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"In mechanized mining, poor equipment efficiency (availability, utilization, productivity, and quality) can endanger the success of the operation. This case study will show how an initiative to improve equipment performance developed into a comprehensive turnaround plan for the mine that placed it in the forefront of performance achievement.As part of a company-wide review process, poor overall equipment effectiveness (OEE) was identified as a major reason for the mine not achieving its targets. A project to improve the OEE identified eight improvement areas (elements) that contributed significantly to the poor performances. Measurement metrics were determined for these elements, followed by determination of baseline and target (improved) key performance indicators (KPIs). Cost savings associated with the improved efficiencies were calculated and tracked throughout the project. The mine team determined the specific actions required to achieve the target KPI in each element. These were individually developed and managed like mini-projectswith allocated responsibilities for delivery. The paper will indicate how this OEE improvement initiative triggered an improvement in almost all sections of the mine. Soon after launch, the initiative gathered momentum as the KPIs starting to improve. A visible tracking system exists at the mine and each employee can see the improvements and feel the success. The original eight elements were extended by five more, and the mini-projects grew as participants saw the success of the initiative.This paper concludes that through management and worker involvement, visible measurement and controls, and carefully chosen improvement elements, the mine was turned around. It is now achieving and exceeding its targets, and employee relations and motivation as well as safety have improved considerably. All of these achievements are reflected in the bottom line."

Jan 1, 2016

By H. B. Arntzen, P. O. Grøntvedt, T. Lindstad, R. J. Ishak, M. Syvertsen

Better utilisation of electric power and coke is vital in reducing production costs and CO2-emissions in production of ferromanganese. All FeMn smelting operations consume 10 to 30 % more carbon than the carbon needed to reduce MnO and FeO to metal and the carbon contained in the alloy. Potassium which re-circulates and builds up in the furnace has been shown to be the main culprit causing both excessive carbon consumption, by catalysing the Boudouard reaction, and increased electric power consumption. The reaction between CO2 and ordinary metallurgical coke or coke impregnated with potassium has been studied at temperatures from 800 to 1100°C in a thermobalance apparatus. Ordinary coke did not react to any great extent at temperatures up to 1000°C, whereas the addition of potassium (2-10 %) resulted in a huge increase in reaction rates. The ultimate goal is to fit the results into a reaction rate model containing the equilibrium constant for the solid-gas heterogeneous reaction between CO2 and a free active site on the carbon reactant producing CO and adsorbed oxygen (an occupied site). The model includes the partial pressures of CO and CO2, a reaction rate constant that is a function of both the total number of reaction sites of carbon, and the potassium content. The potassium dependency is taken care of by introducing activity coefficients for the carbon sites. As the first step towards such a model, a regression line for the Boudouard reaction rate has been established.

Jan 1, 2004

By B. Leong, H. Joubert

Keywords: Pyrometallurgy, furnace, auxiliary equipment, copper slag launders Pyromet has designed copper launders for tapping slag. What makes Pyromet?s launder design innovative and safe is that it does not have any cooling water channels underneath the launder runner, whilst achieving effective cooling of the runner. If matte burn-throughs were to occur through the launder runner, the risk of damaging water channels and the risk of explosions are reduced. In addition, since the cooling water channels are not harmed, the launder is easily repairable and reusable. Pyromet makes use of Finite Element Analysis to optimize the launder geometry to ensure that sufficient energy is removed from the centre of the launder. Factors considered during the launder design include the suitability of the geometry to the client?s needs, experience from existing installations, and ease of fabrication. Pyromet goes so far as to develop procedures for fabricators to ensure that fabrication issues do not compromise the functionality of the launder. When launder orders are received by Pyromet, the entire fabrication process and the functioning of the launders during operations are monitored to ensure that the launder designs are continuously improving with every installation.

Jan 1, 2006

By M. Ng

As part of a long-term study of titanium minerals processing being undertaken by the Julius Kruttschnitt Mineral Research Centre, techniques have been developed to measure the resistivity of ilmenite, rutile, zircon and other associated minerals. The techniques have proven reproducible and have allowed the measurement of resistivity under conditions of varying temperature, surface condition and surface moisture adsorption. The measured values can be linked to the separability of the minerals in the dry plant, and hence are useful as a diagnostic test for existing plants when performance deteriorates, or for greenfield sites to investigate potential problems. One of the major problems in electrical separation of titanium minerals is surface coating on the mineral grains. Coatings can make normally conductive minerals such as ilmenite and leucoxene behave much more like non-conductors. Electrical separation of surface contaminated ilmenite from non-conductors then becomes extremely difficult unless the surface contaminant is first removed. The resistivity measurement technique was used to evaluate the effect of surface cleaning on the resistivity of ilmenite and zircon from a Western Australian deposit which will shortly be in production. Ten different attritioning methods were evaluated, ranging from simple rinsing inwater to chemical attritioning in sulphuric acid combined with ultrasonic leaching. A roasting and quenching step was also investigated. As would be expected, the gentler treatments, such as rinsing in water or Calgon, had only amoderate effect on the ilmenite surface coatings. Ilmenite resistivity decreased by about 1 order of magnitude from 5.6 x108?m to between 2.5 and 4.4 x107?m. More intense treatments had a much more pronounced effect. The most effective, reduced ilmenite resistivity to 6.5 x105?m or three orders of magnitude. Zircon was relatively unaffected by any of the attritioning methods, with only a small increase in resistivity observed from 8.0 x1012?m to 2 x1013 ?m. The results show that measurement of mineral resistivity allows the effect of surface treatments to be easily quantified in a way that has benefits for greenfield site development where only small samples are available for testing. The effect of surface moisture has also been investigated using resistivity measurements. Measurements were made on zircon in an environmental chamber in which both humidity and temperature could be closely controlled. Zircon resistivity at 60 deg C decreased from 6 x1011?m at 5% relative humidity to 8 x108?m at 95% humidity. Moisture content and moisture re-adsorption from dry of zircon and number of other minerals were measured using a Mettler moisture analyser. Zircon adsorbed the least amount of surface moisture (0.05–0.09%) but re-adsorbed moisture from dry the fastest, reaching 98% of the original level in 10 minutes. Leucoxene adsorbed the most moisture (0.67%), but was much slower re-adsorbing this moisture from the dry state, reaching only 63% of the original level in 10 minutes. The difference was attributed to the surface characteristics of the grains, the leucoxene being much more porous than the zircon examined. The resistivities and differing rates of moisture adsorption can be used to quantify the effects of changes in atmospheric conditions of the performance of electrical separation in dry plants.

Jan 1, 2003

By S. Pule, Z. Ndabezimbi, A. Hefer, E. Cupido

This article outlines various projects implemented at Rand Refinery to reduce effluent generation and freshwater consumption. The refinery generates about 2800 m³ of effluent annually and has initiated projects such as granulation water recycle and silver leach optimisation to address these issues. The granulation water recycle project has successfully reduced effluent volumes, while the silver leach optimisation has further decreased effluent by implementing stoichiometric addition of HCl and NaClO3. The vibratory shear enhanced processing (VSEP) trial showed promising results for gold recovery from wastewater, though further trials are recommended. The water savings of the effluent reduction projects are monitored by measuring the amount of effluent pumped to service yard effluent storage facilities with the use of flow meters connected on SCADA. Since the effluent reduction initiative of granulation effluent recycle in FY23, the effluent reduced to 2676 m³. In FY24, the stoichiometric addition of HCl and NaClO3 was implemented in the silver leach process, further reducing the effluent to 2083 m³.

Mar 5, 2025

By P M. Bradbury

The nature of aggressive process chemical requirements typically in the Platinum Refinery Industries, lend themselves to the use of Polymer Composite Glass Reinforced plastics for pipework and other associated equipment in these types of Plants. This paper discusses the basic characteristics of a Polymer Composite glass reinforced piping system and gives sample examples of applications in current present day use.

Jan 1, 2006

By M. L. Bakker

Keywords: Pyrometallurgy, top submerged lance (TSL), nickel, PGM, calcium ferrite, lime ferrite The ISASMELT? top submerged lance (TSL) bath smelting process was developed in Mount Isa, Australia by Mount Isa Mines Limited (now a subsidiary of Xstrata plc) during the 1980s. By the end of 2011, the total installed capacity of the ISASMELT? technology will exceed 9 000 000 metric tons per year of feed materials in copper and lead smelters around the world. Commercial plants, operating in Belgium and Germany, are also batch converting copper materials in ISASMELT? furnaces. This TSL technology is equally effective for continuous converting processes, whereupon it is called ISACONVERT?. This paper presents the recently patented ISACONVERT? process for the continuous converting of nickel and Platinum Group Metal (PGM) containing mattes using the calcium ferrite slag system. The paper focuses on the potential application of the ISACONVERT? technology to existing nickel and PGM smelting complexes.

Jan 1, 2011

By R. L. Pienaar

Paper written on project work carried out in partial fulfilment of B Eng (Min. Eng.) degree A study was conducted to investigated and compare the feasibility of two single level extraction layouts for an intact part of theorebody of the De Beers diamond mine, Koffiefontein. Two layouts were chosen and the tonnage profile, development schedule and production ring blast layouts were calculated by applying the information acquired through a literature study. Current principles used on the mine were also applied. The first layout chosen is described as a simple straightforward layout with 6 production tunnels spaced 15 m apart, and is referred to as Layout A. The second layout, named Layout B, is described as a complex chevron layout with 9 production tunnels spaced 15 m apart. This layout has a rim tunnel situated in the kimberlite ground, which is called a chevron and this made the layout more complex than Layout A. By comparing the financial results of the two layouts, it was found that Layout B is a more feasible option than Layout A. Sensitivity analyses show that both layouts are extremely sensitive to the revenue of the projects. Therefore it is recommended that Layout B can prove to be a source of additional tonnage to add to the total tonnage profile of the mine and to extend the life of mine by 20 months, only if certain financial/economic factors improve. There is, however, still some areas of the project that need to be investigated.

Jan 1, 2006

By E. Yalçin

The data set often contains one or more secondary variables. These secondary variables are usually spatially cross correlated with the primary variable. The addition of the cross-correlated information reduces the variance of the estimation error by using the cokriging method. The grade estimation results of ordinary kriging and cokriging methods are evaluated and it was found that the estimation variance of cokriging method is slightly lower than ordinary kriging. The effect of variation of block dimension on the estimation results is also investigated and it was seen that the cokriging estimation variance values also decrease as the block dimension increases.

Jan 1, 2005

By F. Peer

In most coal preparation processes, water is a necessary medium, but the presence of water in coal after it has been cleaned has a negative impact on transportation costs, handling and specific energy values. The utilization of super absorbent polymers (SAP) in the nappy application is well known. The concept of utilizing these polymers was investigated for the purposes of dewatering coal and other fines, generated by preparation processes such as flotation. SAPs are granular highly cross-linked synthetic copolymers with excellent water-absorbing properties. The dewatering process is characterized by three main stages: (a) contact of super absorbent polymer with high-moisture fine coal; (b) separation of dewatered fine coal from super absorbent polymer; and (c) regeneration of used super absorbent polymer, by exploiting its response to changes in conditions such as pH or temperature. Preliminary tests showed the separation step to be very difficult. The novel idea of encasing a given amount of polymer in a water permeable cloth solved this problem (of separating the swollen polymer from the dewatered coal). Preliminary tests investigating the effectiveness of the sachets of polymer showed a drastic decrease in the moisture contents of slurries. Furthermore, it was shown that it was possible to regenerate the polymer (still within the sachets) through thermal drying. A full-scale experimental programme was then followed to accurately determine the feasibility of using sachets of SAP. The experimental variables were initial slurry moisture content and polymer dosage. It was observed that the sachets seemed to work fastest and most effectively at high moistures and also at higher dosages of SAP. Regeneration of the polymer was also investigated, using two methods: thermal regeneration and pH-induced regeneration. The experimental variables, for investigating the regeneration process, were method of regeneration and grade of water used. Thermal regeneration at 70°C seemed to work successfully. Although the cost of using thermal energy is still a problem, the safety aspect (fire hazards) has been addressed since the polymer does not ignite when heated, unlike fine coal particles that may do so. The alternative method of regeneration, which exploits the pH-sensitivity of the polymer, was less successful, and further work needs to be conducted.

Jan 1, 2003

By P. O. Osifo, K. Premlall, X. Goso, R. H. Matjie, M. R. Mulaudzi, J. R. Bunt, K. Mphahlele

This study investigates the transformation of pyrolytic spent tyre-derived char and crumb rubber into high-performance activated carbon chars for industrial wastewater remediation. Utilising an in-house macro-thermogravimetric analysis system under an argon atmosphere, spent tyre-derived activated carbon char were synthesised via physical temperature activation and aqua regia demineralisation. Comprehensive characterisation using x-ray diffraction, Raman spectroscopy, and scanning electron microscopy, revealed a predominantly amorphous structure with nanoscale crystallites (~1 nm) and active surface functional groups. Proximate analysis confirmed that both crumb rubber and leached tyre crumb rubber with aqua regia derivatives achieved favourable compositions (ash ≈ 9.6%; fixed carbon ≈ 84%), comparable to commercial activated carbon (AC). At an optimal activation temperature of 850°C, the char of tyre crumb leached with aqua regia variant exhibited a significant surface area of 300 m²/g. Crucially, the tyre crumb char produced at 850°C variant developed a pore volume of 0.8 cm³/g—effectively doubling that of commercial activated carbon (0.4 cm³/g)—facilitating the sequestration of large organic molecules. In application tests using high-strength starch wastewater, char of tyre crumb leached with aqua regia and tyre crumb char, both produced at 850°C, achieved total organic carbon removal efficiencies of 60% and 50%, respectively, bridging the performance gap between waste-derived and commercial adsorbents. These findings validate waste tyres as a viable, low-cost precursor for industrial-grade adsorbents, offering a sustainable circular economy route for tyre valorisation and reduced industrial disposal costs. Future research will focus on kinetic modelling and the recovery of zinc from spent tyre-derived activated carbon char residues.

Mar 30, 2026

The effect of composition on electrical conductivity (resistivity), viscosity and liquidus temperature of the slags encountered in electric smelting of PGM containing suphide concentrates is reviewed, along with the relationsip between slag composition, slag-matte separation and metal losses to slag. Optimization of slag composition at furnace temperature is attempted on the basis of opposite and parabolic trends of the viscosity-conductivity relationships of the slags. The importance of surface tension of slags is emphasized using available and estimated information which are grouped into a useful correlation. These values are coupled with or incorporated into slag viscosity plots to illustrate the correlation between the two factors, which influence slag-matte separation as well as refractory attack. The electrode in the slag-resistance furnace is the central factor in the design and operation of the furnace by its role of conveying the smelting power. The obvious parameters are the size and positioning in the slag bath, which are defined by slag resistively, furnace resistance, cell constant and power input. The flow of heat generated by the electrode current determines the energy distribution and furnace dimensions creating viscosity profiles, which in turn affect flow conditions. Thus the flow of slag and matte are discussed in conjunction with the furnace geometry, stirring action of the electrodes, buoyancy and electromagnetic effects. The action of the electric furnace as a settler is discussed. The rectangular furnace is considered as a channel reactor in this analysis, and the action of the electrodes is described to indicate a balanced settling rate in the area of electrode action. Discussion of the design and production capacity of the electric furnace, with reference too perating current, power input, furnace dimensions and electrode size, are based on considerations derived mainly from slag properties such as its resistively, viscosity and liquidus temperature.

Jan 1, 2004

Various reagents are added to flotation pulps to manipulate the chemical environment in order to create favourable conditions for the separation of the desired mineral from the unwanted gangue. Interactions occur between these reagents and between the other chemical parameters existing in the flotation pulp which complicate the elucidation of the behaviour of the respective reagents. This paper discusses the roles of the main classes of reagents added viz. collectors, frothers, depressants and activators, as well as the interactions between frothers and collectors. A case study reporting synergistic interactions between thiol collectors in the flotation of pyrite at pH = 4 is included. The use of Potassium n-butyl xanthate (PNBX) and a dithiocarbamate type collector (DTC) were tested both as pure collectors and as components in a collector mixture. In the batch flotation tests sulphur recovery and grade, water recovery, rate of recovery and image analysis of the surface froth were used to evaluate the effect of the mixture on the overall flotation performance. Bubble loading tests showed that the use of the mixture improved the efficiency of the particle collection process by bubbles. Thermochemical measurements of the adsorption of the collectors onto the mineral, indicated the formation of different surface products by the two collectors.

Jan 1, 1998

By J. Dahner

Total milling cost is composed of energy, liner and grinding media costs. In primary high ball load milling, the grinding media play the biggest role in total milling cost. This cost can be drastically reduced by improving the impact condition inside the mill. The impact condition inside the mill is influenced by shell liner design (as well as feed end and discharge design) and the type of discharge. The improvement of the impact condition will result in a significant decrease in grinding media consumption. The softened impact condition allows for better alloy optimization, resulting in a further reduction in grinding media consumption. Optimized liner design can also improve energy consumption as less energy is wasted in the projection of the grinding media. Magotteaux utilizes tools to simulate and show the grinding media trajectories for shell and end liners. This paper will present some practical examples where the media and energy consumption can be or has been reduced by optimizing liner design. Keywords Comminution, grinding, liner design, grinding media wear.

Jan 1, 2011

By A. H. Swart

Unplanned stope panel collapses occur on most near-surface and shallow mines in South Africa. Although these incidents often occur during blasting, they pose a major threat to the safety of underground workers and the economic extraction of orebodies. Most stope panel collapses occur due to excessive panel lengths (resulting in excessive stope spans) that are not designed according to a systematic design procedure or methodology. Instead, panel lengths are often dictated by the equipment in use and by previous experience under similar conditions. Hence, a rock engineering design methodology for the design of stable stope panels between pillars is of vital importance for optimum safety and production in shallow mining operations. Using the proposed design methodology described in this paper, rock mechanics practitioners and mine planners should be able to identify and quantify the critical factors influencing the stability of stope panels. The critical factors should then be used as input to the design of stable stope panels that will provide the necessary safe environment for underground personnel working in stopes. The proposed design methodology is an iterative process, which includes aspects such as rock mass characterization, estimation of rock mass properties, identification of potential failure modes, consideration of appropriate stability analyses and other elements of the rock engineering design process. This process continues after implementation. During monitoring, new data should be included in the database and the design process repeated on a regular basis. Design approaches included in the proposed design methodology include empirical methods such as different rock mass classification methods, analytical methods such as elastic and Voussoir beam analyses, kinematic analyses, probabilistic analyses, and numerical analyses. Keywords: stability, stope panels, design methodology, hardrock mines, shallow mining operations

Jan 1, 2005

By A. Sandberg, M. Nzotta, Du Sichen, N. N. Tripathi, K. Beskow

The present study was carried out to investigate the impact of slag refractory lining reactions on the formation of inclusions during ladle treatment of steel. The experiments were conducted on an industrial scale in the ladle at Uddeholm Tooling AB in Hagfors, Sweden. The inclusion chemistry and population during ladle treatment were studied along with the composition of the ladle glaze, taken from the ladle lining. The inclusions in the steel were classified into four groups according to the Swedish standard SS 111116. SEM/EDS analyses were carried out to identify the phases present in both the inclusions and the ladle glaze. The number of inclusions in the steel before deoxidation was found to increase with the ladle age, i.e. the number of times the ladle had been in use. A similar increase was also found after vacuum degassing and before casting. A great portion of inclusions before casting was found to be supplied by ladle glaze. This observation was further confirmed and explained by thermodynamic analysis. The present results show that ladle glaze is a major source of inclusions in the ladle at Uddeholm Tooling. Keywords: Slag/ refractory/ lining?reactions, ladle glaze, inclusions, inclusion chemistry, ladle treatment

Jan 1, 2004

By A. K. Singh

Between the main fan and the coalface in a mine a lot of air is lost through leakage at stoppings, doors, air-crossing etc. so that a much larger quantity of air has to be circulated by the fan in order that the stipulated quantity of air reaches the face. Stoppings are of vital importance not only for effective ventilation of underground mines but also for isolation of areas affected by fire or susceptible to spontaneous heating. Generally, isolation stoppings are made of brick in cement mortar. If the area is far from the pit or unapproachable, it is very difficult and sometimes impossible to build these stoppings. To overcome these difficulties, particularly near fire affected zones, an alternate successful attempt was made in Indian mines to make a plug underground, from surface through borehole, using cement concrete. In this paper the salient features of the methodology adopted for construction of the plug and the experimental procedure for the measurement of air leakage by SF6 tracer gas is described. Measurements of air leakage through rows of ventilation stoppings in two mines viz. Moira (Jambad and Kajora seams) and Kuardi11/12 (Niga seam) collieries of Eastern Coalfields Ltd. (ECL) have been incorporated. Results of experiments conducted at the Central Mining Research Institute (C.M.R.I) to determine leakage through25 and 38 cm thick brick stoppings are also discussed. Results of all these studies are compared, which show that the efficacy and reliability of the remote filled cement concrete plug in respect of air permeability is satisfactory.

Jan 1, 2004

By P. Rice, A. Photolo, A. C. Barnard

Introduction -Sampling Tool Project (STP) -History -Results to date -Costs -Questions

Jan 1, 2005

By R. P. H. Willis

Uranium is back on the radar. Uranium has always been a controversial metal, from its role in the arms race to its claim to be the only viable alternative to fossil fuel. This paper will cover its properties and use, its occurrence and production in South Africa, the current market drivers and its future role as a primary energy fuel. It will highlight the difference between uranium used to make a bomb and uranium used in a power station. The recent significant uranium price rise will be put into context of the market drivers including geopolitical issues. Planned expansions in nuclear power station capacity will be reviewed, as will new mine production. Future demand will also be speculated on.

Jan 1, 2006

By B. Salt, R. Sullivan, E. Roos, M. de Vries, K. McKenna, L. R. Nelson, M. J. N. Uys, P. Jacobs, E. Munnik, P. Lewarne

A review is presented of the furnace cooling system design and operating developments since the initial furnace start up in January 2001 of the Chambishi DC-arc furnace to produce ferrocobalt alloy. The furnace operating conditions present a number of challenges to the furnace designers and operators in particular to provide a sustainable lining that can withstand the highly corrosive siliceous slag (roughly 50% SiO2). This is exacerbated by the dual requirement to operate this slag in a relatively highly superheated state (?T ? 400°C when tapped at 1550°C) to ensure that the ferroalloy can be tapped (estimated 1370°C alloy liquidus temperature) prior to atomisation. The core design challenge occurs at the alloy-slag interface, where a single refractory type cannot simultaneously meet the dual requirement of both adequate alloy and slag corrosion compatibility. Progression by the fourth furnace campaign to involve a retrofit of the bath sidewall to Hatch high-intensity, water-cooled, copper Waffle coolers and tapblocks is described. This involves operation of the entire slag bath, the slag-alloy interface and a portion of the alloy within a more chemically compatible refractory/slag (and possibly at times even an alloy) freeze-lining. Due to the high furnace power density employed (up to 500 kW/m2 hearth area) coupled with the large slag superheat needed, the resulting imposed peak bath sidewall heat fluxes are substantial, especially in the alloy (typically averaging 170 kW/m2), and on occasion have exceeded 1000 kW/m2. The performance of the Hatch Copper Waffle coolers under such aggressive process pyrometallurgical conditions is described. Aspects of the design and especially operating strategies to effect sustained production at up to 38 MW power input are also discussed.

Jan 1, 2004