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By S. E. Olsen, T. Færden, G. Tranell, T. Lindstad, J. Lubetsky

The authors are lead authors for chapter 4.3 ?Emissions from Ferroalloy Production? in ?2006 IPCC Guide-lines for National Greenhouse Gas Inventories, Volume 3?. The paper discusses the methods to calculate and report emissions from the production of ferrosilicon, silicon-metal, ferromanganese, silicomanganese and ferrochromium alloys, as well as the basis for the methods and choice of emission factors. CO2 is the main greenhouse gas emission from ferroalloy production, accounting for about 95 % of the total CO2-equivalents. The most accurate method of determining emissions is to base the calculations on reported amounts and analyses of reducing agents and carbonate ores used in the process. If analyses are not available, typical CO2 emission factors for the different reducing agents are recommended. If neither reliable amounts nor analyses of all reducing agents are known, default generic CO2 emission factors for the type of ferroalloy multiplied with amount produced, can be used. The CO2 produced from bio-carbon (charcoal and wood chips) should be reported but will not be accounted for in national emissions. If any bio-carbon is used, the default generic CO2 emission factors cannot be applied. CH4 accounts for less than 1 % of the total emission of CO2-equivalents. Default emissions factors for CH4 are given for the production in open or semi-closed furnaces of silicon-metal and ferrosilicon. In the production of FeMn, SiMn and FeCr in closed furnaces the gas containing CO,CO2 and volatiles can be combusted in boilers and N2O may be formed. While reporting is not required, IPCC Guidelines recommend that the N2O-content in the off-gas is measured.

Jan 1, 2007

By M. Dhainaut

This paper presents computations of the electric field inside a furnace. We first look at the effect of contact between two coke particles from an electrical point of view. We give values for the amount of contact resistance in the total resistance of the system formed by the two coke particles. We show that the effect of contact resistance decreases rapidly with increasing contact area. We then look at the complete electric field inside a full scale furnace. The aim is to evaluate the amount of current that short-cuts the metal bath for different vertical positions of the electrodes. We show that electrodes high above the metal bath are undesirable since they offer a larger surface of conductive charge materials where current can flow through. On the other hand, deeper electrodes force the current to go the whole way down to the metal bath. Ohmic heating along this path ensures a high temperature of coke and slag that are beneficial for metal recovery.

Jan 1, 2004

Bacterial leaching represents an unusual problem in biochemical engineering, because the substrate for bacterial growth is not supplied directly, but is a product of another reaction, the leaching of mineral particles. Leaching arises from the bacterial oxidation of ferrous ions to ferric ions, which in turn oxidize the mineral. For the bacterial dissolution of pyrite, these reactions are: [ ] (Y represents a stoichiometric yield factor, and N represents the amount of bacteria.) Equations [1] and [2] represent a cyclic auto-catalytic system since more ferric ions are added to the system with an increase in the extent of leaching.

Jan 1, 2000

By R. Thomason

Thank you Dr Barcza, President of the South African Institute of Mining and Metallurgy, for inviting me to share our experiences in Australia as regards the competency movement and my Association?s experience in assisting engineers become managers. This is my second visit to South Africa, and I am struck by the similarities between our countries. This extends to the professional issues associated with engineering and competencies in particular. I propose to outline two exciting stories today. ? Development of competency standards for professional engineers in Australia. ? Development of a management programme which has assisted professional engineers regain positions of leadership in Australian industry and government. First of all I would like to outline the Association of Professional Engineers, Scientists and Managers, Australia(APESMA).

Jan 1, 1997

By D. François-Bongarçon

When it comes to sampling theory, a bad sampler is a bad sampler, no matter what, and a sampler is either bad or good. It also is of critical economic importance to tell and understand the difference, especially in a metallurgical plant. In this paper, the grand principles of Sampling Theory are first recalled, then the most popular types of sample cutters for plants are critically reviewed. It is concluded that the industry has a lot of progresses to make in that direction, although improvements usually pay for themselves very quickly.

Jan 1, 2002

By R. L. Lawson

I?ve been asked to appraise the global role of coal and mining, and the best place I can think of to begin is with the World watch Institute, which purports to monitor all things global. Last fall the institute?s magazine, entitled World Watch, in a cover story called for a worldwide campaign to outlaw the use of coal before this century?s end. To my mind the article began the campaign. However, the institute had to admit that no such ban will be possible unless there is special help and heavy intervention?that is, novel policies and punitive taxes. I?ll quote directly from the magazine to underscore the point: ?without them the market will continue to deceive us into thinking coal is cheap, abundant and irreplaceable?.

Jan 1, 2001

The 102nd Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Gold Room, Transvaal Automobile Club, 60 5th Street, Lower Houghton, Johannesburg on Wednesday, 18th August, 1999. Obituaries The President announced the death, during the year, of the following members: Honorary Life Fellows and Past Presidents D.D. Howat Life Fellows O. Deane, J.S. van Zijl Fellow A.A. Hejja Retired Fellows A.L. Forder, C.B. Parker, A.C. Petersen, F.W.J. Ross Members J.S. Stanko, D.H. Gray Retired Member P.K. Bredell Retired Associate I.S. van Eyssen In memory of the deceased and in sympathy with the bereaved, all rose and observed a moment of silence.

Jan 1, 1999

By R. E. Robinson

A novel variation of the GYPCIX process for the treatment of the acid mine effluent water from Grootvlei is described, in which a number of valuable by products can be obtained and the product water can be used for a variety of different purposes. A conceptual case study is presented in which the important cost parameters are described and certain critical path activities are indicated in order to derive a Return on Investment evaluation according to methods previously published. The study indicates that the treatment costs can be dramatically reduced, provided that proper utilization of the by products is taken into account. There are many possible uses for the water. However, by far the most advantageous contribution to the RDP and the best return on capital is derived if the water is used to establish small-lot farming activities providing work opportunities for thousands of people and contributing several hundred million Rands to the GDP. Vastly improved social conditions will be generated in an area of Gauteng that is in danger of rapid deterioration and a contribution will be made to maintaining mining activities in this area. The environmental impact is positive.

Jan 1, 1998

By D. W. Dew

Billiton Process Research has carried out extensive research over the past four years to develop new process technology using bioleaching for extraction of copper and nickel from their sulphide concentrates. Continuous pilot scale and laboratory batch testwork has been carried out with adapted mesophile bacterial cultures at40°C?45°C, moderate thermophile cultures at 50°C?55°C and thermophile cultures at 65°C?85°C. Pilot scale work has demonstrated the commercial viability of mesophile cultures for bioleaching of secondary copper sulphide and nickel sulphide concentrates. Moderate thermophiles offer benefits in terms of reduced cooling requirements for commercial reactors and, in the case of bioleaching of nickel concentrates, some selectivity over bioleaching of pyrite. Continuous pilot scale testwork has shown that thermophiles achieve efficient bioleaching of primary copper sulphide and nickel sulphide concentrates, giving much higher recoveries than achieved by bioleaching with a mesophile or moderate thermophile culture.

Jan 1, 2000

By J. G. Wiese

Reagents are added to the flotation process of Merensky Reef ores to achieve specific functions that enable the separation of valuable minerals from gangue minerals on the basis of the difference in their surface properties. However, due to the complexity of the process, the various interactions that occur as well as the incomplete liberation of the ore and range of minerals present, it is difficult to quantify the behaviour of each of the reagents. More specifically, changes made to achieve a particular outcome may have secondary effects that can override the desired effect. If all the effects and interactions can be accounted for, it is possible to manipulate reagent suites and obtain better overall metallurgical performance. This paper discusses the effect of the addition of copper sulphate at different operating points of the recovery of the sulphide minerals. Batch flotation tests indicated that the recovery of chalcopyrite was not affected when operating conditions were varied, whereas pentlandite recovery was strongly affected by the point of reagent addition, and pyrrhotite recovery was enhanced by copper sulphate addition, irrespective of the point of addition, with the extent being dependent on the ore source. Floatable gangue was activated by copper sulphate in the presence of the dithiophosphate collector. Froth stability was also affected by copper sulphate addition.

Jan 1, 2006

By T. J. Goff, G. M. Denton

Mintek has developed the EnviroplasTM process for the treatment of solid wastes from the metallurgical industry, especially steel plant dusts, without requiring agglomeration to produce inert slag and at the same time recover metal values such as nickel, chromium and zinc. The products that are generated in the plasma-arc process are usually a metal and a non-toxic slag, which are tapped from the furnace in liquid form. The metal is mainly composed of chromium, nickel and manganese. During the production of stainless steel between 30 and 70 kg of dust and fine waste is generated per ton of steel. Mintek has successfully processed around 1000t of AOD/EAF dust on a toll treatment basis in order to recover the contained Cr and Ni. The metal produced contained 18.5 per cent Cr, and 5.5 per cent Ni. All slag samples tested conformed to US EPA regulations for disposal. The chromium and nickel recovery to metal was 90 and 98 per cent respectively, on a once through basis i.e. no baghouse dust recycle. Slag tapping temperatures varied between 1650°C and 1750°C. The average actual energy requirement excluding furnace heatlosses of smelting steel plant dust with anthracite as reductant was 1.36MWh/ ton of dust. The total mass of feed reporting to the off-gas stream was 10 per cent. The average ZnO content of the fume was 35.5 per cent.

Jan 1, 2004

Council for 1999/2000 President M.H. Rogers President Elect Dr L.A. Cramer Vice Presidents Senior A.A.B. Douglas Immediate Past President J.R. Dixon Junior S.J. Ramokgopa Honorary Treasurer J.A. Cruise

Jan 1, 2000

The excavation of ramps and tunnels often requires high-speed development with (or without) the use of high-energy mining equipment such as loaders, dump trucks, TBMs and roadheaders. This high-speed development creates a challenge in terms of providing a safe and productive working environment. For example, heat from continuously exposed surrounding rock, heat from broken rock, heat generated by mining equipment, potential in flows of hot ground water, pollution from associated diesel equipment and the distance of the advancing face from fresh through-ventilation all have to be taken into account when designing ventilation systems for high-speed ramp and tunnel developments. This paper discusses methods of achieving acceptable environments at the face and along the length of the tunnel. The methodology has been successfully implemented in the development of long (up to 20 km) TBM drives in the Lesotho Highlands Project and in mining projects in hot rock using drill and blast methods as well as mechanized methods using continuous miners and roadheaders. The determination of heat loads includes calculation of the heat flow within the surrounding rock, evaluation of the operating cycle of the equipment and the contribution to the overall heat load of the broken rock as it travels out of the tunnel. The determination of heat loads from surrounding rock in new tunnels required a modification of the algorithms generally used for established excavations. The paper also examines the use of, for example, mobile duct and fan systems to ensure that fresh air is delivered to the specific areas where workers are located.

Jan 1, 2000

By A. L. Edwards

A two-year study focused on current noise exposure levels in the South African mining industry, aimed at helping the Mine Health and Safety Council of South Africa meet its milestones for eliminating noise-induced hearing loss (NIHL). Methods A multi-task methodology was adapted from international baseline studies to determine the exposure to noise in both large-scale and small- to medium-scale mines. Results On average, 66.7 per cent of the employees sampled in year 1 and 78.4 per cent in year 2 were exposed to noise levels of above the 85 dB A legislated occupational exposure level. Conclusions Information obtained through the study could be developed into a national personal noise exposure database, including audiometric results, equipment noise emission levels and initiatives for noise engineering control by mines and equipment manufacturers to facilitate targets of eliminating NIHL. Keywords Noise exposure levels, mining industry, noise-induced hearing loss

Jan 1, 2011

Direct reduced iron (DRI), produced by the reaction between iron ore and reducing gasses, is used as a source of low-residual iron, in addition to ferrous scrap and pig iron, in the production of steel mainly through the electric arc furnace (EAF) route of steelmaking. The main DRI technologies in use are those of Midrex and Hyl, but in recent years a myriad of newer processes emerged based on variations in feedstock, reducing agent and fuel sources. Since the beginning of the nineties, DRI has increasingly emerged as a cheaper, low-residual iron feedstock for EAFs, which have traditionally relied almost entirely on ferrous scrap feed. The main stimulus behind the interest in DRI has been the increasing popularity of the EAF and the ?mini-mill? set-up as the favoured steelmaking option compared to the traditional and much less flexible blast furnace/ basic oxygen converter. This, however, has been creating a problem with regard to availability of low-residual scrap, resulting in upward pressure on high quality scrap prices and leaving DRI, traditionally the ?expensive alternative?, as a much more competitive consideration. The second main determinant has been the increasing production efficiency of existing steel plants which, in the light of improvements such as continuous casting and near net shape casting, has been constraining the supply of low-residual domestic scrap, traditionally the prime source of EAF feed. The explosion of current and proposed DRI projects has been accentuating the mounting interest of global role-players in assuring the availability of reliable sources of low-residual iron units for the future, especially in cases where definitive competitive advantages exist with regard to proximity to primary sources of iron ore and fuel (gas or coal).

Jan 1, 1999

By R. P. H. Willis

For technology transfer to be successful a process, from research to full scale application, has to be followed. This paper describes such a process and how it is applied in practice. Some of the ?do?s? and ?don?ts? are highlighted. Recommendations are made on how to communicate existing knowledge and to ensure that a framework exists to effectively plan future projects with final technology transfer objectives firmly in place. The Impact Ripper System is used as a case study to illustrate lessons learned. Key words: Technology transfer, implementation

Jan 1, 2002

The modern theory of sampling of particulate minerals essentially consists of a recent generalization of the procedures for applying and calibrating the formula usually known as ?Gy?s Formula? for sampling variance control, in which the central concept is a parameter called the liberation factor l. A model which can be experimentally adjusted was proposed by one of the authors several years ago, based on geostatistical considerations. This new model, which relates the liberation factor to the sizes of the fragments and mineral grains, solves the usual difficulties faced in the past, and permits predictions that are well verified in practice. Unfortunately, an older, arbitrary and less general formula is still widely used. The vast majority of today?s misapplications of Sampling Theory of Particulate Materials can be traced back to the use of this antiquated and generally incorrect model. Following a brief history of the models used for the liberation factor and a description of its main variable, the liberation size, and to illustrate the importance of proper modelling of l, this paper presents demonstrative calculations of the absurdity of the incorrect model using the particular case of gold mineralization as an example, followed by some more positive examples of application.

Jan 1, 2002

By Peter W. Lotz

Contents of: ?Sampling for Cyanide in Metallurgical Processes? ?Sampling at process level of operation ?Sampling at environmental level ?Sample stability and integrity issues ?each citing possible objectives, practical example and reasons for surprises Overall recommendations on sampling plans and procedures to maintain sample integrity

Jan 1, 2005

By G. Broadbent

It is an honour to be invited as a speaker to this ICCR conference and a pleasure to be with you here in South Africa. I have been asked to talk about the competitiveness of coal versus other energy alternatives. Coal supplies nearly one-quarter of the global primary energy. Its most direct competitors are gas, nuclear and renewables. Oil is predominantly for transport fuels. Fuel oil is competitive with coal when crude is below its long-run average price and has some niche opportunities. But I will confine my comments to nuclear, renewables and particularly natural gas as the most potent current competitive threat to coal. Competitiveness is more than just cost and price; there is environmental acceptability, security or reliability and increasingly image. These factors are more of a spectrum than discrete issues. Dollars and cents remain the key issue for competitiveness but one must recognize the impact of politics in sustainable development and energy security.

Jan 1, 2001

The validity of a steady state assumption made by Adams and Nicol (1986) in the modelling of the elution of gold from activated carbon was investigated. It is shown that the accuracy of the steady state approximation is dependent, not only on the magnitudes of the solution flow rate and reactor volume, but also on the lumped elution rate constant. Under the experimental conditions used by Adams and Nicol (1986) the steady state assumption was inaccurate. This could be circumvented in this instance by applying a rigorous general model which accounts for unsteady state behaviour in the solution and in the activated carbon to the experimental data.

Jan 1, 1997