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The peak in Sulphur price late 2008 caused again intensified investigation into the decomposition of sulphates and spend acid. One option is the recycling of sulphur from spend acid, which already started more than 40 years ago in the field of spend acid from organic processes in refineries and acrylic glass manufacturing. Since this acid couldn't be neutralized and discarded due to high organic contents, another source of SO2 to produce sulfuric acid is the decomposition of metal sulfates. The decomposition of metal sulfates was investigated at the next peak in Sulphur price in the 80?s. The first major scale pilot tests and studies of gypsum decomposition were carried out for clients in Florida. The decomposition of gypsum was quite often mainly influenced by the strategic decision of some countries to get own and independent acid production. In other cases the industry doesn?t have enough space to dump the gypsum. Therefore the company was also forced to convert the gypsum into ?saleable? products to avoid these residues. Other projects were made for the recycling of iron-sulfates from the pigment industry. The motivations for these projects were not only given by acid price. For the German pigment industry it was no longer permitted in the 80?s to dump the iron sulphate residues into the sea. These regulations forced the industry to develop new technology, which allows converting of the FeSO4-residues into iron oxide and acid. Therefore economical and mainly environmental factors influenced the decision of the companies to develop and to build these plants. Beside the above mention iron- and calcium-sulphates many other process exist, which produce metal sulphates as an intermediate product. These cases are not forced by environmental or strategic factors. In cases like Ni, Co or Mn-decomposition the main product of the plant is treated in the decomposition plant and later on used as ferrous-alloys. These final products are higher in price compared to e.g. CaO, which exclude the high-energy consumption for the endothermic chemical decomposition reaction. The reaction of SO2 generation based on acid or sulfate decomposition takes place in the range of 1000°C. The energy demand of the endothermic reaction is considerable and leads due to the high fuel-combustion off-gas stream to a diluted SO2 gas. Energy prices are usually increasing at the same time like sulphur. Sulphuric Acid based on decomposition is therefore more expensive than as acid based on sulphur combustion. The paper describes fluid bed technology and possible process concepts for decomposition plants. Additionally the thermodynamic background of the decomposition process and the main influence factors are provided to receive a better understanding of this technology.

Jan 1, 2009

The peak in Sulphur price late 2008 caused again intensified investigation into the decomposition of sulphates and spend acid. One option is the recycling of sulphur from spend acid, which already started more than 40 years ago in the field of spend acid from organic processes in refineries and acrylic glass manufacturing. Since this acid couldn't be neutralized and discarded due to high organic contents, another source of SO2 to produce sulfuric acid is the decomposition of metal sulfates. The decomposition of metal sulfates was investigated at the next peak in Sulphur price in the 80?s. The first major scale pilot tests and studies of gypsum decomposition were carried out for clients in Florida. The decomposition of gypsum was quite often mainly influenced by the strategic decision of some countries to get own and independent acid production. In other cases the industry doesn?t have enough space to dump the gypsum. Therefore the company was also forced to convert the gypsum into ?saleable? products to avoid these residues. Other projects were made for the recycling of iron-sulfates from the pigment industry. The motivations for these projects were not only given by acid price. For the German pigment industry it was no longer permitted in the 80?s to dump the iron sulphate residues into the sea. These regulations forced the industry to develop new technology, which allows converting of the FeSO4-residues into iron oxide and acid. Therefore economical and mainly environmental factors influenced the decision of the companies to develop and to build these plants. Beside the above mention iron- and calcium-sulphates many other process exist, which produce metal sulphates as an intermediate product. These cases are not forced by environmental or strategic factors. In cases like Ni, Co or Mn-decomposition the main product of the plant is treated in the decomposition plant and later on used as ferrous-alloys. These final products are higher in price compared to e.g. CaO, which exclude the high-energy consumption for the endothermic chemical decomposition reaction. The reaction of SO2 generation based on acid or sulfate decomposition takes place in the range of 1000°C. The energy demand of the endothermic reaction is considerable and leads due to the high fuel-combustion off-gas stream to a diluted SO2 gas. Energy prices are usually increasing at the same time like sulphur. Sulphuric Acid based on decomposition is therefore more expensive than as acid based on sulphur combustion. The paper describes fluid bed technology and possible process concepts for decomposition plants. Additionally the thermodynamic background of the decomposition process and the main influence factors are provided to receive a better understanding of this technology.

Jan 1, 2009

By H. H. McGregor

Introductory remarks by author When Mr R. C. J. Goode suggested preparation of a paper in the area of manpower utilization in South Africa, I was, while keen to accept his invitation, somewhat hesitant for two reasons. Firstly, I recognized the great difficulty of making a factual contribution, because of the lack of really relevant statistical information available, the fact that much of it is out of date, and the difficulty of researching and co-ordinating it and of evaluating a statistically sound resultant viewpoint. Experience in the actual preparation of this paper has done nothing to change my view in this respect. Secondly, it is obvious that a paper presented to a meeting of this Institute, by a member of it, would be expected to devote considerable attention to the subject in the mining industry. I am not directly employed by the mining industry, although my company has carried out extensive assignments for various sectors of it both in this country and in other parts of the world, since the 1939-45 war. I am more conscious than most of the tremendous technical and managerial skills at the disposal of the industry in this country, and consequently am equally conscious of the hazards of publishing facts and figures which might be taken to indicate any criticism of performance. I am aware that some of the information that I am about to present may indeed generate comment, and possibly even critical comment. I would like to be regarded therefore in presenting this information, as a member of the group, rather than an external critic. Under these circumstances, comment can only be constructive, and this is my earnest hope. The contribution of my paper, if contribution there is, will I hope be in the area of assessing labour productivity in mining, and in secondary industry in such a way that the performance of each against its own past results is comparable. This task has not for the present been to my knowledge attempted, and in advance I wish to take out authors' insurance against legitimate criticism from professional economists and others, by stating that I am well aware of possible short-comings in the arguments. Nevertheless I believe that under the circumstances I have, with the important assistance of several people, been able to take the subject further than has been the case in the past. Finally, I have related productivity in the mining industry and in secondary industry to a target of productivity in the Republic of South Africa. I was fortunate recently in being able to attend a series of lectures by a prominent economist in America. He introduced his subject by calling it 'A broad survey of macro-economics'. Perhaps I might be permitted to describe my paper, in the same idiom, as 'The macro-management of labour'.

Jan 6, 1970

By A. Bain

The use of plastics in the coal mining industry is making slow progress whereas these materials could make a greater contribution to safety, to a reduction of working costs and to the higher productivity of mine workers. Possibly the reluctance to experiment with the new material of our age is due to the low profit margin of coal mining. This note has been prepared to present a brief survey of what has been done in the last few years and to mention some of the investigations the author has made and is making in an attempt to develop more use of plastics in the industry. Some of the plastics used on the mines have taken their place in the industry in the same manner that they are used in everyday life while others have been introduced because there has been a need for them. New uses and applications are being developed and these are the ones that are most interesting. The plastic that is specially developed to give the maximum benefit and not the one that is a modification of some other everyday product is the next development in the field. Many manufacturers are keen to promote such investigation but are not aware of the problems the mines wish to solve and therefore it is only through management itself that this development can be carried out. This note deals with plastic material under three headings: (a) Plastic as the superior material, and briefly describes how plastic has replaced a few major items which are better when made from plastic. (b) Plastics of necessity, being a short summary of how plastics had to be introduced because of laws and conditions making it a necessity. (c) Development of new ideas, being briefly some of the ideas being developed overseas and some of the ideas being tried by the author. Plastic items in common use such as in housing, electric cables, laboratory equipment, awnings, nylon bearings, locomotive brake linings, etc. being well known are not discussed. PLASTIC AS THE SUPERIOR MATERIAL Plastic belting underground Following a fire in a belt road in England resulting in the deaths of many workers, and subsequently a fire accompanied by fatalities in a belt road in a mine in this country, a law was introduced which states that only flameproof belting is to be used underground. This ruling forced the mines to use P.V.A. belting as no other was available. This belting has non-inflammable characteristics that are superior to rubber. Due to the high tension on long-distance belts used today the need for stronger belting material called for something better than cotton and the answer to this was nylon. Nylon also has the ability to withstand dry-rot which reduces the life of a belt very quickly.

By N. A. Barcza

This paper describes the development of large-scale thermal-plasma systems, which was motivated, in general, by the potential cost savings that could be achieved by their use as a replacement for the more conventional methods used in the generation of thermal energy. The anticipated cost savings arise not only from the use of plasma-generating devices but from the manner in which they have been interfaced with a furnace to process particular materials, mostly as fines. Thermal-plasma systems fall into two categories: non-transferred-arc and transferred-arc devices. In general, transferred-arc devices have been interfaced with open-bath furnaces in which melting or smelting processes carried out, while non-transferred-arc devices have normally been applied to shaft furnaces. Water-cooled transferred-arc devices are somewhat limited in power (about 5 MW) because of the relatively voltages (300 to 500 V) that can be attained in open-bath furnaces, where very long arcs are undesirable, and because only relatively low levels of current can be carried. Graphite electrodes can overcome the restriction current, and power levels of 30 to 50 MW seem feasible, even with one electrode, if direct current is used. Multiple water-cooled devices are capable of attaining similar power levels, but the capital costs are much higher. Costs due to electrode wear are lower for water-cooled systems, but expensive gases are needed for transferred-arc devices. Mintek conducted extensive pilot-plant work in which water-cooled devices were used initially but graphite electrodes were used subsequently to produce ferochromium from fines. Transferred-arc open-bath configurations were used. This work led to a decision by Middelburg Steel & Alloys (MS&A) to install a 16 MVA furnace of semindustrial scale to produce ferochromium aloys based on the ASEA d.c. arc furnace developed for the Elred process. Non-transferred-arc devices have atained reasonable scale-up to the 6 to8 MW power level, and high-voltage operation, which is inherent in such devices, has enabled lower currents to be used. Nevertheless, multiple systems are still necessary to accommodate large-scale applications, and this can be costly from a capital point of view. The cooling requirements are large, and can represent a considerable loss of electric energy. Shaft furnaces equipped with non-transferred-arc devices are suitable for the processing of materials that have volatile species, e.g. silica or manganese, or where the shaft is used to prereduce oxides that are amenable to gas-solid reactions. It is probably in the treatment of light and refractory metals that plasma technology will achieve its greatest development in the years to come. The energy requirements for the production of these metals are high, and very low oxygen potentials are necessary. These are factors that favour thermal plasma. Much developmental work is still needed in this interesting field. It should be remembered that electrically generated thermal energy is a unique temperature source that, in many instances, cannot be replaced technically or economically by the combustion of a fuel.

Jan 1, 1986

"Chairman: Dr DeV. HarrisRapporteur: Mr A.H. MunroPapers:Corporate exploration strategies by MacKenzie, B.W.The Engel Simulator and the search for uranium by Griffiths, J.C. and Singer, D.A.The Chairman opened the session by tracing the changes which have taken place in the exploration field since the days of the lone prospector who relied upon his individual skills and to a large extent on luck. The deposits which now remain to be discovered are better covered and are of lower grade. A much greater team effort, involving geoscientists and engineers, is required. The gamble is thus much greater -not only are the probabilities of failure still significant but the consequences are more severe. A recent Canadian survey indicated that expenditures of between two and nine million dollars on regional exploration programs are required to locate one significant deposit.The Chairman went on to say that these facts have led companies to regard exploration as another form of investment and to treat it accordingly. This had placed exploration in the context of corporate strategics and structures, which was the subject of the first paper of the session.In introducing his paper, Dr B. W. MacKenzie said that the paper suggested a decision framework for exploration planning. Initially the environment is analyzed to define observable and relevant economic characteristics. The terms of reference for exploration planning and the appropriate allocation of capital and skills are then established in the light of corporate objectives and growth alternatives. With the aid of this information and in the light of profit and corporate risk criteria, exploration strategies can be selected.Dr MacKenzie went on to say that the usefulness of the concept and criteria outlined in his paper depended critically upon three characteristics of any particular economic environment, namely, the return resulting from an economic discovery, the unit discovery Cost and the probability of making an economic discovery. He then showed by means of a case history relative to the Canadian Shield and Cordilleran areas that these three characteristics could, in fact, be evaluated for regions with reasonable histories of mineral activity.The first contributor to the discussion of the paper, Mr Alfred Weiss, mentioned that his group had been involved in exploration modelling for some ten years and were thus particularly interested in the paper. He went on to say that they had experienced greatest difficulty with reconnaissance programs and that he sensed that these difficulties were also present with the methodology which had been outlined. Mr Weiss asked Dr MacKenzie how he would deal with such situations when no information was available but where there was the potential for both exploration and discovery. Dr Mackenzie agreed that the lack of information was a very severe limitation and said that at the present time his methodology probably did not provide a basis for breaking down the broad geological regions he considered into areas for further assessment."

Jan 1, 2014

By P. R. Jochens, D. D. Howat, C. W. Wolhuter

Prof D. D. Howat (Member): I am a man with a grievance this afternoon. The other authors of the paper entered into a conspiracy to ensure that I presented the paper, and finally even had the audacity to say that this was the least that could be expected from me as I had done so little of the other work. Looking at the distinguished audience here that includes some figures who have forgotten more about cement that some of us have ever learned, I realise how right the other authors were. I feel very much cast in the role of the fool who was pushed in where angels fear to tread. I hesitate to say, Sir, that I would not use the word angels in any definition of the authors of this paper. In presenting the paper, may I try to put forward a few simple points about cement that are probably as little known to the majority of the audience as they were to me-at least until very recently. Concrete, made by mixing Portland cement, sand, crushed rock and water is the most widely used constructional material in the world. Generally the production of actual Portland Cement is about two-thirds that of steel and by the time this is formed into concrete the total is about five times the world tonnage of steel produced. A very rough approximation suggests that world consumption of concrete is about one ton per person per annum. Apart from fresh water mankind consumes no other material in such quantities. What mankind originally required was a mortar to be used for joining blocks of stone or bricks. Such mortar was originally made from limestone burned in a kiln and then mixed with water. Production of mortar of this type began over 5,000 years ago. Some samples from pyramids in Egypt have shown this mortar to be in good condition although over 4,500 years old. The progress of technological development was very slow until 1824 when an English bricklayer, Joseph Aspidin, patented a new mortar material which he made by burning limestone and clay together in his kitchen stove. Aspdin called his product 'Portland Cement' because, in colour, it resembled a well-known building stone quarried in the Isle of Portland on the south coast of England. Aspid's same types of raw materials are used today in modern cement production and the product is still referred to as Portland cement. A lime-containing material such as chalk or shell and a clay-type material such as shale, slate or clay itself, are mixed in the required proportions, ground and fed to a kiln where the minimum burning temperature is about 1,500°C. The raw materials react to form hard chunks of a material known as 'clinker'. About 5 per cent of gypsum is added to the clinker and the mixture is then ground to a very fine powder, the function of the gypsum being to control the rate of setting of the concrete. The key oxides in cement production are lime, silica, alumina and iron oxide. The possible reactions occurring during and the products of the burning process are shown in Table I.

Jan 12, 1968

"Chairman: Professor E. P. PFLEIDER Rapporteur: Mr P. R. JANISCHPapers:Optimum design of an open pit by D. A. PhillipsAn open pit design system for stratiform ore bodies by L. A. J. Pronk van Hoogeveen, J. R. Cutland and M. WeirAn open pit design model by R. H. Robinson and N. B. PrennThe Chairman in opening the session highlighted the current situation in the United States of America where some 85 to 90 per cent of all mining (except for coal) is done by open pit methods, and where some 40 per cent of the coal is mined by open pit. The South African industry is, of course, dominated by the deeper level underground gold mines; however, with the aid of an extensive open-pit technology developed in other countries, South African companies arc continuing to explore possibilities of open-pit exploitation of base mineral, coal and diamond deposits. Several successful ventures are already in operation at Phalabora, Optimum Colliery, Kimberley and elsewhere, and South Africa is undoubtedly benefitting in this regard by drawing on the experience of others.The papers of this session were therefore particularly pertinent, particularly when viewed in conjunction with those presented at an earlier South African conference devoted specifically to open pit mining.Two themes dominated the discussion which followed presentation of the three papers at this session. The first related to the practicability of using the reported techniques as a tool for management, and their acceptability as such to mine management. This was, of course, not peculiar to this particular session, but rather the major point of debate over the entire conference.The second theme concerned the reliability of the initial drill hole data on which any open-pit design must necessarily be based. This gave added emphasis to the problem of practicability, for no management is likely to accept an elaborate pit design unless confidence can be placed in the ore reserve assessment.In noting these two features of the discussion, it should be remembered that all the three papers dealt largely with design and pre-planning; there was an unfortunate lack of papers or discussion on the subject of controlling the day-to-day mining of open pits, and this is an area where the potential impact which can be made by the computer is even greater.In introducing his paper, Mr D. A. Phillips pointed out that it was concerned only with optimization, and that it therefore assumed, firstly, an adequate subdivision of the orebody into ore blocks characterized by grade, rock type, structure, etc., and, secondly, an acceptable forecast of costs and mineral prices in order to generate a suitable profit matrix. However, programs dealing with these problems for both massive, disseminated and stratiform ore bodies are available to Roan Consolidated Mines. The method of optimization which he had described had been used on a region split into 28 000 blocks, for which the program used three hours of C.P.U. time on an IBM 360/40 computer. The computer design had provided a three per cent improve¬ment on a normal design of the same area."

Jan 1, 2014

"Chairman: Professor H. S. SICHEL Rapporteur: Miss M. I. WATSONPapers:Unrolling of Copperbelt orebodies by J. H. E. Perry and V. H. WiikAn exploration model for tabular orebodies by G. S. Koch and R. F. LinkHarmonic analysis of copper and gold occurrences in the Arbitibi area of the Canadian Shield by F. P. Agterberg and A. G. FabbriMathematical models of orebodies by M. J. Newton and A. G. Royle Estimation of lateritic-type orebodies by A. JournelIn his presentation Mr Wiik said that unrolling could be regarded as a reversal of the natural process of folding, so that the aim of an unrolling procedure would be the reconstruction of original pre-tectonic conditions. While simply formulated, this aim might not always be achieved. The geometrical relationship between points on the deformed surface and corresponding points on the original surface is process-dependent, and a true reconstruction could be achieved only if the deformation history were known in detail.In this computer unrolling procedure all these complexities were ignored. Referring to one particular marker horizon, Mr Wiik said that it was assumed in the procedure that this marker was deposited as a horizontal stratum and that it had subsequently been deformed by simple flexure-type folding.The procedure allowed the geologist to incorporate his knowledge and conception of the deposit through repeated re-contouring with dummy points. This 'manumatic' aspect of the procedure had proved invaluable, not only in resolving specific unrolling problems but also in making the system more acceptable to the geologists in general.Unrolling served towards removing what might be termed `tectonic noise' superimposed on the primary distribution patterns for regionalized variables such as metal content and orebody thickness. From this point of view, variograms derived on the basis of unrolled-plan co-ordinates should be more meaningful in terms of depositional environment than are variograms calculated from a normal map projection.Mr M. M. Oosterveld remarked that it appeared from the paper that there were problems in applying the unrolling technique to ore reserve calculation, and asked whether there were not other methods that might be used for that purpose.Mr Wiik replied that at present unrolling played only a minor role in practical ore reserve estimation within Roan Consolidated Mines, Limited. The techniques currently in use differed from one orebody to another, but in general they involved projection onto a vertical longitudinal section or a horizontal plan, with subsequent grid interpolation by means of a standard computer contouring package."

Jan 1, 2014

By T. P. Letsebe, L. Magwaza, T. A. Sethu, S. M. Rupprecht

"The authors were tasked with introducing safe and efficient drilling and blasting practices to a small artisanal mine located in the Eastern Province of Rwanda. The current mining methods employed at the mine are inefficient as rockbreaking is conducted utilizing hammer and chisel, or by drilling and blasting with no understanding of the rockbreaking process. The paper discusses the drill and blast cycle, as well as the associated activities necessary to support the mining cycle. The challenges and critical aspects in implementing drill and blast activities are discussed, as well as some of the technical aspects, i.e.drilling pattern, initiation and timing of the blast, and handling of misfires. Ancillary issues such as ventilation, training, communication, effective planning, logistics, and human relations are also examined. IntroductionRockbreaking accounts for 60% of the direct mining costs in small-scale mining. When drilling and blasting practices are poorly implemented the process becomes inefficient and dangerous. The introduction of a proven drill and blast system to artisanal mining offers a number of challenges, with safety being considered the backbone of any sustainable operation and a standard that cannot be compromised.The paper is based on a project at an artisanal cassiterite (tin) mining operation in a small village in the Kayonza District in the Eastern Province of Rwanda. A drill and blast programme utilizing industry best practice was introduced at an underground development end; a raise developed at an inclination of 23 degrees. The underground working is accessed via a 17 degree incline shaft with an operating length of 105 m and serviced by a single drum winder. The winder operates at a speed of about 3.5 m/min hoisting two 1 t wagons from the bottom of the incline to surface for tipping (Figure 1)."

Jan 1, 2017

R. C. J. Goode (President): South Africa is known for its sunshine and mineral deposits-especially its gold and its diamonds-and as this year marks the 75th Anniversary of the establishment of the South African Institute of Mining and Metallurgy, it is appropriate that I say a few words about mining and metallurgy and the part this industry and our Institute has played in the life of this country. Africa, as the Dark Continent, with its fascinating tales of Prester John, Ophir, Queen of Sheba and its myths and legends has throughout the ages fired the public imagination. Pharaoh Necho, 600 years before the birth of Christ, sent an expedition from Egypt around the Cape to probe this strange land. The gold for King Solomon's throne was said to come from Monomotapa-the country now known as Rhodesia. Centuries later the Arabs and Portuguese searched for this mineral wealth. The Arabs found little gold but unfortunately established a lucrative trade in black slaves. Now let us take a brief look into the closing stages of the Stone Age when the indigenous population of the lower portion of this continent consisted of the Bushmen, a nomadic hunting people who knew no metals and kept no stock, and the Hottentots who were a pastoral folk with cattle and sheep. Then somewhere about the 11th century the Bantu started their long migration southwards and brought with them the knowledge of smelting of iron ore. One of their settlements was here in Johannesburg on the Melville Kopje at Emmarentia. These people were the first miners and metallurgists on the Witwatersrand and the beautifully preserved iron smelting furnace constructed nearly 1,000 years ago is a tribute to their technical ability. This ability to use iron to make better spears for hunting or to fashion hoes for cultivating the soil led to their establishment as a superior tribe. The earlier Bushmen were pushed back to the inhospitable swamps and deserts and the Hottentots fled to the south. The Bantu also knew the art of copper smelting. In the days of the Dutch East India Company, at the end of the seventeenth century, Bantu workers brought copper from the north-west Cape to Simon van der Stel, but it was another two hundred years before the white man turned this to advantage. Stories of the Bantu mining gold spurred the early European hunters to travel deeper into the heart of Africa in search of wealth, and we are told that Karel Kruger, in 1834 whilst leading an ivory hunting expedition, discovered gold on the Witwatersrand, and took samples to Cape Town; but when he returned with a larger expedition a few years later his party was attacked by Moselekatze's Matabele near Potchefstroom. Kruger was killed and only the legend survived. The real spur to mining in this country was the discovery of diamonds in Griqualand West in 1867. The field seemed fabulously rich and diggers flocked to the scene from the four corners of the earth. With them came Cecil Rhodes, Barnato, Beit and some of the finest mining and financial brains the country had yet seen. These giant entrepreneurs were not tempted by the small deposits of gold in the Barberton and Pilgrim's Rest areas when these were made a few years later but

By W. J. Jordaan

The ability of soils to retain and hold cations is called the cation exchange capacity (CEC). Adsorbed cations, however, can be replaced by other cations through the process of cation exchange. Heavy mineral deposits contain a significant portion of slimes including the very fine clay minerals. In most circuits the slimes fraction hampers efficiency and has to be removed during early stages of the process. Being a nonvaluable process stream, the processing of the slimes is a costly exercise. In thickening applications it might be possible to manipulate the ability of clay minerals to retain and hold positively charged cations in order to optimize flocculation and therefore reduce flocculation costs. The CEC value of the slimes could be a measure of this possibility. To investigate this hypothesis, different slimes samples were characterized for size, chemical composition and clay minerals present. The CEC value of each sample was determined and explained in terms of the mineral phases present. Settling tests were conducted and an attempt was made to explain the CEC characteristics of the clay minerals in terms of settling rate. The scope of this investigation was to test the hypothesis and should not be seen as an in-depth study of the subject matter. A greater number of samples and detailed analyses to identify and quantify minerals and phases present would be required to investigate further the relationships between clay minerals in the deposit, CEC and settling rates. Location and geological setting Exxaro KZN Sands is mining a heavy minerals deposit at Hillendale mine located at Richards Bay, South Africa. The orebody consist of a dune some 8 km inland from the coast to the north of eSikhawini. A geological synopsis undertaken by Botha1 concluded that the Hillendale mining area represents a coastal dune sequence that accumulated north of the Tugela River. The northward movement of sediment by long shore drift currents result in a high sand budget on the beaches north of the river youth and is the dominant contributing factor to the accretion of the coastline and development of parallel dune systems along the coastal zone in this area. Beach swash zone processes and enrichment of the fine sand fraction occurs during wind transport off the beach by ascending parabolic dunes that form the coastal barrier dunes. This process results in heavy mineral concentration on the windward dune face and localized enrichment parallel to the dune forms. The aeolian sedimentary facies processes result in the primary concentration of higher grades in the upper silt-enriched reddish brown horizons of the profile. The synopsis by Botha1 further showed that an additional component of heavy mineral concentration can be ascribed to the post-depositional relative enrichment of heavy minerals due to weathering. Therefore, it is likely that the Hillendale orebody protolith was pedogenically weathered to form the homogeneous, silt-enriched, clayey reddish brown to dark red, palaeosol profile that grades downwards into yellowish brown, less clay-enriched sand. Slimes characterization Samples The Hillendale orebody was divided into geochemically discretized zones based on the concentration of ilmenite and other specific minerals and/or phases. Six composite samples were made up from exploration samples taken from Zone 9, Zone 11 and Zone 12. The red and orange horizons within these composite samples were separated and test samples were prepared to conduct test work and analyses. The test samples were submitted for preparation and analysis to characterize the slimes properties. Each test sample was deslimed at 45 µm representing the slimes fraction (-45 µm) and dried at 40°C. The -45 µm slimes samples were then split to conduct size analysis, chemical analysis, XRD and to determine the CEC. Size analysis The size distribution of the composite samples is shown in Table I. The size analysis shows that there is a difference in size distribution between the orange and red horizons of each zone. The orange horizons contain less 850 µ material as well as less slimes (-45 µm). The red horizons contain yore slimes (-45 µm). The size distribution of the slimes fraction (-45 µm) was determined using Malvern size analysis. The cumulative particle size distribution of the slimes is shown in Figure 1. The red horizons of the different zones show similar size distributions. The orange horizons show some differences. However, there is a difference in size distributions between the red and orange horizons.

Jan 1, 2007

The Annual General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 30th August, 1972. Professor D. D. Howat (President) was in the chair. There were also present sixty-two Fellows, twenty-four Members, two Associates, three Students and eighteen Visitors, making a total of one hundred and nine. The President declared the meeting open at 4.05 p.m. OBITUARIES The President: It is my sad duty to announce the death of six members of this Institute. The first of these is Dr A. J. Orenstein, Honorary Life Fellow, who joined the Institute in 1916 and died on Seventh July. Dr Orenstein became almost a legendary figure in Medicine as a result of his work in the control and elimination of malaria during the digging of the Panama Canal and I believe he was actually engaged working until four days before his death. The other members who have died are: F. Meyer, died on 8th June; S. D. Loxton, Fellow, died on 13th May; J. Innes, Fellow, died on l0th January, 1970; O. B. Prentis, a Member, died on 4th June, and J. Brits, Associate, died on 27th June. As a mark of respect to the memory of the deceased and in sympathy with the bereaved may I ask you to rise and observe a few moments silence. MINUTES The President: 'The second item on the Agenda, the minutes of the meetings held on March 22nd and May 10th, 1972, as tabled. May I confirm these minutes'? Agreed. WELCOME TO VISITORS 'On behalf of the Council, may I say how delighted we are to have such a splendid gathering with us on this our Annual General Meeting. Dames en here vir die omvang van my Afrikaanse woordeskat verdien ek weinig lof, boonop is dit nog Afrikaans met 'n Skotse aksent, wat u asseblief moet verskoon. Tog wil ek se hoe dankbaar ons is dat sy Edele, die Minister van Mynwese, dr Koornhof en mev Koornhof vandag hier teenwoordig kan wees. In addition to our own newly appointed Minister of Mines, we are also honoured by the presence of the Minister of Mines of Rhodesia, Mr I. B. Dillon. I think not even our oldest members can recall an occasion on which two Ministers of Mines were present at a meeting of the Institute. It is a particular pleasure to welcome them this afternoon. I am happy to say that Minister Koornhof is an Honorary-Vice President of the Institute, and Minister Dillon is an Honorary Member. The presence of your goodselves, gentlemen, with us this afternoon, I am sure underlines the great significance which we believe both countries attach to the economic exploitation of the vast mineral resources of Southern Africa. For over 70 years, this Institute and its members have been making their contribution to this great task of mineral exploitation, and we feel that your presence with us today, is a token of the confidence of your governments in what this Institute and its members have been endeavouring to do. Also present with us today, is Mr R. C. J. Goode, President of the Chamber of Mines, and Honorary President of this Institute. I was going to say I welcome Mr Goode, but it is rather difficult to welcome a man to his own home, and this is the case with Mr Goode. He is a very distinguished and a very recent past president of this Institute and he remains now, as he has been for as long as I can remember, one of our most active and valuable members. This I think, ladies and gentlemen, is the second rather unique feature of this occasion this afternoon, because no one else can recollect an occasion on which the President of the Chamber of Mines was also a past president and an active member of our Institute. A special word of welcome, Mr Goode. Mr Tommy Gibbs, our Government Mining Engineer, is in a somewhat similar position as he is also a member and an old and valued friend of our Institute, - welcome to you, Mr Gibbs. Mention I think, must be made of the fact that we are very glad to have with us Dr A. J. A. Roux, President of the Atomic Energy Board, and Mr Stanley Craib, President of the Associated Scientific and Technical Societies. Then, within the great family of the A.S. and T.S., we have the presidents, or the vice-presidents of I believe 13 of the constituent societies. These gentlemen, like all the rest of us, have the rather tiring task of supporting and upholding their fellow presidents on occasions such as this. We particularly appreciate their presence this afternoon and the effort they have made to be with us. We are happy to have with us: Dr R. E. Robinson, Director-General, National Institute of Metallurgy, Mr E. Boden, Manager, Associated Scientific and Technical Societies, Dr H. G. Denkhaus, President, The S.A. Institute of Mechanical Engineers, Mr G. Goedhals, Vice-President, S.A. Institute of Electrical Engineers, Mr E. Dalton, President" S.A. Institute of Certificated

By D. D. Howat

In the field of high temperature smelting processes there have been two dramatic changes in the past twenty years. These are, first, the application of tonnage oxygen for direct injection for the refining of molten iron and other metals and to provide the means of enriching air used for the combustion of fuel. Second, the application of electric power for the generation of high temperatures in place of the combustion of fossil fuels. Of these two developments the application of tonnage oxygen for the refining of molten iron has virtually revolutionised the steel industry throughout the world. The magnitude of this development is exemplified by the fact that less than 5 per cent of the world's steel production in 1960 was made by this process or 16 million tons out of a total of 350 million tons of steel produced, while in 1970 over 40 per cent of the world steel production was made by this process, ie, 251 million tons out of 628 million tons total. In the same period the proportion of steel produced by the old-established open-hearth process has shrunk from 75 per cent to 38 per cent. In the whole history of the development of high temperature metallurgical smelting processes there has never been anything remotely approaching this. The other development, the application of electric power for the generation of high temperatures has not had the impact of the oxygen injection process but I believe that what we should call the electric smelting revolution in metallurgical processes has very far-reaching ramifications for steel production and other pyrometallurgical processes. This may seem a bold and brash statement but it must be remembered that the oxygen injection process constitutes a link in the chain critically dependent upon the production of vast tonnages of molten iron from very large modern blast furnaces. The Achilles heel of this chain of processes, upon which such a large percentage of the world's supply of steel depends, is the availability of metallurgical coke in turn dependent on natural resources of coking coal. Without any exception each industrial country in the world faces a shortage of resources of coking coal and in some cases a critical shortage. Certainly within the present century the major iron and steel producing countries of the world will face this critical shortage of coking coal and major modifications to steel making processes will become inevitable. W. F. Cartwright (Deputy Chairman of B.S.C) said recently that there are considerable doubts as to whether the world will be able to provide enough coking coal to meet world steel demands from the late 1970's onwards if the B.F.remains the main means for making iron from ore. This is one of the supreme ironies of the world metallurgical situation to-day when the technology of iron and steel production has reached an extremely high peak of technical efficiency. The newest modern iron blast furnace capable of producing 6 000 to 8 000 tons per day of molten iron represents probably the most efficient piece of high temperature metallurgical plant and operation known to man. The conversion of this molten iron into steel by the oxygen injection process has made available to the engineering industry steel of a quality and at a price which is quite remarkable. Yet this vast metallurgical pyramid rests on the completely insecure and uncertain foundation of inadequate world resources of coking coal. The shortage of reserves of coking coal in this country is acute and it is possible that these resources will be exhausted within the next twenty years. Yet unless some completely unexpected catastrophe occurs the demand for steel in this country will probably rise at a faster rate than in the Western world due to the expansion of the Bantu population and the increased standard of living. To offset the inevitable shortage of coking coal are our much greater resources of bituminous coal which although of low grade provide a suitable fuel for electric power generation. The geographical disposition of the coal fields in relation to the great industrial areas of the Transvaal makes it inevitable that the development of the pyrometallurgical industries must depend heavily on electric power. The position in this country with regard to electrical power generation and consumption is rather anomalous. Per capita consumption of electric power is high - in 1964 almost twice the world average of 870 KWH and twenty-five times the average of 34 KWH for the Continent of Africa. In 1964 fifty-four per cent of the total world electric power was used in industry - the ratio being approximately 1/9 mining to manufacturing uses. As shown in Table I in 1969 67.2 per cent of the total output of electric power from ESCOM was used for mining and other industrial uses but almost in the ratio 6/4 mining to industrial uses. These figures emphasise the enormous importance of the mining industry to the economy of this country and underline the major contribution made by the gold mining industry. What is of very significant importance is that although the mining industry remains by far the largest single consumer of electrical power the consumption of power for industrial uses is rising rapidly as shown in Table II.

The following notes have been compiled to assist authors in the preparation of papers for presentation to the Institute and for publication in the Journal. STANDARDS FOR ACCEPTANCE To merit consideration papers should be of sufficient high standard and contain matter that is new, interpretations that are novel or of new significance and conclusions that cast a fresh light on old ideas. Their publication should be of real interest to technical men and of benefit to mining and industry. Authors must realize that because a mine shaft is new or the mine itself is newly established, this in itself does not justify a paper unless significantly new techniques or processes were involved in the opening-up procedure. A few well selected diagrams and illustrations are often more pertinent than an amorphous mass of less well chosen material. Over-statement and dogmatism are jarring and have no place in technical writing. The amount of textbook material included in a contribution should be the minimum essential to the argument. The length of a paper is not the criterion of its worth and it should be as brief and concise as possible, consistent with the lucid presentation of the subject. Avoid the use of the first person, be objective and do not include irrelevant or extraneous matter. Papers should be submitted at least three months prior to the intended date of presentation. The text should be typewritten, double-spaced, on one side only of foolscap paper, leaving a left-hand margin of 11-inches, and should be submitted in duplicate to facilitate the work of the referees and editors. Galley proofs are sent to the authors for the correction of printers' errors and not for the purpose of making alterations and additions which may be expensive. Should an author make alterations which are considered excessive, he may be required to pay for them. ORTHODOX SEQUENCE Title and author's name together with author's degrees, titles and position Summary, abstract or synopsis Introduction Development of the main substance Conclusions References. Title: This should be as brief as possible, yet give a good idea of the subject and character of the paper. Style: Writing should conform to certain prescribed standards. The Institute is guided in its requirements by: Collins, F. H. Authors' & Printers' Dictionary-Oxford University Press. Hart, H. Rulesfor Compositors and Readers. Humphrey Milford (familiarily known as the Oxford Rules). Fowler, H. W. & F. G. The King's English-Oxford University Press. Generally: Avoid unnecessary use of capitals and hyphens, while punctuation should be used sparingly and be governed by the needs of sense and diction. Sentences should be short, uninvolved and unamiguous. Paragraphs should also be short and serve to separate basic ideas into compact groups. Quotation marks should be of the 'single' type for quotations and "double" for quoted matter within quotations. Interpretations in the text should be marked off by parenthesis ( ), whereas brackets [ ] are employed to enclose explanatory matter in the text. Words to be printed in italics should be underlined singly. For small capitals they are to be underlined DOUBLY and for large capitals TREBLY. Abbreviations and symbols are laid down in British Standard 1991 and proof correction symbols in British Standard 1219C. Abbreviations are the same for the singular and plural, e.g. ft for foot and feet, lb for pound and pounds. Percentages are written in the text as per cent; the symbol % is restricted to tables. Likewise ft and in. should be used, x' y" only being permissible in diagrams and plans. Drawings and diagrams are to be in black India ink and should be about 6 in. wide. Numbering of tables should be in Roman numerals: I, II, etc. and figures in Arabic numerals: Fig. 1, Fig. 2, etc. Photographs should be black and white glossy prints. As a guide to the printer the author should indicate by means of notes in the margin of the typescript where drawings and diagrams, etc. are to appear in the text. When submitting graphical representations avoid a fine grid if possible. Curves should be in heavy line to stand out. Lettering too should be bold as a reduction in size is often involved in the printing process. SUMMARY ABSTRACT OR SYNOPSIS It is most important that the summary should provide a clear outline of the contents of the paper, the results obtained and the author's conclusions. It should be written concisely and in normal rather than abbreviated English and should not exceed 250 words. While the emphasis is on brevity this should not be laboured to the extent of leaving out important matter or impairing intelligibility. Summaries simplify the task of abstractors and therefore should present a balanced and complete picture. It is preferable to use standard rather than proprietary terms. FOOTNOTESAND REFERENCES Footnotes should be resorted to only when they are indispensable. In the typescript they should appear immediately below the line to which they refer and not at the foot of the page. References should be indicated by super-script, thus . . .1 . . . 2. Do not use the word Bibliography. When authors cite publications of other societies or technical and trade journals, titles should be abbreviated in accordance with the standards adopted by this Journal.

The following notes have been compiled to assist authors in the preparation of papers for presentation to the Institute and for publication in the Journal. STANDARDS FOR ACCEPTANCE To merit consideration papers should be of sufficient high standard and contain matter that is new, interpretations that are novel or of new significance and conclusions that cast a fresh light on old ideas. Their publication should be of real interest to technical men and of benefit to mining and industry. Authors must realize that because a mine shaft is new or the mine itself is newly established, this in itself does not justify a paper unless significantly new techniques or processes were involved in the opening-up procedure. A few well selected diagrams and illustrations are often more pertinent than an amorphous mass of less well chosen material. Over-statement and dogmatism are jarring and have no place in technical writing. The amount of textbook material included in a contribution should be the minimum essential to the argument. The length of a paper is not the criterion of its worth and it should be as brief and concise as possible, consistent with the lucid presentation of the subject. Avoid the use of the first person, be objective and do not include irrelevant or extraneous matter. Papers should be submitted at least three months prior to the intended date of presentation. The text should be typewritten, double-spaced, on one side only of foolscap paper, leaving a left-hand margin of 11/2 inches, and should be submitted in duplicate to facilitate the work of the referees and editors. Galley proofs are sent to the authors for the correction of printers' errors and not for the purpose of making alterations and additions which may be expensive. Should an author make alterations which are considered excessive, he may be required to pay for them. ORTHODOX SEQUENCE Title and author's name together with author's degrees, titles and position Summary, abstract or synopsis Introduction Development of the main substance Conclusions References. Title: This should be as brief as possible, yet give a good idea of the subject and character of the paper. Style: Writing should conform to certain prescribed standards. The Institute is guided in its requirements by: Collins, F. H. Authors' & Printers' Dictionary-Oxford University Press. Hart, H. Rules for Compositors and Readers. Humphrey Milford (familiarily known as the Oxford Rules). Fowler, H. W. & F. G. The King's English-Oxford University Press. Generally: Avoid unnecessary use of capitals and hyphens, while punctuation should be used sparingly and be governed by the needs of sense and diction. Sentences should be short, uninvolved and unamiguous. Paragraphs should also be short and serve to separate basic ideas into compact groups. Quotation marks should be of the 'single' type for quotations and "double" for quoted matter within quotations. Interpretations in the text should be marked off by parenthesis ( ), whereas brackets [ ] are employed to enclose explanatory matter in the text. Words to be printed in italics should be underlined singly. For small capitals they are to be underlined DOUBLY and for large capitals TREBLY. Abbreviations and symbols are laid down in British Standard 1991 and proof correction symbols in British Standard 1219c. Abbreviations are the same for the singular and plural, e.g. ft for foot and feet, lb for pound and pounds. Percentages are written in the text as per cent; the symbol % is restricted to tables. Likewise ft and in. should be used, x' y" only being permissible in diagrams and plans. Drawings and diagrams are to be in black India ink and should be about 6 in. wide. Numbering of tables should be in Roman numerals: 1, 11, etc. and figures in Arabic numerals: Fig. 1, Fig. 2, etc. Photographs should be black and white glossy prints. As a guide to the printer the author should indicate by means of notes in the margin of the typescript where drawings and diagrams, etc. are to appear in the text. When submitting graphical representations avoid a fine grid if possible. Curves should be in heavy line to stand out. Lettering too should be bold as a reduction in size is often involved in the printing process. SUMMARY ABSTRACT OR SYNOPSIS It is most important that the summary should provide a clear outline of the contents of the paper, the results obtained and the author's conclusions. It should be written concisely and in normal rather than abbreviated English and should not exceed 250 words. While the emphasis is on brevity this should not be laboured to the extent of leaving out important matter or impairing intelligibility. Summaries simplify the task of abstractors and therefore should present a balanced and complete picture. It is preferable to use standard rather than proprietary terms. FOOTNOTES AND REFERENCES Footnotes should be resorted to only when they are indispensable. In the typescript they should appear immediately below the line to which they refer and not at the foot of the page. References should be indicated by super-script, thus . . .1 . . . 2. Do not use the word Bibliography. When authors cite publications of other societies or technical and trade journals, titles should be abbreviated in accordance with the standards adopted by this Journal.

By N. Mangesana

The effect of high solids concentration and coarse particle sizes (d50 ranges 90?300 µm) on the viscosity of a suspension of water and silica sand was investigated. The experiments were designed to include conditions that have been tested by other authors and those encountered in the operation of tumbling mills. The rheological data was measured using a tube rheometer with operating pseudo shear rates of up to 1500 s-1. The rheograms obtained depicted dilatant behaviour. The Otswald-de Waele, Bingham, Herschel-Buckley and Casson models were fitted to the experimental data. The Herschel-Buckely model, which approximates the yield point and gives an indication of the shear thinning or shear thickening behaviour of the suspension, was found to provide the best description of the flow curves for all slurries. The Herschel-Buckely model was then used to determine the apparent viscosity of all the tests. The apparent viscosity and yield stress increased with solids concentration and particle size at the different pseudo shear rates. The increase in slurry viscosity with solids concentration was attributed to increased frequency of particle-particle interactions. The increase in slurry viscosity with particle size was attributed to increased inertial effects. At low shear rates the sand slurry exhibited shear thinning behaviour for all solids concentrations. At higher shear rates above 1000 s-1the high solids concentration suspensions exhibited a transition from shear thinning to a shear thickening behaviour.

Jan 1, 2008

The successful commissioning of the Cerro Verde project in Peru at the end of 2006 marked the culmination of the efforts of many in the industry over many years to have high pressure grinding roll technology recognized and accepted as a legitimate alternative to the conventional approach to large-scale hard rock comminution circuit design. Other hard-rock projects that have recently adopted HPGR include Freeport (Indonesia), Boddington (Australia) and Amplats Potgietersrus (South Africa). With the increasing acceptance of this technology, the need for technical presentations and articles exhorting the industry to adapt has diminished somewhat, and it is considered appropriate now to shift the emphasis to the provision of information for those considering embracing change. This article endeavours to answer frequently asked questions on the subject of high pressure grinding roll technology, with particular reference to its application in the hard rock minerals processing sector.

Jan 1, 2010

A wide range of drill holes and process streams are sampled for resource estimation, grade control and contractual purposes in the minerals industry. However, despite the availability of training courses, conferences and both national and international standards on correct sampling practices, it is still surprising how often little attention is given to ensuring that representative samples are collected for analysis. The reason for this is that the responsibility for sampling is often entrusted to personnel who do not appreciate the significance and importance of sampling, with cost being the main driving force rather than whether the sample is representative of the material from which it was extracted. This seriously undermines the precision and accuracy of the analyses subsequently generated and can render the analysis process a total waste of time and money and expose mining companies to serious, potential, financial losses. Company management needs to reverse this situation and ensure that sampling is given the attention it deserves to generate representative samples for analysis.

Jan 1, 2009

By L. Thomson

"The smelter at Sudbury Integrated Nickel Operations, located in Sudbury, Ontario, operates a single electric AC furnace. This furnace treats nickel sulphide concentrates produced by Glencore and third-party feeds and as such its performance is key to the company’s nickel supply chain. Currently the plant has two shutdowns per year in order to carry out significant repairs on matte tap-holes.Improved monitoring systems that enable better prediction of tap-hole wear have been a continued focus. The electric furnace is an essential piece of the smelter flow sheet requiring the need for planned tap-hole maintenance along with robust systems for management according to to this plan.The ability to meet our goal of zero harm is ensuring that safe practices are in place. Detailed procedures and cool-down practices have been implemented to ensure that required matte chemistry and temperature criteria can be met during the period leading into a shutdown for tapblock maintenance.A significant repair of the electric furnace will take place in 2015. During this rebuild, the sidewalls and matte endwall will be replaced. There is work underway to improve wall and matte end performance in an attempt to extend the time between rebuilds. This paper will review the approach taken towards this end."

Jan 1, 2014