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There are presently no suitable underground mine production scheduling optimisation models available for application to sublevel stope mining. Scheduling underground production for maximum return is therefore still a manual process, which generally involves scheduling production from the next available highest cash flow stope within the operational constraints of the project. In most mining operations, the scheduling problem is too large and complex to guarantee truly optimal results through manual scheduling. This paper reviews some general optimisation studies that have been proposed for underground hard rock mining. Furthermore, an example of a mixed integer programming model is presented for a small conceptual sublevel stoping operation. Comparative results of a schedule generated by a mixed integer programming (MIP) production scheduling model and a manually generated model on a nine stope example is presented. Results indicate that the potential benefits of the MIP production scheduling model for the purpose of maximising NPV are significant. Finally, a new constraint was formulated to limit multiple exposures of fill masses for use in an existing MIP production scheduling model. Testing of the formulation took place on the central stope of the nine stope example, which showed that the formulation performed its task without breaking other operational constraints.

Jan 1, 2007

A back-propagation model, which is typical of the models used in the science of artificial neural networks, was applied to the prediction of gossans from the southeast area of Habei Province in China. A success rate of 100 per cent was achieved. The results show that the neural-network approach is good, and that it can be used effectively in the prediction of multi metallic deposits.

Jan 1, 1995

By G. Nino de Guzman, L. C. Woollacott

The isotherms that are usually taken to represent the force 'driving' the adsorption in carbon-in-pulp processes may change from contactor to contactor. This paper reports on an investigation into the extent to which this Isotherm shift is Influenced by the changes in oxygen and cyanide concentration that occur in operating plants. The impact of the isotherm shift on the reliability of simulation results is examined.

Jan 1, 1993

By S. Nana, M. B. Cortie

Duplex stainless steels containing high levels of manganese and copper and lower-than-normal levels of nickel were produced and evaluated. The experimental alloys containing 3 per cent copper by mass could not be successfully hot-rolled. Alloys containing less than 2 per cent copper could be hot- and cold-rolled without difficulty. The wrought experimental alloys that contained copper were found to offer some advantages over the 2205- type duplex stainless steel in sulphuric acid at 52°C. Resistance to pitting attack was governed primarily by the chromium, molybdenum, and nitrogen contents, and one of the experimental alloys was superior to the 2205-type alloy in the ferric chloride test. It is concluded that manganese is a useful substitute for nickel in duplex alloys, but that further work is required before the present alloys, or variations of them, could be commercially viable.

Jan 1, 1993

By P. Harris, N. Heywood

An existing 1 800 m long pipeline, which carried waste mica slurry from kaolin processing, is to be recommissioned. The mica solids throughput is to be substantially increased from 5.2 t/h up to a maximum of9.53 t/h, but with a typical throughput of around 7.5 t/h. Because of this throughput increase, it was unclear whether the existing 80 mm diameter pipe would be adequate. In addition, the pipe route is to be extended by 250 m to 2 050m, and its elevation at discharge to settling lagoons increased from 66.2 m to 80 m. The pipeline hydraulics of waste mica slurry were investigated for the 80 mm diameter pipe using the Saskatchewan Research Council?s (SRC) Two-Layer Flow Model, for the maximum mica solids throughput of 9.53t/h. The pipe operating velocity was compared with the predicted deposit velocity for several mica concentrations, ranging from 20% to 50% by weight. Estimates were made of the total differential pressure across the proposed2 050 m long pipeline, as well as the power imparted to the slurry by the pump, and the specific energy consumption (SEC). Two pipe diameters were assumed: 80 mm when no mica wall deposit is present, and 70 mm when there is a 5mm mica wall deposit. This parameter has a significant effect on the determination of the appropriate pipe operating conditions. For the pipe operating velocity to remain adequately above the deposit velocity (and therefore for the heterogeneous flow pattern to prevail in either horizontal or inclined pipe), it was concluded that if the newly commissioned pipeline contains no mica wall deposit, the pipe should initially be operated at a mica concentration of between 20% and 25% by weight, probably with a target mica concentration of about 23%. A 23% mica

Jan 1, 2007

Duties: The successful applicant will be responsible to the Planning Superintendent for long and short term Mine Planning. The current expansion programme requires production to be derived from new mines, using the most modern equipment. Considerable forward planning is required. Qualifications: Applicants should possess a degree or diploma in Mining Engineering. Experience: Five to eight years' experience in hard rock mining is required of which some part has been spent on mine planning. Conditions: Salary to $7,000. Ample opportunity for further promotion exists in this expanding organisation. The person appointed will be eligible for benefits including discretionary annual staff bonus. An executive home will be provided in the new township with services at nominal rates. Primary schooling is available at Kambalda and the bus service operates for post primary students attending schools at Kalgoorlie. Reasonable relocation expenses within Australia will be met by the Corporation. Employment is conditional upon passing the necessary medical examination for admission to the Western Australian Mining Industry. Written applications, which will be treated in strict confidence, stating nationality, age, marital status and setting out qualifications and experience should be addressed to: The General Manager Operations-W.A., Western Mining Corporation Limited, Post Office Box 80, BELMONT, W.A., 6104. The envelope and application to be marked- "Attention: Senior Mining Engineer".

By V. M. Lovell, N. P. Finkelstein

The concepts involved in flotation research are discussed and aims are presented. Three different method. of investigation can be used, all of which are applied at the National Institute for Metallurgy (N.I.M.), and these are the empirical, trial and error method, the chemical engineering method, and the physicochemical approachs This paper is devoted to the last of these. Because of the complexity of the physicochemical interactions involved, the work has, to a large extent, been concentrated on only one aspect, viz. the interaction between the mineral surface and reagents in solution, which was considered of major importance in the understanding of the process. The aspects on which work has been done are the concentration of uranium, the reaction between salt minerals and fatty acids, mixed xanthate-cationic collector systems, and the reaction between sulphide minerals and thiol reagents. Selected problems from the first two of these are discussed in some detail and deal with the agglomeration flotation of uranium and the chemical control of the flotation process for phoscorite. A detailed discussion is also presented of the progress made in the understanding of the interaction between sulphide minerals and thiol reagents, which is of more general application. Finally, an indication is given of the future direction of physicochemical research at the N.I.M.

It is perhaps somewhat unusual for a contributor to comment on the authors' reply to his critique. However, I should like to return to a specific comment made by the authors. Award to Bob Laburn The Federation of Societies of Professional Engineers (FSPE) is pleased to announce that the 1984 FSPE Award for Services to the Engineering Profession was presented to Dr R. J. (Bob) Laburn at a function held on 14th February, 1984.

Jan 1, 1984

A theory is presented providing a concise mathematical description of the performance of a percussive rockdrill in terms of its principal mechanical dimensions. The theory defines the relationships between the values of thrust required to produce optimum rates of penetration at different throttle air pressures in terms of the piston areas and derives an equation for the prediction of these rates. An analysis of drillsteel life and bit wear is also made.

By N. B. Strydom

Die bedryfsfisioloog en lugbesoedeling N. B. STRYDOM, Ph.D. (Phys.) (Illinois) (Genoot) Although the industrial physiologist can still be regarded as a rarity in South African industry, it is obvious that he could make a positive contribution to the control of air pollution. For the past twenty-two years, the gold-mining industry has invoked the aid of industrial physiologists in solving various problems that continually crop up in the more effective and safer utilization of man-power. Air pollution is only one facet that has received attention. It can be stated emphatically that other industries could gain many advantages from the employment of this type of specialist. Because of inadequate opportunities for academic training, however, the industrial physiologists available might not be enough to fill all the possible posts in industry at present, but confidence is expressed that interested persons will soon be able to follow a full university course in this field of study.

By A. L. Hinde, A. A. Bradley, K. H. Stanton, P. J. D. Lloyd, G. K. Schymura

As part of its programme to develop methods for concentrating minerals underground, the Chamber of Mines of South Africa in conjunction with Lurgi evolved and tested a I MW centrifugal mill. The machine is capable, in the autogenous mode, of grinding more than 25 t/h of minus 75 plus 44 mm hard quartzite to a minus 3 mm product containing over 50 per cent minus 75 µm material, and as a ball mill of grinding more than 60 t/h of minus 19 mm quartzite to a minus 3 mm product containing over 35 per cent minus 75 µm material. Extrapolation of computer models of the process suggests that these limits can be comfortably exceeded. Long-term continuous testing is in hand, aimed at proving that this I m in diameter by I m long mill is in every respect the equivalent of a conventional 4 m by 6 m ball mill.

Jan 1, 1982

By M. McChesney

Modern materials for underground support* by M. McChesney The properties required of a support material for underground tunnels are discussed and, because concrete is both economical and easy to apply, a number of new reinforcing materials for concrete are examined with particular reference to these properties. From about thirty tests on different types of reinforced concrete, it is concluded that the addition of polymer to a concrete does not seem to influence the concrete's post-failure behaviour, and the on'y benefit to be achieved by this addition is to increase its flexibility (or to decrease it, depending on the polymer). Steel fibres tend to increase both the strength and stiffness of the concrete, but polypropylene fibres, although having definite loadcarrying capacities, provide non-stable failure, also known as brittle failure. The best result was obtained for concrete reinforced with steel wire: the post-cracking strength was very good and was maintained for a considerable deformation.

Jan 12, 1976

By S. Selmer-Olsen

New trends and developments in the production of ferro-silicon, ferro-manganese and ferro-chrome alloys are discussed, with emphasis on the general trend to the adoption of large production units. Problems which arise, both of a metallurgical and an electrical nature, due to the use of large electric furnaces, are outlined with specific reference to the limitations imposed by the power carrying capacity of Soderberg electrodes, the furnace resistance and the furnace reactance. The implications of combining high resistance within the furnace with good metallurgical operating conditions are illustrated by considering the production of ferro-silicon and ferro-manganese. The possibility of replacing electric furnaces used for ferro-manganese production, by large low shaft blast furnaces using oxygen enriched blast, is mentioned. The continued use of small electric arc furnaces for ferro-chrome production is also mentioned, and is ascribed to lack of ore suitable for treatment in large furnaces. Agglomeration of chromite ores appears to be a possible answer to this problem.

By E. J. Magri

For life-of-mine planning, as well as for short- and medium-term planning of grades and mine layouts, it is extremely important to have a clear understanding of the patterns followed by the distribution of gold and uranium within the mining area. This study is an attempt to reconcile the geostatistical approach to the determination of ore-shoot directions, via an analysis of the spatial distribution of gold and uranium values, with the sedimentological approach, which is based on the direct measurement of geological features. For the routine geostatistical estimation of ore reserves, the Hartebeestfontein gold mine was divided into 1I sections. In each of these sections, the ore-shoot directions were calculated for gold and uranium from the anisotropies disclosed by geostatistical variogram analyses. This study presents a comparison of these results with those obtained from direct geological measurements of paleo-current directions. The results suggest that geological and geostatistical studies could be of significant mutual benefit.

Jan 1, 1978

By R. S. J. Du Toit

SYNOPSIS This paper is based on a thesis dealing with the problem of basing the current rate at which money is collected from mine owners to pay compensation for pneumoconiosis in the future, on the current dust hazard on mines. The certification of pneumoconiotics and the incidence of pneumoconiosis are discussed against the background of existing legal provision for collecting funds for compensation. The various pneumoconiosis indices are considered. In the data analyzed, the only pneumoconiosis index common to a number of classes of mines is the time it takes to develop pneumoconiosis. Sets of dust indices and pneumoconiosis indices are computed. Expressions are derived for the time it takes to develop pneumoconiosis as a function of the dust hazard, and for the collection of funds as a function of the time available for collection. From these two expressions follows an expression for the rate of collecting funds as a function of the dust hazard.

NOTICES The Institution of Mining and Metallurgy The Institution is to hold a one day meeting entitled "Sampling in the mineral and metallurgical processing industries" at Imperial College, London, on 2nd July, 1973. International Conference on Air Pollution This Conference is organised by the Department of Health and the National Association for clean air. Consas 74 The Fifth Conference of Southern African Surveyorswill be held in Salisbury, Rhodesia, from 3rd to 9th February, 1974.

By E. O. M. Hanisch

Copper working in the Messina district E. O. M. HANISCH. B.A. (Pretoria) (Visitor) By reference to the available literature, an account is given of the manufacture of metal ingots by the Messina copper workers. These workers are thought to have been Balemba tribesmen, of the Musina Clan, who came from across the lebombo Mountains. A description is given of their methods of mining, smelting, and casting, and of the vlrious types of ingots they produced.

Jan 1, 1974

By M. G. Atmore

As is usual when preparing for this type of occasion, I looked back at the subjects covered by my predecessors when they assumed the presidency of this Institute. You will appreciate that, in the eighty odd years since the Institute was founded, the diversity of subjects has been very great. In almost all cases it is quite natural that the speaker should have chosen a topic of special interest to him and one in which he was particularly knowledgeable.

Jan 1, 1979

By D. P. Enright, D. D. Howat

Austenitic manganese-steel castings are very widely used in crushing and grinding in the' gold-mining industry in South Africa, The service life of a casting in a short-head crusher is difficult to predict because there are no clear-cut criteria by which such a judgement can be made, The addition of molybdenum and zirconium to the castings for crushers failed to result in improved performance, The results of extensive tests with through-hardened steel castings were very disappointing, mainly because of a design factor in the bowl liner. The design of the bowl liner is an important determinant of the life and performance of these castings. The extent to which the material in a crusher is reduced in size has profound effects on the consumption of metal and power, and on the effective life of a casting. Tests on manganese-steel castings in an 8 ft by 12 ft rod mill provided data on the total consumption of metal, and on the variations in the pattern and rates of wear of liners over lengthy periods. Progressive changes in the wear profiles of the lifter bars and the other liner components showed unexpected features. There are clear indications that, whereas a set of lifter bars will at first lift the charge strongly with relatively little slippage, there is a later period characterized by more slippage and greater wear on all the liner components.

Jan 1, 1980

Colloquium and General Meeting A General Meeting and Colloquium was held on 'New Advances in Non-ferrous Pyrometallurgy' in Kelvin House, Johannesburg, on Wednesday, 17th March, 1976. The President, Dr R E. Robinson, opened the proceedings at 1OhOO,by welcoming the authors and delegates, who numbered approximately one hundred and twenty. Tinplate Conference The Tin Research Institute is organizing the 1st International Tinplate Conference, which is to be held in London from 5th to 8th October, 1976.

Jan 6, 1976