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By R. Watts, R. A. Laybourne

This paper describes how a 'mined out' coalfield is being mined successfully by opencast methods. The coalfield is that at New Vaal Colliery, which is situated in the Vereeniging-Vanderbijlpark-Sasolburg industrial complex. Al three coal seams at New Vaal had been mined previously, when the better-quality coal had been removed. The coal-preparation plant at New Vaal, which is also described, supplies coal to the 3600 MW Lethabo Power Station. The Colliery has been designed to supply 600 million sales tons of coal over its forty-year life.

Jan 1, 1990

By M. Sciarone, B. Collins

The production, properties, and selection of ferrosilicon powders for heavy-medium separation by B. COLLlNS. B.Sc Eng. (Rand) (Fellow). T. J. NAPIER-MUNN. B.Sc. (Eng.). A.R.S.M. (Visitor). And M. SCIARONE. M.Se. Eng. (Delft) (Visitor). There are basically two types of ferrosilicon powder available to operators of heavy-medium plants in South Africa spherical and milled grades. The production processes are described, and the properties of the two types are examined and compared. Guidelines are given for the selection of the correct grade of ferrosilicon for any particular application.

Jan 12, 1974

By X. M. Prevost

A computer system to store, retrieve and process coal borehole and analytical data together with other geological, geographical or topographical information is described. As a result of the large volume and variety of data stored since its inception in 1979, as well as the basic versatility of the system, the National Coal Data Base has been performing a number of new tasks for which it was not originally designed. As considerable sets of data are used on almost every project, the use of statistical application programs has become an important processing tool.

Jan 1, 1987

By L. Wade

Laboratory testing of the self-heating propensity of coal, using crossing-point temperature and differential thermal analysis techniques, involves the frequent recording of several temperatures. The volume of data and the desire for high accuracy of measurements motivates an automated recording system. The data which are recorded must be adjusted for calibration factors and the results presented in both graphical and tabular form. The paper describes hardware and software features of a computerised system which is being used to establish the relative propensity to self-heating of a wide variety of coals.

Jan 1, 1987

By P V. Savage, T Glück, RCA Minnitt, C Bothma

Manganese Metal Operations ?Manganese Metal Company (MMC), a subsidiary of Samancor BHP Billiton, has two production facilities for electrolytic manganese metal in South Africa and produces a range of about 44 Mn metal products. ?The company is accredited with ISO 9000 and uses Six SigmaTM for continuous improvement. ?The control of the process relies on the effective functioning of approximately 250 different control loops at 50% automation.. ?Approximately 50000 samples are analysed every month. ?There are pyro, hydro and physical unit operations for the production of electrolytic manganese metal flake and value added products ? [ ]

Jan 1, 2005

National Coal Board. Gate belt conveyors. London, H.M.S.O. (Price 95p.) Although the preface of this handy little book states that it has been written for the guidance of miningoperation trainees, it will prove valuable to the practising engineer as well. NIM reports Report no. 1733 A mineralogical investigation of weathered carbonatite from Salpeterkop. (14th Apr., 1975; re-issued 28th Feb., 1978). Report no. 1823 The recovery of gold and pyrite from a residue dump at Crown Mines. (10th Jul., 1976; re-issued 28th Feb., 1976). Report no. 1829 An investigation of weathered carbonatite from Salpeterkop. (20th Jul., 1976; reissued 28th Feb., 1978). Report no. 1932 A BASIC computer programme for the evaluation of intensity data from the Telsec Lab-X-250 Analyser. (12th Jan., 1978). Report no. 1940 The extraction of the noble metals with n-octylaniline,and its application to the analysis of platinum-bearing materials. (30th Jan., 1978). Report no. 1945 Analyses of the NIMROC reference samples for minor and trace elements. (28th Feb., 1978). International futures conference A conference entitled 'The Road Ahead' is being organized by the 1820 Settlers National Monument Foundation to be held in Grahamstown from 3rd to 7th July, 1978. Conference of metallurgists The technical programme has been established for the 17th Annual Conference of Metallurgists sponsored by the Metallurgical Society of the Canadian Institute of Mining and Metallurgy. This year the Conference will be held in Montreal, Quebec, on 27th to 31st August, 1978, together with the 8th Hydrometallurgy Meeting.

Jan 1, 1978

By C. Mueller

In many automated mines, multi media video and audio funtionality has to be combined with sensor information or steering commands, which is the idea of a new, PC based integrated and multi media capable control system. The new control system (Multimedia Control - MMC) bases entirely on TCP/IP networking and internet technology. For the first time, this enables the ‘intelligent’ use of video and audio information: pictures and voice sequences may be forwarded on request only, they may be stored if particular events occur (e.g. video black boxes) and sensor signals as well as actions from the automation system can directly be assigned with multi media sequences. MultiMedia Control entirely bases on object oriented software. It uses most modern software technology. As user interface, only a standard web browser is required. This makes the handling of different machines easy. By using mobile web pads, dedicated local operator interfaces are not required any longer. The service staff just connects to the automated equipment by – wireless –LAN to make required adjustments. Customization is easy using an open Application Programming Interface. Software modules may be added to the system without touching or recompiling existing components. The system was prototyped in 2000 using a demo-application. The performance tests showed very positive results both regarding the control system behaviour and the speed/latency timing behaviour of the multi-media information processed. The system now is slightly reshaped to completely meet the final product requirements. It is expected to be available by the end of 2001. Key words: Machine Automation; Control System; Multi Media; Remote Control; Teleoperation; Ethernet; TCP/IP; Internet Technology; Streaming Video; Quality Assurance; Service; Control Centre.

Sep 1, 2001

[Consider the situation where we wish to estimate the value of a block of ore W from the values of n samples wt (i = 1, 2.... n). The samples can be located anywhere inside or outside W. The blocks and the samples can have any size or shape (Fig. 8.1). We define ws as the set of all the samples wi: WS = Iw1; W2; W3.. . wn and we wish to estimate the block W using the samples ws. Let xi be the value of the ith sample and µw the unknown average value of the block. We can estimate µw from the average value of all the samples. Let µw be the estimator of µw. As the samples need not be of equal size, the sample average is: µw = wi xi/~ wi. (8.1) The mean squared error made when estimating µw by µw is known as the variance of estimation of W by ws. It is the error made when giving the value of the sample set ws to the block W and is written o2E (WS to W). By definition: o2E (ws to W) = E [(µw - µw)2]. (8.2) If n = 1, this error is known as the extension variance. Since the sum of the weights given to the sample values is equal to 1,0, the estimator µw is unbiased (the question of the absence of bias is studied in more detail in Chapter 9): E [( µw - µw)1 = 0. (8.3) The error (µw - µw) has zero mean and a variance o2E = E (W8 to W). If we assume that this error is normally distributed, we can define confidence limits for µw. Let tP be the value of the standardized normal variance t such that the probability that t is less than tP is p: (t,) = .\/27T f exp (- t2/2) dt = p (8.4) The probability that µw is larger than µw + t1-P oE is p. The probability that µw is smaller than µw- t1-P oE is p. The following approximation formulae are often used to calculate 2p central confidence limits for the block value: 68% central confidence limits (p = 16%): µw - o2E, and µw + o2E. 95 % central confidence limits (p = 2,5 %): µw - 2 oE, and µw + 2 oE. Tables of the function 0 can be found in any textbook on statistics (for example, Fraser, 1958, p. 388) (see Table 7.2). [ ] The last line of Table 2.2, corresponding to f = 00, also contains the value of tP for p = 80, 90, 95 and 97,5 %.]

Jan 1, 1978

By N. B. Strydom

I have read with interest all the papers dealing with heat transfer and the setting of heat stress limits that have appeared during the past two decades. Scientifically speaking, most of them can be rated as being of a high standard, and some of them have been acclaimed internationally as masterpieces of logical and calculated reasoning. Weathering of ore minerals A short course on 'The Weathering of Ore Minerals and the Textural Evaluation of Base Metal Gossans' is to be given by Dr I.M. Reynolds in Grahamstown from 4th to 6th October, 1982.

Jan 1, 1982

By J. Kempken, T. Schreiter, R. Degel, H. Schmieden

After a short summary of the historical milestones of the submerged arc furnace, the paper will highlight different applications and their specific smelting furnace requirements in the non-ferrous area. Additionally, aspects of rectangular furnace design and the features of the copper cooling system for the side wall will be emphasized. Finally a state-of-the-art design tool as well as a new invention to improve slag cleaning technology will be featured, which shows great potentials especially for the PGM and copper related industry. Keywords: submerged arc furnaces, aerro alloys, non-ferrous, copper, slag cleaning, PGM, rectangular furnace, DC technology

Jan 1, 2006

By H. E. James

The 13th Congress of the Council of Mining and Metallurgical Institutions (CMMI) was held in Singapore from 11th to 16th May, 1986. Tours to Australia, Malaysia, Thailand, South Korea, and Japan took place the week before and the week after the Congress. Registrations By far the largest contingents at the Congress were from Australia (157 delegates and 65 affiliates) and South Africa (127 delegates and 99 affiliates). The other 25 countries represented at the Congress accounted for 118 delegates and 37 affiliates. Thus the total registrations amounted to 402 delegates and 201 affiliates.

Jan 1, 1986

By R. L. C. Maggs

The following members of the Orange Free State Branch and visitors paid a mini-visit to the H.J. Joel Gold Mine on 23rd January, 1991: Members E.N.D. Westgate Organiser R.LC. Maggs Hon. Secretary S.V. Stander S.P. van Wyk D.S. Minnie O.W. Fourie Visitors C. Knight-Hassel J. Campos E.W. Booysen J. Steyn P.!. Masseratte C.J. Higgins S. Guven F. Scof N. Hastings R. Hays On arrival at the Mine, the visitors were welcomed by the General Manager, Mr Chris Naude, who introduced the staff who would be involved in the visit.

Jan 1, 1991

By A. L. Hinde, P. J. D. Lloyd, A. R. Atkins, J. G. MacKay

The control of milling circuits by A. R. ATKINS, M.Se. (Elee. Eng.) (Visitor), A. L. HINDE, S.Se., Ph.D. (London) (Visitor), P. J. D. LLOYD, S.Se. (Chem. Eng.), Ph.D. (Cape) (Fellow) and J. G. MACKA Y, S.Se. (Chem. Eng.) (Visitor). The general behaviour of mills is described in an attempt to find a control philosophy that will permit milling circuits to produce a constant particle size. Although the experimental work has been confined to a single section of the milling circuit of one mine, it is felt that the findings are applicable to other milling circuits.

Jan 6, 1974

By R. J. Mason

Background to the Transvaal Iron Age-new discoveries at Olifantspoort and Broederstroom R. J. MASON*, Ph.D. (Visitor) The work being done on Iron Age sites in the Transvaal is described, with particular reference to the finds at Olifantspoort and Broederstroom. The material so far found provides evidence for the production of iron and copper, the farming of cattle and sheep, and the construction of large villages by people who were probably ancestral to the present Bantu population. The material dates from as early as A.D. 270, but clear indications occur from AD. 460 onwards.

Jan 1, 1974

By J. D. Smit, K. C. Garner, P. C. van Aswegen

The initial results obtained from the implementation of computer-controlled strategy on the milling circuit are reported. An analysis of these results showed that a peak-power pebble-mill controller on a high throughput hardrock wet-milling circuit reduces the stability of the system. It was concluded that the milling circuit should be regarded as a single system in which the measurement of grinding efficiency, circulating load, product size distribution, and feed rate should minimize the product variance and maximize the feed rate according to the grinding power available. Work is proceeding on such a system.

Jan 1, 1980

By R. Hutchings

The paper reviews current understanding of the effect of ion implantation on the wear process, and the state-of-the-art of ion implantation as a commercially viable treatment to impart wear resistance. Ion implantation involves the firing of high-energy ions into the surface of a material, which modifies the surface properties and so causes a transition in the dominant wear mode. The process is best suited to specialized engineering applications involving critical dimensional tolerances or surface finishes, but has gained little industrial acceptance because of its poor reproducibility and the lack of a suitable method of inspection.

Jan 1, 1986

Introduction and Background For many years people were aware of the vast deposits of titaniferous magnetite containing vanadium in the Bushveld Complex. From 1957 onwards some exploitation of this ore was carried out by Minerals Engineering of S.A. (later the Vantra Division of Highveld Steel and Vanadium Corporation Limited), who produced vanadium pentoxide via a roast-leach process. Canadian Institute of Mining and Metallurgy The Finance and Executive Committees of the Canadian Institute of Mining and Metallurgy have agreed that members of SAIMM should be invited to register at all future CIM meetings at the same rate as CIM members.

Jan 1, 1980

By I. E. Lane

Conventional demand management techniques invariably fail to offer optimum control flexibility in an operationally complex gold mining environment. An improved control system for electrical demand management is proposed. The system is designed to provide more effective load scheduling and control strategies by means of a computer aided demand management system (CADMS). The objective of the CADMS is to provide a responsive computational aid and adaptive control system for effective demand management. The system consists of a short term load forecasting module, an interactive load scheduling module, an incentive based electricity cost allocation module and a power management information module.

Jan 1, 1987

FOURTH INTERNATIONAL CONFERENCE ON VACUUM METALLURGY This Conference will take place in Tokyo from June 4th-8th 1973. The language used will be English. Inquiries should be addressed to: Mr S. Tabata, Conference Secretariat, The Iron and Steel Institute of Japan, (Nippon Tekko Kyokai), Keidanren Kaikan (3rd Floor), 9-4, Otemachi 1 - Chome, Chiyoda-ku, Tokyo, JAPAN. SYMPOSIUM ON BLAST FURNACE (A.I.M.M.) February 15-17, 1972 Circulars setting out the programme for the symposium, and registration forms, may be obtained from the Secretary of the S.A.I.M.M.

By J. Ungar, F. X. McGarvey

The selectivity of ion-exchange sites varies with the matrix of the polymer, the nature of the site. and the method of application. The effect of these variables on the recovery of uranium is examined. with particular attention to vinyl pyridine and to symmetrical and asymmetrical quaternary ammonium sites. The effect, on the loading. of high concentrations of chlorides in the liquors is discussed. and other components of the liquors that may cause fouling of the resin are also considered. The discussion is supported by the results of tests conducted on various types of resins. The economics of the process is discussed briefly.

Jan 1, 1981