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By A. F. Silva, R. Dockendorff, J. M. Girao Sotomayor, V. F. Navarro Torres, C. Castro

This paper shows the importance of performing probabilistic analyses in open pits, especially for mine planning, which can lead to more efficient ore extraction and meeting the acceptability criteria for safety in mine slopes. Three-dimensional stability analyses were performed to evaluate the future geometry of a large open pit for iron ore extraction in Brazil. The strength parameters of the lithologies were calibrated using ruptures in the pit walls. After determining the factors of safety (FoSs) from the calibrated parameters, probabilistic analyses were performed using the total range of values of each parameter under different field conditions to verify the reliability of the initial analysis. In this sense, it was possible to plot the probability of failure (PoF) and the FoS on the graph of slope height versus slope interramp angle (IRA) for the future pit in each lithology. IRA recommendations are made for two scenarios: (1) the best scenario: dry without ubiquitous joints and (2) the worst scenario: the water table at 10 m depth with ubiquitous joints in the most unfavourable direction. The results show that probabilistic evaluation is an important tool for establishing alert mechanisms in slopes that can be termed stable.

Jul 2, 2022

By S. Kauchali

"Underground coal gasification (UCG) is recognized as an efficient mining technique capable of chemically converting the coal from deep coal seams into synthesis gas. Depending on the main constituents of the synthesis gas, chemicals, electricity, or heat can be produced at the surface. This paper provides a high-level graphical method to assist practitioners in developing preliminary gasification processes and experimental programmes prior to detailed designs or field trials. The graphical method identifies theoretical limits of operation for sensible gasification within a thermally balanced region, based primarily on the basic coal chemistry. The analyses of the theoretical outputs are compared to actual field trials from sites in the USA and Australia, with very favourable results. A South African coal is studied to determine the possible synthesis gas outputs achievable using various UCG techniques: controlled retractable injection point (CRIP) and linked vertical wells (LVW). For CRIP techniques, an important result suggests that pyrolysis, and subsequent char production, are important intermediate phenomena allowing for increased thermal efficiencies of UCG. The conclusion is that South African coals need to be studied for pyrolysis-char behaviour as part of any future UCG programme. The results also suggest that UCG with CRIP would be a preferred technology choice for Bosjesspruit coal where pyrolysis dynamics are important. Lastly, the use of CO2 as oxidant in the gasification process is shown to produce syngas with significant higher heating value. Introduction and literature surveyCoal is a commonly utilized fossil fuel, providing over 40% of global electricity demand and about 90% of South Africa’s primary energy needs. However, less than 20% of the known world resources are suitable for possible extraction using conventional surface and underground mining techniques (Andrianopolous,, Korre, and Durucan, 2015). Underground coal gasification (UCG) has the potential to recover the energy stored in coal in an environmentally responsible manner by exploiting seams that are deemed unmineable by traditional methods. The UCG process, if successfully developed, can increase coal reserves substantially. For example, in the Limpopo region of South Africa alone, the estimated potential for UCG gas, based on existing geological records, is over 400 trillion cubic feet (TCF) natural gas equivalent – this is about a hundred times more gas than the existing 4-TCF Pande-Temane natural gas field reserve in Mozambique (de Pontes, Mocumbi, and Sangweni, 2014)."

Oct 1, 2018

By J. K. Pothal, S. Basu, R. Barik, P. K. Senapati, A. Dubey

The aim of this paper is to study the characteristics of limestone particles (size varies from 4 mm to 20 mm) during its transportation from open cast mines through pipes. The influence of four different size fractions of limestone samples (4–6 mm, 6–10 mm, 10–15 mm, and 15–20 mm) on pipe flow characteristics during vertical transport in a 100 mm NB hose pipe was investigated. The flow velocities in the vertically lifting pipe was varied from 0.95 m/s to 2.78 m/s and a rotary feeder of 2 to 4 tonne/hr. capacity was employed to feed the limestone samples to the lifting pipe. The pressure drop data for the different size fractions of limestone samples at different mixture velocities were analysed. The effect of input volume fraction and superficial velocity of limestone samples on hold-up ratio were discussed. It was indicated that there was no substantial increase in pressure drop of slurry samples in the studied range of concentrations (CW = 4.22% - 12.54%), particle size, and low to medium range mixture velocities with respect to water run head loss data. The hold-up for the larger size fractions (15–20 mm) of limestone samples was found to be significant as compared to smaller size fractions, which may be due to terminal settling velocities of individual fractions of the studied samples.

Mar 4, 2025

By Y. G. Zhu, G. B. Zheng, X. X. Hu

Reverse flotation by cationic collectors is the classical method to reduce the silicon content in magnesite. But because of the low selectivity, there is a large loss of magnesite in the reverse flotation froth. To improve the efficiency of the collector, a novel collector named BK433 was developed in this paper. In order to determine the performance of the BK433 collector, a systematic experimental study was carried out with a high silicon magnesite in China. The suitable pH environment of slurry was confirmed, the depression effect of different depressants was investigated, and the flotation effect was compared with commonly used traditional collectors. The results show that the BK433 shows remarkable good selectivity and collection ability. After the 4 stages reverse flotation, the SiO2 content decreased from 3.76% to 0.25%, SiO2 impurity removal rate reached 94.69%. Meanwhile, the MgO content increased from 45.06% to 46.73%，the recovery of obtained concentrate (calculated by MgO) was 82.79%. Keywords: Magnesite, Desilicication, Reverse flotation, Collector

Jan 1, 2020

By P. Gauvillé

The key driver for choosing a circulating fluidized bed (CFB) boiler is the ability to burn a wide range of fuels with highly efficient combustion while meeting low emission requirements. Reduced sorbent and water consumption compared with pulverized coal (PC) plants and the ability to deal with corrosive fuel constituents while still meeting local regulations make a CFB boiler-based power plant particularly attractive. CFB-based power generation is particularly relevant in coal mining areas. During mining, a portion of the roof and floor material may be extracted along with the coal seam in order to create adequate working height for the equipment and miners. Therefore, run-of-mine coal which comes directly from the mine contains impurities. The raw coal can undergo a washing or screening process in order to improve its quality by reducing the ash content in the fuel in order to sell it on the export market or to comply with domestic customer requirements. The coal discarded from the washing process usually has a high ash content and difficult mechanical properties resulting from the initial properties, the mining, and the coal cleaning processes. It can contain a large volume of stones or can be very fine as a result of the washing treatment. To create value from burning this discarded coal, the boiler supplier has to meet several technical challenges in developing the appropriate design. This paper highlights the performance achieved with Alstom's CFB boilers developed for power generation over the last two decades to extract value from discarded coals. Emile Huchet Power Plant is the first 125 MWe CFB unit developed for burning coal slurries (called schlamms in France). The Emile Huchet discarded coal fuel is a very fine high-ash residue with an average particle diameter by mass (d50) of around 80 µm as received from the washing plant. The paper describes the performances and the basic design of the CFB boiler to manage such a fine fuel. The performances of two other CFBs of approximately 300 MWe output in operation in the USA and PR China are also mentioned to demonstrate the capability of this technology to burn either low-volatile bituminous or anthracite waste coals. The significant issues experienced during commissioning are reported, and the conceptual choices for burning such fuels are mentioned.

Jan 1, 2012

By K. Harlow

"Zircon is a naturally occurring radioactive material (NORM) and as such is subject to a variety of regulations around the world. The regulatory processes and their implementation are summarized and the key issues affecting zircon and zirconia highlighted. Having absorbed the activities of the former Zircon Minerals Committee, the strategy of the Zircon Industry Association (ZIA) is to be the ‘go-to place’ for information on these matters, and its activities in the NORM space are described. Chemical industry regulations such as REACH are spreading around the world, and the paper provides an update of their status in the key jurisdictions. As mineral sands are transported to market in oceangoing vessels, they are subject to the regulations of the International Maritime Organization, which are summarized in the paper. IntroductionFrom a global perspective, zircon is generally not found in high concentrations other than in placer and dune deposits where it has been deposited along with other heavy minerals such as ilmenite, rutile, and monazite. Such deposits have been sorted and concentrated over geological time by the action of tides, waves, and wind to form concentrated deposits of heavy minerals along old coastlines and in river beds and deltas. Consequently, zircon is mostly found in association with the principal titanium minerals ilmenite and rutile. These secondary concentrations in placer deposits provide the commercial sources of zircon.All geological materials contain natural radioactivity, although the term NORM (naturally occurring radioactive material) is mostly used for minerals and other materials with above-average uranium and thorium concentrations. Importantly, the radioactive nature of zircon has not changed, but the way in which radioactivity is viewed by regulators has, affecting the zircon industry throughout the value chain."

Jan 1, 2017

By C. A. Preece

Finsch Diamond Mine, part of De Beers Consolidated Mines (DBCM), is situated between Kimberley and Postmasburg in the Northern Cape, South Africa. The kimberlite pipe was discovered in 1960 and De Beers assumed full mining rights three years later. Production commenced in 1966 from an opencast mine, and the operation moved underground in 1990 by developing and implementing a new mining method of blast hole open stoping. A mechanized block cave was brought into production in 2005. While block caving was not new to DBCM, with productive caves having operated in Kimberley and Cullinan, from the outset, the Finsch caving operation was designed as the most advanced with a semi-automated ground handling system. The extraction level was laid out as a single sided herringbone system due to the very poor ground conditions on the south side of the pipe. These factors combined to create a unique environment, which necessitated a completely new approach to draw control. The required system was developed by a team consisting of DBCM personnel from head office and Finsch, GEMCOM and Sandvik-Tamrock, the equipment manufacturers. It was essential that the system could be run quickly, provide daily updates and issue calls directly to the LHDs. It was also important that the base data were obtained from the resource model, which was to be depleted on a monthly basis, thus forming a close link between mine planning and draw control. A further requirement of the system was that it would form a central database for the extraction operation where all data pertaining to delays and changes in conditions, be they production or ground condition related, could be recorded and analysed. The design brought together empirical rules and tables developed at Cullinan plus concepts from programming developed for the front cave at Koffiefontein so that the new system was based on sound practical experience. These facets were incorporated into PCBC (GEMCOM) and CMS and PCS (Sandvik-Tamrock programmes). The system has now been operational for just under a year and while modifications have had to be made, it has proved itself as a practical and reliable tool with which to manage the draw control at Finsch. The system is unforgiving and has forced the production team to focus on the specified drawpoints. Problems have been encountered but most of these have been related to re-educating a workforce, familiar with a flexible mining method, to the strict discipline required for a modern block cave.

Jan 1, 2007

By V. Oberholzer

The presence of fines (particles smaller than 6 mm in diameter) causes hydrodynamic problems in gasifiers and therefore it is of great importance to minimize the amount of fine coal in the feed. This serves as motivation for understanding coal?s breakage mechanisms, which could lead to the ability to predict the generation of fines. The aim of this project was to simulate the pulsating effect of the conveyor belt in order to investigate factors influencing the breakage. Results indicated that an increased initial particle size had an increasing effect in the amount of fines generated. Weathering had an insignificant effect on the breakage of coal. To conclude, a breakage model was developed to describe the rate of breakage out of the top size when a combination of two breakage modes is present.

Jan 1, 2009

THE BRITISH COUNCIL AWARDS 1971-1972 The British Council invites applications from permanent residents of the Republic of South Africa and South West Africa, for the following awards: SCHOLARSHIPS Scholarships are available to such permanent residents who hold university degrees or comparable professional qualifications. The scholarships are tenable for postgraduate study at universities and other educational establishments in Britain for the academic year of approximately ten months beginning 1st October, 1971. BURSARIES Bursaries are available to such permanent residents who hold university degrees or who, being already established in their professions or trades, hold other qualifications. The bursaries are tenable at British educational institutions or other suitable establishments in Britain for a course of training, study or research lasting not less than two months or more than six. The British Council may, at its discretion, bear the cost of single or return fares to Britain. The closing date for applications is 31st July, 1970. TRAVEL GRANTS Travel grants each of £300 are available in respect of journeys to Britain undertaken between 1st April, 1971 and 31st March, 1972 and are provided to facilitate visits to British universities by persons holding staff appointments or graduate research posts at South African universities. Visits must normally be of at least six months duration. The closing date for applications is 31st October, 1970. For further particulars and the relevant application forms please write stating the type of award for which you wish to apply to: The Cultural Attache, British Embassy, Pretoria. THE SECOND INTERNATIONAL CONFERENCE ON THE PROPERTIES OF LIQUID METALS Tokyo, September 1972 The Second International Conference on the Properties of Liquid Metals will be held under the auspices of The Japan Institute of Metals and The Physical Society of Japan from 3rd to 8th September, 1972 in Tokyo. The purpose of this conference is to continue and extend the efforts towards the objective of the First International Conference on the Properties of Liquid Metals at Brookhaven, 1966. The tentative Conference subjects presently planned are: Structure of Liquid Metals and Alloys; Atomic Transport Properties (Diffusion, Viscosity, etc.); Electronic States and Transport Properties; Thermodynamical Properties; Melting and Phase Transitions. Correspondence regarding the Conference and the request for the First Notice should be addressed to: Professor S. Takeuchi, Chairman of the Organizing Committee, The Research Institute for Iron, Steel and Other Metals, Tohoku University, Sendai, 980, Japan. PROCEEDINGS OF THE NINTH COMMONWEALTH MINING AND METALLURGICAL CONGRESS 1969 Volume 4 of the Proceedings of the Ninth Commonwealth Mining and Metallurgical Congress 1969- Physical and fabrication metallurgy-contains the 24 papers presented under this general heading at the Congress. Also included are discussion, authors' replies, name and subject indexes, and plenary addresses by Sir Val Duncan, O.B.E. and Sir Ronald L. Prain, O.B.E.

YEAR 1943-1944 Vol. 44 Page A major change-over in the ventilation of a deep level mine, by F. G. Hill and E. C. Ranson, 27; Discussion 56, 62, 67, 71, 72, 79, 123, 129 131 A note on the quarrying of surface limestone in the Sinai Desert, by V. L. Bosazza.. .. 59 Mining with diamond drills at the Nkana Mine of the Rhokana Corporation, Limited, Northern Rhodesia, by W. A. Odgers and A. G. Stirling, 95; Discussion 117, 121, 122 123 On silicates and dusts from the Witwatersrand gold mines (some preliminary notes), by J. J. Frankel, 169; Discussion .. 178 Presidential Address-Review of the rock pressure problem, by C. Biccard Jeppe, 3; Discussion 11,15 17 The chemistry, production and application of plastics, by P. N. Lategan, 138; Discussion 151 153 YEAR 1944-1945 Vol. 45 Page A microtechnique for the size-grading of mine dust, by S. R. Rabson, 34; Discussion 49, 50, 52 55 Activated carbon for regenerating used lubricating oil, by F. J. Tromp and J. J. Matthee 90 A contribution to the study of the production of zeolites, by C. C. le Grange and A. J. Petrick 235 A laboratory method for the determination of the suitability of South African coal and coal blends for the manufacture of metallurgical coke, by R. F. J. Teichmann .. .. 202 Copper containing cements for self-sanitising surfaces, by R. S. Young and H. L. Talbot 156 Notes on some sulphide minerals from the Far East Rand, by E. Mendelssohn, 84; Discussion, 88 89 Presidential Address-A review of underground support on the Witwatersrand with its Bearing on the Problem of ultradeep mining, by P. J. Louis Bok, 3; Discussion, 24, 25 27 Scientific management with particular application to a Witwatersrand gold mine, by J. S. Ford, 63; Discussion, 77, 80, 82 83 Some aspects of rock-drilling practice (the Witwatersrand gold field), by C. J. Irving, 163; Discussion, 185, 190 *197 Temperature measurements in a mine on the Witwatersrand with an electrical resistance thermometer, by O. Weiss, 127; Discussion, 136 137 The measurement of the geo-thermic gradient by means of the clinical thermometer, by R. A. H. Flugge-de Smidt, 105; Discussion, 136 137 The micro-chemical determination of free and combined silica in mine dust, by S. R. Rabson, 43; Discussion, 49, 50, 52 55 The oxidation of pyrites associated with South African coals, by R. F. J. Teichmann 141 YEAR 1945-1946 Vol. 46 Page Air cooling plant, No. 4 Shaft, City Deep, Limited. A review of layout and results achieved, by H. W. Unwin, A. Malcolm and R. E. Campbell Pitt, 66; Discussion, 100, 102, 103, 106, 110 115 A preliminary note on the Waterberg coal field as a possible source of coking coal, by P. E. Hall 124

By R. C. W. Webber-Youngman

The mining industry in South Africa faces real challenges with regard to the reduction of safety-related incidents. The purpose of this paper is to highlight the need for alternative interventions in addition to other safety improvement strategies already employed on mines. It furthermore supports an existing paradigm: incident investigations. An investigation into fatalities in the South African mining industry shows that although great progress has been achieved through the reduction in fatalities in all sectors of the industry over the last few years, more can and should be done to achieve status of ?zero harm?. Fatalities and lost time injuries on mines result not only in large financial losses, but also in disruptions of mining operations in general through Section 54 stoppages to resolve the situation. The approach of the paper is therefore not to try and prove whether there is high fatality rate and/or lost time injuries, but in what way incident reconstruction simulations (IRS) can have an impact in the future prevention of such incidents. The challenge therefore lies in the utilization of pro-active systems that would show employees the possible outcomes of being exposed to certain hazards. In real life, these incidents cannot be re-enacted and in most cases we can only learn through the previous mistakes of others. A virtual reality (VR) education and training system will enable employees to be ?exposed? to different hazards in a safe environment, and simulation, in a ?forgiving? environment, of the possible consequences of unsafe acts. According to the Occupational Safety and Health Act (OSHA), unsafe acts and unsafe conditions are indirect causes of safety-related incidents, but there are also direct causes; for example, unplanned release of energy and/or hazardous material, and basic causes, for example, management safety policies, personal factors, and environmental factors. The administrative workload associated with any incident investigation places a large burden on the investigation team, and in most cases other employees are informed through vague administrative processes what the ?real cause? for the incident/accident was. New preventative strategies are often put in place without showing the employees what the real causes of the incident/accident were. This can be mitigated through the use of interactive VR simulations/animations of the hazards that they are exposed to and how to deal with them. If VR interventions are not used as proposed by this paper, the real causes and consequences of almost all fatalities and lost time injuries may never be fully understood. This paper also emphasizes what potential impact IRS could have on the prevention of future mine incidents as part and parcel of a pro-active risk prevention strategy. The intention is therefore not to replace any other risk prevention strategies, but to visually enhance the reality of the incident. Keywords virtual reality, risk management, incident reconstruction simulations, interactive safety training, usability context analysis, mine safety.

Jun 1, 2013

By J. Moema, L. Mampuru, M. Phasha, D. Mkhonto

The global liquified natural gas (LNG) storage market size is projected to reach USD17.5 billion by 2025. Currently, owed to its high toughness, tensile strength, and excellent weldability, the 9% nickel steel is the most used in building infrastructure for cryogenic applications such as the construction of tanks and pipes for storage and transportation of LNG. However, this alloy is not readily available because of its complex production process and high cost. This provides an opportunity for suitable alternative materials to build infrastructure for cryogenic applications. Among strong contenders is the Fe-Mn based alloys, which have sparked global interest due to their desirable properties such as relatively lower density, low cost, high toughness and strength, due to a high manganese (Mn) content. These attractive properties render Fe-Mn based alloys preferred candidates to replace traditional steels in engineering applications in which strengthweight ratio is critical. In response, as a build-up to designing and developing austenitic Fe- Mn alloys, the present study employed density functional theory (DFT) based first-principles computational materials modelling technique to investigate the structural, thermodynamic, and magnetic properties of binary Fe-Mn alloy composition in competing FCC, HCP, and BCC crystal structures. Using this approach, it was possible to unravel the key underlying elastic properties that are directly correlated to experimental tensile strength and high toughness in binary Fe-Mn alloys. Besides successfully validating the existing experimental data, the current predicted properties and the deployed approach will serve as a benchmark from which further alloying required to improve other properties will be conducted.

Mar 4, 2025

By J. H. Viljoen, J. F. Morrison, C. H. Wyndham

SYNOPSIS Heart rates, oral temperatures, shovels/min and number of 3/4 ton cars/hour trammed over distances of up to 350 ft were measured in samples of 6-10 miners, engaged in tram-shovelling, at 76°, 84°, 86°, and 89°F wet bulb temperatures in stopes in a mine. From the results it has been concluded that a man with an 'average' maximum oxygen intake capacity of about 2. 8 litres/min should be able to work: at 6 shovels/min, or 30 cars/shift per two men, at 76°-84°F; at 5 shovels/min, or 27 cars/shift per two men, at 86°F; and at 4 shovels/min, or 24 cars/shift per two men, at 89°F wet bulb air temperatures. INTRODUCTION A number of gold mines in South Africa still use tram-shovelling extensively. In this method of rock removal from the face of the stope, Bantu mine workers load rock into cars and tram the cars to a centre gulley where they are emptied. Previous studies from this Laboratory3 have shown that tram-shovelling is one of the most arduous tasks underground. The rate of energy expenditure is relatively high, being an oxygen consumption of about 1.4 litres/min over a period of some hours. In cool air conditions the upper limit to the rate of production of the well-motivated men employed on tram-shovelling has been shown1 to depend upon their capacities for physical work of an endurance nature (as measured by their maximum oxygen intakes). However, in hot conditions the factors which set the upper limit to the rate of production are different. They are primarily the ability of the body to maintain a heat balance between the rate of heat production, due to physical work, and the hot atmosphere, so that the men do not develop excessively high body temperatures8. In order to give mine managers guidance on the 'optimum' rate of production of Bantu mine workers engaged upon tram-shovelling under different temperature conditions underground a study was carried out in a mine. The number of shovels per minute and cars per hour were recorded and heart rates and oral temperatures were measured throughout the duration of the shift on samples of 6-10 Bantu mine workers in different air conditions. The results of the study are recorded in this paper and conclusions are drawn as to the number of shovels per minute and cars per hour which Bantu mine workers of 'average' maximum oxygen intake capacity should be able to produce at wet bulb air temperatures of between 76° and 89°F without either excessive fatigue or danger of heat illness.

By M. de Beer

The conversion of carbon-containing feedstock into liquid fuels can proceed via the Fischer-Tropsch synthesis, which is catalysed using supported cobalt catalysts. These catalysts contain noble metals to facilitate the reduction of oxidic cobalt species in the catalyst precursor to metallic cobalt, which is the catalytically active species for the Fischer-Tropsch synthesis. This is thought to occur via hydrogen spillover, i.e. the diffusion of atomic hydrogen over the support from the noble metal to the oxidic cobalt moieties. Noble metals may also affectthe dispersion of cobalt in the active Fischer-Tropsch catalyst. The economic aspect of the addition of noble metals to the Fischer-Tropsch catalyst is discussed.

Jan 1, 2014

By G. T. G. Emere

With the assistance and encouragement of Mr B.C. Alberts, the Institute's immediate Past President and Iscor's Senior General Manager: Mining, the Committee of the Johannesburg Branch recently organized a two day excursion for members to the northern Transvaal. The itinerary included visits to the Grootegeluk colliery, the Matimba power-generation utility, and the Thabazimbi iron-ore mine.

Jan 1, 1989

By D. Visser

This paper is based on the Townlands Ore Replacement Project whereby the concept of conventional sinking of one large diameter shaft was declined and replaced with three smaller raise bored shafts. A wire line geophysical survey was done and the results indicated that a single shaft larger then 4 m diameter unsupported would not be suitable. The shafts were placed 28 meters apart measured from centre to centre. To ensure that the skin to skin pillars between the shafts remained regular and to minimise any deflection, the pilot holes were drilled with the Rotary Vertical Drilling System. The different shaft sinking methodologies are discussed explaining the risk associated with each method.

Jan 1, 2009

By D. Visser

This paper is based on the Townlands Ore Replacement Project whereby the concept of conventional sinking of one large diameter shaft was declined and replaced with three smaller raise bored shafts. A wire line geophysical survey was done and the results indicated that a single shaft larger then 4 m diameter unsupported would not be suitable. The shafts were placed 28 meters apart measured from centre to centre. To ensure that the skin to skin pillars between the shafts remained regular and to minimise any deflection, the pilot holes were drilled with the Rotary Vertical Drilling System. The different shaft sinking methodologies are discussed explaining the risk associated with each method.

Jan 1, 2009

By J. Stacey

There are four components to this guideline 1. Guidance on the socio-economic aspects of closure policy 2. Socio-economic closure activities mapped against the mining project life-cycle (a ?check status? tool) 3. A process guide for mine closure planning and implementation 4. Tools in support of mine closure planning and implementation How to use this guideline The four components are part of a hierarchy with: ?Overarching policy as the starting point ?The mine life cycle model as a quick process check tool ?The process guide for detailed practical planning and implementation as practical guidance ?Supportive tools as resources to address specific planning and implementation steps.

Jan 1, 2010

Ninth International Symposium TECHNIQUES FOR DECISION MAKING IN THE MINERAL INDUSTRY The Symposium which is to be held in Montreal during the week of 14th to 19th June, 1970, follows the Computer Symposium held in Salt Lake City in September, 1969. The purpose of the Symposium is to define the role of decision-making techniques within the mineral industry and to stimulate the development of specific applications. The subject of the Symposium-mathematics, operations research and computers as applied to the mineral industry-have permitted us to structure it in such a way that a complete picture of the mineral industry in its public policy, corporate, financial and technological environment emerges. Topics for the sessions are: . The Public Policy Environment;. The role of Decision Making Techniques in the Mining Company; . Information Storage and Retrieval; . Markets-Forecasting, Patterns and Strategies;. Search for Mineral Deposits;. Quantification of Geological Variables;. The Mine Development Decision; Production Systems;. Planning, Scheduling and Control Systems. The sessions will be directed energetically by chairmen who have been in continuous contact with the authors, providing them with information about related papers and sessions. This symposium is sponsored by the Canadian Institute of Mining and Metallurgy, McGill University and Ecole Polytechnique. Further information may be obtained from: The 9th International Symposium. W. H. Gauvin, General Chairman, J. Elbrond, Programme Chairman. Department of Mining Engineering, Ecole Poly technique, P.O. Box 501, Snowdon, Montreal 248, Quebec, Canada. ACHEMA 1970 The European meeting of Chemical Engineering and the Achema Congress 1970 is being held at Frankfurt/Maine, from 17th to 24th June, 1970. The programme includes some 110 plenary and specialised lectures, numerous technical films, excursions, and technical discussions in front of the exhibits which form the central feature of the Achema-Exhibition Congress. Further information may be obtained from the honorary representative of Achema in South Africa, Mr F. Schilling, P.O. Box 31274, Braamfontein, Johannesburg. NINTH COMMONWEALTH CONGRESS PROCEEDINGS Publication of the proceedings of the Ninth Commonwealth Mining and Metallurgical Congress, 1969, is being undertaken by the Institution of Mining and Metallurgy, London. There will be four volumes covering papers presented at the Congress together with the discussion and author's replies, and the addresses by Sir Duncan and Sir Ronald Prain. These will be available April-June 1970. Special pre-publication prices apply to orders received before 1st April, 1970. Order forms may be obtained from Secretary S.A.I.M.M., P.O. Box 1183, Johannesburg. 6th World Congress on the Prevention of Occupational Risks This Congress, dealing with industrial accidents and occupational diseases, will be held in Vienna from 10th to 15th May, 1971. Further information may be obtained from: VI Weltkongress für Unfallverhütung, Postfach 745, A-1015 Wien, ÖSTERREICH. International Vacuum Metallurgy Conference 1970 The Vacuum Metallurgy Division of the American Vacuum Society is organizing an international meeting that will be held at the Convention Center in Aanaheim, California from 15th to 19th June, 1970. Enquiries should be directed to the Arrangement's Chairman, L. M. Bianchi, TRW Inc., 23555 Euclid Avenue, Cleveland, Ohio 44117, Tel. No. (216) 383-2111. AIME WORLD LEAD-ZINC SYMPOSIUM This symposium is being held from 21st to 23rd October, 1970, in St. Louis, Missouri, U.S.A., in conjunction with the Fall Meeting of the Society of Mining Engineers, and a Rapid Excavation Conference. In addition to local field trips to smelter and refinery operations there will be a number of extended trips of six to eight days. Information may be obtained from: Mr. John C. Fox, Secretary, Society of Mining Engineers of AI.M.E., 354 East 47th Street, New York, N.Y. 10017, U.S.A. NEW SUBSCRIPTION RATE TO THE JOURNAL As from 1st JANUARY, 1970, the subscription rate for the Journal has been increased from R12.00 to R18.00 per annum, i.e. R1.50 per issue instead of R1.00. The discount to booksellers is 15 per cent. COURSEOF THE THEORYOF THE UNIT OPERATION OF GRINDING The South African Institute of Chemical Engineers is arranging for Prof. L. G. Austen to conduct a course on the above subject in September, 1970. Interested persons should contact Dr G. S. Harrison, S.A. Institution of Chemical Engineers, A.E. & C.I., 15 Anderson Street, Johannesburg. METRICATION The S.A. Bureau of Standards has published a document entitled "Metric Scales and Units for use in the Building and Construction Industry." It has been compiled by the Metrication Committee of the National Building and Construction Advisory Council and is the first of the series of informatory documents relating to the programme for the metrication of the Building Act Construction Industry. This document is obtainable from the South African Bureau of Standards, Private Bag 191, Pretoria at 50c per copy.

By J. Petersen, H. Naderi, M. H. Nikzad, M. Karimi

In this research, the thermodynamic study of sodium persulfate (Na2S2O8) solution in the presence and absence of H2SO4 and Fe3(SO4)3 was done. Eh-pH and equilibrium distribution diagrams were constructed using Outotec HSC Chemistry Software and the main stable ionic species were determined. Also, the mean activity coefficient and Pitzer model coefficients were evaluated. Effects of system composition, sodium persulfate concentration and temperature were investigated. According to the results, HS2O7 -, HS2O8 -, S5O3 2-, S4O3 2-, S3O3 2-, HS- and NaSO4 - are the main stable species in these three systems. Increasing of sodium persulfate concentration resulted in disappearing of SO4 2- and the appearance of NaSO4 -. The main effect of increasing the temperature from 25 to 75oC, is changing the stability regions of HS2O7 -, NaSO4 -, SO4 2- and S2-. From equilibrium studies, it was concluded that at 25 and 50oC, increasing the persulfate concentration results in a 55-60% decrease for HS2O7 - and an 20- 30% increase for HS2O8 -. At 75oC, HS2O8 - becomes the main species and its percentage decreases with increasing the persulfate concentration. Keywords: Thermodynamic, sodium persulfate, activity coefficient

Jan 1, 2020