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By M. Hermanus

1. INTRODUCTION It gives me great pleasure to extend my warmest greetings to everyone attending the 30th International Conference of Safety in Mines Research Institutes. I would also like to bid a special welcome to all of the international delegates who have travelled to Johannesburg to take part in what surely be a most rewarding session of deliberations. As you come together over next four days, you will have a wonderful opportunity to exchange ideas and information on strategies and practices for the implementation of sustainable patterns of development. The objectives of this meeting are both timely and far-reaching, as countries around the globe work towards the sustainable use of the world resources. Each of you brings a high level of expertise to these deliberations. I know that you will make the most of this opportunity to address the challenges and opportunities to highlight the most innovative and technologically efficient methods of social protection in order to ensure an increase in the quality of life, health, safety and living environment for the peoples of the Africa. Our country, although endowed with an immense and diverse array of mineral deposits, is perhaps best known in the mining industry for the fact that it is the world’s biggest producer of gold. Although South African gold production has declined over the past years and the industry faces serious problems, it is a myth that the South African industry is moribund. There is a new energy coursing through the South African producers which will ensure their powerful presence for many years to come, based not only on their domestic production but also and probably increasingly on their external operations. Africa features prominently in the latter category.

Jan 1, 2003

By S. J. Thomas, P. A. Lilly

With support from the Australian mining industry and the Federal Government, three Australian universities are collaboratively developing flexible-format, web-based course content and delivery in rock mechanics for undergraduate mining engineering students. This paper describes the educational philosophy behind the development and summarises other salient features of the Program. Mit der Unterstuetzung von der austlalischer Bergbauindustrie und der Bundesregierung, drei austlalische Universtaeten in Zusammenarbeit entwickeln flexibel Netzgengruendet auf Lehrganginhalt und Lieferung in Felsgestein fuer Bergbaustudenten. Dieses Schreiben erlautert das Unterrichtsphilosophie hinter der Entwicklung und Zusammenfassung anderer Hauptpunkte von diesem Programm" Avec l'assistance de l'industrie miniere australienne et du gouvernement federal , 3 universites Australiennes collaborent a la mise en place d'un programme de mecanique des sols pour etudiants- ingenieurs en mines. Ce programme serait a la fois flexible et accessible par Internet. Ce document decrit la philosophie pedagogique de ce projet et en souligne les characteres importants.

Jan 1, 2003

By Y. Rao, Y. Huang, G. Wang, W. Liu

The properties and deterioration in strength of cemented tailings backfill (CTB )in the underground acidic environment under oxidizing conditions were studied. X-ray diffraction analysis and scanning electron microscopy of the surface of the CTB was carried out, and the sulphuric acid corrosion mechanism elucidated. The properties tested included compressive strength, elastic modulus, cohesion, internal friction angle, variation in the hydrogen ion concentration, and stress-strain relationship in different corrosion periods. The damage model of the CTB was established considering the effects of parameters such as corrosion time and strain on the damage evolution. It was found that the compressive strength, elastic modulus, cohesion (binder effect), and internal friction angle increased at first and then decreased with exposure time. In the long term, the peak stress decreased with corrosion time while the peak strain increased; elastic modulus, and deformation modulus also decreased. The damage caused by corrosion and by load were related by means of a mathematical model, which revealed the relationships between sulphuric attack, load, and damage to backfill in complex underground environments. During corrosion, the expansion of gypsum and ettringite caused microfractures in the CTB. With increasing corrosion time, micro-cracks developed and proliferated. The mechanism of corrosion damage was found to be the dissolution of hydrogen ions and a sulphate ion reaction that produces an expansive substance, resulting in deterioration of the strength of CTB.

Jun 1, 2021

By Dr Peter Laxen

Dr Peter Laxen, the Mintek Consultant on gold and uranium, has won the 1982 award of the Percy Fox Foundation. The presentation was made by the Minster of Finance, Mr Owen Horwood, at a banquet on 6 March.

Jan 1, 1982

2nd CONGRESS OF THE INTERNATIONAL SOCIETY FOR ROCK MECHANICS The 2nd Congress of the International Society for Rock Mechanics will be held in Belgrade, 21-26 September, 1970. The Congress will include: working sessions, study tours, receptions, excursions introduced in the working sessions and post-congress excursions and special programme for accompanying persons. Anyone interested in rock mechanics and its applicarion may take part in the 2nd Congress. Official languages of the Congress are: English, French and German. Simultaneous translation service will be provided during the Congress. All the correspondence concerning the 2nd Congress of the International Society for Rock Mechanics should be addressed to: Sekretarijat 2. kongresa Medjunarodnog drustva za mehaniku stena Institut za vodoprivredu "Jaroslav Cerni" Bulevar vojvode Misica 43, Postanski fah 530 Beograd - Jugoslavija NINTH INTERNATIONAL SYMPOSIUM TECHNIQUES FOR DECISION MAKING IN THE MINERAL INDUSTRY The Symposium which is to be held in Montreal during the week of June 14-19, 1970, follows the Computer Symposium held in Salt Lake City this year. 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-allows a complete picture of the mineral industry in its public policy, corporate, financial and technological environment to emerge. This is another of the series of symposia on this and related subjects started in the early 1960's at the University of Arizona. Sponsorship has included a number of Universities and the Society of Mining Engineers of the American Institute of Mining. This 1970 symposium is the first to be held outside of America, and is being sponsored by the Canadian Institute of Mining, McGill University and Ecole Polytechnique. A number of delegates from South Africa have participated in these symposia and several have already arranged to attend this symposium in Montreal. Enquiries should be directed to: Secretariat, The 9th International Symposium, Department of Mining Engineering, Ecole Polytechnique, P.O. Box 50l, Snowden, Montreal 248, Quebec, Canada. 24th INTERNATIONAL GEOLOGICAL CONGRESS This Congress is to be held in Montreal, Canada, from August 21 to 30, 1972. A very detailed and extensive programme has been proposed, and includes a number of excursions. Copies of the first circular are obtainable from: The Organizing Committee, 24th International Geological Congress, 601 Booth Street, Ottawa 4, Ontario, CANADA. SYMPOSIUM ON THE RECOVERY OF PYRITE The proceedings of the Symposium on the Recovery of Pyrite, held in Johannesburg on 12th to 13th June 1969 are now available. Copies may be ordered from the Secretary, S.A.I.M.M., P.O. Box 61019, Marshalltown, Transvaal at a cost of R10.00. Papers and addresses presented at the Symposium were: Opening Address by Mr J. K. E. Douglas (President). 'The world sulphur position,' by W. C. J. van Rensburg (Member). 'The South African sulphur position,' by D. L. Taylor (Member). 'The recovery of pyrite at Government Gold Mining Areas Limited,' by R. J. Westwood (Member), G. S. Stander (Affiliate) and H. R. Carlisle (Member). 'Recovery of pyrite concentrates from colliery-waste discards-A preliminary assessment,' by W. A. Gilbert (Visitor) and E. A. Nugent (Member). 'The role of pyrite in upgrading the uranium content of Witwatersrand conglomerate ores by means of the heavy-medium separation process,' by D. J. Tutt (Associate Member). 'Pyrite recovery by jigs at Durban Roodepoort Deep Limited,' by E. J. Dominy (Affiliate), F. Diamond (Affiliate) and A. D. Graham (Affiliate). 'The storage of pyrite concentrates,' by Joan C. Campkin (Visitor) and P. J. Lloyd (Member). 'The flotation plants of the Anglo- Transvaal Group,' by L. A. Bushell (Member). 'Pyrite flotation with amines and cyanidation of the products,' by E. H. D. Carman (Member). 'Gold recovery by cyanidation from mill products obtained after pyrite flotation,' by P. G. Mrkusic (Graduate), M. Sciarone (Visitor) and H. E. Simonsen (Visitor). 'The influence of sulphydral and cationic flotation reagents on cyanidation of native gold,' by K. G. Ashurst (Visitor) and W. P. Finkelstein (Member). 'Laboratory tests on the flotation of pyrite from Witwatersrand gold ores by cationic collector,' by J. Levin (Member), and M. L. Veitch (Visitor). Closing Address, by Dr R. E. Robinson (Director, National Institute for Metallurgy).

By M. Helm

Over the last 40 years, numerous investigations have focussed on the preg-robbing capacity of carbonaceous material during gold ore processing. Various techniques have been applied to characterize the physical and chemical properties of the carbonaceous material in efforts to predict its preg-robbing capacity. The present study, which forms part of an ongoing investigation, is specifically designed to increase the understanding of preg-robbing in ores containing carbonaceous material. In excess of 100 samples from 13 gold mines located in major gold provinces of the world have been incorporated into the present study. These samples were characterized using industry standard metallurgical techniques and were shown to have gold adsorption capacities ranging from a few grams to many hundreds of grams of gold per ton of ore. Further analysis showed that the crystalline nature of the carbonaceous material, which is related to its geological history, is important in determining the preg-robbing capacity of an ore. This finding builds on the common understanding that the preg-robbing behaviour of an ore is related to the amount (or abundance) of carbonaceous material present in that ore. In this study, Raman spectroscopy was used to evaluate the physical nature of carbonaceous material. This is a tool which has been successfully applied by researchers for the characterisation of carbon materials, with respect to crystallite size and lattice defects. Raman analysis of the samples included in this study showed varying degrees of disorder in the carbonaceous materials from the different deposits. Comparison of the Raman spectra with the gold loading capacities of the samples indicated a direct relationship between the structure of the carbonaceous material and its capacity to preg-rob gold. From this, a simple and robust method has been developed based on the Raman spectra of the sample and carbonaceous material content to predict the preg-robbing capacity of an ore. The potential exists to develop a predictive tool using Raman spectroscopy for characterising the preg-robbing capacity of an ore. Such a tool would have potential application in projects ranging from the early stage of exploration through to more detailed feasibility studies and mining operations. The result of applying the predictive method outlined in this paper would be the effective and proactive management of the deleterious influence of carbonaceous material on gold recovery in mining operations.

Jan 1, 2009

The paper discusses the improvements achieved after an external sparger flotation column was installed as a final cleaner at the Northam Platinum Ltd. UG 2 concentrator in South Africa. It further discusses the improvements achieved after the conversion of a conventional flotation column, utilized as cleaner in the Merensky concentrator, to an external sparger flotation column. Finally, the application of the above knowledge in the design and commissioning of an external sparger flotation column as final cleaner in the furnace slag concentrator, is also discussed. 1. FINAL CLEANER AT THE UG 2 CONCENTRATOR The MF2 designed UG 2 concentrator is processing 75 000 tonnes run of mine ore at a head grade of 4.0 g/t 3PGM+Au and a feed Cr2O3 concentration of 28 %. Since commissioning of the plant in 2001, Cr2O3 in final concentrate amounted to approximately 5 % of the total mass. Although final concentrate produced from the UG 2 concentrator is blended with final concentrate obtained from the Merensky concentrator before smelting, blended Cr2O3 values in excess of 1.6% lead to difficulties in the subsequent smelting process. Several options for reducing the amount of Cr2O3 in final concentrate have been evaluated namely:- ? Differing types of depressants at various dosing rates. This test work did not reduce the amount of Cr2O3 reporting to final concentrate by any significant extent. ? Reduction in mass pull to minimize the entrainment of Cr2O3 in the concentrate stream.. This process change had a detrimental effect on PGM recovery. Conclusions were drawn that conventional mechanically agitated flotation cells could not achieve the required selectivity without sacrificing PGM recovery. As a consequence an alternative mechanism needed to be incorporated for the final cleaning of PGM concentrate.

Jan 1, 2007

By H. S. Sichel

Statistical valuation of diamondiferous deposits By H. S. SICHEL, D.Sc The valuation of diamondiferous deposits depends on (i) the density distribution, (ii) the size distribution of stones and (iii) the selling price structure prevailing at a particular time. In the density distribution the stochastic variable is defined as the number of individual stones found per sample unit irrespective of the stone size. The density distribution is discrete and allows for barren sample units. As diamonds often occur in clusters, a Poisson mixture distribution is derived which is entirely new, as existing discrete distributions cannot represent the stone number frequencies found in nature. For the sizes of diamonds, which are measured by weight, a new compound logarithmic normal distribution is developed. Combination of (i), (il) and (iii) leads to a meaningful appraisal of diamondiferous ground expressed in monetary value per production unit of mining. Finally, confidence limits are calculated which allow for inferences from sampling to recovery.

By S. Dessureault

Computer Integrated Mining (CIMG) is a process of using computer networks to transform islands of enabling technologies into a highly interconnected mining system. CIMG involves the integration of advanced technologies at various levels in the mine business to achieve higher flexibility, better quality of processes and control, and improved profitability. Justifying the benefits of CIMG are difficult as many of the advantages are derived from improved flexibility, quality, and control. Justification is based on the evaluation of the benefits to be gained, compared to the required capital investment. Management tools used in mining are currently inadequate in assessing the value of advanced technology whose benefits are primarily qualitative. A key aspect of successful implementation is management acceptance, which has to be won through the capability to justify the technology's financial costs and the true value of all of its benefits. The manufacturing industry faced similar justification difficulties when adopting advanced technology in factories. A significant amount of funding and research was invested into developing management strategies and approaches to justification. Many of the problems that faced the transformation of the manufacturing industry in the late eighties and early nineties are now facing mining. The solutions derived for manufacturing may help mining in its transition to an increased reliance on integration technology. Reviewing the industrial history of computer integrated manufacturing identifies several tools and strategic frameworks that can be adapted for mining. Keywords: Computer integrated mining, justification techniques, CIM, information technology.

Jan 1, 2003

By Wei Sun, Ruolin Wang, Wenjuan Sun, Junhao Fu, Haisheng Han, Zhao Wei

Pb–benzohydroxamic acid (BHA) (lead complexes of benzohydroxamic acid) exhibits high selectivity but low collecting efficiency in scheelite flotation. This paper reports the manner in which BHA and sodium dodecyl sulfate (SDS) were employed as ligands to coordinate with the lead ions to obtain a colloidal lead-group multiple ligand complex, i.e., the Pb–BHA–SDS, for improving the collecting efficiency of Pb–BHA. The flotation mechanism of Pb–BHA–SDS with respect to scheelite was investigated from the viewpoint of interface science based on the pure mineral flotation, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. The results showed that the BHA and SDS coordinated with Pb2+ to form novel leadgroup multiple ligand complexes, which are different from the traditional understanding associated with the mixed collectors. Pb–BHA–SDS was a better collector with stronger collecting ability and excellent selectivity in regard to a scheelite flotation than Pb–BHA. The addition of SDS to Pb–BHA enhanced the latter’s adsorption ability on the scheelite surface and improved the hydrophobicity of the collector’s nonpolar groups, rendering Pb–BHA–SDS as a more efficient collector at a low dosage. Keywords: Scheelite; Pb-BHA complexes; sodium dodecyl sulfate; multiple ligands; Pb–BHA–SDS

Jan 1, 2020

By A. W. S. Schumann

G. H. HENDERSON INTRODUCTION It is a pleasure to have read Mr Schuman's wide ranging and highly informative paper and also to congratulate him. Before proceeding to give views on the use and preservation of coal in South Africa, it is perhaps apposite to look at the South African scene on the world canvas. Mr Schuman's figures in his Table I are highly revealing. The Table shows expected consumption, export and import demand in the year 1980 by the continents of the world. The Republic of South Africa is shown as one of only four exporting countries at that date, although in the interim, Australia has become an exporter and will continue to grow as an exporter of coal. Huge fields have been proved in recent years. There is reason to think that for some years, coal and its economical uses have been under-estimated. The importation of oil carries a constant question mark and the exciting possibilities expressed in the uses of Dranium a decade ago for power generation, appear to have met with some setback. Present indications are that breederreactors will be delayed until about 1990. The capital cost of such reactors, too, is enormous. By 1980 it has been estimated that 20 per cent of the energy required by the leading ten nations of the world will come from nuclear power, but 80 per cent would then remain for fossil fuels and hydro generation. COAL DEMAND AND USAGE It is of interest to record that coal production in all the countries of Europe has declined markedly in the last 25 years. This is due to competition from oil, gas and nuclear power and also for sociological reasons; but there are signs that efforts will be made to resuscitate, at least in some measure, the mining of coking coals for which there is a strong and growing demand. Possibly all hard coal now mined in Germany has coking properties and that country is self-sufficient in this commodity. Germany might perhaps consider selling coking coal to her neighbours and importing additional coal for power-raising purposes. It has been frequently stated in American publications that the coal reserves of the D.S.A. are sufficient for 1 000 years. What that means, I do not know, but it is at least an indication that America has huge reserves of coal. Domestic and export demand in the U.S.A. in 1968 exceeded production for the first time. In 1969, the United States' output amounted to some 556 million tons, an increase of less than 2 per cent on the previous year. The output achieved fell short of demand, domestic and export, by more than 7 000 000 tons. This has caused and is continuing to cause anxiety in the U.S.A. In many countries young men for a number of reasons, largely environmental and social, are not coming forward in sufficient numbers for mining requirements and the same pattern has revealed itself in the Republic. This is, indeed, alarming because mining men in large numbers will be required to meet the estimated tonnage requirements set out in the following Table: It is difficult to visualise the replacement of these coal requirements either by oil or by nuclear fuels. The coal must be mined and men are required for the purpose. Unless a greater section of the population is allowed to participate in the more responsible aspects of mining, there is a serious likelihood that demand will not be matched by output. In addition to local demand, a lively export trade is possible. Exports are dependent on the future capacity of the South African Railways and Harbours and on Government policy. An export figure of 10000000 tons per year during the decade can be visualised and this figure would raise total estimated sales production to a figure of over 100 000 000 tons in 1980. At this point, it is necessary to examine the desirability or otherwise of exporting coal. How much coal

Jan 11, 1970

By S. Sekhar, S. Bhargava, A. K. Godugu, J. L. Porathur

Cemented backfilling has enabled underground hard rock mines to extract orebodies more safely with improved ore recovery. It is important to estimate the minimum required strength parameters for a backfill mix by optimizing the binder percentage to enable cost-effective and safe stoping operations. We conducted three-dimensional numerical modelling to study the effect of various stoping parameters on the stability of a free-standing backfill wall. A Mohr-Coulomb material model was used for the backfill material and the rock-fill interface. A strength reduction technique, excluding friction angle, was employed to arrive at a minimum stable strength value for the backfill. For a given combination of strength values, the stability state of the backfill wall could be demarcated using a displacement and yield zone tracking method. The numerical modelling results are compared to some earlier theoretical models. From the simulations, a predictive equation is developed to predict the required strength parameters for a backfill mix to ensure a stable free-standing wall. Examples are given of the successful use of the predictive equation at some underground hard rock mine sites in India.

May 2, 2022

Since 2001, the Hybrid Stress Blast Model (HSBM) project members have developed a software suite to model the complete blasting process from non-ideal detonation to muck pile formation. To preserve the physics and improve solution time, the breakage engine uses a combination of analytical models and 2D axisym-metric finite differences to model near-field crushing, coupled to 3D discrete lattice fracturing and distinct element numerical methods to model throw and muck pile development. The model has been validated by comparison with laboratory and field tests in kimberlite. Multiple blasthole simulations are used to demonstrate how changes to blasting parameters can influence downstream efficiencies. Case studies of wall control blasting show that the presplit design must balance the two opposing effects of increased damage with increased charge and decreasing attenuation of the seismic waves with decreasing charge. Modelling of decoupled explosives needs further development. Reducing the charge towards the back of the trim blast results in a much more significant decrease in back damage than altering the timing. The model demonstrates how separation along the weaker planes in a jointed rock can coarsen the fragmentation, leading to inefficient beneficiation, and extends the damage to a distance of at least twice the burden behind from the blasthole, severely compromising the wall stability.

Jan 1, 2012

Termination of membership In accordance with By-Law 7.6.1. of the Constitution of the Institute, the names of the undermentioned members have been removed from the membership register. Colloquium and General Meeting A General Meeting and Colloquium on 'Heavy-medium separation and ore sorting' was held on 18th September, 1974, at 09h15, in Kelvin House, Johannesburg.

Jan 12, 1975

1. Book reviews A report by the Monopolies and Mergers Commission on the efficiency and. costs in the development, production and supply of coal by the NCB (Chairman G. Le Quesne). London, Her Majesty's Stationery Office, Jun. 1983. £20 for report and appendices (2 vols). Reviewer: M. J. Martinson Canadian mines handbook 1983-84, edited by M. R. Brown. Toronto, Northern Miner Press Ltd, 1983. 444 pp. $22. Reviewer: Northern Miner Review Editor 2. New publications Developments in geophysical exploration methods-5, edited by A. A. Fitch. Barking. Applied Science Publishers Ltd (Ripple Road, Barking, Essex IG II OSA, England), 1983. 255 pp. £35.75. High-pressure researches in geoscience--behaviour and properties of earth materials at high pressures and temperatures, edited by W. Schreyer. Stuttgart, E. Schweizerbart'sche Verlagsbuchhandlung, 1983. 545 pp. DM 188. Dynamics of oil and gas accumulations, by Alain Perrodon. Pau, Elf Aquitaine (Documentation Centre Micoulau, 64018 Pau, France), 1983. 368 pp. 240 FF. New paths to mineral exploration, edited by F. Bender. Stuttgart, E. Schweizerbart'sche Verlagsbuchhandlung, 1983. 169 pp. DM 58. Results of the First Workshop on Standards in Geothermics, edited by R. Haenel and M. Gupta. Stuttgart, E. Schweizerbart'sche Verlagsbuchhandlung, 1983. DM 98. E&MJ book of jlowsheets edited by Paul C. Merritt. New York, McGraw-Hill, 1983. 214 pp. $42. 1983 E&MJ international directory of mining. New York, McGraw-Hill, 1983. 808 pp. $70. The future of heavy crude and tar sands - volume 11. New York, McGraw-Hill, 1983. 1300 pp. $1l0. 3. Mineral Policy and Energy publications Aluminium, by A. Johnston. 12 pp. . Arsenic, by J. J. Hogan. 4 pp. Cobalt, by D. G. Fong. 6 pp. Selenium and tellurium, by A. G. Johnston. 7 pp. Stone, by D. H. Stonehouse. 13 pp. Uranium, by R. T. Whillans. 16 pp. 4. Mintek publications Report M88 'l'he recovery of platinum-group metals and gold by the lead-collectionstep of thefire-assay procedure. Report MI04 The preparation and analysis of reference materials, and the provision of recommended values. Progress report no. 5. Report Mll1 The determination, by flow-injection analysis, of iron, sulphate, silver, and cadmium. Special publication 3 A guide to the presentation of papers.

Jan 1, 1983

By H. Han, Z. Gao, Y. Gao, W. Sun, J. Wang

Strategic Ca-bearing minerals like scheelite and fluorite are usually separated by flotation, yet the separation is quite difficult due to their similar surface Ca active sites. Compared with the conventional strong collector sodium oleate (NaOL), lead nitrate-benzohydroxamic acid (Pb-BHA), complex collector shows a better selectivity for scheelite, yet its high cost hinders its wide application. Therefore, a novel collector (Pb-BHA-NaOL complex) was initially developed in this work to overcome the abovementioned dilemma. The flotation results of a single mineral showed that Pb-BHA-NaOL had a better selectivity for scheelite than Pb-BHA. Under the conditions of sequential assembly of Pb, BHA and NaOL at the molar ratio of 240:120:1 and pH 9.0, selective separation of scheelite from fluorite could be achieved without adding any depressants. In addition, for the same preferred scheelite recovery, Pb- BHA-NaOL could also save approximately 20% Pb and BHA compared with Pb-BHA. The analyses of the zeta potential measurement and X-ray photoelectron spectroscopy indicated that Pb-BHA-NaOL showed stronger adsorption on scheelite relative to fluorite. Meanwhile, Pb-BHA-NaOL showed more adsorption modes and higher utilisation of Pb and BHA on scheelite than Pb-BHA, which was due to the accelerator, NaOL. Keywords: Scheelite, fluorite, lead nitrate, benzohydroxamic acid, sodium oleate, flotation

Jan 1, 2020

By J. K. Williams, M. P. Wells

"As part of the planning system at each division of Nchanga Consolidated Copper Mines, Limited, the Mine Planning Department is required to produce a detailed production schedule for each shaft.Because of the difficulties in producing a schedule which satisfies all the mining constraints, and because of the large clerical effort involved, the full range of possible schedules can never be considered.It has been found possible to produce a schedule using linear programming which satisfies the majority of the many varied mining constraints. Computer programs have been written to enable the mine planning department to use this mathematical system without assistance.The system has a large degree of flexibility to enable the planner to include conditions which cannot be incorporated readily in the linear program. This system permits the more efficient production and evaluation of schedules and reduces the amount of clerical effort."

Jan 1, 2014

By S. T. L. Harrison, J. R. Amaral Filho, M. Smart, J. Broadhurst, J. Weiler

Technosol production from mine waste, following amendment with additional organic residues, to provide healthy and functional topsoil is an advantageous alternative to the long-term dump disposal of mine waste. Minimising the legacy of mine waste and supplying soil for mine site rehabilitation contributes towards more sustainable mining practices. Following the creation of the physicochemical structure of the soil from appropriate mixtures of coal waste with low sulfur content, physical ameliorants and nutrient sources, the inoculation of Technosols with active microbial suspensions may accelerate the decomposition of organic matter present and ensure nutrient availability for plant growth through active nutrient cycling, particularly of nitrogen, sulfur and phosphorous. In this paper, South African ultrafine coal waste was used as the main mineral matrix, and malt residue was used as source of organic matter and nutrients. In order to evaluate the effects of Technosol inoculation, five microbial treatments were used, including the addition of: commercial grade efficient microorganisms (EM Prosoil), anaerobic digested sludge supernatant from treating brewery waste, and ‘tea’ extracts prepared from compost, vermicompost and soil native to the mining area. Growth experiments were carried out using Eragrostis teff, commonly known as teff, a grass typically used for the rehabilitation of mined areas in South Africa. Preliminary results showed that Technosols inoculated with microorganisms performed better in terms of nutrient availability and plant growth. Varied performance was observed as a function of the microbial inoculation applied. This suggests that the inoculation of Technosols with appropriate microorganisms may be recommended to accelerate nutrient availability assisting plant growth during the initial establishing of the Technosols. Technosols continue to show promise as an alternative to both mine waste disposal and the burrowing of topsoils for mine rehabilitation. Keywords: Fabricated soil, mine waste, coal discards, malt residue, nutrient availability, soil microbiology, plant growth

Jan 1, 2020

By C. A. Snyders

The research presented in this paper investigated the practical aspects of the recovery of platinum group metals (PGMs) from a dilute cyanide leach solution containing base metals, in a manner similar to that used for gold extraction in a typical CIP process, and focuses on both the adsorption and elution stages. The carrier-phase extraction of precious metals using activated carbon offers significant advantages over other processes in terms of simplicity, the high pre-concentration factor, rapid phase separation, and relatively low capital and operating costs. As a sorbent, activated carbon is still by far the most important material because of its large surface area, high adsorption capacity, porous structure, negligible environmental toxicity, low cost, and high purity standards. Adsorption tests were conducted on a pregnant alkaline leach solution (0.15 ppm Pt, 0.38 ppm Pd, 0.1 ppm Au) resulting from cyanide extraction performed in column leach tests. The initial adsorption rates of Pt, Pd, and Au were very fast and recoveries of these three metals were approximately 90 per cent after 2 hours, and 100 per cent for Pt, 97.4 per cent for Pd, and 99.9 per cent for Au after 72 hours. The parameters that influence the extraction of PGMs and Au were examined to assess their relative importance during the adsorption process in order to provide the basis for process optimization. The concentration of thiocyanate was not identified as significant factor for PGMs adsorption, while Ni concentration was the most significant extraction process parameter. Base metal cyanide complexes adsorb and compete with the PGM complexes for sites on activated carbon, and while copper adsorption can be minimized by adjusting the residence time, Ni adsorbs at approximately the same rate as the PGMs, influencing the loading capacity and adsorption kinetics of the PGMs. The feasibility of eluting platinum and palladium cyanide complexes from activated carbon using an analogue of the AARL process was investigated. Platinum and palladium elute from activated carbon almost to completion in 4 to 5 bed volumes at 80°C, while the elution of gold at this temperature is slow, with a significant amount of gold still to be eluted after 16 bed volumes. The equilibrium loading of gold is exothermic in nature (Fleming and Nicol, 1984) which will result in an increase in gold elution kinetics with an increase in temperature at similar pre-treatment conditions. A similar result was found for the elution of Pt and Pd. Cyanide pre-treatment was found to have a significant influence on PGM elution. Higher cyanide concentration in the pre-treatment step results in more efficient elution up to a point, and results suggest the possibility of an optimum cyanide concentration, beyond which elution efficiency starts decreasing due to increased ionic strength.

Jan 1, 2013

By T. Nishimura, H. Kiyama, K. Wakimoto

Discussion on the load bearing capacity of ground and the stability of tunnel is presented. We derive a simplified solution of a circular lined-tunnel in an elastic ground. The solution results in a better understanding of characteristic curves. Use of DEM allows us to consider effects of possible yield of the overstressed zone around the tunnel and inherent discontinuity of ground on the curves. Diskussion auf der Last Tragfähigkeit Bodens und die Stabilität des Tunnels wird dargestellt. Wir leiten eine vereinfachte Lösung eines kreisförmigen Ausbautunnels in einem elastischen Boden ab. Die Lösung ergibt ein besseres Verständnis der Kennlinien. Um Gebrauch DEM erlaubt uns, zu betrachten Effekte des möglichen Ergebnisses der überbetonten Zone den Tunnel und zugehörige Unstimmigkeit des Bodens auf den Kurven. La discussion sur la portance de charge de la terre et de la stabilité du tunnel est présentée. Nous dérivons une solution simplifiée d'un revêtement-tunnel circulaire dans une terre élastique. La solution a comme conséquence une meilleure compréhension des courbes caractéristiques. L'utilisation de DEM nous permet de considérer des effets du rendement possible de la zone surchargée autour du tunnel et de la discontinuité inhérente de la terre sur les courbes.

Jan 1, 2003