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By H. M. Stewart, N. F. Dawson, J. P. Beukes, P. G. van Zyl, Q. P. Campbell, A. Jordaan, R. I. Glastonbury, L. N. Sadiki

"SynopsisThe physical properties of oxidative sintered pellets produced from typical South African UG2 ore are compared with the physical properties of pellets produced with conventional South African metallurgical-grade chromite ore (from the Lower Group 6 or the Middle Group 1 and 2 seams). A statistical evaluation of the cured (sintered) compressive strengths proved that pellets prepared from UG2 ore are likely to have the same, or better, compressive strength than pellets prepared from metallurgical-grade chromite ore. The cured abrasion strength of the UG2 pellets was also superior to that of the metallurgical-grade pellets. Scanning electron microscopy (SEM) backscatter, secondary electron, and elemental X-ray mapping were used to determine the reasons for the general superior strength of the UG2 pellets. The case study UG2 ore also required 13 kWh/t less energy for milling to attain the required particle size distribution prior to pelletization, which can lead to substantial cost savings. Results presented in this paper can be utilized by ferrochromium (FeCr) producers to better quantify the advantages and disadvantages associated with the use of UG2 ore for FeCr production.IntroductionChromite, a mineral of the spinel group, is the only commercially viable source of virgin chromium units. Geologically, commercial chromite deposits in the world are found in three forms, i.e. alluvial-, podiform-, and stratiform-type deposits (Murthy et al., 2011; Cramer et al., 2004). Alluvial deposits were formed by weathering of chromite-bearing rock with the subsequent release of chromite and gravity concentration by flowing water. However, these deposits are relatively small and of comparatively minor commercial interest. Podiform-type chromite deposits usually occur as irregularly shaped pods or lenses, and their distribution within a mineralized zone is usually relatively erratic and unpredictable, making the exploration of these deposits difficult and costly (Cramer et al., 2004). Stratiform-type chromite deposits occur as parallel seams in large, layered igneous rock complexes with more regular layering and lateral continuity (Cramer et al., 2004). The largest example of a stratiformtype chromite deposit is the Bushveld Complex (BC) in South Africa, which holds an estimated three-quarters of the world’s viable chromite ore resources (Cramer et al., 2004).Several chromite seams exist in the BC. The seams of economic interest are the Lower Group 6 (LG6), the Middle Group 1 and 2 (MG1 and 2), and the Upper Group 2 (UG2) seams (Cramer et al., 2004). The LG and MG seams are specifically exploited for their chromium content, while the UG2 seam is mined primarily as a source of platinum group minerals (PGMs) (Xiao and Laplante 2004). Extraction of the PGMs from the UG2 ore usually involves the liberation of the sulphide by milling and subsequent recovery of the PGM concentrate through flotation (Xiao and Laplante, 2004). Chromite in the PGM concentrate is undesirable; therefore, PGM recovery circuits are specifically designed to ensure maximum rejection of the chromite to the tailings stream. However, the chromite in the PGM tailings can potentially serve as feedstock for ferrochrome (FeCr) production, after beneficiation to increase the chromium content."

Jan 1, 2015

The term geostatistics was introduced by Matheron (1960) to cover the development and application of mathematical and statistical models which take specific account of the spatial structure of a 'regionalised' variable. In ore valuation the relative positions of available ore values within an ore body or portion thereof, can only be ignored in the unlikely case where there is no significant pattern of association or correlation between them - that is, if they do not disclose any significant spatial structure. A structure might not be evident in the available data, e.g. where the spacing of the available values is relatively wide such as in surface drilling on a new deep gold mine. However, practical selective mining considerations could dictate the need for eventual underground valuation on a scale much smaller than that represented by this spacing and the possibility of a significant structure on such a smaller scale cannot then be ignored. Some spatial structure must be present wherever the average variability among the values of check ore samples from the same, adjacent or nearby grooves or of borehole cores from the deflections in the same borehole, is lower than the overall variability for ore values within the whole ore body. Another practical check on the presence of a spatial structure is where it is evident that there is or will be a significant variation in the ore grades for individual ore blocks. Any correlation between peripheral and follow-up internal ore block values also provides evidence of a spatial structure, and hence the regression techniques covered in §1.16-1.2 1 can be accepted as the first application of the geostatistical procedures. The spatial structure of a regionalised variable can be studied and measured by the pattern, usually a decreasing function, in the level of correlation or of the covariance between pairs of values as the distance or lag between the values increases, that is, by the correlogram or covariogram (Krige, 1968, 1969, 1976; and Fig. 18). In geostatistics, for various practical and theoretical reasons (Matheron, 1960, 1971), the measure most commonly used is the semivario- gram, which increases as the lag increases. The semivariogram and covariance values are interrelated and for the lognormal- de Wijsian pattern used extensively for gold ore valuation both measures as well as their relationship can be defined on a fairly straightforward basis. Provided the underlying as- sumptions are realistic, the choice of measure - correlogram, covariogram or semivariogram - will be dictated mainly by convenience. Paragraph 2.2 will cover some general geostatistical terms and $2.3-2.12 will deal mainly with the theoretical side of the lognormal-de Wijsian model for spatial structures. Wherever the relevant variable lends itself to normalisation via the 3-parameter lognormal distribution (see 51.9) the de Wijsian semivariogram model is also likely to be suitable and will provide substantial advantages in application. Various practical applications will be covered in Section 3. Although confined to the lognormal-de Wijsian model, much of the theory covered and the general approach is applicable to all spatial structures. [ ]

Jan 1, 1981

METRICATION In order to bring South Africa into line with metric countries the world over and in view of the indisputable advantages of using the comma as a decimal sign, the Metrication Advisory Board has decided to recommend that the comma be used consistently as decimal sign as from April 1, 1971. Numbers consisting of more than three figures are separated by spaces into groups of three to the left and right of the comma, and not by commas, e.g... 2 734 671,512 73 A quantity such as 12,41 kg is read as "twelve comma four one kilograms" and 31,34 km as "thirty-one comma three four kilometres." A motor-car previously described as a 3.8 litre model now becomes a 3,8 litre model. THE BRITISH COUNCIL AWARDS 1972-1973 The British Council invites applications from permanent residents of all races in the Republic of South Africa and South West Africa, for the following awards:- SCHOLARSHIPS Scholarships are available to such residents who hold University degrees or comparable professional qualifications. The scholarships are tenable for post-graduate study at Universities and other educational establishments in Britain for the academic year of approximately ten months beginning 1st October 1972. All arrangements will be made by the British Council and the scholarships will include tuition fees, a maintenance allowance, approved travel in Britain, return fares to Britain, a books grant and a clothing grant. The closing date for applications is 31st July, 1971. BURSARIES Bursaries are available to such permanent residents who hold University degrees or who, being already established in their professions or trades, hold other qualifications. The bursaries are tenable at British educational in-institutions or other suitable establishments in Britain for a course of training, study or research lasting not less than two months or more than six. The British Council will arrange full programmes and professional contacts, and the bursaries will include a maintenance grant, a books grant, authorised course fees and certain other expenses. The British Council may, at its discretion, bear the cost of single or return fares to Britain. The closing date for application is 31st July, 1971. TRAVEL GRANTS Travel grants each of £300 are available in respect of journeys to Britain undertaken between 1st April, 1972, and 31st March, 1973, and are provided to facilitate visits to British Universities by persons holding staff appointments or graduate research posts at South African Universities. Visits must normally be of at least six months duration though grants are occasionally made for visits lasting for one complete term. Grant holders will make their own arrangements with the universities which they wish to visit and will be responsible for finding their own accommodation. The British Council's assistance is limited to the contribution towards cost of fares. The closing date for applications is 31st October, 1971. For further particulars and the relevant application forms please write stating the type of award you wish to apply to: THE CULTURAL ATTACHE BRITISH EMBASSY PRETORIA

By M. I. Mthenjane

"BackgroundThe paper discusses post-mining land use however, the essence of the topic is the emotional motivation behind the decisions related to mining investment and development. Therefore this is not a typical SAIMM technical paper about the science and techniques of post-mining land use. There are already numerous papers written and conferences held on this aspect of post-mine land use; the science is well understood, but the evidence of the practical application of the (environmental, social, and economic) science is sparse. At a recent conference held in November 2017 on the theme of ‘Science, Business, Society Dialogue – linking science, society, business and policy for the sustainable use of abandoned mines in the SADC region’, it was demonstrated through the delivery of several papers on the possible viable options of post-mine land use. The conference was structured in nine sessions, covering the following relevant topics:? Sessions 1 and 2: Nature and magnitude of the problem: raising awareness? Sessions 3 and 4: International experiences in remediation: case studies? Sessions 5, 6 and, 7: Technological solutions: converting liabilities into assets? Session 8: Implementing solutions: social and legal aspects? Session 9: Wrap up, lessons learned: conference resolution.Summaries of the key outcomes of the sessions are available for reference.The aim of this paper, accompanied by the video speech, is to provide a visualization of the possibilities of post-mine land use. Mining contributes approximately 7% to South Africa’s GDP - this is the lowest it has ever been and is attributable to both a diversifying economy and to poor mining and investment policy which has resulted in reduced investment in the sector. The objective of the paper is to highlight the opportunities, for succeeding and diversifying economic activity following mining and mineral extraction which can continue to sustain the livelihoods and wellbeing of communities and societies beyond mining.During mining, very few alternative and local economies develop. Dependence on mining and its value chain prevails until mining ceases. This idea is conveyed in Figures 1a and b."

Jul 1, 2019

By D. S. van Vuuren

Titanium bearing resources can selectively be chlorinated at temperatures below 200°C if the Ti02 in the feed is nitrided before chlorination. However, the nitriding reaction is highly endothermic, requires highly reducing conditions, is only thermodynamically favourable at elevated temperatures, and is affected by mass and heat transfer restrictions. At the required processing conditions, problems might also be experienced with sintering and with melting of slag forming components in the raw materials. A test programme was undertaken to study the effects of raw material type, temperature, gas composition, bed depth, carbon to raw material ratio and residence time in order to simulate conditions required for scaling up a nitriding process. In contrast to previous experience with low-grade titanium-bearing slag containing about 30% Ti02, ilmenite and chlorinateable slag do not form melting phases under the studied nitriding conditions and hardly sintered at all. Both feed materials can readily be nitrided with conversions in excess of 90% at temperatures around 1300°C and using bituminous coal as reducing agent with fixed carbon in excess of 1.1 times the stoichiometric requirement. The conversion decreases as the bed depth of the feed material increases and the N2/CO ratio in the gas decreases. Analysis of the relative rates of mass and heat transfer into the reacting beds of ilmenite and slag showed that the heat transfer rates are more limiting than the mass transfer rates. In order to increase the throughput that can be achieved in a kiln, it would be necessary to take special measures to enhance the heat transfer rates into the mass of reacting material. One such a measure is to pre-form the mass of reacting material into thin-walled, hollow brick shapes prior to introducing it into a kiln. Depending on bed depth, temperature and N2/CO ratio, required residence times in the high temperature zone of the kiln can vary between about 6 and 10 hours. Keywords Titanium dioxide, titanium nitride, carbo-thermic, reduction, ilmenite, slag, tunnel kiln, residence time.

Jan 1, 2011

By Y. Mao, D. Xie

The viscosity of TiO2-containing blast furnace slags may increase rapidly (commonly referred to as thickening) under strong reducing conditions in the blast furnace. To elucidate the mechanisms for slag thickening, measurements have been made of changes in the composition and rheological properties of TiO2-CaO-SiO2-Al2O3-MgO slags during the reduction process. The slag composition covered the range of 17–33 wt% TiO2, 9–19% Al2O3, 8–16% MgO and theCaO/SiO2from 0.8 to 1.4. The viscosities were measured using the rotating cylinder method at temperatures up to 1550ºC and the fusibility temperatures were determined from ‘breaks’ in the viscosity-temperature curves. The reduction of the slag was carried out in graphite crucibles at1500ºC for 2–6 hours The rheological properties of the slags during reduction were predominantly influenced by the slag basicity (CaO/SiO2), and the effect of other components depended largely on basic or acidic behaviour of the oxide. The reduction of TiO2in the slag by carbon was initially fast to formTi2O3, followed by further reduction to TiO and TiC. Correspondingly, the viscosity showed initially a slight decrease, followed by a gradual and then rapid increase. The thickening was found to be accelerated by an increase in TiO2content and a decrease in the CaO/SiO2in the slag. In addition to the existence of 1~3 wt% TiC, the thickened slags also had a significant amount of TiO (3~7 wt%), suggesting that TiO may play an important role in the ‘thickening phenomena’ ,possibly by forming solid solutions with TiC to significantly increase the number of solid particles in the heterogeneous slag. Keywords: TiO2slags, viscosity

Jan 1, 2004

By M. Natarajan, C. J. Cutler, E. Mponda

Keywords: Pyrometallurgy, furnace, KCM Nkana, Zambia The Nkana smelter was initially commissioned in 1931, with two reverberatory furnaces, two Peirce-Smith converters, and blister copper casting facilities. Reverberatory furnaces were the mainstay of production up until 1994, when an El Teniente Converter (CT) was installed to upgrade reverberatory furnace matte to white metal, prior to converting in conventional Peirce-Smith (PS) converters. In 2000, a decision was taken to increase the proportion of concentrate smelted in the CT by introduction of bone-dry concentrate injection through the tuyeres. A flash dryer with a nominal capacity of 1 200 metric tons per day of dry product, and associated tuyere injection system was commissioned in March 2004. Based on the projected concentrate arisings from the KCM mines into the future, as seen in 2004, it was decided to develop the CT to be the primary smelting vessel at Nkana, to handle a minimum of 1 250 tons per day of concentrate, and to operate only one reverberatory furnace in slag-cleaning mode pending a full evaluation of alternative slag-cleaning technologies. The anticipated cathode production from Nkana was to be in the range 140 to 150 000 tons per annum. This paper details the outcomes from trials that were carried out in August and September 2004, using two reverberatory furnaces for slag cleaning. The results of these trials, plus further work in October and November, provided confidence to move to one reverberatory furnace for slag cleaning in December 2004. With the advent of Vedanta as the majority shareholder in KCM at the end of 2004, the approach has been to maximize the available smelting capacity. Currently, two reverberatory furnaces and the CT are on-line, with the higher silica concentrates going to the reverberatory furnaces with an appropriate amount of pyrite, and the cleaner concentrates going to the CT. Expansion of the smelter is currently under investigation.

Jan 1, 2006

Anglo Platinum commenced commercial underground borehole radar (BHR) surveys during 2006 following a series of trial surveys using both the ?slimline? Geomole and Aardwolf systems. Current borehole radar systems comprise radio frequency transmitter ? receiver antennae operating at 30 -100MHz that measure the time taken for a transmitted pulse to traverse a rock volume and be received (Fig 1). The time taken can be converted to distance if the transmission speed of the pulse through the rock volume is known. The transmitted pulse may be reflected off a suitably orientated geological reflector (in reflection mode) or may be recorded in receivers located in other boreholes (cross-hole tomographic mode). In the Bushveld Complex lithologies, these radar systems have ranges of 30-50 metres in reflection mode depending on the electrical properties of local stratigraphic units. Both the Merensky Reef (MR) and the underlying UG2 have been shown to act as reflectors, which offer the opportunity of using BHR as an imaging or mapping tool. Reflection of the radar signal occurs wherever a strong contrast in dielectric constants occurs such as between norite and harzburgite or where chromitite stringers are present. [ ] Fig 1 Main elements of a borehole radar system Much experience has been gained in the practical application of BHR surveys in platinum mining. The value of a BHR survey is that it provides a continuous line of information to ?connect the dots? rather than a few discrete pierce points. BHR surveys can be used to mitigate risk in three crucial areas: ? Mine planning at the strategic as well as tactical level ? geotechnical evaluation of proposed shaft sites, detailed profiling or mapping of reef and disruptions of the reef such as faults, rolls and potholes; ? Mineral resource classification ? identification of structural discontinuities in orebodies affecting resource classification e.g. potholes and reef facies; ? Safety ? identifying areas with poor ground conditions that are often associated with faults, dykes and potholes.

Jan 1, 2007

By Gift Makusha, Dave Minney

Anglo Coal South Africa mines coal for both the domestic and export market using open cast and strip mining methods. To establish a mine, a process is set in place to gather ever increasing amounts of geological and metallurgical data to confirm a proven reserve. Increasingly, geotechnical data are also included in this process to confirm that reserve is easily and safely mineable. The mine design process is an iterative one using a combination of numerical modelling and empirical data to arrive at a mining layout that is both, practical, productive and safe. In South Africa it is a legal requirement to compile a code of practice to combat rock fall and slope instability accidents and these have to be revised annually, reinforcing the iterative process of continual improvement. To ensure best practise occurs, all Anglo Coal operations are subjected to annual 2nd party audits and ad hoc 3rd party audit by independent consultants. This paper attempts to explain the process described above in a concise, but understandable manner. 1.0 GEOLOGICAL SETTING The Ecca sediments date from the Permian period and the coal deposits were formed in glaciated valleys on a basement of Dolomite, Ryolite or Granophyre rock types. The sediments overlying the coal deposits are typically flat lying and multiple bedded. The sediments consist of mudstones, shales and sandstones and are generally capable of forming stable highwalls given the time that they must stand up for. Anglo Coal extracts coal from the Witbank, Highveld and Vereeniging coalfields. The Witbank coalfields contain five seams numbered from the base upwards, 1 to 5 Seam; Highveld coalfield the 2 and 4 Seam and the Vereening area the seams are described as Top, Middle and Bottom seams. Coal deposited over the basement Dolomite formation display very erratic dips, as contemporaneous subsidence occurred in some instances over sinkholes that were forming, resulting in local thickening of the coal deposit and resulting in strata that dips toward the centre of the sinkhole.

Jan 1, 2006

By Jeremy Bosman, Johan de Korte

Traditionally the feed to coal preparation plants was de-slimed at 0,5 mm. The +0,5 mm size fraction was processed via dense-medium cyclones and the -0,5 mm size fraction was beneficiated with froth flotation, water-only cyclones or spirals. With the introduction of large diameter cyclones, the aperture sizes of de-sliming screens have progressively increased to about 3 mm in the belief that the larger cyclones are not able to effectively beneficiate coal which has a particle size below the ?breakaway? size. The efficiency of separation in the large dense-medium cyclones is improved by presenting a coarser feed to the units. At the same time, the capacity of the de-sliming screens is increased due to the larger screen apertures and in effect, the throughput capacity of the dense-medium section is increased. The 3 x 0,5 mm size fraction, which was previously processed in the dense-medium cyclones, is now added to the fine coal size fraction and processed by water-only methods such as Teetered Bed Separators (TBS) and spirals. Whether this practice is the most economical way to process the 3 x 0,5 mm size fraction requires further thought since the best processing route for the 3 x 0,5 mm size fraction will depend on a number of factors, amongst which are: o The washability of the coal and the amount of near-density material o Processing efficiency o Specification of the required product o The price paid by the customer for the product o The cost of processing the coal Breakaway size The ?breakaway? size is defined as the particle size below which the Epm of the smaller particles starts to decrease significantly. Bosman1 provides an approximate breakaway size versus cyclone diameter (Figure 1). It should be kept in mind though that the Epm of the small particles is a function not only of the cyclone diameter but also of feed pressure, medium density, medium viscosity, particle shape and density, top-size of particles in the feed, etc.

Jan 1, 2006

This publication is provided on an "as is" basis without warranties of any kind, either expressed or implied including, but not limited to warranties of title or implied warranties of merchantability of fitness for a particular purpose. The information contained in this publication is for general information purposes only. It does not constitute professional, technical, financial or other advice to the user of this publication and must not be relied upon as such by any person whatsoever. The use of this publication is at the users own risk. The authors/creators of the information contained in this publication have tried to ensure that the information contained herein is correct, but errors or inaccuracies may exist or the information may be incomplete, unreliable or no longer up to date. Therefore, no warranties of any nature whatsoever are given and any liability to any person in respect of anything and in respect of the consequences of anything done or omitted to be done, wholly or partly in reliance upon the whole or any part hereof, are disclaimed, including and without limitation any contractual, dialectal, direct, consequential or financial damages or losses. On no account will Organisers and/or any of the contributors or any person or entity involved in creating, producing or distributing the information and or software available in this publication be liable for any such damages arising out of the use of or inability to use this publication. Copyright Reserved The South African Institute of Mining and Metallurgy P O Box 61127, Marshalltown 2107, South Africa www.saimm.co.za All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical photocopying, recording or otherwise without the written permission of the copyright owner. Although the greatest care has been taken in the compilation of the entire contents, the editors and publishers do not accept responsibility for errors or omissions. First Edition Copyright February 2004 Proceedings ISBN: 0-9584663-5-1 (1 volume and CD-ROM)

Jan 1, 2004

By K. Forsberg, Ş. Kaya, C. Dittrich, M. Svärd, E. M. Peters

Scandium can be recovered from waste streams of other metallurgical processes such as red mud from the Bayer process and titanium dioxide acid waste. This is accomplished by an integrated process comprising leaching using acidic media, solvent extraction using organic solvents and stripping of Sc from the organic phase using NH4F solutions. The precipitation of scandium as (NH4)3ScF6 from NH4F strip liquors has been demonstrated at lab-scale with recoveries and purities greater than 98% and 98.3%, respectively. It is desired to assess the possibility of recovering the solvents for re-use in the process to improve its economy and environmental friendliness. Investigations have been conducted to recover alcohol by simple distillation from strip liquor-alcohol mixtures containing about 50 v/v% alcohol. The mixtures were obtained after anti-solvent precipitation of (NH4)3ScF6 using an alcohol to strip liquor volumetric ratio of 1:1. The starting strip liquor contained about 2000 mg/L scandium in 3 mol/L NH4F solution. In the recovery of methanol, the first distillate product collected had a purity of about 87 v/v% and this decreased slightly with time over two hours. The methanol distillate collected in the first 30 minutes with a purity of ca. 85 v/v% was re-used in anti-solvent crystallisation of (NH4)3ScF6 from the initial strip liquor, and the scandium recovery attained was about 98.6 w/w%, almost similar to that of 99.2 w/w% obtained using 100 v/v% methanol. For ethanol recovery, the first distillate product collected was approx. 84 v/v% pure and the distillate collected in the first 30 minutes with a purity of about 75 v/v% achieved a scandium recovery of about 97.2 w/w% in comparison to 98.5 w/w% obtained using 100 v/v% ethanol during anti-solvent crystallisation. Keywords: Alcohol recovery, methanol, ethanol, anti-solvent crystallisation, (NH4)3ScF6

Jan 1, 2020

By M. Gao

The Zinifex Century Mine employs a large number of Detritor mills for fine and ultra-fine grinding to liberate silica and sphalerite at 80 per cent passing 7.5 microns before final zinc flotation. A joint project between CSIRO Minerals and the Zinifex Century Mine was carried out to evaluate the Detritor mill performance. Plant surveys were conducted around the Detritors in conjunction with laboratory tests. The survey data showed that the Detritors in the ultra-fine milling circuit performed well. They reduced a feed F80 sizing of 46 microns to a product P80 sizing of 7.5 microns at a gross energy consumption of 37.2 kWh/t. Scale-up of ultra-fine milling Detritors was studied using a 0.55 kW laboratory batch unit and a 355 kW full-scale Detritor by processing Century zinc concentrate with 1 mm sand media. The results indicated that the 0.55 kW laboratory mill underestimated the energy consumption of the full-scale Detritor by about 20 per cent for a product P80 of seven microns. The performances of a horizontal IsaMill and a vertical Detritor were compared as ultra-fine milling devices for processing Century zinc concentrate. The experimental data demonstrated that, when using the same grinding media, the energy efficiency of the two mills is similar despite the difference in mill designs. The Detritors used for regrind duty at the Century Mine performed poorly when processing feed at 80 per cent passing 88 micron. The energy consumption was high and the product size distribution was broad with particles above 100 microns in the feed unbroken and particles below ten microns overground. A coarser ceramic media of 3 mm was therefore tested in a laboratory Detritor to process the regrind Detritor feed as an alternative to the 1 mm Colorado sand used at the Century Mine. The ceramic media reduced the energy consumption significantly and produced a narrower product size distribution, which is more desirable for the downstream flotation process.

Jan 1, 2007

By D. Limpitlaw

Industrial mining in Zambia started in the 1930s when the world class copper deposits near the border with Katanga were developed. The discovery of these deposits began at the turn of the century when the first claims in the Copperbelt were pegged at Chambishi, north of what became the town of Kitwe1. World War I and the difficulties of raising sufficient capital for such large scale undertakings delayed the exploitation of these deposits. Following this hesitant start, a large copper mining complex was built, resulting in the development of five major towns, all highly dependent on the mining and beneficiation of copper and cobalt. Copper became so important to the country that, on independence, the only non-mining town to make it onto a list of the top six was the capital, Lusaka. From commissioning of the mines to the end of the colonial period in 1964, copper production increased to just over 640 000 t annually2 (see Figure 1). After the establishment of the new Zambian state, production continued to increase, supported by a benign legislative environment and strong international copper prices. The government of Kenneth Kaunda was intent on improving the conditions of the rural poor and reducing unemployment in urban areas. To this end, the government embarked on an ambitious project of refocusing Zambia's economy away from the colonial role of commodity supply to one of decentralized mass employment. The Copperbelt industrial complex was key to the success of this approach, and in 1969 the Zambian State acquired a 51 per cent stake in Zambia's two main copper producing companies: Roan Selection Trust and Rhodesian Anglo American Corporation. The former became Roan Consolidated Mines Ltd (RCM) and the latter became Nchanga Consolidated Copper Mines Ltd (NCCM). In the year they were nationalized, the mines produced at least 720 000 t of copper? and employed approximately 48,000 workers (see Figure 2)2-4. The subsequent economic policies of the Zambian Government depended heavily on the state's ability to monopolize the proceeds of copper mining.

Jan 1, 2011

1. Recent books D. K. Hsiao, D. S. Kerr, and S. E. Madnick. Computer security. New York, Academic Press, 1979.276 pp. $18. W. C. J. van Rensburg and S. Bambrick. Economics of the world's mineral industries. Isando, McGrawHill, 1979. R18,95. Soviet metallurgical research 1973-1977. Vo!. 1. Subject index and author index (1963-1972). Vo!. 2. Chronological listing of titles with full bibliographical information (1960-1972). London, Scientific Information Consultants Limited (661 Finchley Road, London NW2 2HN). £24 per set. W. Hoosen. Miners' dictionary. London, Institution of Mining and Metallurgy, 1979. (Reprint.) £11 (£9 for members). G. J. Pitt and G. R. Millward. Coal and modern coalprocessing: an introduction. New York, Academic Press, 1979. 224 pp. $18. D. Stephenson. Rockfill in hydraulic engineering. Amsterdam, Elsevier, 1979. 228 pp. U.S. $45, D.fl.90. 2. NIM reports Report no. 2015 The preparation of synthetic standards for use in instrumental neutron-activation analysis. Report no. 2029 The commissioning of a 5 kW inductively coupled plasma unit for use with a 3,4-metre Ebert spectrograph. Report no. 2032 The Cancer Project: a summary of the computer-aided operation of a 48 MV.A ferrochromium furnace. Report no. 2036 The determination of thallium in ores, concentrates, and metals. Report no. 2040 A solid-state constant-current power unit for the magnetic analyser of the MS702R mass spectrometer. Report no. 2044 The separation and determination of anions by ion chromatography. Computer congress In October 1980, Japan and Australia are hosting the 8th World Computer Congress. This Congress is a triennial event conducted under the sponsorship of the International Federation for Information Processing. INFACON 80 The Second International Ferro-Alloys Congress, organized by IPFEO (Institute of Western European Ferro-alloy Producers), is to be held in Lausanne, Switzerland, on 13th to 16th October, 1980.

Jan 1, 1980

By B. W. J. van Rensburg, M. J. Schmidt

Bulk materials handling systems are extensively used in the mining and minerals industry, where a fairly high incidence of structural failure is experienced, notwithstanding design compliance with appropriate standards. A number of case studies are explored to demonstrate how insufficient controls or protection systems have contributed to structural failures on mobile bulk handling equipment. The importance of design integration across engineering disciplines is highlighted. The revision of ISO 5049-1 (1994) is proposed to provide specific rules and guidelines pertaining to machine protection systems. It is further recommended that the structural design engineer of the original equipment manufacturer(OEM) fulfils a more prominent role during the final acceptance and handover of mobile bulk handling equipment, with specific reference to protection systems.

Jan 1, 2015

By D. P. Roberts

This paper reviews the use of crush pillars on mines in the Bushveld Complex and the Witwatersrand Supergroup. Stress measurements were undertaken in order to determine the residual strength of these crush pillars. The results from these stress measurements are compared with previous attempts to determine the residual strength of crush pillars using back analysis. It is concluded that the residual strength of such crush pillars lies in a band between 13 MPa and 25MPa. Using the data from the stress measurements, as well as published and unpublished data, a stress-strain curve for a crush pillar with a width-to-height ratio of 2:1 is proposed. Where further work is required, this is indicated in the text.

Jan 1, 2005

By Christian Roche

Our study is focused on the sub-assembly con-tact shoes, pressure rings and pressure bellows. We were keen to mainly study [ ] 1.The contact shoe design 2.The most efficient pressure to ensure an optimal electrical contact between the contact pad itself and the casing 3. The contact shoe cooling circuit in view to provide to the shoe the best mechanical and electrical characteristics in order to bring to the users of COFOR® components a new standard in process setting technical solutions. A finite elements simulation, combined with a thermal and structural studies were used. Our presentation which follows is dedicated exclusively on the influence of the contact shoe cooling system on the process through a thermal and structural analysis. [ ]

Jan 1, 2007

By P. G. Gresse

The Orange-Vaal River system is known to be the primary secondary source for alluvial diamond deposits in the northern Cape and along the west coast of Namaqualand. The higher order sources for diamonds contained within this system are still not defined entirely to satisfaction, but certainly include kimberlite pipes exposed in the catchment regions of these rivers. The focus of alluvial diamond mining along the Orange-Vaal system recently changed from the traditional areas in the upper catchment regions?the Barkly West, Christiana, Bloemhof, Wolmaranstad, Schweizer-Reineke region, and the lower regions near the mouth of the Orange River at Baken, Alexander Bay and Oranjemund, to the area between Douglas and Prieska?the so-called mid-Orange region (Figure 1).

Jan 1, 2003

By J. Engelbrecht

South Africa?s re-entry into the fast moving and competitive global economy calls for some careful strategic planning and a good deal of co-operation between suppliers and end-users. The issues that need addressing are generally well known and include: ?South Africa was ranked 45th out of 46 i.r.o. productivity ?SMMEs contribute 1% to exports compared to 40-60% for the ?tigers? ?High unemployment ?Limited skills of the majority of workers ?Slow growth rate of the economy ?The vast majority of suppliers are not world-class ?The vast majority of suppliers are not export or marketing orientated. In order to survive, all parties, i.e. government, labour and business, will have to play their part.

Jan 1, 1999