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By F. P. A. Robinson, J. W. Fourie

Austenitic stainless steels are welded using low-heat inputs. However, owing to differences in the physical metallurgy of austenitic stainless steels and duplex stainless steels, low-heat inputs should be avoided for duplex stainless steels. This paper highlights the differences in solidification mode and transformation characteristics of these two types of alloys. Recent work on the effect of heat input on the properties of weldments of duplex stainless steels is reviewed.

Jan 1, 1990

A General Meeting, followed by a Colloquium on 'Pilot plants and problems of scale-up', was held on 22nd March, 1978, in the Main Hall, Kelvin House, Johannesburg. The President, Mr P. A. von Wielligh, opened the meeting at 09h15. He thanked the authors and contributors for their co-operation, and announced the names of the undermentioned candidates, who had been admitted to membership of the Institute:

Jan 1, 1978

By M. Dworzanowski

The difference in the magnetic properties of minerals is the basis for magnetic separation. All minerals can be generally classified as ferromagnetic (strongly magnetic), paramagnetic (weakly magnetic) or diamagnetic (non-magnetic). Magnetic separation can be conducted dry or wet. The majority of the applications of wet magnetic separation in the mining industry are based on the wet drum magnetic separator. The wet drum magnetic separator has been in use for over 50 years and its design is based on a rotating drum installed inside a tank. Inside the drum are stationary, permanent magnets arranged in an arc to provide the magnetic field. These magnets can be of the ceramic ferrite type providing a low intensity magnetic field or of the rare earth type providing a high intensity magnetic field.

Jan 1, 2010

By P. Beukes, D. Bessinger, R. Glenewinkel

High titania slag is produced by the smelting of ilmenite and a suitable carbonaceous reductant in electric furnaces. Currently liquid slag is cast into large blocks, which take about 10 days to cool down before they can be crushed, milled and classified into two final products. The two products, chloride and sulphate grade slag, are differentiated according to their size. Granulation of titania slag has been identified as a possible alternative to the conventional block route. This paper discusses some of the work carried out at Exxaro Research and Development to investigate both wet and dry granulation of titania slag.

Jan 1, 2007

Namakwa Sands, an Anglo Operations Limited subsidiary, is a world-class producer of heavy minerals. A layer of duricrust imposes a pseudo-stratigraphy to the primary deposit and has sterilized part of the generally unconsolidated ore in the open cast mine. The bulk of this ore cannot be treated by the present infrastructure, which employs conventional mineral separation technology. The mineralogy of the cementing agent consists of magnesium and calcium silicates and minor carbonates in addition to clay minerals such as sepiolite and those from the smectite group. Although the duricrust ore is friable and can be easily crushed, the significant clay-sized slime fraction produced, in particular the highly sorptive sepiolite, adversely affects mineral separation. The geometallurgical challenge is to cost-effectively remove the slimes from the ore before it is delivered to the concentrator.

Jan 1, 2007

DISCUSSION: The value of incentive payments in the mining industry by K; SMITH Published in the Journal, May 1974 H. P. CARLISLE* The author has drawn attention to one of the most important of mining problems, viz productivity, and in so doing has highlighted, perhaps inadvertently, the difficulty of assessing productivity. Competition for Students Each year the Institute offers a prize (or prizes should the entries warrant it) of up to R100 for the best paper or dissertation on a topic appropriate to the interests of the Institute. Corrigendum The Journal, May 1974, p. 377 We regret that the last portion of A. A. Hazell's contribution to the paper 'The value of incentive payments in the mining industry' by K. Smith was printed in the wrong sequence.

Jan 10, 1974

By W. F. Nothard, J. R. C. Hill

The Rhodesian approach to the vegetating of slimes dams by J. R. C. HILL, B.Sc.(Agric.) (Visitor) and W. F. NOTHARD (Visitor) To prevent environmental pollution from mine dumps, it is necessary to stabilize them either mechanically or biologically. In the long term biological stabilization is more attractive because of its permanent nature. Initially, the basis of stabilization is in the correct siting and construction of the dump. The main toxic factors influencing plant growth on Rhodesian mine dumps are arsenic, antimony, copper, nickel, a high ratio of magnesium to calcium, excessive soluble salts, high pH, and Iow macronutrient content. Root-growth studies in culture solution and pot experiments are used to supplement information on the suitability of plant material obtained from replicated field trials on mine dumps. In addition to the selection of plants for toxic tolerance, it is advisable to provide multiple-layer protection with trees, shrubs, and grasses. Further, a range of different plant species gives greater biological stability. Protection must be provided for young plants against wind erosion and the abrasive effects of windblown sand. Planted wind breaks are preferred to mechanical forms; windrows of garden refuse make good wind breaks and at the same time introduce organic material to the dump and provide a good environment for seedling establishment. The use of artificial fertilizers and sewage effluent is recommended to hasten the development of a complete and protective plant cover.

Jan 12, 1973

SYMPOSIUM ON THE RECOVERY OF PYRITE The proceedings of the Symposium on the Recovery of Pyrite, held in Johannesburg in June 1969, may be ordered from the Secretary, S.A.I.M.M., P.O. Box 61019, Marshalltown, Transvaal, at the reduced price of R5.00. Papers and addresses presented at the Symposium were: Opening Address by Mr J. K. E. Douglas (President). "The world sulphur position," by W. C. J. van Rensburg (Member). "The South African sulphur position," by D. L. Taylor (Member). "The recovery of pyrite at Government Gold Mining Areas Limited," by R. J. Westwood (Member), G. S. Stander (Affiliate) and H. P. Carlisle (Member). "Recovery of pyrite concentrates from colliery-waste discards-A preliminary assessment," by W. A. Gilbert (Visitor) and E. A. Nugent (Member). "The role of pyrite in upgrading the uranium content of Witwatersrand conglomerate ores by means of the heavy-medium separation process," by D. J. Tutt (Associate Member). "Pyrite recovery by jigs at Durban Roodepoort Deep Limited," by E. J. Dominy (Affiliate), F. Diamond (Affiliate) and A. D. Graham (Affiliate). "The storage of pyrite concentrates," by Joan C. Campkin (Visitor) and P. J. Lloyd (Member). "The flotation plants of the Anglo-Transvaal Group," by L. A. Bushell (Member). "Pyrite flotation with amines and cyanidation of the products," by E. H. D. Carman (Member). "Gold recovery by cyanidation from mill products obtained after pyrite flotation," by P. G. Mrkusic (Graduate), M. Sciarone (Visitor) and H. E. Simonsen (Visitor). "The influence of sulphydryl and cationic flotation reagents on cyanidation of native gold," by K. G. Ashurst (Visitor) and W. P. Finkelstein (Member). "Laboratory tests on the flotation of pyrite from Witwatersrand gold ores by cationic collector," by J. Levin (Member), and M. L. Veitch (Visitor). Closing Address, by Dr R. E. Robinson (Director, National Institute for Metallurgy). INCOME TAX: POST-GRADUATE STUDY COURSE CONCESSION As a result of representations made by the Associated Scientific and Technical Societies of S.A. and the Suid-Afrikaanse Akademie vir Wetenskap en Kuns, engineers and scientists will now be allowed to deduct expenses incurred on post-graduate study courses from their taxable income. The conditions of this concession are set out in section 16 of the Income Tax Act, 1969, which reads as follows: 16. (1) The following section is hereby substituted for section 16 of the principal Act: 16. "Notwithstanding the provisions of section 23(a) and (b), there shall be allowed to be deducted from the income of any person who is a dentist or medical practitioner or practises any profession referred to in paragraph (a), so much as the Secretary may allow of any expenditure incurred by such person in the circumstances contemplated in paragraph (c), if the Dental Association of South Africa in the case of a dentist, or the Medical Association of South Africa in the case of a medical practitioner, or the "Suid-Afrikaanse Akademie vir Wetenskap en Kuns" or the Associated Scientific and Technical Societies of South Africa in any other case, certifies in such form as the Secretary may prescribe that such person- (a) if he is not a dentist or medical practitioner, is the holder of a degree in engineering or allied technology or natural sciences awarded by a recognized university on completion of a prescribed minimum period of study of not less than four academic years or the equivalent thereof and enabling the holder thereof to practise the profession of an engineer or a profession for which advanced and specialised scientific knowledge is required which relates directly to- (i) the development or exploitation of natural resources; (ii) mining or prospecting for minerals; (iii) the production of pastoral, agricultural or forest produce ; (iv) the breeding or care of farm animals; (v) any industrial process; or (vi) the training of specialists in any branch of science or technology connected with any aforementioned profession; (b) has practised his profession for not less than three years; and (c) has incurred such expenditure during the year of assessment in respect of the attendance by him of any postgraduate study course approved by such body to improve his qualifications for carrying on his profession in the Republic". (2) The amendments effected by subsection (1) shall first take effect in respect of assessments for the year of assessment ending on the twenty-eighth day of February, 1970. From this section it is clear that the concession will only be granted if the application is accompanied by a certificate, which certificate must be either signed by the Chairman of Die Akademie or the President of the Associated Societies. In terms of the authority granted such certificates must certify that: (i) the taxpayer concerned has practised his profession for not less than three years; (ii) the expenditure was incurred by the taxpayer during the year of assessment indicated in the certificate; (iii) the expenditure was incurred by the taxpayer in respect of the attendance by him of a post-graduate study course approved by the Associated Scientific and Technical Societies of South Africa or Die Suid-Afrikaanse Akademie vir Wetenskap en Kuns, as the case may be, to improve his qualifications for carrying on his profession in South Africa; (iv) the taxpayer is the holder of a degree in engineering or allied technology or natural sciences, which degree was awarded by a recognized university,

By Gernot Beer, Christian Dünser, Marcos Noronha

The main findings of the joint research initiative “Numerical Simulation in Tunnelling” and a follow-on project on efficient numerical simulation models for tunnelling are presented. Die wichtigsten Resultate des Forschungsschwerpunkts „Numerische Simulation im Tunnelbau“ und einem Folgeprojekt über effiziente numerische Simulationsmethoden werden präsentiert Les résultats les plus importants du point principal de la recherche "simulation numérique dans la construction de tunnels" et un projet consécutif sur des méthodes de simulation numériques efficaces sont présentés

Jan 1, 2003

By J. D. Austin

"Mining Projects: Evaluation, Finance, and Management" held in May 1980 rounded off a theme started with the colloquium on "Exploration Feasibility Studies and Investment Analysis" held in 1979. Seven papers on various aspects of the potential path of an ore-body from an exploration concept through to discovery, evaluation, and financing, to the management of the construction phase, were presented to the 300 delegates at the colloquium held at the National Institute for Metallurgy.

Jan 1, 1980

This paper details the preliminary design work carried out before and during the implementation of an extensive backfilling programme on Cooke 3 Shaft, Randfontein Estates Gold Mining Company (Witwatersrand) Limited. The design work is of relevance to any system utilizing a cementitious binder, and the quality control aspects are of particular significance. Problems associated with correlating laboratory results to actual field results are also briefly discussed.

Jan 1, 1988

By John Taylor

?Introduction to Black Mountain ?Historical metal accounting practice ?Metal accounting audit ?Feed measurement ?Sample precision ?Concentrate measurment ?Current metal accounting practice ?Further refinements to the metal accounting practice

Jan 1, 2005

By G. Raspa

The paper describes a computer procedure for evaluating and selecting recoverable reserves in a mine worked by sublevel stoping. The boundaries of the volume to be mined are optimally defined by means of the 3-dimensional Lerchs-Grossmann algorithm, separately applied to both sides of the panels. The procedure, which has been developed for Masua Mine (Sardinia), also provides for smoothing the optimized boundaries, positioning the drilling drifts, interactive design of drilling fans and calculation of tonnage and grade of each volley. These tonnages and grades form the input of another procedure evolved for production planning.

Jan 1, 1987

By R. Tabanrad

This article examines the stability analysis of intake tunnels of Karun III dam & power plant. The tunnels have been excavated with a 3-dimensional and fairly complicated geometry in Pabdeh weak formation rocks at Zagros region. Due to the particular excavation geometry and inapplicability of plane-strain status, the stability of these excavations has been analyzed using both the 3D elastic software Examine 3D and the 2D non-elastic software UDEC simultaneously. The geomechanical parameters have been estimated by back analyzing the measured displacements from instruments, which were installed in the tunnels, and the parameters have been used in non-elastic numerical model. The results of the analysis show that the strains occurred in surrounding rock mass are less than the allowable failure strain and that the tunnels are stable. In addition, considering the results of non-elastic 2D analysis, the areas with unstable potentiality were identified and after the instability occurred at the areas predicted by the model , it was stopped up to the allowable strain limit through installing additional support . Bei diesem Artikel handelt es sich um eine Analyse der Festigkeit der Eingangstunnel des Damms und Elektrizitätswerks “Karoon III”.Die Tunnel haben drei Dimensionen und eine sehr schwierige Form und sind in brüchigen Felsen in “Pabedeh ,in Zagrossgebirge”eingebohrt.Aufgrund besonderer Form der Bohrung wurde ihre Festigkeit durch elastische dreidimensionale Soft-ware analysiert,die gleichzeitig die drei-und zweidimensionale unelastische Soft-ware UDEC benutzt hat.Die geometrische Parameter sind mit Ausnützung der Analyse berechneter eingesetzter Versorgungen,die in Tunnel aufgebaut sind,bewertet.Und diese Parameter sind in Zahlen-Analyse benutzt.Die Ergebnisse dieser Analyse zeigen,dass die Drücke an Felsen weniger als problematischer Grad der Drücke sind und die Tunnel fest sind.Ausserdem wurde mit einem Einblick auf die Ergebnisse der unelastischen zweidimensionale Analyse die eventuellen unfesten Teile bestimmt.Nach entstandener Unfestigkeit an diesen Teilen wurde die problematischeDrücke für Aufbau mehrere Anlagen gestoppt. Cet article examine l'analyse de la stabilité de tunnels de la prise de Karoun barrage III et centrale électrique. Les tunnels ont été excavés avec une 3 dimensionnel et compliqué géométrie dans Pabedeh que la formation faible balance à région Zagros équitablement. Dû à la géométrie de l'excavation particulière et inapplicabilite de statut de tension plane, la stabilité de ces excavations a été analysée en utilisant les deux le 3D logiciel élastique Examen 3D et le 2D logiciel non - élastique UDEC simultanément. Les paramètres du geomechanical ont été estimés en analysant le déplacement mesuré d'instruments qui ont été installés dans les tunnels et les paramètres en arrière a été utilisé dans les modèles numériques non - élastique. Les résultats de l'analyse montrent que les tensions se sont produites dans masse du roc environnante est plus petit que la tension de l'échec admissible et que les tunnels sont stables. De plus, les régions avec potentialité instable ont été identifiées étant donné les résultats de 2D analyse non - élastique, et après que l'instabilité se soit produite aux régions prédites par le modèle, il a été arrêté jusqu'à la limite de la tension admissible à travers installer du support supplémentaire.

Jan 1, 2003

By C. J. Badenhorst

Occupational illnesses and diseases tend to be chronic and are generally characterized by temporary or permanent physical dysfunction. With the exception of some symptoms, they are not generally visible. Therefore, safety overrides health in mining because occupational ailments take years to develop and management observes less physical trauma, if they witness anything at all. Occupational health issues need to be addressed systematically, encompassing all aspects of the interaction of employees within the work environment. Risk assessment is central to the management of occupational health. This should not be seen as a complex process and may involve little more than simply considering the consequences of one?s actions before starting work. Competent risk assessment provides the starting point and defines the scope of further action. The objectives and final use of an occupational health risk assessment determine the process and the method by which it is carried out. The occupational health risk assessment is therefore a systematic procedure to identify potential health hazards, evaluate the extent of exposure subjectively and/or objectively, and to establish the need for, and effectiveness of existing control measures. Furthermore, it facilitates the drafting of occupational exposure monitoring, medical surveillance and occupational health education programmes. Various models for conducting occupational health risk assessment provide step-by-step guidance for the identification and assessment of significant occupational health hazards and assist in producing suitable and significant occupational health risk assessments. The paper gives an overview of an occupational health risk assessment model based on the basic principles of occupational health and the legislative requirements, which will simplify the occupational health risk assessment process and ensure a sound base for the development of all other occupational health systems.

Jan 1, 2004

By Paul Fouchè, Danie van der Merwe

Contents ?Purpose ?Introduction ?Development of RF tracers ?Test procedure ?Results ?Conclusion ?Way forward ?Acknowledgements

Jan 1, 2005

By F. L. Wilke

The use of operations research techniques and computer models has become entrenched in the mining industry, particularly in the area of mine planning. The paper considers three major areas where increasing efforts are likely to be directed in the future: the integration of multiple disciplines in a single model; the decentralization of computing capacity within a structured network; and the incorporation of sophisticated techniques such as computer aided design and artificial intelligence.

Jan 1, 1987

By C. H. Wyndham, N. B. Strydom, S. Benade

A group of 23 underweight men weighing less than 50 kg were subjected to an acclimatization procedure in which the work rate was gradually increased from 35Watts on the first day to 70Watts on the eighth day. Excessively high body temperatures and heart rates were observed on these subjects throughout the acclimatization period and on their performance they must be rated as heat-intolerant. It can be concluded that such underweight men should not be subjected to acclimatization at such high work rates and that they should not be allocated to tasks involving these rates in a hot environment. The fact that their body surface areas are inadequate to enable them to get rid of the internal heat produced during strenuous work plus their low work capacities are the major reasons for their inability to tolerate heat.

By Sh. Arshadnejad

Stress analysis in a rock medium is essential to determine the stress concentration between two consecutive circular holes and prediction of fracture behaviour. When two consecutive circular holes in a hard rock medium such as granite are loaded internally by the pressure of non-explosive expansion material (NEEM), stress concentration occurs between the holes which then causes the rock to fracture. In this work, finite element (FE) analysis using Phase2 code was employed to study the stress concentration between two consecutive circular holes under internal pressure induced by NEEM. Effects of different hole diameters and spacings, rock properties and NEEM pressures have been analysed. The data gained from the numerical analysis and analytical solutions were then used to develop two models. These models were then modified by using the FE data and polynomial regression analysis. The developed analytical models showed to be in a very good agreement with the FE analysis. Hence, the developed models can be used with confidence to determine stress distribution and concentration factors around two consecutive circular holes in a hard and brittle rock which are loaded internally by the pressure induced from the NEEM. Keywords Finite element method, non-explosive, quarry mining, stress concentration..

Jan 1, 2011

As part of a broad program to optimise the performance of their grinding circuit, BHP Billiton Cannington have installed an OCS© Expert system together with three VisioRockTM online particle size analysis cameras. The main purpose of the system is to stabilise grind size and feed to the flotation circuit. This particular application of OCS© is the first installation to incorporate Metso Minerals Process Technology-Asia Pacific's (MMPT AP) Dynamic SAG/AG Mill Model, which is able to predict numerous mill parameters that were previously unable to be measured with the existing plant instrumentation. Integrated into the logic of the control algorithm are online vision based, particle size measurements of the AG mill feed and recycle crusher product. This paper will describe the history of the project from initiation to date, the model and OCS© logic configuration, and demonstrate the significant benefits realised at Cannington mine.

Jan 1, 2007