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Fathi Habashi, Chalcopyrite. Its chemistry and metallurgy. New York, McGraw-Hill, 1978. 165 pp. RI9,95. Loss prevention and safety promotion The Proceedings of the 2nd International Symposium on Loss Prevention and Safety Promotion in the Process Industries, Heidelberg, 6th to 9th September, 1977, are now available. Chemical reaction engineering The Proceedings of the 4th International/6th European Symposium on Chemical Reaction Engineering (4th ISCRE) held at Heidelberg, Federal Republic of Ge rmany, from 6th to 8th April, 1976, are available from DECHEMA Deutsche Gesellschaft fur Chemisches Apparatewesen, P.O.B. 970146, D-6000 Frankfurt/ Main, West Germany, at the price of DMlOO plus postage and packing. Books received The Institution of Mechanical Engineers Proceedings Volume 190. Tribos abstracts on friction lubrication wear. Published by BHRA Fluid Engineering, Cranfield, Bedford MK 43 OAJ England. Price £30 (UK), US$72 (Europe), Seawater corrosion handbook, edited by M. M. Schumaker. Noyes Data Corporation Publicity Department, Mill Road at Grand Ave., Park Ridge, NJ 07656. 494 pp. Australian mineral industry quarterly 31(1) 1978 and 31(2) 1978. Bureau of Mineral Resources, Geology and Geophysics, Box 378, Canberra City, ACT 2601 Australia. Subscriptions $8, individual number $2. Mineral and NIM reports Report no. 1996 The extraction of gold from chloride solutions. (10th Nov., 1978). Report no. 1898 Batch and pilot-plant tests on M erensky Reef ore from the Western Platinum Mine. (8th Jun., 1977; reissued 30th Jan., 1979). Report no. 1920 A mineralogical investigation of Mamatu'an and Wessels manganese ores. (15th Sep., 1977; reissued 3rd Jan., 1979). Report no. 1978 The preparation and certification of a referencesample of magnetite ore. (22nd Dec., 1978). Report no. 1998 Electrode response to the addition of zinc during the cementation of gold. (25th Jan., 1979). Report no. 2002 The spectrochemical determination of phosphorus, magnesium, and iron in phosphate rocks and sulphuric acid leach liquors. (26th January, 1979). Report no. 1992 The use of emission spectrometry for the determination of impurities in metals. (24th Jan., 1979). Report no. 2003 An electrodeless conductivity meter of improved sensitivity and reliability. (28th Feb., 1979). Report no. 2005 The spectrometric analysis of manganese-bearing materials with particular reference to ferromanganese slags and metals. (16th Mar., 1979). Report no. 2006 An examination of procedures for the analysis of dry powders by atomic-absorption spectrophotometry. (28th Feb., 1979). Report no. 2007 The instrumentation and computerization of a 25 MV.A submerged -arc furnace. (25th Mar., 1977; reissued 16th Mar., 1979). Corrosion The International Corrosion Council has decided to hold the next Internat ional Congress on Corrosion in Mainz, Federal Republic of Germany, from 6th to 11th September, 1981. Process control The First European Symposium on Real -time Datahandling and Process Control will be held in West Berlin from 23rd to 25th October, 1979. Geomechanics The 28th Geomechanics Colloquy, organized by the Oosterreichische Gesellschaft fur Geomechanik, is to be held at Salzburg on 18th and 19th October, 1979. Geosta tistics A short course on 'Geostatistics for exploration and production planning' is being conducted by the Applied Earth Sciences Department, Stanford University, California, from 27th to 31st August, 1979. Business administration The Twelfth Executive Development Programme of the Graduate School of Business Administration, University of the Witwatersrand, is to be held from 9th July to 17th August, 1979. The engineer and the law A series of four meetings on the above subject is being conducted by the Measurement, Computation and Control SubCommittee of The South African Institute of Electrical Engineers. Lead smelter for South Africa? The National Institute for Metallurgy and Gold Fields of South Africa are making a comprehensive joint investigation of the technical and economic viability of an integrated lead smelter. Conference on titanium The Fourth International Conference on Titanium will be held from 19th to 22nd May, 1980, in Kyoto, Japan.

Jan 1, 1979

By F. H. Guise-Brown

Raise-boring experiences in the gold mines of the Anglo American Corporation Group by J. W. WILSON and P. C. GRAHAM Published in the Journal, October, 1972. Discussion by F. H. Guise-Brown., B.Sc. (Min. Eng.) (Member) INTRODUCTION Messrs J. W. Wilson and P. C. Graham are to be congratulated on an excellent paper containing several thought-provoking remarks. The concept of allocating a machine and equipment valued initially at some R300 000 on an experimental basis is courageous, and the results obtained could be of interest to the mining industry as a whole. The Gold Fields of S.A. Group approached this problem differently. In pioneering the start of this work in South African gold mines, they considered that expenditure of this magnitude would be warranted only if the proposition was viable right from the start. To this end, a Robbins R41 was purchased expressly to assist in the duplication of part of the No. 1 shaft system of the Doomfontein Gold Mine. Mr M. J. Koortsl has summed up the initial results of this work and given some preliminary costing, but inflation since that period has made these figures somewhat out of date.

Jan 10, 1972

By A. V. Z. Brink

This paper describes the development of a monitoring architecture that allows for continuous monitoring of the process of mining, the underground environment, the state of the rockmass and its response to mining. The system is based on an open standard and is non-propriety. It allows for dense sensor arrays in the workplace, wire less communication to the closest power line, and TCP/IP communication to a central server. Continuous monitoring and quantification of the appropriate parameters allows a mine to optimise its mine process; to dynamically access the safety and health risk to people and equipment; and to quantify exposure to potential heath hazards such as dust, gas or noise. Current application examples of continuous monitoring include an application to optimise drilling and blasting thought fragmentation monitoring; an application of wireless sensor network-based monitoring in to provide early detection of potential rockfalls; and a trail to continuously assess the gold grade at the shaft through correlation with radioactivity. It is unlikely that a single monitored parameter will provide adequate knowledge of the assessed risk or even an optimisation approach. Multiple parameters are being combined using cognitive science tools such as Bayesian theory and other statistical methods to improve the accuracy and relevance of, for example, risk quantification. The decision maker is not confronted with massive amounts of raw data but rather with a single knowledge statement such a probability of failure, a human physiological strain index or an optimisation index.

Jan 1, 2008

By Y. Jeong, K. Kim

Excess water can lead to instability and even failure in tailings storage facilities (TSFs). Simply reducing the amount of water in TSFs could be the best way to ensure the safety of nearby communities. In this case study we investigated the effects of reducing the water content in tailings slurry at a copper-cobalt-zinc mine in Mexico. An environmentally friendly polymer was used as a drag reduction agent (DRA) to offset the increase in solids percentage. The potential effects of the increased solids concentration on the tailings transportation system were also assessed. A series of ‘what if’ studies was conducted to assess whether adding the polymer would allow the solids concentration to be increased without changing the pressure loss in the tailings pipeline. The studies entailed conducting pipe loop tests to investigate these changes under various solids/ polymer concentrations and then constructing a computational fluid dynamics (CFD) simulation model using the test results. The validated model was used to determine the optimal polymer percentages needed to maintain the same pressure loss under baseline (30% solids) conditions, and to assess the potential risks (clogging, increased erosion rates) to the pipelines. The potential water savings were found to be significant, varying from about 1.852 Mm3/a at 35% solids to 3.915 Mm3/a at 45% solids.

Dec 13, 2023

By T. J. Otto, C. H. Cloete, T. Mkhatshwa, T. J. van Heerden

The value realised by an open pit mine depends on the quality and integrity of the mine planning process as well as the level of execution against these mine plans. When managing the execution against the mine plan, how well the mine plan is executed spatially, is of critical importance. The short-term mine plan is the plan that is physically executed on most open pit mines. At the same time, the spatial mine-to-plan compliance is typically reconciled against the annual business plan. Short-term mine planning, therefore, plays an important role in the effectiveness of the spatial mine-to-plan compliance reconciliation process by providing operational teams with detailed designs and schedules, while ensuring that mining execution is spatially aligned with the business plan. The Sishen open pit iron ore mine (Sishen) strives to continuously improve spatial compliance to the business plan. Sishen enhanced the role that short-term mine planning plays in enabling the forward-looking component of the spatial mine-to-plan compliance reconciliation process. The enhanced short-term mine planning process focuses on detailed tactical sequence designs per mining pushback, the health of value chain buffers, spatial plan-to-plan reconciliation, and the associated management routines. This led to improved spatial mine-to-plan compliance to the business plan from 71% to 94% over the four-year period from 2020 to 2023 inclusive. These results indicate that the application of short-term mine planning as part of an integrated spatial mine-to-plan compliance process at open pit mines can contribute positively to improving the level of spatial execution against the business plan. This paper presents the enhancements made to the short-term mine planning process, which other open pit mining operations can consider to improve spatial mine-to-plan compliance.

May 27, 2025

By P. Sebola, S. Rasmeni, K. Seripe, D. Chetty

"South Africa’s Northern Cape Province hosts semi-precious and gemstone occurrences that are sporadically mined on a small scale by local communities. Tiger’s eye, a gemstone known for its chatoyancy properties, is found in important deposits located near the town of Prieska, where is it intermittently mined. Challenges faced by small-scale and informal mining include mining without proper permits, risky mining practice in dangerous terrain, and illegal export of raw material without concerted effort at domestic beneficiation. As part of a study aimed at job creation and social upliftment in the region, tiger’s eye deposits in the Prieska area were assessed to assist small-scale miners to understand tiger’s eye grades and their distribution. This will allow not only more efficient and safer mining of these deposits, but also beneficiation of the raw product into tumbled stones, cabochons, jewellery, and other small artefacts for sale. A hub established in Prieska by Mintek trains locals in the beneficiation of tiger’s eye. Supply to the hub must make use of a consistent grading system, which is discussed in this paper. Together with proper mine licensing, such an approach will develop mining and beneficiation skills, and create and sustain employment for the local community. IntroductionTiger’s eye is a semi-precious stone known for its chatoyancy property, which is caused by parallel, silicified asbestos fibres that impart a silky lustre to specimens. Deposits of tiger’s eye in the surrounds of the town of Prieska, Northern Cape Province, formed the focus of a study aimed at small-scale mining and beneficiation of this commodity. The Prieska tiger’s eye deposits are located along the N10 route to Upington (Figure 1). Tiger’s eye is unevenly distributed and occurs as lenses of various sizes, interbedded in gently folded metasedimentary rocks of mostly banded iron formation (BIF). The tiger’s eye occurrence in the Northern Cape Province, especially in the Prieska area, has not been extensively researched. There is thus limited information available in the public domain. The lack of knowledge on tiger’s eye distribution has resulted in local small-scale miners adopting a trial-and-error method of mining. Basic geological mapping and field evaluation of the deposit, coupled with professional judgement, are important aspects of any small-scale mining operation and can contribute significantly to the formulation of various acceptable and equally viable mining methods and practices."

Jan 1, 2016

By M. B. Shongwe

Pt-based alloys are being developed for high-temperature applications with the aim of replacing some of the currently used Ni-based superalloys (NBSAs) in the highest temperature applications. The Pt-based alloys have a similar structure to the NBSAs, and since Pt is more chemically inert than nickel and has a higher melting point, they can potentially be used at higher temperatures, up to 1300°C, and in more aggressive environments. Several experimental Pt-based alloys were studied at Mintek, and an optimum composition was found to be Pt84:Ahi:Ru2:Cr3 (at.%). On the basis of hardness and microstructure, a later study identified a new optimum: Ptr8:A111:Ru5:Cr6 (at.%). There are at least two Pt3A1 allotropes, and the high-temperature cubic structure has better properties than the lower temperature tetragonal form, and so needs to be stabilized. This work describes the latest results obtained in transmission electron microscopy (TEM) studies of the quaternary Pt-based superalloys. These results are both interesting and important, because the samples have a higher precipitate density compared to those from earlier work. The precipitate morphology is mainly cubic, with minor areas having irregular-shaped precipitates. The high volume fraction of the precipitates is a major breakthrough, since the objective of this work is to improve the alloys. A prior disadvantage was that the proportion of the precipitates was too low in samples before this work, especially compared with the work from Germany on Pt-Al-Cr-Ni¬based alloys as well as the NBSAs. TEM -Pt3A1 diffraction patterns were studied, and for each diffraction pattern, many possible lattice point combinations were tried, with the angle between the lattice spots as well as interplanar spacings being calculated for each phase (cubic or tetragonal) to match the measured results. An overall analysis of the diffraction results indicates that the cubic phase fitted the experimental lattice points with much lower errors compared to the tetragonal phase. Thus, with the close match achieved with the cubic structure, the structure of -Pt3A1 precipitates is likely to be cubic. X-ray diffraction has been carried out on selected samples, and the results confirmed the presence of cubic -Pt3A1 and (Pt). Different X-ray diffractometers were used to further verify the results, and the results were also compared with those from TEM.

Jan 1, 2012

By J. K. E. Douglas

Brigadier Ralph Shelton Griffin Stokes D.S.O., C.B.E., M.C., who died in England on 24th February, 1979, at the age of 96 years, was one of the most colourful personalities in South African mining history. After the South African War, in which he served as a trooper, he joined the Crown Reef Mine as an assistant assayer (1902), and was to serve the mines of the Corner House Group intermittently for the next 57 years until his retirement in 1959.

Jan 1, 1979

By D. Gerhart, J. Hung, J. Hackwood, A. Pix

A computer-based, real-time mine management system has been installed in a number of underground operations. The system’s innovative software application is coupled with wireless data acquisition and database management to provide complete mine monitoring and control execution in closed-loop control fashion. The system is well suited to automatically assign equipment, acquire status, and reassign resources based on status; and to automate information handling. The system has provided mines with improved utilization of the equipment fleet and mining crews, and reduced workplace cycle time. This paper describes the deployment of systems at a number of underground mining operations and discusses future development of the system. Keywords: Computer-based: Real time: Utilization: Mining cycle control: Monitoring: Productivity

Sep 1, 2001

By P. K. Van Manen

Anglo Platinum?s Polokwane Smelter is situated outside Polokwane, in the Limpopo Province in South Africa. A single 168 MVA six-in-line rectangular furnace smelts dry concentrates containing platinum group metals (PGMs). Furnace energy consumption since commissioning is presented, showing that energy efficiency improves as capacity utilization increases. An energy balance for the furnace is outlined, indicating the measured or calculated energy losses from the hearth and side-wall cooling, the copper coolers, the upper furnace walls and roof, and the energy losses in off-gas, matte, and slag. From the energy balance, the potential to improve energy efficiency by controlling the slag temperature, the slag level, and the off-gas volume is derived. Furthermore, the impact on the energy balance of different concentrate types is discussed, as well as the potential impact of replacing all upper waffle coolers by plate cooler panels.

Jan 1, 2009

By E. Moosavi, K. Tolouei

In mine production scheduling problems are well-known, where most are categorised into deterministic and non-deterministic NP-hard problems because of their complexity. Many researchers have attempted to solve the problem by applying various optimisation techniques. While using traditional methods they observed extreme difficulty in solving highly complex problems. In the 1990s, many researchers addressed long-term production scheduling (LTPS) by using simulated annealing, the genetic algorithm, the tabu search algorithm, and the ant colony algorithm. These algorithms are known as the meta-heuristic algorithms, and have proved to be the most efficient algorithms for solving LTPS thus far. The firefly algorithm is one of the best methods for visualising problems related to LTPS, and provides the best possible optimisation. It is one of the simplest methods, and easy to apply to any NP-hard problem. The experimental, and comparison with other recently published algorithms shows that the proposed algorithm is feasible, and is an effective approach for long-term production scheduling problems. The results indicated that a better solution is obtained by the proposed method, compared to other methods in terms of cumulative net present value, and average ore grade. Additionally, the CPU time via the proposed model is roughly 2.52% higher than the other method.

Sep 1, 2021

By L. Linzer, J. Oelofse, T. Rangasamy

Extraction of isolated blocks of ground with elevated levels of stress and/or seismicity is a common occurrence in South African gold mines. Isolated blocks of ground that are divorced from the main orebody and are bound by complex, dip and strike parallel, non-persistent geological structures dominate the Klerksdorp gold fields. No quantifiable methods exist to assess the risk associated with mining these and other classes of remnants. A case history, from a gold mine that planned to extract three remnant blocks hosted in a large complex fault system, is used to illustrate the decision making process based on a combination of underground observations, numerical and seismic techniques. Simple risk estimation matrices were developed and used to estimate remnant-mining risk and finally to quantify the decision on which of the three remnant blocks could be extracted at the lowest possible geo-mechanical risk. Il est courant dans les mines aurifères sud-africaines d’extraire des blocs de terrain isolés qui possèdent des niveaux élevés de contraintes et/ou sismicité. Les régions aurifères de Klerksdorp sont dominées par des blocs de terrain isolés qui sont séparés du gisement principal et qui sont retenus par des structures géologiques non continues, à parallèle de pendage et direction, et complexes. Il n’existe pas de méthodes quantifiables pour évaluer le risque associé à l’extraction de ce genre et autres genres de résidus. Une observation de cas, celle d’une mine d’or qui avait l’intention d’extraire trois blocs de résidus qui se trouvaient dans un grand système complexe de faille, est utilisée pour illustrer le processus décisionnel basé sur une combinaison d’observations souterraines, et de techniques numériques et sismiques. Des matrices simples d’estimation de risque furent développées et utilisées pour estimer le risque lié à l’extraction des résidus et finalement pour quantifier la décision sur lequel des trois blocs de résidus pouvait être exploité au moindre risque géo-mécanique. Die Extraktion isolierter Gesteinsblöcke mit erhöhtem Spannugsniveau oder Seismizität ist in südafrikanischen Goldminen üblich. Isolierte Gesteinsblöcke, die von der Haupterzader getrennt und durch komplexe, parallele abfallende und horizontale nicht persistent geologische Strukturen gebunden sind, beherrschen das Klerksdorp Goldfeld. Es gibt keine quantifizierbare Methoden die das Risiko welches mit dem Abbau dieser und anderer Klassen verbunden ist beschreiben. Eine Fallstudie einer Goldmine, welche die Extraktion von drei in einem großem komplexen Verwerfungssystem eingelagerten Einschlußblöcken plante, wird verwendet um den Entscheidungsprozeß zu illustrieren, der auf einer Kombination von Untertag Beobachtungen und numerischen und seismischen Techniken basiert. Einfache Gefahreinschätzungsmatrizen wurden entwickelt und angewendet um das Abbaurestrisiko abzuschätzen und letztendlich die Entscheidung zu quantifizieren, welcher der drei Einschlußblöcke unter dem niedrigst möglichen geo-mechanischen Risiko extrahiert werden konnte .

Jan 1, 2003

By K. Esmeli, A. Ozkan

The enhancement of shear flocculation of a galena suspension by ultrasound in the presence of sodium isopropyl xanthate and potassium ethyl xanthate was investigated by studying the effects of surfactant concentration on flocculation efficiency, contact angle, and zeta potential. Strong flocculation was obtained under alkaline conditions (pH > 9) and a high ultrasound power level (150 W). Although the ultrasonic treatment increased the negativity of the zeta potential of the galena particles, this did not decrease the flocculation efficiency, thereby showing that the hydrophobic interactions between the particle were stronger than the electrical double-layer repulsion resulting from xanthate adsorption. The findings indicate that the ultrasonic treatment promoted the adsorption of surfactants onto the mineral surfaces.

Jul 5, 2023

By P. K. Van Manen

Anglo Platinum's Polokwane Smelter is situated outside Polokwane, in the Limpopo Province of South Africa. Wet concentrate is received from various concentrators along the Eastern Bushveld Complex. Approximately 60% of the total concentrate received is from UG2 Reef, and 40% is from Merensky Reef. The concentrate is dried in two flash dryers, and smelted in a single 168 MVA furnace. A PGM-rich nickel-copper matte is cast, crushed and transported to Rustenburg for converting. The plant was commissioned in March 2003. The wet concentrate, containing 12-18% moisture, is weighed, sampled by one of two auger samplers, and off-loaded into a concentrate shed, either directly through a grizzly into a hopper, or onto the floor. From the shed the concentrate is conveyed to 12 concrete silos. Each of the two identical flash dryers can be fed from six silos. From the flash dryers concentrate is transported pneumatically to a 3 000-ton dry concentrate storage silo. The flash dryers are rated at a nominal 66 tph of dry concentrate at 14% moisture, while the furnace can smelt 90 tph of dry concentrate. Therefore both flash dryers are required to operate when the furnace runs at design throughput. Each flash dryer consists of a hot gas generator (HGG), a disintegrator and drying column, and a section for gas/solids separation. In the HGG, gas heated up to 700° C is produced from the combustion of coal peas in a fluidized sand bed. The hot gas and wet concentrate are introduced to the disintegrator at the bottom of the drying column. The disintegrator breaks up any lumps of concentrate, and throws the concentrate up into the drying column, where it travels co-currently with the hot gas. A fan draws the hot gas from the drying column and through the gas/solids separation section, which consists of three primary cyclones, a multiclone and a high-temperature bag house. The dry concentrate reports to a 450-ton dry concentrate storage bin. A portion of dry concentrate is recycled to the wet concentrate feed in a paddle mixer, so that concentrate that is too wet does not enter the disintegrator. The drying column outlet temperature is controlled at 120° C. Coal is received by road, screened for oversize and conveyed to a 400-ton concrete silo. From here it is pneumatically conveyed to a small feed bin at each of the HGG' s. The optimization work consists of process control improvements relating to the HGG outlet temperature, to control the drying column temperature during the ramp-up of the HGG outlet temperature and bag filters. Furthermore a heat balance is used to evaluate options to increase the instantaneous drying capacity of the existing equipment. The coal consumption derived from the heat balance is compared with the actual coal consumption. The purpose of the optimization work is to achieve an operating schedule for the flash dryers such that they operate simultaneously for as short time as possible. Most of the time one flash dryer should operate, allowing maintenance to be done on the other flash dryer, while drawing down the dry concentrate stock. Keywords: Anglo Platinum, Polokwane Smelter, pyrometallurgy, metallurgy, platinum, platinum group metals (PGM), base metals, flash drying, fluidized bed.

Jan 1, 2006

By J. K. E. Douglas

PRESIDENTIAL ADDRESS Given by Mr J. K. E. DOUGLAS, M.Se. (Eng.) (Rand) SYNOPSIS Lime is the most widely used and the cheapest chemical alkali known to man and virtually every product we use or eat has required lime in some phase of its manufacture. Its use goes back to the earliest days of man and many ancient buildings and writings bear testimony to this. The manufacture of lime involves quarrying, crushing and screening of limestone and the burning of the sized stone in kilns of which there are several types. The earliest kilns were of very crude design and only in comparatively recent times have large capacity, automated and scientifically controlled kilns been developed. The history of the South African lime industry is largely that of the three main lime companies and their story is briefly told. No other material used in industry has a greater diversity of uses or more varied functions and lime has applications in most South African industries. The main applications are in the production of gold and uranium, iron, steel and ferrochrome, carbide, sugar and paper and for water treatment, agriculture and building. The Republic is well endowed with high quality limestone and the conclusion is drawn that many other minerals will have been exhausted before we run out of limestone with which to process them. The expansion of the lime industry has in the past kept pace with the requirements of industry and the future demand is expected to grow in parallel with the growth of these industries. Since the war this growth has been phenomenal and with our expanding populations and abundance of raw materials it should continue in the years ahead. Limiting factors are the shortage of skilled labour and the distance from export markets. Confidence is expressed that the challenges of the future will be met and that the lime industry will continue to make an important contribution to the growth and prosperity of South Africa. INTRODUCTION Lime, gentlemen, is known to all of you. Like myself, most of you have undoubtedly found it to be, on the appropriate occasion, a most pleasant flavouring for gin. But this lime, or rather its juice, was in earlier days more than just a flavouring. In the days of sail it was vital to the health of sailors as a deterrant against the scourge of all sea-going men-scurvy. It thus played a small but important role in the opening-up of trade routes around the world on which was based the original wealth of many of today's more advanced nations. I propose to address you on the subject of lime this evening, not the citrus variety I have just mentioned, but the most widely-used and cheapest alkali known to man, which, largely unsung, plays an even more vital part in modern industry than did its namesake in the development of inter-continental trade. In the time at my disposal, I propose to tell you something of the history, geology and technology of lime manufacture. Then I will briefly sketch for you the development of this industry in South Africa and indicate the role it plays in supplying the requirements of many of our important industries. Finally we will attempt to look into the future. The importance of this chemical alkali to our modern civilization is seldom fully appreciated-virtually every product we use or eat has required lime in some phase of its manufacture, either directly or indirectly. It is one of those basic materials, along with iron, coal, sulphur, salt and petroleum without which industry and, in fact, our modern way of living could not exist. Fortunately, nature has endowed the world with a plentiful supply of the limestone from which lime is derived and most countries have deposits adequate for their requirements. As a result, not only has there been little trade in lime products between countries but in the past the widespread occurrences of limestone have set a pattern of numerous small plants each serving a limited area. These plants were generally crude affairs incapable of producing a quality product. It is not surprising that, in an industry comprised of small producers with limited financial resources and in fierce competition with each other, there was little interchange of information. Technological development was therefore slow and the industry tended to be regarded as a backyard operation. Its popularity was not enhanced by the fact that lime is difficult and unpleasant to handle if proper facilities are not provided. In recent years the lime industry has undergone very radical changes to meet the more exacting requirements of today's more sophisticated consumers. Only since the war have the larger companies emerged with proper management, highly mechanized plants and a scientific approach. HISTORY Lime was one of the first chemical reagents used by man and consequently lime burning is one of the oldest of the chemical industries. The use of limestone dates back to the stone age when primitive man used limestone to build fireplaces, construct shelters and make crude tools and weapons. It is probable that lime was first discovered by him when the stone in these fireplaces disintegrated to a white powder which he could use for decorative purposes. The first recorded use of limestone was when huge blocks of limestone were used to build the pyramids of Egypt in 4,000 to 2,000 RC. It was not long after this that the beauty of marble, which is in fact a limestone, came to be appreciated and it found wide application in sculpturing and for decorative wall construction. Originally lime, mixed with sand, was used mainly as a mortar for building purposes, the earliest record of its use for chemical purposes being in 350 B.C. in a report of the wreck near Marseilles of a ship carrying a cargo of linen and lime 'for its bleaching'1. Cato mentioned the burning of lime kilns in 184 B.C. and the Romans made extensive use of both limestone and lime for highway construction. A treatise on architecture by Vitruvius who had an official position in the rebuilding of Rome under the Emperor Augustus remained for nearly two thousand

By B. van Beek, J. H. Zietsman, A. Lexmond, N. J. Andrew

"In platinum group metals (PGMs) smelting, the slag-to-matte ratios are very high (approximately 4:1 to 9:1). The slag temperature therefore has a strong influence on matte temperature, which is a continual concern due to the low matte melting temperature and its resultant high superheat. Maintaining a stable slag temperature is therefore a critical safety and operational issue. This project aims to improve the understanding of the slag bath temperature drivers so that a more effective slag bath temperature control strategy can be implemented.With the aim of developing a multiphysics model of the furnace, extensive data analysis was performed to develop an in-depth understanding of the process before the start of modelling work. In this work, the effect of fluctuating furnace feed composition on slag temperature was examined. The results are based on equilibrium calculations using FactSage, implemented with ChemApp.A method was developed, using an equilibrium calculation at 25°C, to convert the available chemical assays to approximate mineralogical assays in order to determine the feed enthalpies. Actual 2013 furnace feed data was used and the average specific energy requirement to produce slag and matte at 1600°C was calculated to be 671 kWh/t concentrate. The furnace energy input was then kept constant, and it was found that the slag temperature varies significantly as a function of the feed composition. These results were compared to actual slag temperatures measured on site. It was found that close management of the furnace energy balance is important for maintaining a stable slag temperature."

Jan 1, 2014

By L. C. Woollacott, A. K. Tripathy, J. H. Potgieter

This paper presents the second of a two part study on density stratification in a laboratory batch jig. The first study, reported elsewhere, investigated the effect of operating conditions on the stratification profile achieved at equilibrium. The study reported in this paper investigated their effect on the kinetics of density stratification under 18 different sets of operating conditions - five for binary systems with different particle densities; and 13 for a ternary system with different configurations of the jig cycle. Although the study was academic in nature (it involved simple systems of 8 mm glass beads) it has a number of practical implications. It found that the most influential operating variables affecting stratification kinetics are the amplitude of water displacement, the pulsion hold time, and, to a lesser extent, the pulsion time. It also found that reasonable rates of stratification can be expected in systems with density differences as low as 237 kg/m3 but below this the kinetics deteriorate significantly. The two studies together suggest that, within a broad range of operating conditions, the equilibrium stratification profile is independent of control variables and it is the control of stratification kinetics that has the primary influence on the quality of density separations in a jig. Keywords: Jigging kinetics, stratification, equilibrium stratification, batch jig

Jan 1, 2020

By J. Levin

The Bond standard grindability test provides a Work Index that is widely used to estimate the energy required for grinding, but the test cannot be applied to fine materials such as plant tailings and middlings. For such materials, a comparative grinding test must be used in which a reference material from an operating plant is ground in a laboratory mill to determine the 'equivalent' energy consumption per revolution of the laboratory mill. As the Bond grindability test mill and its operating conditions are specified, its equivalent energy consumption per revolution should be a constant, here designated as B. Once B has been determined, the mill can be used to estimate the grindability of fine materials without the need for reference materials. A value of B can be calculated from any Bond grindability test, and 245 tests that were conducted at Mintek were examined to determine its value. A wide range of values was found, but most of them were grouped around 198 x 10- 7 kWh/rev, which is taken as the best estimate of B that is available at present. Values of B that are not close to this figure are obtained from materials for which the Bond grindability test gives misleading or 'spurious' Work Indexes. These spurious Work Indexes lead to the apparent departure of B from its true value. Some limitations of the Bond grindability test arise from its use of a mill without litters and of screening, instead of classification, to close the circuit.

Jan 1, 1989

By K. Moxham, B. McKeown

The South African gold and platinum deposits were formed in very different ways and yet both have many similarities. They are flat dipping tabular orebodies, extremely narrow and located in hard abrasive country rock. The mining methods employed are also similar. Primary access is via shafts or declines; secondary access is via haulages and cross-cuts; and tertiary access is from raises. The proposed solution for rapid access described in this paper is focused on the haulages and cross-cuts.

Jan 1, 2006

By K. Bryan, O&apos

A 10-year program to integrate crushing and screening models into daily flowsheet design practice has proven successful. A Circuit Analysis Program (CAP) is used worldwide to design and evaluate new and existing crushing flowsheets. To gain user acceptance of CAP and maximize effectiveness, model development, simulation flexibility, ease of use, and developing international access are key issues. These issues have been resolved effectively resulting in flowsheet simulations to assist in justifying increased capital investment. CAP is presently utilized in Canada, United States, and South Africa with intentions to expand to Europe and Asia.

Jan 1, 1987