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By R. J. Gordon, N. J. Keys, N. F. Peverett

Photometric sorting of ore on a South African gold mine by N. J. KEYS. B.E. Met. (Queensland) (Visitor). R. J. GORDON. (Visitor). And N. F. PEVERETT. B.Sc. (Eng.) (Wits) (Fellow) This paper concerns the development and application of a high-throughput, multi-stream photometric sorting machine developed for the South African gold mines. It is now believed that this sorter and its progeny may be found suitable for a large proportion of all possible sorting applications. A laser-light source and sensitive photomultiplier are employed in a scanning system to detect light reflected from the surfaces of rocks passing through the sorting zone. Electronic circuitry then analyses the photomultiplier signal, which represents the varying intensity of the reflected light, and produces control signals to actuate the appropriate valves of an array of air-blast rejection devices to remove from the feed certain particles selected by the analysing process. Typical throughput per machine ranges from 50 t/h for a minus 60mm plus 30mm feed to 200 t/h for minus 150mm plus 70mm material.

Jan 9, 1974

By G. C. Lindeque

"A downward trend in tyre life on haul trucks at an open pit iron ore mine prompted an investigation into the current tyre management strategy in order to improve tyre life. ‘Best practice’ was compared to the current tyre management strategy at the mine to determine aspects that could be improved. Aspects that showed significant room for improvement included employee tyre awareness, tyre pressure maintenance, and road conditions. For each of these aspects a plausible alternative was suggested.A new tyre management strategy was formulated as a step-by-step guide on how to implement the proposed changes. Each step introduces new initiatives but at the same time builds on the previous step’s success. A sensitivity analyses was performed to determine the impact of the proposed changes, with the variables being the reduction in the percentage of premature tyre failure, and the reduction of the site wear rate.The ‘most likely’ scenario showed an increase in tyre life of 41% for the Komatsu 730 trucks and 105% for the CAT 777 trucks if the entire tyre management model is implemented. This would result in a possible annual saving related to tyre usage of R9.2 million. OverviewThe study focused on the tyre life on the main haul fleet at an open pit iron ore mine. The haul fleet consisted of 17 Komatsu 730 (180 t) haul trucks and 12 CAT 777 (90 t) haul trucks.The haulage operation consists entirely of tyre-based haul trucks. Five per cent of the total mining budget is related to tyre costs. Since 2012 there has been a steady decrease in tyre life as measured in operating hours (Figure 1) due to the high percentage of tyres that fail prematurely. In 2014 a total of 41% of all tyres failed prematurely and 61% were classified as ‘worn out’."

Jan 1, 2016

By H. Jeram

The ilmenite, rutile and zircon processes of the mineral separation plant generate tailing streams, which still contain valuable mineral. This is due to a combination of factors, which include separator equipment efficiency, particle size effects and inefficient operating practices (equipment overloading, blockage, etc.). Recent developments by metallurgical equipment suppliers have led to increased mineral separator performance enabling recovery of previously lost valuable mineral. Mineralogical studies were conducted using QEM*SEM and MLA techniques to identify and quantify gangue mineral species and determine mineral association. Laboratory and pilot-scale test work was then conducted to develop suitable process flowsheets for the recovery of ilmenite, rutile and zircon from current and stockpiled tailings.

Jan 1, 2007

By R. M. Morris, G. A. Matthesius, M. J. Desai

Slow pyrolysis experiments were caried out on samples of coal from north em Natal having a volatile mater content ranging between 10 and 25 per cent by mass and a constant particle-size distribution. The tests were conducted at atmospheric pressure in a helium atmosphere, and ata heating rate of 10 KImin and a final temperature of 1220 K. The pyrolysis products were taken as coke and volatile mater (tar and eight other species), and tMir respective yields were measured. The experimental results were used in the modification of an existing mathematical model and in the derivation of new corelations for some of the parameters of the model, so that the volatile products of a coal can be predicted from ultimate and proximate analyses of the coal. The pyrolysis tests showed good agreement between the model predictions and the experimental results.

Jan 1, 1987

Advanced process and equipment analytics have been around for a while. However, with accessible IT infrastructure and site maturity, it is possible to analyse, monitor, and control processing plants and equipment easily. These various disparate systems provide different reports requiring the involvement of various personnel and attention to different reporting platforms. For efficient harnessing of the systems? capabilities, as well as effective improvement and monitoring of process and equipment, a single point of entry is required. A process and equipment optimization solution was required at a concentrator in South Africa, focussing on the product stream of platinum group metal (PGM) concentrate from the UG2 Reef. The investigation of data to identify strategies for optimization was required to allow visibility into plant operations to guide operators, an easier method to identify process loop problems, identification of imminent equipment failures, and advanced process control to optimize throughput and stability. A collaborative effort between the client and General Electric Intelligent Platforms (GEIP) investigated data-driven solutions to each of the problems. With the focus on process optimization and asset monitoring, as well as equipment monitoring, a combination of approaches was utilized to address the various problem areas that were identified. Each was implemented separately in the control layer of the plant IT infrastructure. The integration was done in a centralized web-based reporting tool that integrated the detailed results from the various solutions. On the process control side, monitoring of control loops was included by calculating performance statistics that were reported daily to identify sub-optimally performing control loops and indicating potential problems. The advanced process control solution for this site includes a surge tank controller, stabilizing flow through the flotation banks, and preventing the surge tank from overflowing or running empty. Equipment monitoring was investigated, for preventative maintenance, by making use of statistical data models to indicate imminent equipment failure. These predicted alarm events included the cause for failure, drilling down, and allowing focus on a specific variable for preventative action. The results included a more stable flow through the mill, with fewer stoppages due to surge tank overflows or running empty. The causes for process drift could be identified and operators could react early. Alarms warning of equipment failure 2½ and 4 months in advance were identified in an offline analysis.

Jan 1, 2012

By J. W. Latilla, J. J. van Wijk

In late 1997 a request was received to assist with determining the powered support unit (shield) load capacities for the planned 2 seam short wall. This project had a number of aspects which made it attractive to utilize numerical modelling in conjunction with other more conventional design tools in the design of the shields. Amongst these were: The 2 seam panels were to be laid out about 25 m below the previously short walled 4 seam, the 4 seam had in turn been over-mined by the 5 seam long wall, the proposed face height of the 2 seam short wall was 5.5 m while the 4 seam had been mined at 4 m. The top seam in the area (5 seam) had been mined at between 1.5 and 2.2 m high, the face conditions with about 95 m of broken material applying dead weight loading to the 2 to 4 seam inter-burden septum were hard to predict and cyclical loading due to the presence of strong sandstone bands in the 2 to 4 seam inter-burden. The basic thrust of the study was to take the known, and successful, situation (4 seam short wall) and carry out comparative modelling to enable prediction of likely 2 seam conditions. Some two dimensional aspects studied were: 5 m goaf hanging up behind shields, stresses in beams to determine likely first goaf roof span, stresses in cantilever beams to asses cyclical loading due to sandstone bands in the interburden being loaded by the overlying goaf and stresses on chain and crush pillars adjacent to the goaf edge. Three dimensional aspects that were investigated included: Load distribution along face for close goafing and 5 m goaf hang-up and load in a 1 m wide rib modelled in the position of the powered support units. From the modelling it was possible to determine the optimal shield leg capacity of the new 2 seam equipment. These outputs were used when drawing up the technical specifications for manufacture of the new equipment. The face was successfully commissioned in August 2002. Fin 1997, requête fut faite pour aider à la détermination des capacités de charge pour l’unité de soutènement mécanisée (bouclier) pour la couche 2 courte taille en projet. Certains aspects de ce projet le rendaient intéressant pour utiliser la modélisation numérique en même temps que d’autres méthodes conventionnelles pour la conception des boucliers. Parmi ces aspects se trouvaient : Les panneaux de la couche 2 devaient être placés environ 25 m au dessous de la couche 4 courte taille ; la couche 4 avait été remplacée par la couche 5 longue taille ; la hauteur de taille proposée pour la couche 2 courte taille était 5.5 m, tandis que la couche 4 avait été exploitée à 4 m. La couche supérieure de la région (couche 5) avait été exploitée entre 1.5 et 2.2 m de hauteur ; il était difficile de prédire les conditions de taille, avec environ 95m de matériaux cassés ajoutant une charge morte à la plaque de séparation entre les couches 2 et 4 et un chargement cyclique causé par des bandes de grès dans l’entre-fardeau 2-4. L’idée principale de l’étude fut de prendre la situation connue et réussie (couche 4 courte taille) et de faire une modélisation comparative pour prédire les conditions probables de la couche 2. Certains des aspects à double dimension qui furent étudiés étaient : Un accrochage de remblai de 5m derrière les boucliers ; contraintes dans les poutres pour déterminer le premier intervalle probable entre remblai et toit ; contraintes dans les poutres en porte-à-faux pour évaluer le chargement cyclique causé par les bandes de grès dans l’entre-fardeau qui est accablé par le remblai et les contraintes sur les piliers par chaîne et d’écrasement adjacents au bord du remblai. Aspects à trois dimensions qui furent étudiés : Distribution de la charge le long de la taille pour les remblais proches et l’accrochage de remblai de 5 m et la charge dans une nervure de 1 m de large modelée dans la position des unités de soutènement mécanisées. La modélisation a permis de déterminer la capacité de portée optimale du bouclier du dispositif nouveau pour la couche 2. Ces résultats furent utilisés pour dresser les spécifications techniques pour la fabrication de l’équipement nouveau. La taille fut commissionnée avec succès en août

Jan 1, 2003

The following comment has been received from Mr A. D. Osche* on the above paper, which was published in the Journal in October 1977 (vol. 78, no. 3, pp. 51-62). Obituary: T. K. Prentice The Institute records with deep regret the death on 30th January of its senior surviving Past President, Mr Thomas Kennedy Prentice, at the age of 83. Book reviews R. A. Rich, H. D. Holland, and U. Petersen. Hydrothermal uranium deposits. (Developments in Economic Geology, vol. 6). Amsterdam, Elsevier Scientific Publishing Co., 264 pp. with 77 illustrations and diagrams, 30 tables. U.S. $34,75. M. David. Geostatistical ore reserve estimation. Amsterdam, Elsevier Publishing Company, 1977. 364 pp. World mineral industry The Australasian Institute of Mining and Metallurgy is celebrating its sesquicentenary in 1979. A conference will be held in Perth from 13th to 18th August, 1979, as part of the celebrations, the theme being 'Australia's Role in the World Mineral Industry'. Engineering teaching staff UNESCO has extended its technical assistance to the Venezuelan government in the training of engineers to suit the rapidly developing economy of the country. UNESCO vacancy Vacancy for a post of expert under the UNDP. (1) Title of post: Expert in metallurgical engineering. (2) Duty station: Instituto Universitario Politecnico of Ciudad Guyana (Venezuela). Shell Design Awards The annual Shell Design Awards, organized by the Design Institute and sponsored by Shell South Africa (Pty) Ltd, focus attention on achievements in South African design.

Jan 1, 1978

By A. M. Copeland, A. J. Barrett

The use of hydraulically placed backfill in the deep gold mines of South Africa has increased rapidly over the past decade. The backfill that is delivered to the placement areas has a relatively high moisture content, and it is therefore pumped into geotextile containment bags that allow excess water to drain out but retain solid particles. The specific problems associated with this process that are addressed in this paper include the loss of solid particles entrained in the excess water, the rate of strength gain of the backfill, and the post-placement shrinkage of the backfill. The results of laboratory, surface stope, and underground tests are described. The parameters that were varied included the slurry density, the particle-size distribution, and the feed rate of the slurry the concentration of added flocculant; and the type of geotextile used as containment. Suggestions are given for the optimization of the placement properties of backfill.

Jan 1, 1994

By R. J. MacAulay, R. C. More O’Ferrall

Preliminary tests on cement-consolidated gold-plant slime are outlined, together with preliminary underground tests on the behaviour of two paddocks of the material. Further large-scale testing of the same material pumped to the underground workings from a batching plant on surface is described.

Jan 1, 1978

By P. Valicek, M. Farren, G. Harrison, G. van den Berg, P. van Dorssen, P. Kramers

Full mechanization of the stoping operation using rockbreaking methods other than blasting has been a target of research for decades because of the considerable payoffs in terms of increased face advance rates, productivity and safety. However, the unavailability of economically viable rock breaking tools has prevented progress so far. This has changed with the invention of activated cutting tools, which achieve significantly reduced operating forces, power consumption and wear compared to non-activated tools and thereby permitted the development and evaluation of the first mining system using this technology. Targets for the mining system were a face advance of 100 metres per month on a double shift basis for a 30 metre long panel and eventually fully automated man-free stoping. The purpose of this paper is to describe the design, development and evaluation of the mining system. This was a major collaborative effort between Anglo Platinum’s Rustenburg Platinum Mines Rustenburg Section — Townlands Business Area, Anglo Platinum’s Research and Development Department within the Mining Technology Division, the inventor of the technology Bechem GmbH, the equipment manufacturers Long-Airdox Ltd and Zollern GmbH, and CSIR Miningtek who managed the project. A structured process was followed during the development to minimize the risks involved in using such leading edge technology. The system was rigorously evaluated to ascertain the economic viability of the method and to collect data for the design of a production system.

Sep 1, 2001

By H. A. D. Kirsten

The effects of the mining of deep-level tabular reefs are usually evaluated by use of continuum, elastic mining simulation analyses. This paper gives the results obtained from a series of analyses in which stopes of limited span are considered to be excavated in a non-linearly non-elastic, jointed and fractured rockmass. In particular, the theoretical influence of soft backfill in these conditions is evaluated. It is shown that the stress distribution and behaviour of the rockmass, alternately taken as an intact-elastic and as a fractured non-elastic medium, are completely different. The relevance of the energy-release rate commonly calculated in mining-simulation analyses, and the efficacy of its correlation with seismicity and the associated rockbursts, are reviewed. In deep-level mining operations, it is not practically feasible to obviate releases of seismic energy. The fact of their occurrence should therefore be accepted and, rather than considering the reduction of energy release as the primary objective, efforts should be concentrated on minimizing the effects of such release. Analytical results are given to demonstrate that this approach is not only correct, but also the only feasible solution to the rockburst-seismicity problem in deep mines.

Jan 1, 1989

By P. H. S. W. Kulatilake

The paper introduces a computer simulation technique to estimate the target detection probabilities associated with search surveys. The technique takes into account the inherent randomness associated with the distributional properties of geologic targets. Use of the technique is illustrated through examples. The paper provides information as to how this technique can be used in obtaining the optimum sampling pattern and optimum spacing associated with target detection surveys.

Jan 1, 1987

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 B. P. Watson

Uniaxial tests performed on core from instrumented sites at Amandelbult 1 shaft, Impala 10 shaft and Union Section Spud shaft showed a nonlinear elastic relationship between applied load and induced deformation. This nonlinear behaviour does not appear to be dependent on borehole orientation but in the case of the Amandelbult and Union sites appears to have been influenced by the stress condition of the rock mass at the time of drilling. Cores drilled at these two sites under destressed conditions, such as over a stope, showed a linear elastic response to the applied load whereas most of the cores drilled under relatively high radial stresses were nonlinear. The Impala 10 shaft tests, however, all showed strong nonlinear behaviour irrespective of the stress condition of the rock mass at the time of drilling, although high stress conditions may have influenced the severity of the nonlinearity. A comparison between underground stress change measurements and an elastic model indicated that the rock mass became nonlinear when the virgin stress condition was relaxed to about 10 MPa. The cores for laboratory testing were retrieved from vertical boreholes drilled up from the centre of a stope and from horizontal boreholes drilled over pillars and stopes at about 600 m, 1 100 m and 1 400 m below surface for the three sites respectively. The k-ratios under virgin conditions were estimated from sockets, modelling and stress measurements to be 1.0, 1.3, and 0.5 for the Amandelbult, Impala and Union sites respectively. Of the three sites, therefore, Impala 10 shaft appears to have had the highest virgin stress state. Tests performed on similar rocks from shallower depths at Impala Platinum essentially showed a linear relationship between stress and strain. From the small Impala Platinum rock test database available to the project, it appears that the nonlinear elastic behaviour initiates at this mine from about 1 000 m below surface and seems to become progressively more nonlinear below this depth. In addition, the nonlinear elastic rocks are weaker, have a lower Young?s modulus and a higher Poisson?s ratio than their linear elastic equivalents. Interestingly the tangential Poisson?s ratios of the nonlinear elastic materials are often greater than 0.5 at 50% of the failure stress, suggesting an early failure initiation. The paper describes the microscope and modelling work done to determine the causes of the nonlinear behaviour and discusses some implications of the behaviour for deep-level mining.

Jan 1, 2009

By A. Hoogervorst

Cyanide is a key contributor to the efficiency of gold extraction. Public perceptions of cyanide are emotive and following some publicised incidents involving cyanide, the gold mining industry established a voluntary cyanide code for the manufacture, transport and use of cyanide in the production of gold. The paper describes the development of the code, its content and the third party auditing of the code as a means of establishing and maintaining benchmark standards. In adhering to the cyanide code requirements, there are overlaps with other management systems such as ISO 14001 and OHASA 18001 and the paper seeks to show how existing mine systems can readily accommodate cyanide code compliance and that operating and auditing the cyanide code can assist in the integration of mine heath, safety and environmental management systems.

Jan 1, 2009

By V. V. Getman, V. A. Chanturiya, T. N. Matveeva

Most of the Au and PGM ores in Russia are characterised by a thin mineral impregnation of noble metals in sulfide minerals, and a large variety of mineral forms that lead to high loss of precious metals with fine fractions during flotation. In modern flotation technology, the rational choice of reagents is one of the main trends for selective separation of minerals and effective metals recovery. New data on the selectivity of the thermo-sensitive polymer with specific functional groups (TMPPh) as a flocculant and collector of Au and Pt fine fractions are available. The selective modified collector (DEDTCm) for the recovery of Au and Pt from complex ores is discussed in this paper. Scanning electronic microscopy (SEAM), laser SIM and AFM microscopy, UV and IR spectroscopy were applied to study the adsorbed layer of new reagents on the mineral surface. Flotation tests of TMPPh on the gold-bearing ore of the Olimpiada deposit showed an increase in Au extraction and Au content in the concentrate of the rougher flotation. Using a combination of reagents TMPPh and ButX, the quality of the Au and Pt concentrates increased in 1.7 time with an increase in recovery up to 15 % compared with the traditional reagent mode. Testing of TMPPh polymers in flotation of Pt-Cu-Ni ore at Norilsk Nickel has shown the ability to obtain a concentrate with a higher Pt content. Recovery of platinum is 17% higher than recovery in an experiment without polymer. Application of DEDTCm helped to achieve higher technological parameters in flotation of lowgrade Rt-Cu-Ni ore. Compared to the basic mode Pt recovery was plus 13%, Pd recovery was plus 9% and the content of precious metals in the rougher flotation concentrate increased in 2,5 - 4 times. The studies have been supported by Grants of the President of RF “Scientific School of Academician V.A. Chanturiya” NSh-220.2012.5, NSh-748.2014.5. Keywords: Au and Pt complex ores, flotation, flocculation, thermo-sensitive polymer TMPPh, modified collector

Jan 1, 2020

By M. C. Harris

Float-sink analysis has wide application in the coal laboratory. This paper evaluates the established methods used for the float-sink analysis of fine coal, and then describes a new method and apparatus that can be used for material down to a few micrometres in size. The method is rapid and accurate, and requires only a small amount of sample. The results presented show close agreement with the float-sink analyses obtained by the more classical technique using separating columns. The new centrifugal method reduces the time required for the analysis by a factor of ten.

Jan 1, 1986

By M. Bryson, V. Deeplaul

As a national facility, Mintek?s brief is to conduct high calibre research that allows the most effective utilization of South African resources. The research takes two different forms, with the efforts being directed at both high-risk endeavours that may lead to the development or adoption of new technologies or the reapplication of technologies to potential new operations. Starting in the 80s Mintek began developing a process to upgrade the UG2 ore and invested heavily in projects, equipment and people to service the industry. Some of the highlights of that work that has been conducted here include: ?Development of a milling and flotation process for UG2 ores ?Development of the ?Mintek Process? for maximizing PGM recovery for UG2 ores ?Conversion of the UG2 milling circuits to open circuit ?Development of a robust pilot plant facility for use in plant design studies ?Use of dense media as a waste rejection option ?Use of attritioners in flotation circuits. More recently, and with the future in mind, the following processes are being researched, some of which have already been commercially applied: ?Development of a flowsheet for Platreef ores ?Use of optical sorting technology for upgrading platinum ores ?Use of a mini-plant for reagent optimization studies. Each of the highlights listed above will be discussed in the paper.

Jan 1, 2004

By H. E. Cross

The conversion of a uranium plant to the recovery of zinc by H. E. CROSS. B.Sc. (Eng.)(Hons.) Rand (Fellow) The conversion of the Vogelstruisbult Uranium Plant into a plant for the production of electrolytic zinc is described. The reasons for the conversion, the preliminary investigations. and the basic design principles are all outlined, and a brief account is given of operating experience.. during the commissioning of the plant, with equipment that had been put to a use for which it was not originally Intended.

Jan 11, 1973

By S. L. Miller

The development of a pilot gold geostatistical ore reserve system proved that geostatistical methods worked well for the routine production of annual ore reserves on gold mines of the Gold Fields of South Africa (GFSA) group, and that the techniques could also be practically implemented, understood and accepted by Survey Department personnel. Many side benefits of the pilot system became apparent, and a variety of useful management information was provided by manipulating the data values that were already captured. It was decided that it was a priority computing project to develop a standard production system (GORS) for routine use by all the GFSA gold mines. Experience with the pilot system enabled detailed functional specifications for GORS to be laid down. These, together with group computing policy determined the terms of reference and constraints for the GORS development. System design could not be finalized until new and appropriate mainframe database software and graphics workstation equipment and software had been found. With these in place the basic system was structured to take best ad- vantage of the interactive features of the workstation, the number-crunching power of the mainframe and the flexibility offered by a relational database and associated 4GL tools. Application sub-systems were developed for data capture, statistical applications, geostatistical calculations, contour plotting and graphical queries. GORS is being introduced to the mines in a phased manner with suitable documentation, training and support structures to enable it to be routinely and effectively used on a day-to-day basis by all group gold mines.

Jan 1, 1987