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By R. E. Robinson

A novel variation of the GYPCIX process for the treatment of the acid mine effluent water from Grootvlei is described, in which a number of valuable by products can be obtained and the product water can be used for a variety of different purposes. A conceptual case study is presented in which the important cost parameters are described and certain critical path activities are indicated in order to derive a Return on Investment evaluation according to methods previously published. The study indicates that the treatment costs can be dramatically reduced, provided that proper utilization of the by products is taken into account. There are many possible uses for the water. However, by far the most advantageous contribution to the RDP and the best return on capital is derived if the water is used to establish small-lot farming activities providing work opportunities for thousands of people and contributing several hundred million Rands to the GDP. Vastly improved social conditions will be generated in an area of Gauteng that is in danger of rapid deterioration and a contribution will be made to maintaining mining activities in this area. The environmental impact is positive.

Jan 1, 1998

By I. Benning

Since the dismal performance of the Rand Mines management was called to account by its shareholders in 1994, the waves of change have continued to ripple across the South African mining industry .The number of listings on the gold board of the Johannesburg Stock Exchange, that once numbered 40 or 50-odd, have now dwindled to no more than a handful as unprecedented restructuring has taken place. The redefining of the industry has not been limited to the gold sector, but across the base metal, coal, diamond, platinum and industrial mineral sectors as well. At the same time the Mining Houses began to reconsider their funding strategies. Originally established in the early part of the century to ensure the long-term sustainability of their group mining operations by providing substantial financial muscle and technical support, the Mining Houses were faced with a rapidly changing political environment, which proved to be a critical catalyst in giving momentum to the change. Furthermore, the significant development costs and increasing risk profile for new projects, coupled with pressure from shareholders demanding respectable returns, opened the door to opportunities for banks to begin providing external debt by the way of project finance. However, the provision of long-term debt to the South African mining industry had generally not been common since mining companies had financed new projects with equity, or with the cash flows from existing operations. Those banks that had the appetite for exposure to the perceived high risks of the mining sector rapidly built up specialist resource banking divisions capable of addressing the increasing demands of the industry. The application of project finance, the principles of which were developed in the 1970s specifically for infrastructure projects and privatization, is now commonly applied in the financing of greenfield and brownfield mining projects. This paper outlines the approach that lending banks would typically adopt when arranging or providing mining project finance, their usual areas of concern and the way in which the finance is structured to mitigate the many inherent risks.

Jan 1, 2000

By N. Sahay

Improvement in work place environment by conventional methods viz., installation of higher capacity fan, fans in parallel operation or booster fan is a risky proposition in many coal mines in India because of difficult geo-mining condition such as shallow depth, multi seam workings having thin parting and inter connected goaves one above the other. The situation is further worsened if the mines have fire affected sealed off area connected to different ventilation circuits. On many occasions circulation of more air quantity by increasing fan pressure have resulted in initiation of spontaneous heating. To address these problems, authors have made some improvement in conventional Dynamic Balancing of Pressure Technique and worked out few ventilation schemes which are aimed for neutralization of pressure differential across sealed off area at the same time having improvement in ventilation in the mine. The excess pressure differential across sealed off area is mainly caused by introduction of higher capacity fan. Similar situation prevailed in one of the mines of Jharia Coalfield, India. The problem was solved by application of the above technique. In this paper, brief description of the technique, the problem in the mine, results of investigation, computer simulation studies of various schemes and methodology adopted for implementation of the technique in the mine have been discussed in some detail. Keywords: Dynamic Balancing of Pressure Technique, Spontaneous heating, Work place environment.

Jan 1, 2003

By F. T. Cawood

?It is in the interest of stability and investor confidence that the healthy and necessary debate on such a (minerals) policy should soon find its way to consensus.? (President Nelson Mandela at the104th (1995), AGM of the South African Chamber of Mines) Inauguration of the new political dispensation in South Africa initiated a dynamic period in the historical development of its minerals policy. The process of substituting the current South African mineral policy framework with an acceptable ?post apartheid? system, started soon after the 1994 election of the African National Congress (ANC) government. The Green Paper on a Minerals and Mining Policy for South Africa released for public discussion in February 1998, calls for radical transformation in mineral rights ownership. A shift towards exclusive state ownership of mineral rights, away from the present dual system of private and state ownership, is the most significant proposal. The current holders of mineral rights, or their nominees, who lawfully enjoyed security of tenure under past and present mineral laws are opposed to this transformation because mineral rights were often acquired at considerable cost. The situation is compounded by poor public record-keeping and passive mineral rights administration over a very long period. This paper represents a summary of the historical developments leading to the current legislative environment and forms the basis for any discussion on which future sculpturing of South Africa?s policy regarding mineral rights can take place. One cannot plan for the future without considering the past!

Jan 1, 1998

Instability in rockpasses at deep levels often initiates as a result of stress induced fracturing of the rock on the walls of the pass. This may then progress to a stage at which the geological structure of the rock mass becomes dominant and permits large joint-defined blocks and slabs to become unstable. In this paper, a technique is described in which jointing parameters and their variabilities?orientations, spacings and lengths?are taken into account in estimating the extent of failure that may develop around a typical unsupported deep level gold mine rockpass. The results of this prediction are compared with the results obtained from a review of pass performance in the gold mining industry.

Jan 1, 2005

By M .. Hori, H. Onishi, Y. Goda

The split-lining structure was newly developed for the air-tight lining of the underground compressed air storage cavern. This structure consists of separated reinforced concrete (RC) segments and air-tight membrane. It is most important for the Compressed Air Energy Storage Gas Turbine (CAES-G/T) system to develop the economical lining. In order to verify the applicability of split-lining structure, CAES-G/T pilot plant was constructed and operated for 6 months. We confirmed the practical usefulness and safety of this system through the operation. This paper presents the mechanical behaviour of surrounding rock mass and the lining structure observed through the operation of CAES-G/T pilot plant. Nous avons mis au point une structure de revêtement modulaire pour le revêtement des cavernes souterraines hermétiques à pression. Ce revêtement est composé de segments de béton armé et de membranes hermétiques. Il était très important, pour le CAES-G/T (Compressed Air Energy Storage Gas Turbine), de développer un revêtement économique. Afin de vérifier l’aptitude d’application de notre revêtement modulaire, nous avons construit un système pilote CAES-G/T et nous avons effectué des essais de fonctionnement pendant six mois. Ces essais nous ont permis de confirmer l’utilité et la sécurité du système. A travers le présent rapport, nous rendons compte de la structure de ce nouveau type de revêtement et du comportement mécanique de la masse rocheuse environnante que nous avons pu observer au cours desdits essais. Als luftdichter Druckbehälter wurde eine gegliederte Belagsstruktur für tief unterirdisch liegende Felshöhlungen entwickelt. Diese Struktur ist aus Stahlbetonabdeckung und luftdichter Plane aufgebaut. Bei der Entwicklung des Pressluftgasturbinen – Stromerzeugungssystems (CAES-G/T) war es die wichtigste Aufgabe, einen wirtschaftlichen Belag zu entwickeln. Deswegen wurde zum Nachweis der Effektivität der gegliederten Belagsstruktur eine Pilotanlage errichtet und 6 Monate lang betrieben. Durch den Betrieb konnten wir die Praktikabilität und Sicherheit des Systems bestätigen. Dieser Aufsatz ist ein Bericht über das Verhalten der durch Betrieb der CAES-G/T Pilotanlage beobachteten Belagsstruktur und umliegenden Felsmasse.

Jan 1, 2003

By H. Saroglou

Anisotropy is a characteristic of intact foliated metamorphic rocks (slates, gneisses, phyllites, schists). Testing was used to establish the anisotropic behaviour of selected gneissic rocks. The effect of anisotropy on various mechanical properties (strength, deformation) and dynamic properties (wave velocity) was examined. The rock samples were also tested at successively higher confining pressures in order to evaluate the effect of anisotropic behaviour at high overburden pressures.

Jan 1, 2004

By A. H. Swart

Rock engineering is concerned with the design of rock structures generated by mining activities. Therefore, rock engineering designs have major implications for the safe recovery of mineral deposits and operating costs. The paper deals with a few challenges facing rock mechanics engineers operating in the hard rock underground mining environment in South Africa. Finally, examples are included, which may assist rock mechanics engineers in providing better designs, which could ultimately lead to further improvement in safety and lower operating costs.

Jan 1, 2005

Tracey Khanna, Assistant Editor of UK?s Mining Magazine discusses some of the new and important environmental challenges, physical and social, that are facing mining companies. The tide of public opinion has turned strongly against those companies which are unable to show that they are practising responsible environmental stewardship. This is, no doubt, in part due to the recent focus of the international media on environmental issues and constantly improving means of communications, which has brought the whole subject of mining and the environment to those who, in the past, had only a limited awareness of the industry. Mining companies today face new and important challenges with regard to the environment, both physical and social. New technology and a greater understanding of waste management techniques has helped to bring about improved handling and disposal of mines wastes, so reducing some of the impacts. However, improved technology has also brought about the economic viability of exploiting increasingly lower-grade ore from open pits, resulting in a greater visual impact.

Jan 1, 2000

By M. J. Nicol

The kinetics of the dissolution of colloidal silver in aerated cyanide solutions has been investigated with the aim of developing a relatively rapid and convenient method for monitoring the ?leaching power? of solutions typically used in the cyanidation process. Experimental results obtained are consistent with an electro-chemical model, in which the mixed potential is set up in the active region of the polarization curve for the anodic dissolution of silver, giving rise to a rate of dissolution which is controlled by the rate of mass transport of either cyanide or oxygen to the surface of the silver. The rate of dissolution of colloidal silver was found to respond to variations in the reactant concentrations in a similar manner to gold (and silver) in a typical free-milling ore. The use of this technique for the monitoring and control of the cyanide leach process is discussed.

Jan 1, 1998

To the members of The South African Institute of Mining and Metallurgy We have audited the annual financial statements set out on pages 239 to 245. These financial statements are the responsibility of the Institute?s Council. Our responsibility is to report on these financial statements. We have conducted our audit in accordance with generally accepted auditing standards. These standards require that we plan and perform the audit to obtain reasonable assurance that, in all material respects, fair presentation is achieved in the financial statements. The audit included an evaluation of the appropriateness of the accounting policies, an examination, on a test basis, of evidence that supports the amounts and disclosures included in the financial statements, an assessment of the reasonableness of significant estimates, and a consideration of the appropriateness of the overall financial statement presentation. We consider that our auditing procedures were appropriate in the circumstances to enable us to express our opinion presented here. In our opinion these financial statements fairly present the financial position of the Institute at30th June, 1997, and the results of its operations for the year then ended in conformity with generally accepted accounting practice.

Jan 1, 1997

By I. Ewart, E. Roux

Skorpion Zinc operates a solvent extraction/electrowinning zinc plant producing over 150 000 t/a of special high grade (SHG) zinc (>99.995% Zn). In the current flow sheet copper and cadmium are cemented from the neutral leach solution using zinc powder, to prevent galvanic corrosion of plant equipment and build-up of copper in plant solutions. This process is effective but unfortunately consumes expensive zinc dust and produces a low value copper product. The EMEW® (Electrometals electrowinning) technology of Electrometals Technologies Ltd. uses a rapid flow of electrolyte through a cylindrical cell to deposit copper or other metals from dilute solution (less than 1 g/L) [1]. The copper can be deposited as powder or may be harvested as a tubular cathode product. The advantage of the use of EMEW® technology at Skorpion Zinc will be to eliminate the use of expensive zinc dust and to produce a high value copper product for sale. Following extensive bench test work, a piloting campaign was carried out at Skorpion Zinc. The tests demonstrated the ability of the EMEW® cell to effectively remove copper from solution through direct electrowinning at lower operating cost than cementation. Keywords: Skorpion Zinc, copper, cementation, direct electrowinning, EMEW®

Jan 1, 2007

By P. T. Slatter

The efficient and accurate design of pipe and pumping plant for non-Newtonian mineral slurries remains a problem. The objective of this paper is to present the development of the Balanced Beam Tube Viscometer (BBTV), an instrument which could facilitate more accurate design for these slurries. The background of rotational and tube viscometry is reviewed and the fundamental principles and inherent advantages of the BBTV are given. The design, data acquisition and processing techniques are introduced and results showing the reliability of the new instrument are presented and discussed. It is concluded that the BBTV is a reliable and versatile instrument for both routine analyses and research work, and has the potential to provide data for the refinement of the design procedure for mineral slurry pipe and plant design.

Jan 1, 1998

Application of Gy?s formula is appropriate for calculation of the Fundamental Error (FE) prior to samples being collected at any stage of the minerals process, provided that sampling parameters K and a (alpha) have been determined by calibration of the ores. Two types of calibration procedure are well established in the industry, the Hetrogeneity test and the 32-piece sampling tree experiment. The sampling tree experiment uses the variance and average grade of metal analyses from four series of samples at different nominal fragment size, as the basic input data. Pierre Gy suggested the cube as an appropriate exponent of the nominal fragment size for use in his equation. More recent work suggests that this exponent is variable and characteristic of specific ores and therefore requires calibration. The method described here explains the experimental procedure of the calibration. It is then possible to calculate a sampling nomogram using the sampling parameters K and a. This allows the sampler to determine a suitable protocol for the sampling event that will ensure that the FE does not exceed a predetermined precision at any point in the sampling procedure.

Jan 1, 2007

By G. Broadbent

It is an honour to be invited as a speaker to this ICCR conference and a pleasure to be with you here in South Africa. I have been asked to talk about the competitiveness of coal versus other energy alternatives. Coal supplies nearly one-quarter of the global primary energy. Its most direct competitors are gas, nuclear and renewables. Oil is predominantly for transport fuels. Fuel oil is competitive with coal when crude is below its long-run average price and has some niche opportunities. But I will confine my comments to nuclear, renewables and particularly natural gas as the most potent current competitive threat to coal. Competitiveness is more than just cost and price; there is environmental acceptability, security or reliability and increasingly image. These factors are more of a spectrum than discrete issues. Dollars and cents remain the key issue for competitiveness but one must recognize the impact of politics in sustainable development and energy security.

Jan 1, 2001

By H. Saroglou

The anisotropic behaviour of Athens Schist has been brought out through the testing of specimens with varying orientation of schistosity with respect to the major principal stress under uniaxial, triaxial and dynamic conditions. A large number of results from tests on intact rock specimens of the Athens Schist were statistically analysed and evaluated.

Jan 1, 2004

By H. S. Marshall

Optimum Colliery is an opencast strip mine producing 18Mt of bituminous coal per annum for the export and inland markets as well as for domestic power generation at the Hendrina PowerStation. Coal is exposed by four 60m3 and four 11m3 walkingdraglines and transported from the open cuts to the processing plants by twelve 130 ton coal haulers. Overburden and interburden areas are drilled by nine 250mm-diameter rotary drill rigs. Until 1997 all surveying tasks were conducted by electronictotal stations requiring accurate control points from which line-of-sight XYZ readings could be taken. In 1997 a GPS system was introduced which consisted of a fixed base station and two rovers. The rovers were able to perform most of the survey tasks assigned to total stations. In addition, two overburden drills were equipped with blasthole drill navigation systems, which includes the drill monitoring and material (strata) recognitions system. The rest of the drilling fleet will also be equipped with GPS systems. Blasthole positions are designed in the office based on survey and geological/geophysical information and transmitted via radio link to an industrial PC on the drills. Together with GPS positional data, both the planned and actual drill positions are displayed on an LCD screen. This eliminates the need for surveyed hole positions to be staked before drilling, and for actual hole positions to be surveyed after drilling. As holes are drilled, performance and rock property data transmitted back to the office. Future applications will include GPS monitoring of dragline positions and pad elevations. GPS receivers on the draglines will utilize the existing base station to calculate and transmit XYZ co-ordinates. Another application will be locating of boreholes in the field prior to the pumping of specified explosive charges into the blastholes. Charging instructions for each blasthole will be loaded into the computer on the explosives truck which will be equipped with a GPS system for hole identification.

Jan 1, 1998

By A. Hammel

This paper summarizes indigenous mining methods used to collectmetal ores in pre-colonial southern Africa, south of 15°S. These methods, for the purposes of discussion, are divided into sections inorder of increasing organizational complexity, from scavenging,which only required basic equipment and a relatively minimal division of labour, to underground mines, which necessitated complex planning to overcome obstacles such as the need for illumination and ventilation. Examples concerning the pre-colonial exploitation of iron, copper, tin, and gold have been taken from the archaeological literature. This review paper provides an introduction to the technology that was available to and used by miners in the past, illuminates some of the factors limiting their operations, and supports the claim to the indigenous nature of this activity

Jan 1, 2000

By M. F. Wells

The method used to salvage South Deep?s Main Shaft after it was flooded by an inrush of water at about 450 m below collar on 1 May1996 is described. The individual techniques employed in the salvage were all proven technology, but the combination in which they were applied is considered to be novel. The operation involved the following activities in order of occurrence. ?the dewatering of the shaft with submersible pumps ?the placement of a French drain on the shaft bottom muck pile ?the positioning of large diameter heavy walled draft tubes, and smaller tightening up, grout intrusion and reverse flow pipes ?the casting and curing of a structural concrete plug; the capping of the draft tubes; the intrusion of several thousand tons of cement grout into the aquifer by pressure induced reverse flow ?the sealing of the aquifer ?extensive probe drilling and sealing of the zone around the inrush point with cement and other specialized grouts ?the mining out of the plug and the re-establishment of normal sinking routines.

Jan 1, 1999

By J. R. G. Williamson

The Mining Division of Iscor, an integrated minerals and metals company, has recently completed a feasibility study for the establishment of a new heavy minerals mine and smelter in the Richards Bay area of KwaZulu-Natal, South Africa. The mine will produce a heavy mineral concentrate containing ilmenite, zircon, rutile and leucoxene which will be beneficiated at a central processing complex close to Empangeni. The ilmenite will be smelted to produce high-grade titania slag and pig iron for export. The ancient dune containing the mineral deposit is located some distance inland of the coastal dunes, and the sands contain a high proportion of extremely fine material which must be extracted ahead of the gravity separation process. Of the 56 million tonnes to be mined annually over the ten-year life of the mine approximately 23,4%?a total of 13,1 million tonnes of minus 45 micron residue fines?will have to be disposed of in a containment facility. The origin of the fine material is from the weathering of amphibole minerals. The remaining coarse sands will be returned to the mined area to re-create the original dune configuration. A number of options for the disposal of the residue fines have been examined and specialised laboratory tests undertaken to determine the deposition behaviour of the fines. The final solution involved the use of a ?sub-aerial? technique for deposition of fine material in a disposal facility. The resulting arrangement will adequately meet technical and environmental criteria. Upon closure after 10 years of operation, the surface of the disposal facility will be returned to sugar cane cultivation The paper refers to the various options considered and describes the problems associated with competent disposal of the residue fines and the development details of the final disposal facility.

Jan 1, 1997