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By M. Nicolle

The Tati Activox® Project will be the first full-scale implementation of the patented Activox® process (The Tati Activox® project was deferred in 2008. Please refer to the Norilsk Nickel press issue on the topic for more info). The process was developed by Norilsk Process Technology and has been tested on Tati mine sulphide concentrates in laboratory, pilot and demonstration plant scales and demonstrated its viability. There are inherent risks to the final scale-up of the process from the demo plant and one of them will be investigated in this paper. Compartment 1 is designed to leach approximately 77% of the total nickel leached. For this reason agitation requirements in the first compartment of the autoclave are reviewed. An attempt is made to minimize the process and mechanical risks associated in achieving oxygen mass transfer into the slurry solution. The agitator powers for oxygen mass transfer are calculated using empirical correlations and compared to demonstration plant testwork. The resulting gassed power per unit volume (P/V) is higher than most commercial autoclaves and raises uncertainty on the viability of using such high unit power inputs. Additionally, there is concern about the ability of the autoclave shell to withstand and support the higher loading of large agitators. An alternative solution to designing for the increased P/V is assessed in which the number of compartments within the autoclave is reduced from 5 to 4 by removing the compartment wall separating compartments 1 and 2. This results in an enlarged first compartment containing 3 agitators instead of 2. Therefore the compartment 1 oxygen demand is supplied through 3 agitators, which lowers the P/V per agitator. The reduction in the number of autoclave compartments raises the potential for short-circuiting the mean flow pattern by slurry particles. Short-circuiting and low velocity zones could result in a lower recovery of metal and localized hot spots, respectively. A computational fluid dynamic (CFD) analysis was conducted to quantify these concerns and also to evaluate further design considerations. The results indicate that the proposed design change to 4 compartments affects short-circuiting. The impact of increased short-circuiting on the overall autoclave recoveries is not quantified, however; it is expected to be negligible based on testwork done in the Tati Demonstration Plant and similar modifications made to another operating autoclave. The CFD analysis also suggests that there will be no low velocity zones within the compartment.

Jan 1, 2009

By N. W. Munro

SYNOPSIS Certain disadvantages associated with the use of Anfex have been raised on previous occasions. This interim investigation shows that by loading at lower pressures the sensitivity to initiation of Anfex can be improved. Associated with this is a reduction in velocity of detonation and charge density which should lead to more desirable fragmentation. The effect of lower loading pressure on other factors is also considered. INTRODUCTION Discussion at the Symposium on the use of Anfex in Underground Mining, conducted by the South African Institute of Mining and Metallurgy during May 1968 showed that there was considerable uncertainty and diversity of opinion on the characteristics of Anfex and its method of application. Some of the disadvantages associated with the use of Anfex were: Inadequate sensitivity to initiation; Excessive fragmentation of the rock and damage to the hanging and footwalls; Wastage as a result of blow-back; Poor water resistance. As a result of this, further investigations on the properties of Anfex have been carried out and, although these have not reached finality, it is considered that a progress review may be of interest and assistance to the mining industry. EXPERIMENTAL TECHNIQUE The work was carried out on a laboratory-scale where, for test purposes, the explosive was loaded into 1 in. (nominal) internal diameter steel pipes unless otherwise stated. Charging was conducted with a 1 in. (nominal) Schutte-Koerting eductor having a 0.2 in. internal diameter venturi nozzle, the Anfex being fed into the eductor from a conical hopper fitted directly above it. A 5 ft long copper loading tube with outside and internal diameters of 3/4 in. and 5/8 in., respectively, was fitted to the discharge end of the eductor. The remote end of the loading tube was inserted into the test pipe so that it was about 6 to 8 in. from the closed end of the pipe. The loading apparatus was withdrawn as the pipe filled, maintaining approximately the same stand-off distance throughout the operation. REVIEW Sensitivity to initiation Sensitivity of Anfex to initiation was found to deteriorate when the dynamic pressure of the air to the eductor was increased. This was attributed to increasing charge density and it was found that at a charge density of about 1.05 g/cm3, which

Numbering of the Journal Because computer and library authorities prefer journal subscriptions to be based on the calendar year, and because the present numbering system of the Journal of the South African Institute of Mining and Metallurgy does not conform with the calendar year, it has been decided to change the numbering system of the Journal.

Jan 1, 1979

By V. C. Robinson

INTRODUCTION Most presidential addresses are in the nature of a review of some specific topic and this will be no different. In thinking about the subjects which might be suitable for this address I decided that as next month will see my retirement from the gold mining industry I might review the four decades since I started in the industry in 1929. These four decades have been more than usually in',~resting and exciting. They have covered a period when the price of gold increased from the old figure of 84/- an ounce to the price of $35 an ounce today, taking in on the way at least two periods of premium sales from which the producer benefitted. The industry in these four decades has survived the most totally destructive war in history and has seen fundamental changes in the political, economic and governmental life of South Africa. There have been great technological changes and improvements, some of which I shall refer to later, and in addition there have been profound changes in the relations between employer and employee in the industry which have affected not only the economy of the industry but the traditional thinking of both management and labour. I believe that the address presented to this Institute on the occasion of its 75th Anniversary by Mr Goode covered more than adequately the history of the Institute and the part it has played in the mining industry of South Africa. It would be merely repetitive, therefore, to discuss the affairs of the Institute of Mining and Metallurgy. Having said this, however, it is also necessary to point out that the history of the Institute is, and always will be, an important record of the history of mining in South Africa. There are many facets, however, on which we ought to look back and to re-examine. One of the most rewarding, but at the same time one of the dullest, places to look for historical facts is in the annual reports of the Chamber of Mines. I suppose that some of the dullest of these have been the reports for which paragraphs have been prepared by me personally. The notes which follow do not claim to be anything like a full record of this exciting period. RISE AND FALL OF THE GOLD MINING INDUSTRY In talking about the mining industry of South Africa it is inevitable that one talks, particularly in the historical sense, about the gold mining industry - an industry of fundamental importance which has made South Africa what it is and which has been dying since the early part of this century. In Table I is shown the progress of the gold mining industry measured by its output of ounces of fine gold from the beginning of operations until the end of 1969, and if you are interested in the productivity of the men who work this industry the table, composed entirely from figures set out in the Chamber's annual reports, also shows the production of gold expressed as fine ounces per European and fine ounces per Bantu worker over a long period. If you are still minded to think of this industry as dying then the last column in the table shows how uranium has played such a vital part in the prosperity of the country.

The May General Meeting of the Institute was held in Kelvin House, Johannesburg on 20th May, at 4.30 p.m. Mr V. C. Robinson (Vice-President) was in the Chair in the absence, overseas, of the President, Mr J. K. E. Douglas. There were also present 16 Fellows: Messrs J. A. Adamson, R. S. J. du Toit, J. A. Drummond, D. F. A. Grave, T. L. Gibbs, G. H. Grange, D. V. Howat, P. H. Kitto, Dr P. J. LIoyd, Messrs B. H. L. Leach, J. de V. Lambrechts, Dr J. T. McIntyre, Messrs C. S. MacPhail, P. W. van Rensburg, S. G. Taussig, W. S. Rapson. Six Members: Messrs E. L. Atkinson, R. Hemp, Dr J. Martinson, Messrs A. H. Munro, G. J. van Jaarsveld and J. H. Qwilliam. Two Associate Members: Messrs B. H. van Rensburg and H. Triiter. Four Visitors: Prof J. E. Kerrich, Dr G. K. Sluis-Cremer, Messrs D. Kisbey-Green and L. W. Isserow. For Secretariat: Mrs S. de Gersigny. Total present: 27. OBITUARY The Vice-President: "It is my sad duty to announce the death of Stephen Ring, a member who joined the Institute in ]961, and passed away on the 31st of December, 1969. I would ask you all to rise and observe a moment's silence. Thank you." MINUTES The Vice-President: "May we confirm the minutes of the Special General Meeting and Monthly General Meeting, held on 20th February, 1970, as published in the April issue of the Journal?" MEMBERSHIP The Vice-President: "I have much pleasure in announcing that the names of the undermentioned candidates, having been published in accordance with By-Law 5 2.2, Council has elected them to membership of the Institute in the following grades: Fellows: Denis Ian Field, Arthur Cecil Waiter Comyn, John Hall, Leon VercueiI. Members: Jan McLellan Vosloo, Jan van Velze. Graduates: Richard Darnley Beck, John Edward Andrews, Roderick Nowell Randell. Associates: Alexander Duncan Ross, Ian James Terrill. Students: Hendrik Jacobus Oostenwald Prins Smith, Graham Peter Gooding, Rudannes Raath Homan. "I welcome the newly, elected members to the Institute." GENERAL BUSINESS The Vice-President: "Are there any matters which you wish to raise under 'General'? There being no matters to raise under 'General', we will proceed to the next item on the Agenda." PAPER FOR PRESENTATION The Vice-President: "It is my pleasant duty to call on Dr du Toit to deliver his paper, entitled, 'The functional relationship between dust hazard and the rate of collecting funds to pay compensation for pneumoconiosis'." After the presentation of the paper (published in the March Journal) the Vice-President said: "This paper is a very important addition to the considerable volume of work applications on this subject of pneumoconiosis. The disease, in all its various forms, has received attention from many, many great men, both in the medical world, and engineers. The fact that there is this big volume of publications of literature on it still doesn't mean that we can get anywhere beyond the old, simple injunction, that the prevention of pneumoconiosis does not depend on compensation, levies or anything else. It simply depends on allaying dust as quickly as possible. "This paper, however, is another scientific landmark and I think, in a cold and dispassionate way, it sets out some important points in this whole subject of the relationship of the levy - the money of compensation to the dust which causes it. "I have, personally, very little to criticise in this paper but when I listened to Dr du Toit's final conclusions, I wondered whether the words, 'Within the data available', aren't the key to this whole situation. I agree that he has demonstrated a workable relationship between the current industries for levy and dustiness, but among the factors which he lists as being important, I know that there is one which is missing. This is extremely difficult to evaluate. It's a factor which has destroyed, on so many occasions, the work which has been done by so many genuine, intent, honest people working in this field, and this is this unknown factor, this hidden factor of political opportunism, which has so often played a very important part in pneumoconiosis compensation. "How many of us have seen the grubby, grasping fingers of power-mad demagogues, and I can name them for you - but I won't - and also the blatant vote-catching of certain politicians interfering in this field. How, at the end of all that, the poor scientist, the poor dedicated man in the Mines' Department, who has to write the law of compensation, can operate, I do not know. "From this picture the ordinary layman recoils in horror. Among the casualties in this particular war, which has been fought over so many years, I am perfectly certain, are some of the criteria of certification, especially in '56/,57, when that extraordinary condition, known as 'pulmonary disability' was introduced. I am sure there were casualties then, in the criteria of certification. "Nevertheless, this paper is a worthy addition to the long list of scientific work done on this so-important

The President: We are very fortunate tonight to have with us Professor Franz Pawlek, Head of the Institute of Extractive Metallurgy for Non-Ferrous Metals of the Technical University, Berlin. In him we have a representative from one of the few mining and metallurgical universities in Western Germany, since I understand there are only three such universities, Berlin, Aachen and Kassel. The latter is represented by Mr Schmelling who has accompanied Professor Pawlek here tonight. The famous Freiberg University is on the other side of the Iron Curtain, and so is Breslau. Professor Pawlek was born in Vienna many, many years ago, and he obtained his diploma and then later his Doctor's Degree in metallurgy, in Vienna. For four years he worked for an Austrian company, and then moved to Berlin and joined the A.E.G. Company. After the war, he joined the Institute, which had been very heavily damaged, and he was closely associated with the rebuilding and re-equipping of the faculty of mining and metallurgy. He has written numerous papers, and I am sure we are going to have a most entertaining and interesting evening's talk. The President: Gentlemen, I am sure you would like me to thank Professor Pawlek for his talk tonight. My knowledge of pressure leaching is particularly small, limited to a friendship with Professor Frank Forward, to whose original work at Fort Saskatchewan reference has been made by Professor Pawlek. I enjoyed Professor Pawlek's talk, and as a mining engineer I managed to follow most of the argument, mainly because it was so lucidly presented, aided by these informative slides; but I never realised how complicated a problem this process can be. I am taking the liberty of asking Professor Howat to express our thanks from a more technical point of view. After Professor Howat has spoken, and possibly posed a few questions, I shall throw the meeting open in the hope that various people here will be prepared to ask questions. I see one or two gentlemen who have been over in Canada studying pressure leaching lately, and I hope they will ask questions, informally if they so wish. We will not record the full proceedings of this meeting tonight, in the hope that there will be more questions of a general nature. Thank you. Professor Howat: Mr President, Professor Pawlek, I am afraid I am up here under false pretences, because the matter that I thought I was asked to do was to propose a word of thanks, and I usually thought that a word of thanks was taken at the end,-however. It is always very intriguing to think that for all these thousands of years that have passed, pyrometallurgical processes have provided the main methods of extracting metals from their ores. Within the last 100 years, hydro metallurgical processes have become of increasing importance, and it is quite interesting to speculate that the largest single hydrometallurgical process is the one that we operate in this country,-which was devised by two distinguished countrymen of mine,-namely, McArthur and Forrest.

By G. A. Wiebols, N. G. W. Cook, N. C. Joughin

Introductory remarks Dr N. G. W. Cook: This paper was published in your Journal in May of this year and you will, therefore, have had the opportunity of reading it over the past six months. I can state that experience has shown that the paper is substantially correct, but a number of questions have to be answered. The first question, Mr President, that I would be happy to answer, is how is it that one is able to cut hard, abrasive quartzite with a strength some six times greater than that of good concrete? The essence of the answer is that there is a tremendous difference between abrasion, or scratching, and cutting, or chipping. For example, it is well known that a diamond will scratch or abrade almost anything. It is also relatively easy to chip, crack or crush a diamond. As a demonstration I have here an ordinary bench grinder, and with the bench grinder I also have a piece of tool steel. The wheel on this bench grinder is a silicon carbide wheel, which is an extremely hard material, and the tool steel is much softer. In rock-cutting we use tungsten carbide for cutting the quartzite. The quartzite and the tool steel have roughly the same hardness. You can sharpen tungsten carbide with a silicon carbide wheel. In fact, this is done. It won't surprise any of you, therefore, when I show you that tool steel can be sharpened with silicon carbide. Now, what I propose to do is to change the configuration of this experiment and use the soft tool steel to cut silicon carbide, and if I can do that, I think you will agree that I have gone some way to being able to cut quartzite, which is about as hard as tool steel, with tungsten carbide, which is harder than quartzite. Let me do this. (Demonstrates.) That, I think, is a very clear demonstration of how it is possible, with a metal, to cut an extremely hard and brittle material. What, essentially, is the difference that we have here? In the first case, I held the tool with a relatively low force against the hard silicon carbide wheel. This generated a relatively low average stress, which was insufficient to fracture the carbide wheel. Nevertheless the protuberances on the silicon carbide wheel indented the tool steel and abraded it at a multiplicity of points, and quickly reduced the section of the tool steel that I held against the wheel. By changing the configuration and clamping my tool steel in a firm post, against the silicon carbide wheel, I changed these conditions very extensively. I now had a high force. I had to exert a considerable moment on that lever. The tool was anchored so that it could sustain these high forces, and they generated high stresses, which were adquate to fracture the silicon carbide. Now, what about wear? It so happens that, in these two experiments I have just done, the power I was using was about the same-a small fraction of a horse power.

May 1, 1968

By K. B. Owusu, W. Skinner, R. K. Asamoah, J. Karageorgos, M. Zanin, C. Greet

High Pressure Grinding Rolls (HPGR) are mostly used prior to pelletising processes to increase the specific surface area (SSA) of iron ore concentrate. For expressing SSA, the Blaine index is utilised as one of the most important dimensional properties of iron ore pellet feed. ISO 21283 is a standard test method that explains the manual of Blaine air-permeability apparatus for determination of this parameter. In this standard, the disaggregation method is based on passing the minus of 1 mm samples from the 0.150 mm sieve. The disaggregation process has an effective role on the results of Blaine airpermeability test especially for regrinding HPGR products. In this research, firstly the Blaine index of samples was measured without disaggregation. Following this, disaggregation was done by passing the minus of 1 mm samples through three sieves with different dimensions, 0.150, 0.090 and 0.045 mm, separately, and the Blaine index was calculated for each one. Finally, lab-mill with rubber balls, called Jar mill, was investigated as another option. Screen analysis and image analysis with SEM were performed to evaluate the effects of the sample's disaggregation on the size distribution and agglomeration of samples. The results showed that the disaggregation method with sieve size 0.150 mm, according to ISO 21283, was not applicable for HPGR products because the particles were still stuck together. In addition, the disaggregation method with the sieve size 0.045 mm or with Jar mill offered reasonable results. Keywords: Disaggregation, Blaine index, specific surface area, regrinding HPGR, ISO 21283, Jar mill

Jan 1, 2020

By K. A. Moxham

The ARM 1100 was described in a paper presented at the 6th International Symposium on Mine Mechanization and Automation in September 2001. It started operation underground at Rowland Shaft in early 2002. This paper covers the results of those trials that resulted in more than 1 100square metres of UG2 being mined.

Jan 1, 2004

By R. P. King

Held on the 22nd March 1972 at Kelvin House. Four papers were presented at this colloquium, which was attended by approximately 120 people. The first paper, 'Flotation Research Work at the N.I.M. research group, University of Natal on the modelling of a Flotation Process' was presented by Dr R. P. King, the leader of the N.I.M. Research Group in the Department of Chemical Engineering at the University of Natal. A discussion panel, under the chairmanship of Dr R. E. Robinson with Mr M. Dawson (PMC), Mr E. Roux (FOSKOR), and Dr B. K. Loveday (NIM), discussed the potential application of the theoretical work on flotation modelling to industrial processes, and alternative approaches to providing a way of control of flotation plants. The second paper, 'Fundamental Studies of the Flotation Process the Work of the National Institute) for Metallurgy', was presented by Dr N. P. Finkelstein. The discussion panel for this paper was under the chairmanship of Professor D. D. Howat,and had as its members Mr H. P. Carlisle (JCI), Professor D. le Roux (University of Pretoria), and Mr E. Rudolph (Anglo American Research Laboratories). A lively discussion on this paper ensued, with several contributions from the floor. After lunch, Mr S. K. de Kok, Assistant Consulting Metallurgist, Anglo Vaal, presented a paper on 'The Flotation of Copper and Zinc Sulphide from Prieska Ore'. The paper was discussed by a panel comprising Dr V. C. Lovell (NIM), Mr A. Gilbert (General Mining), and Dr D. Legge (Anglo Vaal), under the chairmanship of Dr L. Bushell. This discussion, in which many members of the audience participated, revolved around the difficulties associated with the production of copper and zinc concentrates and the lack of fundamental information on the behaviour of copper and zinc sulphides in flotation. The final presentati0n was a paper, 'The Recovery by Flotation of Cassiterite contained in Gravity Concentration Plant Tailings', presented by Mr E. B. Viljoen (Metallurgy Department, Goldfields South Africa Limited). The discussion, led by a panel consisting of Mr O. Tant (Goldfields Laboratories), Mr J. Levin (NIM), and Mr R. I. Shanks (NIM), under the chairmanship of Mr H. Cross (Goldfields South Africa Limited) referred particularly to the use of new reagents for the flotation of tin, with particular emphasis on the fundamental relationship between reagent composition and its ability to float this type of mineral.

Jan 4, 1972

By Z. Khan

Iron, in the form of steel and stainless steel, is the most commonly used metal in the world. Plain steels corrode and oxidize easily, while stainless steels exhibit improved corrosion and oxidation resistance. It has been found that rare earth metal (REM) additions, such as cerium and erbium, result in the improvement of the abovementioned properties in iron-containing compounds. Gadolinium is a REM, however, there is very little information available on the influence of gadolinium on the microstructure and mechanical properties of iron-containing compounds. Thus, the purpose of this research project was to determine the influence of gadolinium additions on the microstructure and mechanical properties of mild steel and 316 stainless steel. Ten alloys were produced for the purposes of this research. Five of the alloys had a base composition of mild steel while the remaining five had base composition of 316 stainless steel. The alloys for each of the base composition contained gadolinium additions of 0.1, 0.5, 1.2, and 5 weight per cent. The as-cast and the cold-rolled alloys were analysed. The alloys responded well to the cold-rolling with the exception of the 5 weight per cent gadolinium mild steel and stainless steel alloys. These alloys were extremely brittle and underwent a significant amount of cracking during the cold rolling process. A microstructural analysis of the alloys was conducted using a light optical microscope, while the chemical analysis of the alloys was conducted using energy dispersive x-ray spectroscopy (EDS). The resulting microstructures and EDS analyses revealed that the gadolinium displayed minimal solubility in the ferrite matrix of the mild steel alloys and minimal solubility in the austenite matrix of the stainless steel alloys. Instead the gadolinium formed as an interdendritic secondary phase in both alloys. EDS analysis revealed that the secondary phase in both alloys was gadolinium-rich. Vickers microhardness tests conducted on both alloys revealed that the alloys were composite-like, with a hard, brittle gadolinium-containing compound dispersed throughout a softer, more ductile matrix. The corrosion resistance of the alloys was determined through potentiodynamic anodic polarization tests. Two solutions were used for the corrosion rate tests: a 0.5 weight per cent NaC1 solution and a 0.5 M H2SO4 solution. The results from the mild steel alloys revealed that in both the solutions, the corrosion potentials and the corrosion resistance of the alloys increased with increasing gadolinium concentration up to 1 weight per cent. The corrosion rate test results from the stainless steel alloys revealed that the passivation current density and corrosion resistance of the alloys increased with increasing gadolinium concentration in both solutions. The oxidation resistances of the mild steel and stainless steel alloys were determined through the use of a Netzstch Simultaneous Thermal Analyser. For both the mild steel and the stainless steel alloys, it was found that the oxidation resistance of the alloys increased as the concentration of gadolinium increased when compared to the as-received mild steel and stainless steel samples. This could be due to a strongly adhering gadolinium oxide scale that formed on the surface of the alloys and resulted in the protection of the mild steel and the stainless steel.

Jan 1, 2012

By H. W. Glen

The National Institute for Metallurgy - usually referred to as NIM - has become the Council for Mineral Technology, or Mintek. The Honourable F. W. de Klerk, Minister of Mineral and Energy Affairs, announced the change of name at the official opening of the main entrance to Mintek's premises on 30th October, 1981. Awards for bravery Two men who disregarded the dangers of fiercely burning timber and falling rocks to douse an underground fire, using their hard hats to scoop water from a drain, received the Chamber of Mines Award for bravery at a ceremony held at West Driefontein Gold Mine near the end of October.

Jan 1, 1981

By W. K. Brisden

The SAG Milling Seminar, which was held at Murdoch University in Perth on 30th November and 1st December, 1989, was a very successful technical seminar. Organizer Dr Norm Stockton reported a total attendance of 130, which was higher than the 70 expected: 20 delegates came from the eastern States and the remainder were from Western Australia.

Jan 1, 1990

1. Journals Quarterly Journal of tke International Tin Research Institute, edited by Colin J. Evans and published by the Institute, Fraser Road, Greenford, Middlesex UB6, 7AQ, England. Engineering, building and construction law review, edited by P. C. Loots and published every two months by Construction Law Review (pty) Ltd (P.O. Box 78020, Sandton 2146, Transvaal), R63,00 per year. 2. Publications of the Mineral Policy Sector Nepkeline syenite and feldspar by B. W. Boyd Potask by G. S. Barry Selenium and tellurium by D. A. Cranstone Sodium sulphate by G. S. Barry Tungsten byG. G. Law-West 3. Mintek reports Report M114 Analytical methods associated with the recovery of uran~um. Report M117 An assessment of tke merits of various types of balls in tke milling of ores. Report MU1 Tke determinatl:on of trace elements in coal by atomic

Jan 1, 1983

By Nelson Sánchez

The Los Bronces Development Project (LBDP) was approved in October 2007 by the Anglo American plc Board at a capital cost of some US$1.74B, and is scheduled to be completed by the end of 2010. The project represents a big step forward for the Los Bronces mine since it will increase the treatment rate by 140%, the mining rate by 64% and almost double copper production during the first four years of the project. This economy of scale will also position Los Bronces as a much bigger and efficient mining operation, better prepared to face adverse market scenarios and allowing Anglo to consolidate its position in base metals. The project addressed numerous scope alternatives such as plant capacity vs mine capacity, cut-off grade strategy to maximise value based on the existing flotation and leaching process, cutback strategy, etc. Main infrastructure aspects of the project are as follows: ?Dump area with 2400Mt capacity for waste and low grade material ?Mining equipment: 1 x electric shovel, 12 x 300t trucks, 1 x drill ?Primary crusher: 60? x 89? ?Three new power lines (144MW capacity) ?Grinding plant at 87kt/day nominal capacity (includes a 4.3km tunnel with a regenerative conveyor belt) ?Grinding plant: 1 SAG mill 40? x 25?, 2 ball mills ?Slurry pipeline (52 km from grinding to flotation plant) with five choke stations ?Flotation plant (rougher, cleaning, regrinding circuits and molybdenum flotation). The history of Los Bronces started in 1867 when it was discovered. In 1978 ENAMI (Government company) sold Los Bronces to Exxon for US$112M. The same year a snow avalanche destroyed San Francisco Flotation Plant. In 1979 the plant was rebuilt at 4.9kt/day and from 1979 to 2002 several plant expansions were made up to 54kt/day capacity. In 2002 Anglo acquired Los Bronces for US$1.3B. The 2002 resource and reserve statement showed reserves at 459Mt at 1.02%CuT and resources at 780Mt at 0.80%CuT. The 2007 statement shows reserves at 1,480Mt at 0.67%CuT and resources at 1,644Mt at 0.45%CuT. Defining the size of a plant expansion is the key challenge that any expansionary project faces. The scope of this paper is a general review of the project, describing all the mining techniques that were used to define the best options that maximise value. In this context, a range of plant capacities (from 58 to 230kt/day) combined with a range of mining capacities (from 83 to 166Mt/a) were evaluated in detail, defining for each option a mine plan, Capex and Opex, and cut-off grade strategy for flotation and leaching processes and the associated Net Present Value (NPV) that was used as the selection criteria. The Los Bronces mineral resources potential provides good growth opportunities for the mine beyond LBDP implementation, offering an exciting invitation to continue studying new initiatives that maximise the value of this deposit.

Jan 1, 2008

1. TRAINING IN ENGINEERING WORK FOR ENGINEERS IN TRAINING 1.1 Registration as engineer in training An engineering graduate who has passed an examination recognised by the Council1 is eligible for registration as an engineer in training in terms of the Professional Engineers' Act2. Application forms can be obtained from the Registrar.

Jan 1, 1979

By HORNICKA OSTRAVA

The Czechoslovak Scientific-Technical Institute has arranged the international conference 'Hornicka Ostrava' for four or five days at the end of October, 1969, as part of the preparation for the international 'Miners' Congress' on deep coalextraction in 1970. The keynote of the conference is 'New Techniques in coal mining,' and will be covered by five groups dealing mainly with: 1. New trends in the opening of mines, optimal parameters, projections, equipment, utilization of computers for economic analyses, etc. 2. Increase in efficiency of coal extraction in deep mines, technology, concentration, pressure control, optimization of material and coal transport. 3. Modernization of devices for increased safety and working conditions, new trends in explosives, new techniques for reducing environmental diseases. 4. Innovations in deep level coal extraction, mechanization, rationalization, automation, etc. 5. Other topics about modern techniques in mining. Address your enquiries to: Ing. Karel Kalas (Secretary of the Conference), Dum Techniky Cs YTS, Ostrava 1, Jesenkiho 7-9, Czechoslovakia.

A method is proposed for the evaluation of the influence of grout prestressing systems on the support resistance offered by timber packs. It is shown that, in order not to reduce the load-carrying capacity of timber packs, grout prestressing systems need to be at least as stiff as a single timber rise. The method was used to establish strength specifications for the grout prestressing systems to be used under non-seismic and seismic conditions. For non-seismic requirements, the 24-hour grout strength needs to be at least 1,7 MPa, and the 7-day grout strength 4,9 MPa. The investigation showed that the proposed strength specification is realistic in the light of current grout-strength capabilities. For seismic requirements, the grout strength needs to be at least 4 MPa and 8 MPa to prevent extensive damage to the grout during seismic events with a peak velocity of 1m/s 3 m/s respectively.

Jan 1, 1996

By J. H. Bulloch

A short review is given of the effects of corrosion fatigue on the materials used in pressurized water-reactor vessels. Selected topics such as testing procedures, test data, and mechanisms in simulated environments are discussed. The main fact that emerges is that most of the data on the growth of fatigue cracks reside below the ASME X1 1980 High-R 'Wet' design-code lines, Le. they fall within that specification. Finally, some recent advances in the understanding of the corrosion-fatigue behaviour of such materials in pressurized water reactors are highlighted.

Jan 1, 1987

1. Books on management The following are available from Knowledge Resources, P.O. Box 3954, Randburg 2125. . Competitive advantage of nations, by Professor Michael Porter from Harvard Business School. This book highlights the importance of industries in contributing towards national competitiveness. It is being regarded as one of the 10 best business books published during 1990. . The borderless world, by Kenichi Ohmae, Managing Director of McKinsey in Japan. This deals with business in the new interlinked economy. . Megatrends 2000, by John Naisbitt and Patricia Aburdene. This book outlines the mega/macro trends that will

Jan 1, 1991