaimed land with species typically suitable to that environment.

Jan 1, 2007

By O. Tshifungat, A. Luzanga, N. Goel, S. Sandoval

"Tenke Fungurume Mining Company (TFM), located in Katanga Province, Democratic Republic of Congo (DRC), began production of copper cathode and cobalt hydroxide in March 2009. Copper production capacity was 115 000 t/a utilizing a semi-autogenous grinding, agitated leach, countercurrent decantation process followed by solvent extraction and electrowinning (SX-EW). Cobalt production capacity (as cobalt hydroxide) was 8000 t/a utilizing a three-stage purification/precipitation process treating raffinate from the copper SX-EW process. Recently a phase II expansion was completed, in which copper electrowinning capacity was doubled and four stages were added to the SX plant. Corresponding enhancements were made to mining, milling, and processing to bring production to 195 kt/a copper and 15 kt/a cobalt. An additional sulphuric acid plant is currently being constructed, adding 1400 t/d sulphuric acid to bring total acid production to 2250 t/d for use in leaching at TFM.Initial copper electrowinning results were satisfactory, but cathode quality and current efficiency decreased as copper production increased. The Freeport-McMoRan (FCX) Technology Centre and TFM personnel began operation of two bench-scale copper electrowinning cells in the tankhouse to diagnose chemistry effects on the cathode and anode. The results indicated an excellent electrolyte chemistry, producing finely crystalline copper at 430 A/m2 current density with 98% current efficiency. Attention next turned to the physical factors of the electrowinning cells, including electrode insulator geometry and performance. A demonstration cell was selected in the tankhouse and was operated with varying cathode and anode insulator geometries. Operation of the demonstration cell with a three-side cathode edge strip, A-style anode insulators, and an improved cell furniture design increased current efficiency from 77% to 89% at 400 A/m2 current density. Cathode quality improved correspondingly. TFM is now operating at 92% current efficiency."

Jan 1, 2016

By R. C. Hochreiter

The paper gives a technical review of the history, occurrence, mining, metallurgy, and end-uses of the platinum-group metals in South Africa, with most emphasis on platinum and palladium. The platinum industry has grown, from the first discovery of the metal in South Africa (in the central Transvaal) in 1923, to the present time, when the country is the largest producer of platinum 10the world, supplying almost 70 per cent of the platinum on the world market.

Jan 1, 1985

By A. V. L. Narasimham

The practice of refractory lining in Fe Cr furnaces is purely based on the behavior of various refractories used in different parts of the Furnace at elevated temperatures. The choice of the pattern of lining is mostly done on traditionally based concepts. Refractory Lining of a furnace is the most crucial enabler for operational excellence for Ferro Alloys production. During the last few years, no major technological change has taken place in ?Refractory Lining Management?, only freeze lining concept is becoming popular. Many ferro chrome furnaces today, have the refractory lining problems especially at tap holes, resulting in shutdowns and production losses. The author with his experiences for the last 37 years in furnaces of all sizes tried to attempt to investigate into the reasons for premature failure of lining.

Jan 1, 2007

By A. M. Engelbrecht

Paper written on project work carried out in partial fulfilment of B Eng. (Chemical) Membrane processes are vital to a diverse range of technical and biological systems, which also feature in mineral processing applications such as the treatment of mine effluent and extraction of metals. In this study, the use of cellular automata to model a semi-permeable membrane that separates two compartments is considered. Cellular automata are simple models that enable the analyst to represent well-understood local effects, such as the chemical or steric interaction between molecules themselves and between molecules or particles and their environment, which can lead to very complex behaviour on a macroscopic scale. Various physical phenomena, including reverse osmosis, were simulated. Initial results for the effect of temperature, membrane structure and chemical properties of the solutes on the performance of the membrane appear promising. Keywords: cellular automata, dynamic modelling, filtration, membrane fouling, osmosis.

Jan 1, 2007

By R. Layton

Expert Systems Technology (EST) is becoming more and more widespread in both its range of applications and the public interest. It appears to be capable of performing tasks unmatched by other techniques. Within the mining industry a large body of unsolved problems now appear to have a solution. This paper examines the current state of EST both in the context of the history of Artificial Intelligence and current efforts at building mining expert systems. It provides recommendations for those wishing to get involved, and outlines the problems for those who believe that expert systems are capable of anything and everything. The paper also provides a detailed analysis of limitations of current EST that must direct research into more fundamental, commonsense areas than have been extensively covered before.

Jan 1, 1987

By B. R. Broekman, D. W. Penman

SYNOPSIS This paper traces the developments in flotation practice at Anglovaal's Prieska Copper Mine, with em¬phasis on the depression/deactivation of lead and zinc. A depressant system was devised to accept feed material that was once regarded as untreatable. Of particular interest is the long-term downward trend of concentrator working costs in real terms. This trend follows the classic Experience Curve, which relates production costs to cumulative experience. It is felt that the experience-curve concept has important implications for the mining industry in general.

Jan 1, 1991

By I. J. Barker

This paper argues that the scale up of furnaces and the supply of electricity are going to be two major issues that will affect the ferro-alloy industry in the near future, and that economic factors will drive this development. The most common type of furnace for producing ferroalloys at present is the submerged-arc furnace with three electrodes, fed from a three-phase AC electrical supply. The scale up of this technology has now reached a fundamental constraint, which is caused by the electrical reactance of the secondary circuit. If the economy of any further scale up is to be achieved in the future then a different technology will have to be used. The supply of electrical power in future is likely to become amore complex issue than it is at present. Existing submerged-arc furnaces tend to run at fairly steady loads, but the ability to swing the load under demand-side management may offer advantages, and may allow a furnace to obtain cheaper power from the organizations that supply this power. This will have to be counterbalanced against the nuisance factors incurred by having a varying load in the operation of the furnace. Various options are therefore discussed in this paper. The possibility of scale up of Søderberg electrodes is discussed, as well as the use of DC power and multiple electrodes. Some of the issues with load swinging are also examined. A particular scenario is also briefly presented to show that considerable further scale up of ferro-alloy furnaces is still possible.

Jan 1, 2011

By G. Y. Nisbet

The contribution made to the economy of South Africa by the-minerals industry is discussed according to four of its aspects. Firstly, the industry supports both students and lecturers in technical and academic institutions. This support covers virtually the whole range of courses available at the universities and technikons, although most is obviously devoted to the engineering and science faculties. Secondly, the industry makes a direct financial contribution to the State in that it contributes about40 per cent of the State's receipts from direct tax paid on incomes and 30 per cent of the contributions to the total State revenue. It provides employment for 28 per cent of the total active labour force, and contributes 24 per cent directly to the gross domestic product. Thirdly, the industry is responsible for over 65 per cent of the country's foreign earnings in spite of the significant rise in exports from the manufacturing sector. South African minerals are of crucial importance to the word, since the country has the world's largest reserves of seven minerals and features very prominently in many others. Finally, the industry makes an indirect contribution, referred to as the multiplier effect. This is the ripple effect on the economy made by a large injection of momey by which that money acquires an added effective value. A study made of the total production of the mining industry in 1978, for instance, showed this multiplier to havea value of 1,5. Thus, if this effect is included, the industry's contribution to the gross domestic product is 44,S per cent. Similarly, the industry is responsible for the creation of jobs both within itself and in other industries, which could amount to 100000 for the period 1981 to 1935.

Jan 1, 1981

By A. van den Berg

Mining of sand in South Africa is rapidly growing to sustain an increasing demand for sand for building purposes. Although mining of sand is regulated by environmental legislation, such as the National Environmental Management Act 107 of 19981, previous bad mining practices have left areas of land degraded and vulnerable to erosion. This study was conducted in the Seringveld Conservancy, where mining of sand has left the landscape with a degraded and unsightly appearance, and where little rehabilitation of the original vegetation has taken place. The aim of the study was to develop rehabilitation techniques for the degraded mined soils on two sand mines, Boekenhout Sand and Krokodil Sand, and to develop an overall strategy of revegetation by regenerating key plant species. Techniques for regenerating indigenous tree species cover, using modified mined sludge if topsoil is not available, were used to develop a practical and cost-effective strategy to be used in revegetation. A comparative trial was used to cultivate indigenous tree species in different soil mixtures. The study is important as it provides new information on the rehabilitation and revegetation of sand mined areas in the Seringveld Conservancy. This study will determine if alternatives could be used to replace topsoil on mined areas where none is available. The study is needed to determine whether revegetation of the mined areas would be possible using indigenous plant species that are difficult to grow. The overall results indicate that replacing topsoil was successful for various modified soil mixtures that could sustain the growth of indigenous vegetation on the sand mines. Different indigenous tree species require different modified soil mixtures for successful propagation. A revegetation strategy was developed to complement and enable the rehabilitation of the mined areas in the Seringveld Conservancy. Keywords Rehabilitation, revegetation, Seringveld, sand mines, Burkea africana, topsoil, germination trials.

Jan 1, 2011

By N. C. Joughin

Potential for the mechanization of stoping in gold mines by N. C. JOUGHIN B.Sc. Eng., Ph.D. (Rand) (Member) The basic requirements for stoping machines are identified first by examination of the mining rates and productivities attained in conventional stoping, and then by examination of a series of problem areas associated with the shape of the reefs, rockbreaking, rockhandling, and the support and design of the machines. Some of the more important machines being developed are described briefly, and their principal features are compared with the basic requirements identified in the first part of the paper. An estimate of the potential demand for the different types of machines is given.

Jan 1, 1976

By By the staff of Gold Fields of South Africa

A diamond-drilling programme conducted from 1971 to 1973 by the Phelps Dodge Corporation revealed three complex sulphide ore-bodies in the highly folded Namaqualand mobile belt on the farm Aggeneys, some 65 km west of the small town of Pofadder on the road to Springbok in the northwestern Cape. Of these, the Broken Hill occurrence is the most promising.

Jan 1, 1980

By J. Palarski

Long waling is used in most Polish coal seams, with backfilling to support the roof, to create an artificial hanging wall to prevent movement if the rockmass, and to eliminate the fire hazard in abandoned mine workings. This paper discusses the results if tests conducted on 7 different backfill mixtures, and gives equations for the estimation if the flow if backfill slurries through gravitational pipelines.

Jan 1, 1994

Prediction of the performance of explosives In bench mining by C. M. LOWNDS, B.Se. Hons (Rhodes), Ph.D (Cape) (Visitor) Some of the problems encountered in the calculation of the relative weight strength of explosives are discussed, and a realistic model of the behaviour of explosion products in a borehole is proposed. The heat flow from condensed to gaseous products is calculated as a function of time, and the relationship between the pressure and the volume of the product gases is found by a consideration of the compression of the rock between radial cracks. Work done on the burden is assumed to cease when the cracks first appear at the face. Reasonable values of burden and crack velocities are obtained from the model. Calculations of the relative weight strengths of aluminized mixtures of ammonium nitrate and fuel oil show that the increased density resulting from the addition of aluminium is the main advantage to be gained.

Jan 2, 1975

Copper cyanide is a common component of cyanide-treatable precious metal ores. The copper concentration in production heaps can be predicted from laboratory column tests, but the exact correlation is not necessarily intuitive. Generally, heap leach operators like to keep copper concentrations in solution below 300?500 ppm and may note problems with gold recovery and cyanide consumption when copper concentrations exceed this amount. There are several methods of copper removal from cyanide solutions including ion exchange; direct electrowinning; acidification, volatilization, and recovery (AVR); and sulphide precipitation such as the sulphidization, acidification, recycling, and thickening (SART) process. SART involves acidification with addition of soluble sulphide, separation of the resulting copper sulphide precipitate, and addition of lime to re-establish alkalinity prior to returning the solution to the leaching process, recovering both copper and cyanide as valuable products. In principle SART is very simple. Yet some SART plants that have been built may have been unnecessarily complex. This paper explores the basics of SART and makes the case for a simple plant design as applied to the heap leaching circuit.

Jan 1, 2012

By D. W. Horsfall

The coal-preparation techniques used in South Africa over the past ten years are reviewed, the term preparation being taken to refer to processes involving beneficiation techniques. The success of the preparation methods adopted can be gauged from the fact that, although South African coals are generally of a fairly low quality, the country is producing coals both that are used locally for the raising of steam and for metallurgical purposes, and that compete successfully on world export markets.

Jan 1, 1980

By C. A. Hunt

The problem of materials balancing is reviewed with particular reference to the minerals industry. A broad statistical framework is established that, besides extending the classical estimation problem, allows questions concerning the value of sample information to be addressed. The following are examples of such questions: How much money should be spent on sampling? Which streams in a plant should be sampled? What should be sampled? The approach adopted makes use of Bayesian analysis. The discussion includes an illustrative example involving a simple flotation circuit.

Jan 1, 1985

By O. S. Lubbe, G. Annandale, J. W. van Wyk

This paper deals with the development and evolution of room and pillar mining in the South African chromitite and platinum mining industry over the past sixteen years. The paper describes the need for cheaper, more effective and safer mining methods in hard rock mining. It also describes how a mining method traditionally only applied in coal mining in South Africa evolved into a method ideally suited to conditions in chromitite and platinum mines. The paper also touches on joint efforts from mining houses, mine management and equipment manufacturers to design and build mechanized equipment custom designed and unique to South Africa in order to overcome challenges presented by the harsh operating conditions encountered in the mines in the Bushveld Complex.

Sep 1, 2001

By S. M. Graham, G. Mellis

"The determination of the oxidation state(s) of an element present in a solid sample may be required for a number of reasons, including the assessment of the degree of reduction which has taken place during a multi-step production of a metal. In addition, possible flaws in a metal may result from small amounts of oxides included in the solid. The analyte of interest may be present as a major component of a sample of interest, or as a minor impurity - beneficial or requiring removal - in another matrix.Numerous methods have been established for the analysis of species in solution samples - for example, Fe2+ and Fe3+ by titration, Cr6+ by colourimetric means, etc. With appropriate knowledge of the solution being analysed, many of these methods are fairly straightforward, extremely reproducible and accurate. In those instances where the analyte in a solution is known to be in only one form, the analysis is even more straightforward, since it can be achieved instrumentally (by AAS, rCP-OES or rCP-MS, for example).However, the situation with respect to the analysis of solids is not as simple. Various techniques - such as X-ray diffraction - are routinely used by our mineralogists to obtain information about the various minerals present in solid samples, and thus about the oxidation states of the analyte elements present. However, these techniques usually give results that are qualitative, or semi-quantitative at best. They are also usually time-consuming and expensive. One of our colleagues at Mintek, Deshenthree Chetty, has done extensive work in developing a method for the quantification of manganese species in solids using mineralogical methods, and this is no small achievement."

Jan 1, 2014