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By A. P. L. Kotzé

Modelling and scheduling for Grootegeluk coal mine, situated in the north- western Transvaal, is by means of a series of modular systems. Modelling of the multilayered body, which is part of the Waterberg coalfield, was based on a detailed study of the behaviour of coal and waste qualities and the sub- sequent use of standard geostatistical techniques. A notable improvement on previous methods was attained. Scheduling procedures and systems were developed to model a multibench pit producing coal for several metallurgical plants as well as a power-station. Scheduling was done by producing a series of longitudinal cuts, the cuts being subdivided into increments. By allocating cuts to certain periods, the resulting calculated product tonnages were com- pared with production targets, and by iteration a final scheduling sequence was determined.

Jan 1, 1987

By J. A. C. Diering

The simulation of mining in faulted ground was recently described by Crouch. His method is extended here to enable a wide range of non-homogeneous mining problems to be modelled. Essentially, the boundary conditions at geological interfaces are incorporated into the overall iterative solution, which is necessary if faults and joints are to be modelled realistically. Two examples are given to demonstrate the method: the mining of coal a seam below a thick dolerite sill, and the mining of a flat reef in close proximity to a vertical fault where hangingwall and footwall rocks have different properties.

Jan 1, 1980

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 C. Botha

The South African democratically-elected government instituted policies and legislation that are intended to bring about change and transformation in the country and have drastically affected different industries, among others, the mining industry. The Mineral and Petroleum Resources Development Act 28 of 2002 (MPRDA) and the Broad-based Socio-economic Empowerment Charter (Mining Charter) were introduced in order to redress previous inequalities and to promote women's employment in the mining industry. This research evaluates the practical implementation of the MPRDA and the Mining Charter with specific reference to women in underground mining. A quantitative research paradigm was used. Data were collected through a process of a face-to-face interview surveys utilizing a structured questionnaire. The research setting was limited to the platinum-mining industry in the area of Rustenburg in the North West Province. The study population consisted of 195 available women working undergound at the mine. It is clear from the findings that mining companies are facing major challenges in their attempt to incorporate women in underground mining activities. Company policies regarding these issues must be firmly in place; however, the challenge lies in the translation of these policies into practice. In this regard, managers will have to play a leading role in the successful phasing in of women into the underground mining arena.

Jan 1, 2012

By C. Botha

The South African democratically-elected government instituted policies and legislation that are intended to bring about change and transformation in the country and have drastically affected different industries, among others, the mining industry. The Mineral and Petroleum Resources Development Act 28 of 2002 (MPRDA) and the Broad-based Socio-economic Empowerment Charter (Mining Charter) were introduced in order to redress previous inequalities and to promote women?s employment in the mining industry. This research evaluates the practical implementation of the MPRDA and the Mining Charter with specific reference to women in underground mining. A quantitative research paradigm was used. Data were collected through a process of a face-to-face interview surveys utilizing a structured questionnaire. The research setting was limited to the platinum-mining industry in the area of Rustenburg in the North West Province. The study population consisted of 195 available women working undergound at the mine. It is clear from the findings that mining companies are facing major challenges in their attempt to incorporate women in underground mining activities. Company policies regarding these issues must be firmly in place; however, the challenge lies in the translation of these policies into practice. In this regard, managers will have to play a leading role in the successful phasing in of women into the underground mining arena.

Jan 1, 2012

By W. P. Nel

A fuel cell is an electrochemical engine that converts the chemical energy of a fuel, such as hydrogen, and an oxidant, such as oxygen, directly into electricity. The emerging fuel cell industry may represent a major opportunity for the global platinum mining industry. This is because low temperature fuel cell systems use platinum group metals as catalysts. Fuel cell vehicles may become the most important driver of future platinum demand within years of their commercialization. A great number of factors impact on and drive the diffusion of fuel cell vehicle innovation. Such drivers range from energy security to environmental concerns and the technological development of fuel cells and systems. Such factors and drivers of fuel cell vehicle diffusion are combined with the generic ?body of knowledge? on ?technology forecasting? and ?diffusion of innovation? to design a framework that provides a holistic approach to the analysis of this complex enterprise. An attempt is made in this paper to address the following questions: Which types of fuel cells require platinum group metals? Which types of fuel cells will achieve dominant design status? Will fuel cell vehicles diffuse successfully? How big will the impact of successful fuel cell vehicle diffusion be on future platinum demand? How well do fuel cell vehicles compete with incumbent technologies such as spark-ignited and compression-ignited internal combustion engine-driven vehicles? How soon will oil depletion start to drive the diffusion of fuel cell vehicles? How important is hydrogen as a fuel? What impact does the inadequate hydrogen fuelling infrastructure have on fuel cell vehicle diffusion? The paper contains some initial results of a research project that has the aim of producing a schedule of future platinum demand generated from fuel cell vehicles. Keywords: diffusion of fuel cell vehicles, technology forecasting, platinum demand forecasting.

Jan 1, 2004

The Annual General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 27th August, 1969, at 4.15 p.m. Mr. R. C. J. Goode (President) was in the Chair. There were also present seventy Members, ten As¬sociate Members, two Affiliates, one Student and twelve Visitors making a total of ninety-five. The President declared the meeting open at 4.20 p.m. OBITUARIES The President: "It is my very sad duty to announce the deaths of the following members of the Institute: Mr James Charles Napoleon Humphreys, a Life Member who joined the Institute on 1st April, 1935, and passed away on 6th February, 1969. Mr Michael John Worrall, Graduate Member, who joined the Institute in 1960 and passed away on 2nd June, 1969. Mr Eric Adam Conrad Dickson, Associate Member, who joined the Institute on 13th June, 1952 and who passed away on 8th June, 1969. Mr Robert Jack, Associate Member, who joined the Institute on 2nd August, 1956, and passed away on 14th June, 1969. Mr R. A. H. Flugge-de-Smidt, Honorary Life Member and Gold Medallist, who joined the Institute in 1922 and passed away on 17th June, 1969. Mr John Gordon Craig, a Member who joined the Institute on 23rd August, 1960, and passed away on 6th August, 1969. As a mark of respect to the memory of the deceased, and in sympathy with the bereaved, I would ask you to rise and observe a few moments silence." MINUTES The President: "May we confirm the Minutes of the General Meeting held on 18th June, 1969, as published in the July, 1969, issue of the Journal?"-Agreed. WELCOME TO VISITORS The President: "We are honoured this afternoon by the presence of the Institute's Honorary President, Mr R. S. Cooke, President of the Chamber of Mines of South Africa, and by one of our Honorary Vice-Presidents, Mr T. L. Gibbs, the Government Mining Engineer, as well as by the presence of many distinguished guests, to all of whom I extend a most cordial welcome. We are happy to have present, Mr S. C. M. Naude, Director of the Witwatersrand Technical College, Mr G. A. P. Louw, Vice-President of the Associated Scientific and Technical Societies, Mr R. P. Randall, Senior Vice-President of the South African Institute of Electrical Engineers, Mr W. T. L. Wayman, President of the South African Institution of Mechanical Engineers, Mr D. F. Odendaal, President of the Institution of Certificated Mechanical and Electrical Engineers of South Africa, Mr E. Haacke, President of the Institute of Land Surveyors of the Transvaal, Mr B. L. Loffell, Vice-President of the South African Institution of Civil Engineers, Mr J. F. Leatherbarrow, President of the South African Institute of Assayers and Analysts, Dr W. S. Rapson, President of the Joint Council of the South African Scientific Societies, Dr P. L. Carman, President of the South African Chemical Institute, Mr F. Jackson, President of the Federation of Societies of Professional Engineers, Mr W. E. Kirkwood, President, S.E.I.F.S.A., Mr J. Steele, President of the South African Institute of Foundrymen, Mr M. Waite, President of the South African Institution of Welding, Mr M. R. Gericke, President of the South African Council of Professional Engineers, Mr G. C. Sowry, Chairman, Witbank-Middelburg Branch, Mr T. Groenewald, Chairman of the South African Chemical Institute (Southern Transvaal Section), Professor O. B. Volckman, Chairman of the South African Institution of Chemical Engineers, Mr H. W. Le Roux, Chairman of the South African Federation of University Engineer¬ing Students, Dr R. E. Robinson, Director of the National Institute for Metallurgy, Mr P. H. Anderson, Deputy-Chairman of Rand Mines Limited, Mr E. Boden, Manager of the A.S. and T.S. and Count Folchi-Vici, from Italy, who has lime interests in this country. I also extend a very special welcome to the lady guests here this afternoon, and to all the visitors." MEMBERSHIP The President: "I have pleasure in announcing that the names of the following candidates, having been published in accordance with By-Law 5.2.2, Council has elected them to membership in the following grades: NEW APPLICATIONS Members: Stuart Denston Hill, Robert Roy Richardson, Gert Paulus van der Vyver. Affiliates: Henry Clifford Read, Allen Edward Hooper, Alan Edwin Edkins. Graduates: Lester Winston Sturgess, Erroll Vincent Bosman. Students: Terence Vernon van Heerden, David Curtis Lindley. MEMBERS TRANSFERRED TO A HIGHER GRADE From Associate Member to Member: Andries Willem van Zyl, Roy Lardner, Nugent Gerald Ward Comyn. From Student to Graduate: Michael John Worrell (now passed away), Peter John Hamilton Short. I wish to welcome the new members to the Institute, and to congratulate those members who have been transferred to a higher grade." ANNUAL REPORT OF THE COUNCIL AND ACCOUNTS FOR THE YEAR ENDED 30th JUNE, 1969 The President: "Ladies and gentlemen, It is with much pleasure that I present to you the Annual Report and Accounts for the year ended 30th June, 1969. These have been laid on the chairs and before calling for their adoption I would like to make a few comments. The Accounts show an excess of expenditure over income of R2,124 and our Honorary Treasurer, Mr D. G. Maxwell, will in due course comment on this. The main difficulty has again been the cost of the Journal and I think most of you are aware of the changes that we propose to make. I shall be sorry to see the last of our old format but then I have always had rather a con¬servative outlook.

By D. van Rensburg

Jointed rock slopes are generally stable, as there is no freedom of movement for blocks of rock. In an open- pit mining environment, blasting opens up space into which blocks of rock can fail, resulting in the common occurrence of slope failure. Prior to the blasting of a trim pattern, the immediate highwall is scaled, where loose rock material is removed by means of a mechanical scaler. As mining of the pit progresses, the height of the scaled highwall from the pit floor progressively increases. These highwalls are never scaled again for the remainder of the pit life, and time-dependant deterioration contributes to these highwalls becoming subject to rockfall and, sometimes, slope failure. This paper documents the development of a South African innovation, a remote-controlled mechanical highwall scaler, a world first for the mining industry. The scaler will enable open-pit highwalls to be scaled from crest to toe whenever the need arises. It will reduce the risk associated with highwalls and deliver on the Anglo American promise of producing safe, profitable platinum.

Jan 1, 2012

By P. F. Ledwaba

"Artisanal and small-scale mining (ASM) in South Africa received official recognition after the change in government in 1994.The Reconstruction and Development Programme (RDP) recognized the sector as a vehicle for social and economic development for historically disadvantaged South Africans (HDSAs) who had previously been excluded from participating in the mainstream economy. Having recognized the ASM sector, government introduced several interventions and support structures to foster the development of ASM, to encourage participation of HDSAs, and to address challenges facing the sector. The objective of this paper is to assess the progress made, with particular regard to challenges in the sector. The paper focuses on the policy requirements that were deemed important for the growth of the ASM sector by the White Paper on Minerals and Mining Policy (1998). These can be collated into five categories: access to mineral rights, access to finance, access to markets, technology and skills, and institutional support. The paper provides a review of the support interventions, their intended roles and impact on the sector, and identifies existing gaps and possible ways of dealing with the challenges. There is a need for research to assess the real impact of these past and existing interventions on the ASM sector to draw lessons for future development.IntroductionThe significant rise in artisanal and smallscale mining (ASM) activities worldwide has led to many countries recognizing the sector. ASM takes place in approximately 80 countries (World Bank, 2013). It is estimated that the sector employs between 20 and 30 million people around the world (Buxton, 2013). This compares to between 3 and 3.7 million in 1999 (International Labour Organization, 1999). ASM activities are widespread, occurring mostly in developing countries in Africa, Asia, Oceania, and Central and South America (World Bank, 2013). There has been a significant increase in the number of people participating both directly and indirectly in the sector and this is expected to continue given the socio-economic realities of most developing countries. High levels of poverty and unemployment and growing inequality continue to be largest problems facing the majority of developing countries today. The ASM sector plays an important role as a source of livelihoods, particularly for those residing in rural areas with limited economic opportunities. In the majority of countries, the recognition of the ASM sector was driven by its increasing contribution to socio-economic development through job creation, poverty alleviation, and rural development. In response, a number of intervention strategies were introduced in support of the sector to address its negative impacts and to increase its potential benefits."

Jan 1, 2017

By R. R. Mankowski

The work described here is an extension of current theory applied to obtaining the power dissipated at the wavefront of a transverse disturbance traveling along a mine hoisting cable. A previously derived empirical relation is adapted to the present problem, and is solved by use of a Lagrange-type reference frame moving with the wavefront. As a result of tie limitations inherent in the original relation, only a lower-bound for the domain of predicted power losses is defined. A qualitative assessment of conditions leading to the undesirable effects of internal frictional losses at the wavefronts are discussed in terms of the operating environment found on typical mining installations

Jan 1, 1990

By C. O. Beale

This paper is the first part of a two-part review on the subject. , , .. Here reference is made to the place of copper among the elements, Its properties, Its historical significance, and its 'end uses both in general and in South Africa. Its current market situation and its prospects are dealt with briefly. Some account is then given of the mining and metallurgical techniques employed. in South Africa in the production of copper, together with the names of the companies at present Involved and brief descriptions of their operations, ,... . .. The operations of these companies are described In greater detail In Part 11(Apn11985 Issue of the Journal).

Jan 1, 1985

By M. Guarascio

Microseismic monitoring of mining areas is a developing technique, described here for the Belvedere Spinello Mine, southern Italy, where dissolution cavities in the mining area have proved problematic. The preliminary condition for locating seismic impulses has been found to be a reliable seismic ground model. Ground signals are continuously recorded by means of data from piezometric wells, for sinkhole data, and linked gephones, for microseismic data. A computer system has been implemented to collect, analyse and interpret the incoming signals consequently, identification and classification of hypocentres of activity is facilitated, with advantages in terms of safety, preventing harmful side-effects, including rock bursts, and for environmental conservation.

Jan 1, 1987

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

1. Book review Economics of mineral exploration in Australia, by Brian W. Mackenzie and Michel L. Bilodeau. Australian Mineral Foundation (Private Bag 97, Glenside, South Australia 5065). 198pp. $A58. $A45 for students. Reviewer: D.G. Krige 2. Recent publications Combustion of coal liquid mixtures, by G.F. Morrison. London, lEA Coal Research, 1983, 52 pp. Hafnium: physico-chemical properties of its compounds and alloys. Vienna, International Atomic Energy Agency, 1981. 408 pp. 620 Austrian schillings. Canadian mines handbook 1984-85, edited by CD. Gardiner. Toronto, The Northern Miner, 1984. 500 pp. $24. Drilling equipment in Canadian mining and exploration- opportunities for the industry, by AJ. Jakubek. Toronto, Micromedia Limited (144 Front Street, Toronto M5J IG2, Canada), 1984. Research report 1984. Port Melbourne, Division Mineral Chemistry, Commonwealth Scientific and Industrial Research Organization, 1984. 190 pp. Surface engineering Wear is an unavoidable problem in virtually all products of the engineering industry, from the minute bearings of instruments to the cutting surfaces of earth-moving plant. Safety in mines About 50 papers will be presented at the 21st International Conference of Safety in Mines Research Institutes at Sydney from 21st to 25th October, 1985. Some 250 delegates from 30 nations are expected to attend. Professional development seminars March 18th-21st, 1985 Underground Blast-hole Mining May Ist-3rd, 1985 Mineral Processing of Gold Ores May 6th-10th, 1985 Mineral Comminution Systems May 13th-15th, 1985 Processing of Metallurgical Residues Analytical chemistry The Second Symposium on Analytical Chemistry in the Mining, Exploration and Processing of Materials is to be held in Pretoria from 15th to 19th April, 1985.

Jan 1, 1985

By T. Bednarski, L. Thomas, G. Banza, D. Muteba, P. Cole, M. Soderstrom

"In copper solvent extraction, aqueous-in-organic entrainment results in the carry-over of unwanted species into the electrowinning process with negative cost implications. The need to bleed is increased and the purity of the copper cathode is potentially compromised, depending on the impurities being transferred (Cl, NO3, Fe, Mn). In some cases, entrainment results in elevated levels of manganese in the electrolyte which can cause oxidative conditions to develop and degradation of the organic phase. Degraded organic phase detrimentally affects the physical performance of the copper solvent extraction process, contributing to even higher aqueous-in-organic entrainment. Aqueous entrainment may be minimized through good operating practices and maintenance of the organic quality, but the accurate measurement of entrainment remains a challenge. This paper presents coalescing devices designed to provide more exact measurements of aqueous-in-organic entrainment. IntroductionMany copper solvent extraction (SX) plants experience high aqueous-in-organic (A-in-O) entrainments but are unaware of the extent of the problem because entrainment is often not measured. Aqueous entrainment results in the carry-over of unwanted species into the electrowinning (EW) process and the need to bleed to maintain acceptable concentrations in the electrolyte. The costs associated with the bleed are exacerbated in copper plants where aqueous entrainment levels are high. Other than these direct costs, there are operational consequences of the build-up of certain species in the EW circuit that can have deleterious effects on plant performance.Minimizing aqueous entrainment in operating plants requires an understanding of the factors that affect entrainment levels. Both chemical and operational influences are discussed in this paper. The difficulty of obtaining a representative sample makes it challenging to obtain an accurate measure of aqueous entrainment from a continuous process like SX. Coalescing devices used to get a more precise measurement of A-in-O entrainment are useful to complete mass balances around the SX circuits. Alternatively, mass balances can be used to estimate aqueous entrainments and are helpful as a tool to troubleshoot operations with a view to improving plant performance."

Jan 1, 2016

By G. Matheron

This paper discusses important aspects, both psychological and methodological, which have delayed the introduction of geostatistics in practice. The evolution of geostatistics is traced through three 'generations', and in conclusion some important questions are raised on the current status of the subject and possible areas of future research.

Jan 1, 1987

By Oaitse Medupe

The feed to the BCL concentrator is made of the ore from Phikwe No3 shaft, Selebi shaft and Selebi North shaft. The receiving bin of the concentrator has daily throughput of 7869mt live capacity of ore with feed grade from underground operation of 0.70%Ni, 0.75% Cu and 0.05% Co. The valuable minerals in the ore are Pentlandite, Chalcopyrite. Cobalt is present mainly in the solid solution in pentlandite. The common non-sulphides minerals are Amphibolites, quartz, micas, and Feldspar while pyrite and pyrrhotite are the major gangue sulphides. Pyrrhotite contains between 0.1% and 1% Ni in solid solution. From the mineralogical investigation, it was found that approximately 65% of the pentlandite in the ore occurs as exsolutions in the pyrrhotite and the grain sizes ranges from 8 to 38µm. about 25% of the nickel bearing pentlandite is medium grained and subhedral. This kind of pentlandite occurs along the cracks of pyrrhotite or as inclusions in pyrrhotite. The rest of pentlandite present is disseminated in the gangue matrix. Because of the fine occurrence of pentlandite, fine grinding was conducted in order to improve the recovery as well as the concentrate quality. A series of subsequent flotation test were performed in order to evaluate grinds of 35, 40, 45, 50, 60 and 80% passing 75µm. It was observed that ? The mass pull increased together with increasing fineness of grind ? Similar nickel recoveries were obtained at 35 and 40% passing 75µm but from 50% and 60% the grind was seen to adversely affect the nickel recovery. At 80% passing 75µm the recovery increased by small amount. ? Flotation kinetics showed higher initial nickel recoveries but these did not translate into higher final recoveries. ? Grinding finer than 80% passing 75µm yield very high grades of the concentrate in the first minute of the flotation test, and the grade is dramatically reduced in the fifth minute of the test. It was concluded that the current grind of approximately 48% passing 75µm is close to the optimum and no significant benefit were found to be associated with finer primary grinds. The inconsistence of the grade and recovery as well as the pentlandite losses will be discussed. Keywords: Pentlandite, Nickel losses, Grain size, Flotation

Jan 1, 2007

By W. J. Jordaan

The ability of soils to retain and hold cations is called the cation exchange capacity (CEC). Adsorbed cations, however, can be replaced by other cations through the process of cation exchange. Heavy mineral deposits contain a significant portion of slimes including the very fine clay minerals. In most circuits the slimes fraction hampers efficiency and has to be removed during early stages of the process. Being a nonvaluable process stream, the processing of the slimes is a costly exercise. In thickening applications it might be possible to manipulate the ability of clay minerals to retain and hold positively charged cations in order to optimize flocculation and therefore reduce flocculation costs. The CEC value of the slimes could be a measure of this possibility. To investigate this hypothesis, different slimes samples were characterized for size, chemical composition and clay minerals present. The CEC value of each sample was determined and explained in terms of the mineral phases present. Settling tests were conducted and an attempt was made to explain the CEC characteristics of the clay minerals in terms of settling rate. The scope of this investigation was to test the hypothesis and should not be seen as an in-depth study of the subject matter. A greater number of samples and detailed analyses to identify and quantify minerals and phases present would be required to investigate further the relationships between clay minerals in the deposit, CEC and settling rates. Location and geological setting Exxaro KZN Sands is mining a heavy minerals deposit at Hillendale mine located at Richards Bay, South Africa. The orebody consist of a dune some 8 km inland from the coast to the north of eSikhawini. A geological synopsis undertaken by Botha1 concluded that the Hillendale mining area represents a coastal dune sequence that accumulated north of the Tugela River. The northward movement of sediment by long shore drift currents result in a high sand budget on the beaches north of the river youth and is the dominant contributing factor to the accretion of the coastline and development of parallel dune systems along the coastal zone in this area. Beach swash zone processes and enrichment of the fine sand fraction occurs during wind transport off the beach by ascending parabolic dunes that form the coastal barrier dunes. This process results in heavy mineral concentration on the windward dune face and localized enrichment parallel to the dune forms. The aeolian sedimentary facies processes result in the primary concentration of higher grades in the upper silt-enriched reddish brown horizons of the profile. The synopsis by Botha1 further showed that an additional component of heavy mineral concentration can be ascribed to the post-depositional relative enrichment of heavy minerals due to weathering. Therefore, it is likely that the Hillendale orebody protolith was pedogenically weathered to form the homogeneous, silt-enriched, clayey reddish brown to dark red, palaeosol profile that grades downwards into yellowish brown, less clay-enriched sand. Slimes characterization Samples The Hillendale orebody was divided into geochemically discretized zones based on the concentration of ilmenite and other specific minerals and/or phases. Six composite samples were made up from exploration samples taken from Zone 9, Zone 11 and Zone 12. The red and orange horizons within these composite samples were separated and test samples were prepared to conduct test work and analyses. The test samples were submitted for preparation and analysis to characterize the slimes properties. Each test sample was deslimed at 45 µm representing the slimes fraction (-45 µm) and dried at 40°C. The -45 µm slimes samples were then split to conduct size analysis, chemical analysis, XRD and to determine the CEC. Size analysis The size distribution of the composite samples is shown in Table I. The size analysis shows that there is a difference in size distribution between the orange and red horizons of each zone. The orange horizons contain less 850 µ material as well as less slimes (-45 µm). The red horizons contain yore slimes (-45 µm). The size distribution of the slimes fraction (-45 µm) was determined using Malvern size analysis. The cumulative particle size distribution of the slimes is shown in Figure 1. The red horizons of the different zones show similar size distributions. The orange horizons show some differences. However, there is a difference in size distributions between the red and orange horizons.

Jan 1, 2007

By W. K. Loftus, H. S. Simpson

Discussion I. R. M. Cheston (Visitor): I should like to congratulate the authors on this interesting paper which graphically illustrates the overall effects of the gradual developments in diamond concentrating processes which have taken place over the past few years. These final stages of diamond concentration represent only a minor factor in the cost of diamond production but because of the shortage of highly trained people for this work, any easing of the burden on the sorting staff has an importance far beyond the immediate economic sphere. The search for the solution of problems posed by the economic and social conditions of industry is never-ending. The Diamond Research Laboratory is, even now, carrying out further work to improve still more the operation of general diamond recovery processes as described in the paper. Before looking at some of the latest developments in this field of final recovery, there are a few points arising from the paper on which I would like to comment. On page 321, reference is made to the X-ray sorters originally developed by the DRL. The paper gives a figure of 100 per cent recovery of diamonds from +7 mesh concentrates in two passes through the prototype machine. Not wishing to claim miraculous powers for our group, I would prefer to see this given as virtually 100 per cent recovery of all fluorescing diamonds. Firstly however much care is taken, there is bound to be an occasional operating loss. In the test work, 100 per cent recovery was made on many occasions but this was not always so. Secondly, although most diamonds fluoresce strongly under X-rays, some diamonds only fluoresce weakly. Type IIB diamonds, in fact hardly fluoresce at all, but the incidence of this special type of diamond is very low in most deposits. However, in operating the commercial X-ray machines, there is a certain background level of reflected radiation from other feed particles. Unless the diamond fluorescence is several times greater than this, it is not possible to achieve sufficient sensitivity in ejection. A certain small but variable proportion of diamonds from each deposit is always found to fluoresce too weakly to be recovered by the X-ray machine. Tests have shown, that for the De Beers mines, this proportion is considerably less than I per cent. These diamonds are nearly all dark brown or black in colour and therefore of low value. The degree of fluorescence does not, however, depend entirely on the colour or quality of the diamond and some of the brightest fluorescence comes from the lowest quality of boart diamonds. Investigations into the property of the diamond which causes this low fluorescence are being carried out. On page 322 it is suggested that zircon fluoresces in the same colour spectrum as the diamond. This is not quite accurate. The total light given out by zircon under X-rays is of the same order as that of diamond. However the zircon radiation has a much wider spectrum band than the diamond fluorescence. Reference is also made on page 322 to the effect of selective milling in small laboratory mills on diamonds. Perfect diamonds are very hard and very strong and are extremely difficult to break. Imperfect diamonds, which form the majority of diamonds recovered from most deposits, although hard, can be very brittle. Even under slight impact some of these diamonds may shatter to powder. Milling conditions must therefore be extremely closely controlled to minimize breakage, and even so, some breakage will always occur. As suggested in the paper, the necessary conditions are: the use of small balls, slow speed mills and very limited water addition. Tests elsewhere have suggested that the water content of the pulp in such a mill must be less than 25 per cent by weight of pulp to prevent diamond breakage reaching significant proportions. The skin flotation techniques described on page 323 operate on a very small scale. It is of interest to note that in West Africa a large-scale continuous skin flotation machine is used to recover the fine diamonds. In this operation the feed is dried and, after standing, is mixed with water and fed in a single layer onto a woven phosphor-bronze conveyor belt. This belt runs at a shallow angle into a water bath and as the particles are carried through the air-water-interface, the diamonds float off and over a weir into a collecting box. The bulk of the particles, being wettable, sink to the bottom of the tank and are continuously removed. If treated without prior drying, the diamond recovery is poor. If material is treated immediately after drying, a lot of the gangue particles also float. During standing, in the hot and humid atmosphere of West Africa, it is found that the gangue particles recover their wettability much faster than the diamond particles. Optimum selectivity is obtained after standing for approximately 24 hours. At the DRL we have been experimenting with optical filters to differentiate between the fluorescence of diamonds and zircon. By limiting the light transmission to the fairly narrow range emitted by diamonds, it is

Jan 4, 1970

By D. Bessinger, N. Rughubir

Exxaro Sands KZN produces?among other heavy mineral products?high titania slag, which is used as feedstock to the pigment industry. The titania slag is produced from the smelting of ilmenite in two 36 MW DC furnaces. In this smelting process carbon monoxide gas is produced. This gas is cooled, scrubbed and washed to remove entrained dust. This paper provides details on the gas cleaning plant system and the chemistry, mineralogy and size distribution of the particulate material contained in the off-gas stream. Characterization of the dust shows that is consists mainly of ilmenite, but with relatively high levels of SiO2and MnO. Smelting of the dust in a 500 kW DC furnace was carried out to investigate the potential for recovering valuable elements from the dust.

Jan 1, 2007