Search Documents

By C. Norden

The purpose of this article is to show how a representative overall equipment effectiveness (OEE) measurement can be calculated for an underground coal mining bord and pillar batch process. The calculation method, the typical losses (which include planned and unplanned availability losses, coal quality losses, and process rate losses) and the underlying logic are presented and discussed. It is argued that the current traditional underground bord and pillar mining process can currently provide a maximum theoretical OEE of only 49 per cent, while a realistic benchmark target should be in the order of 37 per cent, which relates to an average of 2400 t per shift or 1.2 Mt/a. In addition, it is argued that the current bord and pillar process is the current bottleneck to further improvement past the 2400 t per shift benchmark, and that fundamental process changes will be required to eliminate this bottleneck.

Jan 1, 2012

By J. H. van Dalen, P. J. Brandt, F. W. Wessels

A maximum of ten process streams (Merrill barren solutions) can be monitored sequentially with this on-line analyser, and gold concentrations as Iow as 0,005 mg/I can be determined. The design is a further development of the Tell-tale analyser constructed by the Corner House Laboratories during the period 1965-69. The barren solution is preconcentrated automatically by solvent extraction, the solvent being a solution of I per cent Aliquat 336 in di-isobutyl ketone. An aqueous-to-solvent ratio of 40: I is maintained. The extracted gold in the organic phase is determined by flame atomic absorption, each analysis taking approximately II minutes. The long-term reproducibility of the absorbance readings over a 24-hour period of repetitive sampling of four simulated process streams varied from 6,9 to 4,1 per cent relative standard deviation for gold concentrations of 0,0 I to 0,05 mg/I.

Jan 1, 1980

By K. E. Mantell

1. TRACKLESS MINING AT OAMITES by K. E. MANTELL Oamites Mine, brought into production in late 1971, is located 50 km south of Windhoek, South West Africa, on the northern boundary of and just outside the Rehoboth Gebied. Oamites was known as a possible mining proposition at the turn of the century when Hanseatische Minen Gesellschaft was adit mining on the adjacent farm Kamzwas. Rand Mines Limited carried out a small amount of prospecting in the early 1960s, Falconbridge Explorations Limited later taking over the prospect. Approximately 4600 m of diamond drilling was carried out between 1965 and 1967.

MASSMIN 92 edited by H.W. Glen. Johannesburg, The South African Institute of Mining and Metallurgy, 1992. xiii, 485pp. ill. 30 cm. (SAIMM Symposium Series S12). Includes bibliographies. ISBN 1-874832-18-8. R342 (MemberR285; Student Member R218,88. Available in Australia from the AMF Bookshop, 63 Conyngham Street, Glenside, SA 5065 at $A171.00 (approx). This volume is the twelfth in a series of symposia published by The South African Institute of Mining and Metallurgy since 1962. This particular meeting addressed the subject of the underground mining of massive ore bodies.

Jan 1, 1994

METRICATION In order to bring South Africa into line with metric countries the world over and in view of the indisputable advantages of using the comma as a decimal sign, the Metrication Advisory Board has decided to recommend that the comma be used consistently as decimal sign as from April 1, 1971. Numbers consisting of more than three figures are separated by spaces into groups of three to the left and right of the comma, and not by commas, e.g... 2 734 671,512 73 A quantity such as 12,41 kg is read as "twelve comma four one kilograms" and 31,34 km as "thirty-one comma three four kilometres." A motor-car previously described as a 3.8 litre model now becomes a 3,8 litre model. THE BRITISH COUNCIL AWARDS 1972-1973 The British Council invites applications from permanent residents of all races in the Republic of South Africa and South West Africa, for the following awards:- SCHOLARSHIPS Scholarships are available to such residents who hold University degrees or comparable professional qualifications. The scholarships are tenable for post-graduate study at Universities and other educational establishments in Britain for the academic year of approximately ten months beginning 1st October 1972. All arrangements will be made by the British Council and the scholarships will include tuition fees, a maintenance allowance, approved travel in Britain, return fares to Britain, a books grant and a clothing grant. The closing date for applications is 31st July, 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 in-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 will arrange full programmes and professional contacts, and the bursaries will include a maintenance grant, a books grant, authorised course fees and certain other expenses. The British Council may, at its discretion, bear the cost of single or return fares to Britain. The closing date for application is 31st July, 1971. TRAVEL GRANTS Travel grants each of £300 are available in respect of journeys to Britain undertaken between 1st April, 1972, and 31st March, 1973, 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 though grants are occasionally made for visits lasting for one complete term. Grant holders will make their own arrangements with the universities which they wish to visit and will be responsible for finding their own accommodation. The British Council's assistance is limited to the contribution towards cost of fares. The closing date for applications is 31st October, 1971. For further particulars and the relevant application forms please write stating the type of award you wish to apply to: THE CULTURAL ATTACHE BRITISH EMBASSY PRETORIA

The following contributions were received to the paper entitled 'Safety in South African mines: An analysis of accident statistics', by H.S. Eisner and J.P. Leger, which appeared in the J. S. Afr. Inst. Min. Metal., vol. 88, no. 1, Jan. 1988, pp. 1-7. Contribution by H. WAGNER* The paper by Dr H.S. Eisner and Mr J.P. Leger is critical of the safety situation on South African mines and portrays the industry as having little concern for the health and safety of its workers. Moreover, the casual reader gains the impression of deliberate misinformation by the industry to the public concerning safety maters. Furthermore, certain socio-economic reasons are advanced for the apparent differences between the fatality and injury rates reported for coal mines in South Africa and those for the United Kingdom. Contribution by S.A. WATTS. Authors Eisner and Leger are to be commended on their paper, which highlights, according to their interpretation, various shortcomings of both the Chamber of Mines accident statistics and those published by the Department of Mineral and Energy Affairs. Authors' Reply We gratefully acknowledge Dr Wagner's contribution to the discussion on our paper. For convenience, we shal use his sequence of comments in our reply. Before doing so, however, it may be useful to explain how our paper came to be written. After the explosion at Hlobane Colliery in 1983, one of us (HSE), in February 1984, was retained by the lawyers acting for some of the dependants of the victims to advise on technical maters relating to the explosion. Contribution by Ms S.A. Wats Some of the points made by Ms Wats have already been answered in our comments on Dr Wagner's contribution. We are fully aware that the number of accidents leading to absences of less than 4 days would be much greater than shown in our bar chart, and are grateful to Ms Wats for drawing attention to the specific exceptions that can make a 1-3 day accident compensable and that are clearly responsible for the relatively low count in that category of the chart.

Jan 1, 1988

By K. -I. Higuchi, M. Mizutani, K. Haga, A. Shibayama, A. Batnasan

In recent years, the quality of iron ores has decreased due to the increase in the content of impurities, namely quartz, aluminum, phosphorus, and sulfur. It indicates that the removal of impurities from iron ore is an extremely challenging task. In particular, the high amount of phosphorus in iron ore could be a problem for energy consumption and CO2 emission in the steelmaking process. To reduce the impact of phosphorus, mainly two approaches: the utilisation of low-phosphorus iron ore, or dephosphorisation of high-phosphorus iron ore using mineral processing technology, have been suggested. In this paper, the removal of phosphorus from a low-grade high-phosphorus iron ore containing 0.1 mass% P and 57.5% Fe by alkaline roasting and wet grinding is discussed. The iron ore consists mainly of hematite, goethite, and quartz. Effects of sodium hydroxide concentration used as an alkaline source, roasting temperature, grinding time, and particle size on the dephosphorisation of highphosphorus iron ore were investigated. The dephosphorisation efficiency, iron loss, and mineralogical components of low-grade high-phosphorus iron ore under various experimental conditions were characterised by using XRD, SEM-EDS, and particle size distribution analysis. Results showed that the phosphorus content was lowered from 0.1 mass% to 0.034 mass%, while the iron grade reached 59.8 mass% from 57.5 mass% by alkaline roasting with 0.05 w/w NaOH at 300 °C for 2 h, followed by wet grinding in an attritor with water for 30 seconds at room temperature. Under the experimental conditions, the dephosphorisation rate was about 54.7%, and the solution obtained by wet grinding contained 22.7 mg/L of phosphorus and 21.5 mg/L of iron. The recovery rate of iron by this process reached 99.9%. Keywords: Iron ore, phosphorus, dephosphoriszation, alkaline roasting, wet grinding

Jan 1, 2020

By N. X. Feng, S. G. Zhou, X. L. Wu, J. P. Peng, Y. Z. Di

"Szaibelyite–suanite type ore is rich in magnesium oxide and boron oxide. We propose a new method to extract both metallic magnesium and valuable residues rich in boron by reduction using metallic aluminium.Thermodynamic analysis of the reactions between aluminum and MgO, Mg2B2O5, and Mg3B2O6 was carried out. The effects of CaF2 addition, temperature, mass of Al, and pellet formation pressure on the extraction of magnesium were also investigated experimentally.The results indicate that the magnesium oxide phase can be displaced from 2MgO-B2O3 and 3MgO·B2O3 by CaO in the reduction system. The reduction ratio of magnesium oxide was 38% without calcium fluoride addition, increasing to 94% with 5.1% calcium fluoride. The reduction ratio increased with increasing temperature and mass of Al. To obtain a higher reduction ratio, the reduction pellet should be formed under a reasonable pressure.IntroductionBoron and its compounds are widely used in textiles, borosilicate glass, metallurgy, fertilizers, and nuclear shielding. Boron resources are mainly found in Turkey, the USA, Russia, and China. In Liaoning, China, there are abundant szaibelyite–suanite type ores that are rich in magnesium oxide and boron oxide. Szaibelyite and suanite ores are used to produce borax by a carbon dioxide– soda process. Annually, 2 Mt of waste materials containing 3–20% B2O3 and 2–25% MgO are produced during the process. It is necessary to make use of these waste materials containing high concentrations of boron oxide and magnesium oxide to avoid environmental problems as well as for economic reasons (Ozdemir and K1pcak, 2007)"

Jan 1, 2016

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.

The AK6 kimberlite is situated 25 km south of the Debswana Orapa Mine in Botswana and was discovered by De Beers geologists in 1969 during the follow-up of geophysical targets in the Orapa area. The kimberlite was not extensively pursued at the time as the initial bulk sampling indicated it to be of limited size and low grade, factors largely contributed to by the basalt breccia capping. Completion of high resolution integrated geophysical techniques and drill bulk sampling to depth recovered 97 tons of kimberlite during 2003 and 2004, which led to the increased size and grade estimates. Bulk sampling by Large Diameter Drilling (LDD, 23 inch diameter) commenced in 2005; 13 holes were drilled to a cumulative depth of 3,699 m and 689 carats of diamonds were recovered. In July 2006 the De Beers Mineral Resource Classification Committee classified these Phase I LOO results at a High Inferred level with an average grade of 24 carats per hundred tonnes (cpht) at a bottom cut-off of +1 mm, and a modeled average diamond value of 150 dollars per carat. A second phase of LDO drilling was initiated in 2006, and bulk sampling by trenching commenced in 2007 in order to deliver a resource estimate at indicated level. An Indicated Resource of 11.1 million carats at an average grade of 22 cpht was declared for the deposit mining lease application lodged in 2007.

Jan 1, 2010

By P. F. Sorensen

A simple mathematical model is presented that relates the 'head' developed at the surface of pulp in a tank to the power dissipated by the air in producing it. The value for the head is then used in the calculation of the superficial circulating velocity of the pulp and the area of the overflow, and the product of these two values gives the pumping rate of the pulp. Thus, the superficial circulating velocity, and hence pumping rate of the pulp, are related directly to the flow-rate of the air. This hypothesis was tested with good results in an air-agitated pachuca tank (of 1 m in diameter) fitted with a draught tube. The method can also be used for the prediction of the pumping rates in production-scale vessels.

Jan 1, 1985

By B. G. Meyburgh

SYNOPSIS As a result of a test programme over a period of approximately ten years and a decision to extend the uranium plant, it was decided to design and erect the first full-scale Purlex Plant in the Republic of South Africa. The plant at Buffelsfontein G.M. Co. Ltd. was commissioned in August, 1968, and to date has produced results superior to those predicted in the original estimates. The capital expenditure was R678 000 for a plant capable of treating 1 600 gallons per minute of pregnant solution. Compared with the conventional resin ion exchange process, it has been found that the saving in production costs is 21 cents per pound U3O8 produced. The amine loss is 10 parts per million, which is equivalent to a total organic loss of 250 parts per million. The uranium loss in the raffinate is less than 0.001 g/l U3O8. The final product is of a high quality and it is probable that it is pure enough to convert to the fluoride directly.

By D. Moradkhani, S. M. Javad Koleini, M. Abdollahy, F. Soltani

"The objective of the study was to determine the type and distribution of rare earth elements (REEs) in the phosphate flotation concentrate from the Esfordi flotation plant in central Iran, in order to understand their leaching behaviour. Samples of the concentrate were prepared and analysed using XRF, XRD, ICP, and EMPA. The Ce, Nd, La, and Y contents were 5608, 2227, 1959, and 679.7 mg/kg, respectively. The main REEbearing minerals in the concentrate are fluorapatite, monazite, and xenotime. Apatite is the chief mineral of the concentrate and the ratio of apatite to monazite is greater than 60. From EMPA analysis, monazite contains a much higher proportion of REEs than apatite, but more than 50% of the REE content of the concentrate is in apatite, as this is the main mineral constituent of the concentrate. During the leaching of REEs in the phosphoric acid production process, more than 99% of the total rare earth values report to the large amounts of phosphogypsum (CaSO4·2H2O) formed during the dissolution reaction. Accordingly, two process options are suggested for treating the Esfordi concentrate. In the first option, the concentrate is treated with 98% H2SO4 at 200–300°C. After digestion and water leaching, phosphorus and REEs are precipitated out of solution. In the second option, the concentrate is treated in a pre-leach stage. The process residue from the pre-leach stage is then subjected to acid digestion at elevated temperature for phosphoric acid production.IntroductionThe rare earth elements (REEs) comprise a set of 17 chemical elements in the periodic table, specifically the 15 lanthanides plus scandium and yttrium. REEs and alloys that contain them are used in devices such as computer memory, rechargeable batteries, cell phones, catalytic converters, magnets, fluorescent lighting, and many more (Krishnamurthy and Gupta, 2004). China supplies about 94% of the REE demand, with the remaining 6% coming from Russia and Estonia, the USA, India, Malaysia, and Brazil (Zhanheng, 2011). Increased industrial development in China has prompted the Chinese government to limit annual export quotas to approximately 35 kt of rare earth oxides (REOs), while non-Chinese annual demand is expected to reach 80 kt by the year 2015. This constriction of supply is being met by the development of many new rare earth mining projects, each of which has its own unique mining and processing challenges (Jordens, Cheng, and Waters, 2013). One of these projects is the Esfordi phosphate project, which is located in Yazd Province in central Iran. The concentrate from the Esfordi flotation plant contains 1.2–1.5% REEs."

Jan 1, 2017

By C. T. Connor, O&apos

The fifth University of Cape Town (UC1)/University of Stelenbosch (US) Minerals Processing Symposium was held at the Faculty of Engineering, University of Stelenbosch on Friday, 8th August, 1986. This series was initiated in 1982, the symposia being held alternately in Cape Town and Stelenbosch. The South African Institute of Mining and Metallurgy has kindly agreed to sponsor this event for the next three years. Cokemaking On the initiative of the European Cokemaking Commitee, the First International Cokemaking Congress will be held in Essen (F.R. Germany) from 13th to 19th September, 1987. It is being organized by the Steinkohlenbergbauverein, together with the Verein Deutscher Eisenhitenleute.

Jan 1, 1986

By S. R. Xie, S. Gong, E. P. Li, S. S. He, Y. J. Sun, S. J. Li

"Based on the complicated geological production conditions and abnormal strata behavior of the fully mechanized caving face No. 102 in the Xinyang Coal Mine, we analyze the breaking and forming process of distinguishing key block structures in close spaced coal seams. This analysis establishes an integrated mechanical model of these distinguishing structures. Furthermore, the horizontal force TAB generated by downward key blocks A and B is quantified, as is the Pressure PG exerted by key block B on caved gangue. Finally, the interaction mechanism is revealed. Analysis of the results using Mathematica reveal the following: 1. Both TAB and PG exhibit approximately inverse relationships to coal pillar width b; 2. TAB exhibits an approximately exponential relationship with mining height M of which the base is greater than 1; 3. PG exhibits an approximately arctangent relationship with mining height M. Combining these results with field observations, we conclude that the area in the vicinity of supports 100#–120# in the upper area of working face No. 102 is the likely zone of abnormal strata behavior. Thus, this area was classified as a key control area. Based on these results, the graded support control technique is proposed. Application of this technique in the field resulted in a reduction in the rate of hydraulic support system malfunction from 47% to 7% in the key control area. In addition, during times of periodic mining pressure, the roof caving height value never exceeded 0.3 m and the maximum spalling depth never exceeded 0.2 m. Overall, the results indicate that this new technique has markedly increased the stability of surrounding support rock material. IntroductionClose-spaced coal seams are widely distributed in China, and mining proceeds from the uppermost to the lowermost seam (Zhang et al., 2008). In the case of coal seams in close proximity, a particular set of risk factors becomes pertinent. These include disturbance of lower seams during the mining of overlying ones and the decrease in mechanical stability of lower coal seams following repeated movement of key blocks in main coal seam roofs. This inevitably results in behaviour such as heavy wall spalling and support damage to fully mechanized caving faces in lower-lying coal seams, which necessitates a significantly increase in the measures to support surrounding rock material (Zhang et al., 2010; Huang et al., 2013; Xie et al., 2013)."

Jan 1, 2016

One of the main bottlenecks in the carbon-in pulp process for the recovery qf gold is the elution procedure, which typically requires the heading of caustic cyanide eluants to high temperatures for 16 to 24 hours. The present work demonstrates that sodium sulphide solution as an alternative eluant can effect complete elution in about 4 hours at ambient temperatures. Elution efficiencies of around 100 per cent were obtained in 4 hours with a single pass of eluant containing 0,2 M Na2S and 0,4 NaOH about 10 bed-volumes of eluant The initial rate was slow over the first hour of elution, probably because the activated carbon catalysed the oxidation of sulphide to polysulphide. Elution efficiencies of around 100 per cent were also obtained in less than 4 hours during the batch elution of carbon at liquid-to-solid ratio of about 100. Lower liquid to solid ratio resulted in the re-adsorption of gold, probably owing to the oxidation of sulphide to polysulphide, with the resultant formation of gold complexes that were eluted less readily. Improved rates of elution were obtained at higher sulphide concentrations and pH values greater than about 13. Higher temperatures increased the initial elution rate, but lowered the overall extraction efficiency, probably because of the deposition of elemental gold on the carbon. Variation of the ionic strength by the addition of NaCl had no defect on the elution, which confirms that the elution mechanism in the case of sulphide is different from that when cyanide or I1)1droxide is used as the eluant. It is proposed that the elution of gold by sulphide solutions proceeds by means of an initial step that involves the reaction of polysulphide ions with the adsorbed aurocyanide speeds, forming AuCN on the carbon and thiocyanate in solution. This step is followed by the formation of poorly adsorbed complexes with sulphide ions, such as [AUS3-2]-The presence of polysulphides, whether generated in situ by the catalytic oxidation effect of activated carbon or by the addition of elemental sulphur, reduces the elution rate and efficiency dramatically. This is probably due to the formation of complexes such as AUS-3 and AUS-2 , which have a high adsorption affinity.

Jan 1, 1994

By Oaitse Medupe

The feed to the BCL concentrator is made of the ore from Phikwe No3 shaft, Selebi shaft and Selebi North shaft. The receiving bin of the concentrator has daily throughput of 7869mt live capacity of ore with feed grade from underground operation of 0.70%Ni, 0.75% Cu and 0.05% Co. The valuable minerals in the ore are Pentlandite, Chalcopyrite. Cobalt is present mainly in the solid solution in pentlandite. The common non-sulphides minerals are Amphibolites, quartz, micas, and Feldspar while pyrite and pyrrhotite are the major gangue sulphides. Pyrrhotite contains between 0.1% and 1% Ni in solid solution. From the mineralogical investigation, it was found that approximately 65% of the pentlandite in the ore occurs as exsolutions in the pyrrhotite and the grain sizes ranges from 8 to 38µm. about 25% of the nickel bearing pentlandite is medium grained and subhedral. This kind of pentlandite occurs along the cracks of pyrrhotite or as inclusions in pyrrhotite. The rest of pentlandite present is disseminated in the gangue matrix. Because of the fine occurrence of pentlandite, fine grinding was conducted in order to improve the recovery as well as the concentrate quality. A series of subsequent flotation test were performed in order to evaluate grinds of 35, 40, 45, 50, 60 and 80% passing 75µm. It was observed that ? The mass pull increased together with increasing fineness of grind ? Similar nickel recoveries were obtained at 35 and 40% passing 75µm but from 50% and 60% the grind was seen to adversely affect the nickel recovery. At 80% passing 75µm the recovery increased by small amount. ? Flotation kinetics showed higher initial nickel recoveries but these did not translate into higher final recoveries. ? Grinding finer than 80% passing 75µm yield very high grades of the concentrate in the first minute of the flotation test, and the grade is dramatically reduced in the fifth minute of the test. It was concluded that the current grind of approximately 48% passing 75µm is close to the optimum and no significant benefit were found to be associated with finer primary grinds. The inconsistence of the grade and recovery as well as the pentlandite losses will be discussed. Keywords: Pentlandite, Nickel losses, Grain size, Flotation

Jan 1, 2007

By L. A. Vermeulen, C. P. Campbell, D. D. Howat

The production 01material liner than 75 µm in a number of open-circuit mills was investigated. The mils ranged from laboratory rod and ball mils treating a variety 01 ores to large industrial rod mils treating gold and copper ores. It was shown that the dependence on feed rate 01 the production 01 material liner than 751J.1T1 can be accurately described by a simple formula that was derived in previous work. In some 01 the systems reviewed, it proved possible to assess the feed rate 01 ore to the mil at which the rate 01 production 01 material finer than 75 µm can be maximized.

Jan 1, 1991

1. Book review • World mineral statistics 1974 to 1978. Production: Exports: Imports. London, H.M.S.O., Institute of Geological Sciences, 1980. (Reviewer: R. P. King) This edition is the third in a regular series prepared by the Institute of Geological Sciences. It is a useful compilation of statistics on the production, export, and import of fifty-eight different mineral commodities. Each mineral is listed by country, and a table is provided for the annual production, the annual imports, and the annual exports for each commodity included. However, some commodities are treated in considerably more detail; for example, aluminium and bauxite have tables under the following headings: Production of Bauxite, Production of Alumina, Production of Primary Aluminium, Exports of Bauxite, Alumina and Aluminium, Imports of Bauxite, Alumina and Aluminium. The information presented is the latest official information available from primary sources; the compilers have not relied on data from secondary compilations. This publication will be of considerable assistance to all who are concerned with the trading of mineral commodities and their production.

Jan 1, 1981

By F. P. Agterberg, A. G. Fabbri

"A statistical analysis was done on the locations of 718 copper and 1 257 gold deposits in Abitibi. This area of about 20 000 square miles is one of the better-explored metal-producing areas of Canada.Patterns of clusters were studied by harmonic analysis. Several two-dimensional power spectra showed a number of distinct peaks. Sets of crest lines for patterns of interfering waves were constructed on the basis of these peaks. They pass through elongated clusters of deposits which are spaced more or less equally. For copper these periodic regularities in location may coincide with geological structures largely of Archean age (major fractures and sedimentary belts indicating synclinal structures). A directional relationship with swarms of diabase dykes of known ages and distinct attitudes indicates that the gold mineralization is, in part, younger than the copper mineralization."

Jan 1, 2014