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By B. W. Lee, P. O?Shaughnessy

The practice of manganese ferroalloy smelting has traditionally been based on utilising oxide ores which typically contain a high level of manganese. This preference for oxides has even been extended to the modification of natural carbonates into nodulized oxides. However smelting practices developed over the past 30 years have created a market for natural manganese carbonate ores, driven in part by the unique properties that this type of ore can offer. An understanding of the mineralogy of carbonate ore and its thermal properties has provided important information which enables furnace operators to take full advantage of the chemical differences. However changes to traditional operating practices have been necessary. Once furnace operations using natural and unmodified carbonate ore have been mastered, the unique chemical features of manganese carbonate ore are able to contribute, not only to new product development, but also to cost savings. The use of natural manganese carbonate ore is now a well-established aspect of the industry. The sustained increase in demand for carbonate ore worldwide over the past several years confirms acceptance of its quality. There are effectively few limits to its successful use.

Jan 1, 2004

By I. Jones

Geologists, engineers, technicians and surveyors have successfully utilized technical software in the mining industry for over 30 years. Software for processing survey, geology, mine engineering and planning information make these functions more efficient by automating repetitive tasks and reducing data processing errors. While these systems have been improved incrementally overtime, new systems that represent giant leaps in technology have been introduced to help mining operations increase productivity and reduce costs. However, their widespread use within the industry has left individual companies without a competitive advantage. Additionally, the ability of these applications to provide the productivity improvements required in today’s uncertain market conditions has since peaked. The next wave of technology—integration of independent software applications—is just starting to emerge and will have a significant effect on the productivity of mining operations. To reap the productivity gains required to remain competitive, mining companies must exploit the collective knowledge and experience of every employee in the organization. Integration of independent software application allows companies to leverage information from all activities, enabling staff to make better decisions to improve productivity. This paper outlines the importance of integration as productivity enabler. Key performance indicators, strategic mine planning, resources management and mine-to-mill integration are discussed as processes that enable productivity. The Gemcom Enterprise Mining System (GEMS)is introduced as the industry’s first integrated solution that enables these productive processes. The paper concludes with a comment on the level of change required to realize the benefits of integration.

Jan 1, 2003

By M. du Toit

Cromanite?is a new high-strength austenitic stainless steel developed by Columbus Stainless. It contains approximately 19 percent chromium, 10 per cent manganese and 0,5 per cent nitrogen. Cromanite can be welded successfully, but due to the high nitrogen content of the base metal, certain precautions have to be taken to ensure sound welds with the desired combination of properties. Although no matching filler metals are currently available, Cromanite can be welded using a range of commercially available stainless steel welding consumables. Welds produced using E309L, E307, E307Si and E312 filler wires are resistant to hot cracking and the formation of nitrogen-induced porosity, but the hardness, strength, ductility and toughness of the welds are generally inferior to those of the base metal. In applications where full use is made of Cromanite?s high strength, welds with matching strength levels would be required. In wear applications, where Cromanite is used primarily for its work-hardening properties and corrosion resistance, lower strength welds would probably be acceptable. Welds produced using E307 filler metal demonstrate the best combination of properties for use in wear applications. The welds display high rates of work-hardening that would result in increases in hardness and strength when subjected to abrasive or high impact environments.

Jan 1, 1999

By I. Gil, J. -C. Roegiers

Abstract Hydraulic fracturing is a technology that has been utilized for more than 50 years in the oil industry. It was originally used for stimulating hard, brittle formations which typically exhibit low permeabilities and roughly linear elastic behavior. Nonetheless, an increasingly important segment of the industry is currently stimulating very soft and poorly consolidated formations; where the assumptions of ideal elasticity and relatively small fluid leakoff fail to hold (e.g. Gulf of Mexico, West Africa, Alaska, East China). In these rocks, hydraulic fracturing stimulation has been used for several years to control and solve critical production problems such as sanding and formation damage (caused during completion and drilling operations). Although successful1, the application of this method has not been accompanied by robust fracturing modeling techniques. In addition, long term production increases were often not materialized. In other words, engineers have been able, via trial-and-error, to avoid major ‘operational’ problems but with no optimization of such treatments. Thus, most hydraulic fracturing projects carried out in poorly consolidated rocks render unexpected results. A recent worldwide survey on net pressures by the Delft Fracturing Consortium (Papanastasiou, 1997) indicated that net pressures encountered in the field are 50% to 100% higher than the net pressures predicted by conventional fracturing simulators. The difference is yet higher for the case of poorly consolidated formations (Pak, 1997). The theory for the construction of a fully coupled elastoplastic three-dimensional hydrofrac simulator, specifically conceived for unconsolidated rocks, is presented in this paper. This novel model calculates the dimensions and changes in shape of the fracture(s) being created during hydraulic fracturing operations. No assumptions are made regarding either shape or geometry of the crack(s). Three main failure criteria are used simultaneously in this model: tensile and shear stresses, and volumetric strain. Incremental forms of the governing equations of equilibrium and fluid flow are presented. The scheme chosen for solving this problem is the finite elements method, which allows both equations to be solved simultaneously at any instant in time. Résumé La fracturation hydraulique est une technologie qu’a été utilisé pour plus que 50 ans dans l'industrie pétrolière. Elle a été utilisée au début pour stimuler les formations dure et fragile que typiquement ont des perméabilités basses et un comportement élastique à peu près linéaire. Néanmoins, un segment plus important de l'industrie stimule actuellement des formations mal consolidées; où les suppositions d'élasticité idéale et de relativement petite fuite de fluide ne se tiennent pas raison (par exemple le Golfe de Mexique, l'Afrique d'ouest, Alaska, la Chine de l'est). Dans ces roches, la stimulation avec fracturation hydraulique a été utilisée pour plusieurs années pour contrôler et résoudre les problèmes critiques de production comme les dommages de formation et d’ensablement (causé pendant les opérations de l'accomplissement et forage). Bien que prospère, l'application de cette méthode n'a pas été accompagnée de techniques robustes pour le modelage de fractures. En outre, les augmentations à long terme de production n'ont pas été souvent concrétisées. En d'autre termes, les ingénieurs ont pu, via le procès et l’erreur, éviter les majeur problèmes ‘opérationnel’ mais avec aucune optimisation de tels traitements. Ainsi, la plupart des projets de fracturation hydraulique ont été exécuté dans des roches mal consolidées et ont rendu résultat totalement inattendu. Une récente étude mondiale sur les pressions nettes par le Consortium Delft pour Fracturer (Papanastasiou, 1997) a indiqué que les pressions nettes qu’ont été rencontré dans le champ sont environ 50% à 100% plus hautes que les pressions nettes prédites par les simulateurs fracturant conventionnels. La différence est pourtant plus importante pour le cas de formations mal consolidées (Pak, 1997). La théorie de construction d'un simulateur elastoplastic d’hydrofrac à trois dimensions entièrement couplé, en particulier conçu pour les roches non consolidés, est présentée dans ce papier. Ce nouveau modèle calcule les dimensions et les changements dans la forme de(s) fracture(s) étant créé pendant les opérations de fracturation hydraulique. Aucune supposition n’a été faites en ce que concernant la forme ou la géométrie

Jan 1, 2003

By W. J. Errington

The Isasmelt process was developed at Mount Isa Mines Limited in Queensland, Australia in collaboration with CSIRO, the Australian Government research organisation. Originally developed for primary lead smelting, culminating in the construction of a 60,000 tonnes per annum lead smelter at Mount Isa, this technology now also provides a major part of the current 200,000 tonnes per annum copper smelting capacity at Mount Isa. A programme is now in place to expand copper production to 250,000 tonnes per annum. The technology has also been applied to secondary lead smelting at Britannia Refined Metals, a MIM subsidiary company, where a 30,000 tonnes per annum lead plant based on battery scrap feed has been operating since 1991. Mount Isa Mines Limited decided to license the technology in1988, and copper smelting plants utilising Isasmelt technology are now operated by Cyprus Miami Mining Corporation in the USA and by Sterlite Industries in India. In addition, the technology was adopted by AGIP for smelting copper/nickel concentrates in Australia. Union Miniere are currently constructing an Isasmelt furnace to smelt and convert copper-containing materials at their plant at Hoboken in Belgium. This paper discusses these developments and also some likely future developments which include the application of the technology for continuous copper and nickel converting and applications in the treatment of zinc-containing residues.

Jan 1, 1997

A number of impending and actual pit wall failures have been observed and documented, which have been interpreted to initiate on newly generated structural features. This infers failure through intact rock. Failure mechanisms have been postulated resulting from circumferential stress, extensional strain and brittle flexure. These will be discussed in the context of the failures and the associated monitoring. The implications of failure initiating on ?unknown? features has a significant impact for deep open pit mines where designs are based on the expected structural regime. Being able to anticipate such failures is important for design. Equally important is management of such changes as they arise. In this context, monitoring using high resolution microseismic techniques will be discussed as a means of providing early warning of such failures.

Jan 1, 2006

Gravity-driven rock falls account for a large proportion of all fatalities and injuries in underground mines. Potentially unstable blocks of rock are found in the hanging wall of excavations, which may be delineated by natural joints or stress fractures. These blocks, referred to as keyblocks, will fail if their weight exceeds the support capacity or if they are located between support units. This paper describes a computer program which simulates blocks in the hanging wall of an excavation based on measured properties of fractures and joints. Keyblocks are identified and placed at random locations in a predefined excavation. The keyblocks are tested against the support to determine whether they fail the support, drop out between the support or are stable. By repeating the procedure several thousand times, statistics of the probability of failure of the keyblocks are obtained. This approach allows the relative hazard associated with different types of support or excavation orientations to be obtained. It is concluded that a probabilistic approach is suitable for the evaluation of supports effectiveness in situations where large numbers of discontinuities or stress fractures are exposed in excavations.

Jan 1, 1998

By V. Yahorava

Ion exchange is considered to be an effective technology for the removal of various impurities from cobalt advance electrolytes. With the correct choice of resin, ion exchange can consistently remove the required impurities to the levels for the production of high-grade cobalt metal. Although ion exchange was in the past used primarily for nickel removal, more recently it has been also considered for the removal of copper, zinc, and cadmium. Generally, granular ion exchange products are used, but Mintek is currently evaluating ion exchange fibres for a number of applications, including the removal of copper from cobalt advance electrolytes. Fibrous ion exchangers have major advantages compared to granular resins in that they have significantly higher reaction rates, and wash water volumes could be limited. Granular and fibrous ion exchangers were evaluated and compared for the removal of copper from cobalt advance electrolyte. A synthetic electrolyte containing 50 g/L cobalt and 50 mg/L copper was used for the test work. Equilibrium isotherms, mini-column tests, and split elution tests were done. The results were used to size a full-scale operation to treat 100 m3/h of electrolyte. The potential cobalt losses or recycle requirements were estimated, and data to calculate indicative operating costs for each adsorbent was generated. This information was used for a techno-economic comparison of granular and fibrous ion exchange systems for the removal of copper from cobalt advance electrolyte.

Jan 1, 2014

By Alan Bye, Megan Little

Geology, and the detailed understanding of its properties, are fundamental to the optimal design and successful operation of any mine. To that end extensive fieldwork has been conducted at Anglo Platinum?s PPRust operation to collect geotechnical information both from exploration boreholes and in-pit mining faces. Since 1998, geotechnical data has been collected from over 337 km of exploration core, 7 km of exposed mining faces and more than 15 600 field and laboratory tests, in order to define the complete set of geotechnical properties for each rock type in the mining area. The geotechnical information collected is stored in two databases, SABLE Warehouse and MineMapper3D before it is imported into the Datamine mining software package. The geotechnical parameters, mining rock mass rating system (MRMR), uniaxial compressive strength (UCS), fracture frequency per metre (FF) and rock quality designation (RQD), are modelled using geostatistics to generate a 3D geotechnical block model. Data is interpolated between exploration boreholes and exposed mining faces and modelling is constrained, using wireframes, by rock type and structural features. By having detailed geotechnical information available in a 3D model that can be readily accessed and interpreted, significant production optimisations, feasibility studies and planning initiatives can be implemented. From a slope design perspective the model is used to target data deficient zones and highlight potentially weak rock mass areas. As this can be viewed in 3D, the open pit slopes can then be designed to accommodate the poor quality area before it is excavated. It also follows that geotechnical zones can be readily identified and the slopes optimised accordingly. Rather than viewing the drill and blast department as an isolated cost centre and focussing on minimising drill and blast costs, the fragmentation requirements of the comminution and load and haul business areas are studied. It is well understood that chemical energy is the cheapest form of comminution and that major downstream benefits can be derived by increasing drill and blast expenditure. 238 blasts were assessed to determine the optimum fragmentation requirements for ore and waste. Based on the study a mean fragmentation target of 150 mm was set for delivery to the crushing circuit and a mean fragmentation of 230 mm was set for waste loading from the pit. Substantial benefits have been realised in the drill and blast department by developing empirical correlations that relate the MRMR values in the geotechnical model to a blastability index, fragmentation, required powder factor and costs. As the geotechnical model can predict changes in geotechnical conditions, the blasting

Jan 1, 2007

By P. N. Lategan

Mining companies are challenged with increased difficulty in delivering capital projects on schedule and within budget. In 2005, PricewaterhouseCoopers global review of major capital projects in the mining industry only 2.5% of projects could be defined as successful when assessed across the four critical dimensions of scope, cost, schedule and business benefits. Thus 97.5% of major mining capital projects were not successful according to the criteria PricewaterhouseCoopers used. Normally if a project fails on all these criteria it indicates scope creep. Scope creep refers to the change in a project's scope after the project work has started. As a result, the projects drift away from their original design, timeline, and budget, and as a consequence destroy business benefits. The major reasons for scope creep are poor change control and the lack of proper front end loading. Change control and front end loading are based on project processes in the planning and monitoring & control process group of the Project Management Body of Knowledge1 (PMBOK). This paper will focus on key factors to consider during project scheduling/planning with special reference to cost and schedule (using Microsoft Project as a tool although the principal is universal)

Jan 1, 2009

By N. Duda, W. Koperska, S. Anufriiev, P. Stefaniak

In mineral processing plants ore extracted from mines is processed to obtain a concentrate with the highest possible concentration of this valuable product. It is a complicated multi-stage process. Usually, the first step is sieving the ore, which is typically done using vibrating mining screens. There is often only a limited number of these machines in the technological chain, which is why their continuous operation, and proper maintenance is crucial for the whole process. Predictive maintenance is the best strategy in this case because it allows for minimising the number and duration of unexpected stoppages. It consists of the prediction of future failures based on available real-time data, and predictive models built upon this data using, for example, machine learning techniques. In this paper we concentrate on feature generation for future predictive maintenance model development for a vibrating screen, based on an example of a KGHM ore processing facility in Polkowice-Sieroszowice. We focus on two types of measurements: bearings temperature and vibrational data. Based on the raw data, the process of more advanced feature engineering is described. By transforming the temperature data we calculate characteristics of bearing cooling and heating dynamics, while based on vibrational data, the aggregated characteristics of the vibrations are derived. Such features are calculated on a long-term basis, and then they are compared to the data related to vibrating screen maintenance to estimate their significance for the prediction of particular failures of the machine.

Sep 1, 2021

By E. A. van Wyk, M. R. de Villiers

"Mining companies strive to increase and maintain production, while simultaneously remaining competitive in the global economy. Furthermore, they must ensure workers’ safety and maintain good safety records. The use of virtual reality (VR) facilitates the development of tools and systems for various purposes that can improve knowledge and understanding of the work environment. VR is a rapidly growing technology that uses the ever-increasing power of computing to simulate real-world and imaginary environments and situations with a high degree of realism and interaction. The availability of 3D modelling tools and simulation programming engines that work effectively with a mid-range desktop PC and standard 3D graphics card, make VR technology viable and attractive for mainstream training applications. The design, development, and implementation of interactive VR training systems is proposed as an innovative approach to augment safety training. However, in order to assess the impact of such VR training systems it is of particular importance to determine the effectiveness of the design of such systems. This article proposes an evaluation framework for this vital purpose. This framework comprises criteria to assess VR training systems, specifically relating to usability, instructional design, VR systems design, and mining industry context-specific aspects. Although the framework was developed as an evaluation tool to assess effectiveness of the design of such systems, it can equally well be used as a set of design principles to inform the design of VR training systems for mining. IntroductionMining in South Africa has been the main driving force behind the history and development of Africa’s richest and most advanced economy (Coka, 2012). The South African mining industry is frequently criticised for its poor safety record and high fatality rate (Stoddard and Skweyiya, 2016). Inadequate or insufficient training is often cited as a root cause of accidents (Van Wyk and De Villiers, 2009; Tichon and Burgess-Limerick, 2011). Virtual reality (VR) is a rapidly growing technology that utilizes the ever-increasing power of computing to simulate real-world and imaginary environments and situations with a high degree of realism and interaction (Webber-Youngman and Van Wyk, 2013). VR is currently being used or investigated as a training solution in a variety of industries. VR technology has developed rapidly and costs have fallen to levels where it can now be considered for mainstream training applications. The availability of 3D modelling tools and simulation programming engines that work effectively with a mid-range desktop PC and a standard 3D graphics card, make VR even more attractive to mine training centres (Van Wyk and De Villiers, 2009)."

May 1, 2019

By J. Utt

Recent developments in circulating fluidized bed (CFB) once-through supercritical technology (OTSC) have enabled this technology to be offered as a utility-scale alternative competing head-to-head with pulverized fuel (PF) OTSC offerings. One clear example is the CFB supercritical unit at the Lagisza Power Plant in Poland, owned by PoludniowyKoncernEnergetyczny SA (PKE). This unit has now been in commercial operation for three full years, exhibiting very good performance, and has validated Foster Wheeler?s performance model at this utility scale as well as for units in the 600 MWe and 800 MWe size ranges offering net efficiency of ~43 per cent (LHV basis). This operating unit has also proven the use of the world?s first FW/BENSON? vertical-tube OTSC low mass flux technology. Since the Lagisza original international tender specified OTSC PF technology, it is important to note that the alternative selection of CFB OTSC technology over conventional PF technology is of historic significance, not only for the validation of the CFB supercritical platform as a viable alternative to conventional PF technology, but it also positions the CFB OTSC with fuel flexibility for offering of sizes up to and including 800 MWe units. This paper explores the differences between CFB OTSC technology and standard PF OTSC in utility power generation. Selection criteria, fuel burning range in both technologies, and other selection drivers are discussed. Economic analysis of both technologies, based on existing cases, is also provided. Also discussed are the technical advantages and uses of each technology. Foster Wheeler has recently been awarded a contract for four units of CFB OTSC technology, which utilizes a 2 on 1 configuration of two 550 MWe CFB OTSC boilers on two single 1000 MWe turbines. Essentially this provides a fuel-flexible low-emissions alternative to a 2 × 1000 MWe solid fuel power block.

Jan 1, 2012

A single aggregate mix design was developed based on a slag/Portland binder blend and crusher sand. The primary design criterion, after performance, was the fluidity of the shotcrete and concrete product to ensure compatibility with existing manufacturing and shotcrete equipment as well as the pipeline transport system Cullinan Diamond Mine was investigating. Initial work had determined an optimum slag/Portland to aggregate ratio while retaining a water to slag/Portland binder ratio of approximately 0.4 to maintain the flowability of the product. A super-plasticizer was used to further increase the flowability of the product as opposed to increasing the water content. Finally a polypropylene reinforcement fibre was included in the wet shotcrete product to improve the energy absorption characteristics of the shotcrete. Previous work on the strength development of the slag/Portland based shotcretes and concretes suggests that strength class based on the EN 206 specification is C40/50 while the toughness classification based on the EFNARC plate test is c, or greater than 1000 joules1. Typically, Cullinan Diamond Mine wanted a shotcrete with a uniaxial compressive cube strength of 45 MPa and an energy absorption, based on the EFNARC plate test, in excess of 700 joules. This is an EN 206 strength class of C36/45 requiring a uniaxial compressive core strength of 30.5 MPa and a toughness classification of b1. In addition to the shotcrete development, Cullinan Diamond Mine required concrete products with a compressive strength range of between 25 and 60 Mpa for differing construction operations underground to be manufactured from the same mix design and raw materials as for the shotcrete. Finally, Cullinan Diamond Mine carries out extensive dry shotcrete operations and an investigation into the possibility of using the single aggregate mix design for dry shotcreting was also entered into. This paper presents data that indicates that, under the terms of reference, a wet and dry shotcrete and concrete product appears to be possible from a single aggregate less than 6.7 mm in size, and that a slag/Portland binder is suitable for use as the hydraulic binder in all the products, and that the necessary performance parameters of strength and energy absorption can be achieved.

Jan 1, 2006

By John E. Leitch

The cost of corrosion as measured by such cost components as the renovation or replacement of coated steel, or the use of expensive coating systems on steel, is considerable. Extrapolating from figures for the USA would place the overall cost of corrosion for South Africa as a figure of the order of magnitude of something over 1% of the GNP. This is a sizeable amount, of which costs associated with atmospheric corrosion would be a significant proportion. The corrosivity of an atmosphere can be defined as the ability of the atmosphere to cause corrosion in a given metal or alloy (International Standards Organization [1]). The ISO Standard 9223 specifies the key factors in the atmospheric corrosion of metals and alloys, and defines categories of corrosivity on the basis of these factors. Prior to the publication of that ISO standard, Callaghan published the results of his twenty-year exposure programme and his excellent corrosivity map of Southern Africa [2]. The present author published updates of the corrosivity map in 1999 [3] and again in 2003 [4]. The summary of the individual areas of corrosivity around Southern Africa was published in the latter paper, and is reproduced here as the following TABLE 1. Of significance in TABLE 1 are the numerous regions of very high corrosivity (C5 or beyond), particularly the rural West Coast shoreline, the North East Coast (KZN) shoreline, and the coastal cities Cape Town, Durban and Richards Bay. The corrosivity map as published is obviously based on much extrapolation as only a small number of points have been measured. During the past three years further measurements have been made, mostly however at the same sites in order to give greater reliability and to monitor long-term trends with changes in pollution. These two aspects are incorporated in this update. There has become available a greater amount of air pollution data for centres in South Africa than was the case some years ago. In this present paper the pollution data are used to extrapolate the corrosivity over areas where little or no direct corrosivity measurement has been made. This methodology is described in ISO 9223.

Jan 1, 2006

By Willem C. A. van Niekerk, David A. Baldwin, Nardus Potgieter, Willie A. Gericke

Authorities that regulate environmental issues pertaining to industrial wastes in South Africa regard landfill disposal as the only effective environmental management option for slag and other inorganic by-products from the ferro-alloy industry. Metallurgical slags are widely utilised in civil engineering and construction applications in other countries in the world and in line with the overall philosophy of conserving mineral and other natural resources, these materials should be assessed for the possibility of resource recovery, recycling, reclamation, direct re-use or alternative uses. This presentation describes a risk-based approach for the assessment of by-products from the ferro-alloy industry for alternative use. Once a by-product from an industrial process has been identified for alternative use, its intended use would be defined, but it will not be possible to control its actual use or misuse in society, nor will it be possible to control its fate during the application life cycle. In the interest of protection of human health and the environment, potential risks associated with the handling and uses of a material throughout its life cycle therefore have to be quantified. The assessment has to include both human health and ecological risks and must cover the entire life cycle of a product, from its production up to its end-of-life disposal. The presentation introduces the concept of tiered risk assessment and demonstrates how this applies in the overall assessment of by-products from metallurgical industry sector for safe use in society.

Jan 1, 2007

By M. K. G. Vermaak

There are practical indications that flotation recovery of palladium bismuth tellurides is poor. This work tested whether this can be caused by a lack of interaction of the collector with the telluride. Impedance measurements, voltammetry and Raman spectroscopy were performed to determine the interaction of dithiocarbonate collectors (KEX) with Pd-Bi-Te. Impedance measurements showed lower capacitance values in solutions containing KEX, indicating the formation of a continuous surface layer. Anodic and cathodic polarization diagrams show the mixed potential to be higher than the reversible potential of the xanthate-dixanthogen equilibrium reaction; hence the formation of dixanthogen on the surface is possible. Electrochemically controlled in situ Raman spectroscopy did indicate the presence of bulk diethyl dixanthogen on the surface. Raman spectroscopy has confirmed the co-presence of xanthate with dixanthogen, indicating that xanthate retains its molecular integrity when it adsorbs on the surface of the Pd-Bi-Te. As a result, the mineral surface is expected to be hydrophobic and alack of collector interaction with the mineral is not the reason for the low PGM recoveries experienced. Keywords: Raman spectroscopy; Pd-Bi-Te; ethyl xanthate; platinum flotation; Great Dyke; Pd-bearing bismutho-tellurides and moncheite.

Jan 1, 2004

Mineral Resource Throughput Management is based on the extraction of the maximum potential value from an ore reserve with the emphasis to generate maximum ROI and ROR (return on reserve). A steel producing company in India implemented MRTM to significantly improve their ROI and ROR. The value chain of this company consists of their own iron ore and coal mines, ore washing plants, sinter plants, steel plants, and sales and marketing division. The target for the mines was to produce at a stable and predictable rate and at specific quality requirements. These requirements were set to improve productivity and ROI of the steel plant. The implementation constituted the alignment of the reserve potential, total production chain, human resources and management culture at the mines with the requirements of the steel plant. Many typical mining practices were challenged and changed. Production targets regarding lump vs. fines ratio, consistent product tons, quality targets such as Fe, Al content and moist, and standard deviation on the quality targets were not achieved. A reverse distribution model with release mechanisms to satisfy the demand were developed and implemented at the mines. A stable and predictable flow of mine product with quality standards well within the required standard deviation targets were achieved. The contribution from the mines to significantly improve the Net Profit, ROI and ROR of the company were reached.

Jan 1, 2007

By J. P. Bergh

The advent of low-quality export coal demand has brought a new range of possibilities to the South African coal industry. Products that traditionally were only of value to the domestic or combustion industry sectors now have the potential to be exported, with only minor amounts of upgrading required through beneficiation. Comparatively high steam-coal export prices can be obtained for lowquality export coal, which enhances the economic feasibility of expanding low-quality thermal coal exports. There are, however, increasing concerns about the feasibility of lower quality thermal coal exports and the broader implications. These concerns relate to the environmental impact of low-quality thermal coal production for export and the inherent threat to the security of domestic thermal coal supply in South Africa. Against this background, this paper serves to explain the extended value chain in the production of export coal. The technical and economic advantages and disadvantages of low-grade exports versus coal production for domestic use are evaluated. The value chain estimation is calculated by the beneficiation modelling and characterization of two coals. Based on the value estimation, the lowgrade export production scenario, and finally the modelling of potential pollutant distribution, are described. Keywords coal beneficiation, techno-economics, thermal coal, dense medium processing, dry processing, fine coal processing, environmental impact.

Nov 1, 2013

By P. Fredriksson, S. Seetharaman

In the ladle refining process, the ?FeO?-content of the ladle slag is of great importance in the chemistry as well as the energetics of the process. An optimization of the process requires an accurate knowledge of the thermodynamic activities of ?FeO? in the ladle slags. Due to the discrepancies in the existing data, renewed attempts are being made at the Royal Institute of Technology to generate reliable data for binary, ternary and multi component slags containing ?FeO? at steelmaking temperatures. In order to measure the activities of ?FeO? in the slags, a gas equilibration technique was employed in the present work. The slags, kept in Pt-crucibles, were equilibrated with a CO-CO2-Ar gas mixture and quenched after equilibration. The chemical composition of the slag was analyszed. From a knowledge of the thermodynamics of Fe-Pt system, the ?FeO? activities in the slag could be evaluated. The results of the present studies, together with other literature values, were optimized in the slag software, THERMOSLAG® developed in the Royal Institute of Technology, Sweden. The results of the optimization are presented. Model calculations were performed with the KTH slag software, THERMOSLAG®, by using plant data from OVAKO Steel, Hofors, Sweden. It was found that oxygen estimations in the metal from the ?FeO? analyses of slags, obtained by conventional sampling and analysis methods, where less reliable. Estimation of the oxygen levels utilizing the sulphur partition between the slag and the metal were carried out using the THERMOSLAG® software. Reasonable estimations of the oxygen contents in the metal confirmed that this could be a very useful tool for the plant operator. Keywords: ladle, thermodynamics, slags, ?FeO?, experimentation, modelling, sulphur partition

Jan 1, 2004