Search Documents

By R. G. Votteler, A. C. Brent

"The first in this series of two papers, on the potential of renewable electricity sources for mining operations in South Africa, investigated the internal structure of mining corporations to evaluate feasible alternative electricity sources that were identified as through earlier research. The purpose of this paper is to combine current knowledge about the external macroeconomic and the internal environments to produce a clear picture of how renewable sources of electricity could perform from the perspective of mining corporations in South Africa. The multi-attribute value theory (MAVT) approach was adapted to structure the research and results. The model was fed with real-time data provided from five different energy companies and four mining corporations operating in South Africa. The results show that the performance of hybrid versions of the currently used electricity sources (diesel generators and Eskom grid connection) with solar PV and onshore wind is favourable compared with the current sources alone. The advantage of diesel generators is significantly greater than that of the Eskom grid connection. By combining the macroeconomic influences with the MAVT results, hybrid solar PV versions are identified as having the greatest potential. In second place are hybrid wind solutions, which have the shortcoming that good wind conditions occur only in coastal regions where there are fewer mining activities. Geothermal hybrid versions are the least favourable owing to the lack of service infrastructure and high initial investment costs.IntroductionRecent developments in the macroeconomic environment necessitate an investigation of the internal structure of mining corporations to evaluate possible alternative electricitygenerating sources (Roehrl and Riahi, 2000). To be able to combine current knowledge of macroeconomic factors and the internal structure of mining corporations, the research process is presented in two papers. The first paper (Votteler and Brent, 2016) investigated the internal structure and argued that a strategic tool should be used to evaluate electricity sources from the perspective of mining corporations. The multi-criteria decision analysis (MCDA) approach was selected as the most appropriate strategic tool. Based on a literature review of previous similar MCDA approaches in energy planning, it was concluded that no adaptation of MCDA methods could be found from a corporate, mining, or South African perspective. Finally, the paper investigated the internal evaluation structure in collaboration with mining corporations, by identifying the criteria they use to evaluate electricity sources."

Jan 1, 2017

By L. P. Fatti

An important feature affecting the classification of a remotely sensed scene is that the data are, in general, spatially correlated. Various approaches are discussed towards incorporating the correlation between neighbouring pixels when they are classified on the basis of their spectral reflectance data.

Jan 1, 1987

By S. G. Mgenge, J. D. Steenkamp

Tronox Namakwa Sands operates two ilmenite smelters for the production of high-titania slag and low-manganese pig iron. Slag or metal is tapped from one of two product-specific, bi-level tap-holes. In this paper the refractory design specific to the tap-hole refractory layout is described, as well as practices for slag and metal tapping and refractory maintenance. Further developments planned are briefly described.

Jan 1, 2014

By S. K. Mahata, P. G. Suresh Kumar, B. B. Singh

Improvement of post tap hole practices is achievable by mechanized handling of melt during the production of Ferro Chrome, resulting in higher recovery of chromium. The paper deals with modern practices adopted in the production of ferro-chrome since past two decades. The methods and practices deal with various areas : a) Improved method of operating the tap hole by selection of right quality of refractory to maintain the life of tap hole. b) Collection of melt in different types of receptacles like refractory brick lined mild steel ladles, cast steel ladles, cast iron pans being chosen for cost effective and efficient handling. c) Separation of slag and metal, casting of metal, crushing, sizing and stock piling etc. d) Slag disposal and recovery of entrapped metal. The drive behind the above development is continuous improvement, which results in higher chromium recovery and reduces loss of metal in slag by completely mechanized method so as to be at the same level with producers of ferro-chrome in other advanced countries , in the emerging global economy.

Jan 1, 2007

By K. Moxham, B. McKeown

The South African gold and platinum deposits were formed in very different ways and yet both have many similarities. They are flat dipping tabular orebodies, extremely narrow and located in hard abrasive country rock. The mining methods employed are also similar. Primary access is via shafts or declines; secondary access is via haulages and cross-cuts; and tertiary access is from raises. The proposed solution for rapid access described in this paper is focused on the haulages and cross-cuts.

Jan 1, 2006

By J. E. Dickinson, J. L. Sutherland, J. Zhou, M. J. Cole, K. P. Galvin

Interest in early gangue rejection has grown substantially in the minerals industry to reduce energy and water consumption arising from excessive comminution. Recent developments in coarse-particle flotation have proven successful by promoting a quiescent hydrodynamic environment to limit particlebubble detachment and by helping to convey more buoyant particles to the overflow. Current approaches also benefit from upstream classification to remove the finer particles ahead of the coarse-particle flotation. In this study, coarse-particle flotation was investigated experimentally using a novel hybrid gravity-flotation system called CoarseAIR™ that exploits the hydrodynamic advantages of the Reflux® Classifier. The system consists of a lower fluidised bed housing, with a system of inclined channels above. The inclined channels enhance the segregation and hence rejection of intermediate through to relatively coarse particles containing little or no surface liberation. This approach overcomes the need for pre-classification, while offering strong transport of coarse particles made buoyant through their attachment to air bubbles. The paper explores the strong relationship between the solids transport to the overflow and the input gas flux, showing firstly the potential for significant mass rejection at the relatively low gas fluxes, and robust performance in terms of recovery across the full range of gas fluxes. Keywords: Flotation, inclined channels, coarse particle flotation, Reflux Classifier

Jan 1, 2020

By C. Botha

The South African democratically-elected government instituted policies and legislation that are intended to bring about change and transformation in the country and have drastically affected different industries, among others, the mining industry. The Mineral and Petroleum Resources Development Act 28 of 2002 (MPRDA) and the Broad-based Socio-economic Empowerment Charter (Mining Charter) were introduced in order to redress previous inequalities and to promote women's employment in the mining industry. This research evaluates the practical implementation of the MPRDA and the Mining Charter with specific reference to women in underground mining. A quantitative research paradigm was used. Data were collected through a process of a face-to-face interview surveys utilizing a structured questionnaire. The research setting was limited to the platinum-mining industry in the area of Rustenburg in the North West Province. The study population consisted of 195 available women working undergound at the mine. It is clear from the findings that mining companies are facing major challenges in their attempt to incorporate women in underground mining activities. Company policies regarding these issues must be firmly in place; however, the challenge lies in the translation of these policies into practice. In this regard, managers will have to play a leading role in the successful phasing in of women into the underground mining arena.

Jan 1, 2012

By M. Kumral

One of the most significant elements in solving the co-kriging equations is the matrix solver. In this paper, the singular value decomposition (SVD) as an equation solver is proposed to solve the co-kriging matrices. Given that other equation solvers have various drawbacks, the SVD presents an alternative for solving the co-kriging matrices. The SVD is briefly discussed, and its performance is compared with the banded Gaussian elimination that is most frequently used in co-kriging matrices by means of case studies. In spite of the increase in the memory requirement, the SVD yields better results.

Jan 1, 2012

By D. G. Almond

Low-grade, complex mineral deposits have resulted in the need for complicated large-throughput processing plants delivering increased productivity, reliability, and utilization, together with reducing operational costs. Complex mineralogy has resulted in complicated process flow sheets designed to recover minerals as efficiently as possible. In addition, the remote location of many minerals¬-processing plants, continuously rising energy costs, and fierce competition pose significant challenges to the modern mine, compounded by a global scarcity of qualified and experienced operational personnel. Over the last decade the Internet and automation technologies have undergone major advancements. Automation technologies, solutions, and concepts that existed, but were considered risky or unreliable prior to the year 2000, have now gained acceptance and matured. Furthermore, new technologies and different collaboration schemes have appeared, offering innovative solutions to the mining industry to address many of the challenges described. These advancements in reliable remote systems that access technology through the Internet provide significant opportunity to support mining operations, enhance process performance, provide engineering services, and proactively anticipate and execute maintenance services. This paper references a global survey of automation trends in the mining industry and the potential for an intelligent collaborative environment using automation technologies to exploit opportunities in operating the plant of the future, increasing effectiveness, and reducing operational costs. A variety of possibilities are described, including asset management solutions, remote access capabilities, performance monitoring solutions, advanced process control technologies, and the formation of an intelligent collaborative environment. A real example where this technology is used to support the operation and maintenance at a cement plant in Egypt is given to underpin the concepts described in this paper.

Jan 1, 2013

By S. Kahraman

The prediction of rock properties from indirect testing methods is important, particularly for preliminary investigations since indirect tests are easier and cheaper than the direct tests. In this study, we investigate the predictability of the uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS) of rocks from the indentation hardness index (IHI) obtained using point load apparatus. Forty-six different rock types, 14 of which were igneous, 15 were metamorphic, and 17 were sedimentary were tested in the laboratory. The UCS and BTS values were correlated with the corresponding IHI values and the results were statistically analysed. The influence of rock classes on the relationships was also investigated. A strong correlation between UCS and IHI was found for all data. The correlation between BTS and IHI is not as strong as the correlation between UCS and IHI, However, it is in the acceptable limits. When the regression analyses were repeated for igneous, metamorphic, and sedimentary rocks, the correlation coefficients were generally increased. The results show the UCS and BTS can be estimated from IHI, In addition, the effect of rock classes on the relationships between IHI and both UCS and BTS is important.

Jan 1, 2012

By T. Oberthür

The Great Dyke of Zimbabwe constitutes the world&apos;s second largest reserve of platinum group elements (PGE) after the Bushveld Complex in neighbouring South Africa. Within the Great Dyke, economic concentrations of PGE are restricted to sulphide disseminations of the Main Sulphide Zone (MSZ), which are currently mined at the Ngezi, Unki, and Mimosa mines. Near-surface oxidized MSZ ores have a large potential. Their total resources are in the range of 160-250 Mt; however, all previous attempts to extract the PGE from this ore type have proved uneconomic due to low PGE recoveries (<< 50 per cent) achieved by conventional metallurgical methods. Within the ores of pristine, sulphide-bearing MSZ, the PGE are bimodally distributed. Platinum occurs mainly in the form of discrete platinum group mineral (PGM) grains (mainly bismuthotellurides, sulphides, and arsenides), whereas approximately 80 per cent of the Pd (and some Rh) is hosted in pentlandite. Within the oxidized MSZ ores, the PGE are polymodally distributed. Whereas the arsenide- and sulphide-PGMs that make up approximately 25 per cent of the original Pt content of the ore largely remain stable (relict PGMs), the remaining PGMs are disintegrated. The base metal sulphides are destroyed, partly releasing their base metal and PGE contents, and are replaced by iron oxides or hydroxides. Unspecified amounts of the PGE are redistributed and either form secondary PGMs, are found in chemically and mineralogically ill-defined (Pt/Pd) -oxides or hydroxides, or in iron-hydroxides, Mn-Co-hydroxides, and in secondary silicates. The problematic processing of oxidized MSZ ores is attributable to their complex nature and polymodal distribution of the PGE, prohibiting a significant upgrading of the ores by conventional metallurgical methods. Therefore, only bulk leaching methods are viable for ore treatment, and novel metallurgical methods have to be developed for the processing of these ores. Our ongoing work aims at locating the PGE in their mineralogical form in order to understand the mineralogical balance of the PGE in the ores and thereby facilitate the evaluation of metallurgical options for their recovery. A short overview on options and recent advances regarding the recovery of the PGE from oxidized ores is given.

Jan 1, 2013

By Ernst-Ulrich Reuther, Alexander Donmen

Mine ventilation in the German coal mining industry is concerned mainly with problems of thermal environment arising from greater depths and with increasing emission of methane gas. The development of computer techniques over the past ten years for solving these and ancillary problems is reviewed. The emphasis from a planning and control point of view falls mainly on ventilation network calculations, temperature predictions and advance estimates of methane emission.

Jan 1, 2014

By M. Gao

The Zinifex Century Mine employs a large number of Detritor mills for fine and ultra-fine grinding to liberate silica and sphalerite at 80 per cent passing 7.5 microns before final zinc flotation. A joint project between CSIRO Minerals and the Zinifex Century Mine was carried out to evaluate the Detritor mill performance. Plant surveys were conducted around the Detritors in conjunction with laboratory tests. The survey data showed that the Detritors in the ultra-fine milling circuit performed well. They reduced a feed F80 sizing of 46 microns to a product P80 sizing of 7.5 microns at a gross energy consumption of 37.2 kWh/t. Scale-up of ultra-fine milling Detritors was studied using a 0.55 kW laboratory batch unit and a 355 kW full-scale Detritor by processing Century zinc concentrate with 1 mm sand media. The results indicated that the 0.55 kW laboratory mill underestimated the energy consumption of the full-scale Detritor by about 20 per cent for a product P80 of seven microns. The performances of a horizontal IsaMill and a vertical Detritor were compared as ultra-fine milling devices for processing Century zinc concentrate. The experimental data demonstrated that, when using the same grinding media, the energy efficiency of the two mills is similar despite the difference in mill designs. The Detritors used for regrind duty at the Century Mine performed poorly when processing feed at 80 per cent passing 88 micron. The energy consumption was high and the product size distribution was broad with particles above 100 microns in the feed unbroken and particles below ten microns overground. A coarser ceramic media of 3 mm was therefore tested in a laboratory Detritor to process the regrind Detritor feed as an alternative to the 1 mm Colorado sand used at the Century Mine. The ceramic media reduced the energy consumption significantly and produced a narrower product size distribution, which is more desirable for the downstream flotation process.

Jan 1, 2007

By H. E. Bartlett

Previously, the grade of ore at the shaft head was taken to be equivalent to the grade measured in the faces by means of chip sampling. The tonnage mined from the stopes is determined from survey volumetric measurements. Estimates of shaft head grade and tons include the grades and tons of waste, development ore, sweepings from old areas, and other sources, not all of which are sampled. The tonnage of ore delivered at the shaft is often estimated using skip factors. These factors are subject to manipulation and not all the skips are filled to the same level. Consequently, both the grade and tonnage of ore delivered at shaft head are subject to a measure of uncertainty. For many years, these uncertainties have led to disputes between shaft managers and metallurgists over the reconciliation between shaft tons and grade and plant tons and grade. These problems are compounded when several shafts feed a central processing plant. Shaft bonuses and a shaft?s profitability are affected by poor gold allocation methods. Without measurement of the grade and tonnage from all shafts, a poorly performing shaft could benefit at the expense of the other shafts. In order to improve the measurement of grades and tonnage at the shaft head, which is the custody transfer point between the mine and surface operations, South African mining companies have developed a methodology to measure the mass of ore from each shaft using rail weighing equipment, and the run-of-mine grades delivered from each shaft using cross-stream (go-belt) sampling. Harmony Gold Mining Company has implemented the rail weighing and go-belt sampling methods for their shafts. This paper deals with the statistical tests on the procedures and control measures that are in place to establish confidence in the gold allocations. The metal accounting system for examining the allocations follows the first principle of the AMIRA P754 Metal Accounting Code of Practice namely ?The metal accounting system must be based on accurate measurements of mass and metal content. It must be based on a full check-in check-out system?. The check-in is mass and grade of run-of-mine ore and the check-outs are the plant input grades and the recovery and residue from the plant. The balances between check-in and check-out are the subject of the statistical analyses, which have been conducted using the classical statistical tests and procedures that are generally used in all fields of endeavour. It is concluded that the gold allocation procedures that rely on go-belt sampling and rail weighing of ore from shafts has been successfully implemented, and that the system, which has been in operation at Harmony since 1993, has won general acceptance from stakeholders, with the gold allocations being perceived as being fair to all. Apart from the on-mine issues of bonuses and fair allocations, accurate metal accounting assists in the broader issues of generating accurate production figures for management. An added benefit of weighing and sampling ore at the shaft head has been that shafts now have daily moving average grades, which are used for grade control. The go-belt sample at the shaft head is the first accurate sample of production in the value chain from face sampling to gold bullion. Keywords metal accounting, go-belt sampling, run-of-mine sampling, codes of practice, AMIRA P754, train weighing, statistical analysis, gold split, allocation of gold, metal balance, grade control.

Jan 1, 2014

By M. K. Matthews

The use of backfill has important environmental control implications which, although frequently overlooked, can be both beneficial and problematical. Where backfill is widely used, the reduction in stope heat load and improved air utilization influence the overall mine ventilation and refrigeration requirements significantly. A programme of work examining in detail all the environmental consequences of backfilling is currently underway at the Environmental Engineering Laboratory of the Research Organization of the Chamber of Mines. This paper gives an overview of the work and presents some findings. In so doing, the environmental implications to be considered when backfilling are highlighted.

Jan 1, 1988

By D. Francois-Bongarcon

The ?Poisson effect? is defined and characterized. It takes place even when the material to sample is not liberated. Gy, Pitard, Ingamells, and others, including the author, recommend that a minimum average number of particles of mineral of interest characterize the recommended sample size. How many? Recommended numbers range from 6 to 40 particles depending on authors, corresponding to standard deviations of 41% to 16%. Some guidelines are proposed, and the often alleged ?double-Poisson? effect is examined.

Jan 1, 2009

By T. N. Matveev, V. V. Getman, A. Yu. Karkeshkina, L. B. Lantsova, N. K. Gromova

Sulfide-type tin deposits in Russia are characterised by the complex mineral composition of ores and dump products of their processing. Tin-sulfide ores contain industrial quantities of copper, lead, zinc, tungsten, silver, rare and trace elements (indium, scandium, etc.). In addition, the ores are characterised by uneven dissemination of sulfide minerals (chalcopyrite, galena, arsenopyrite, etc.) and tin minerals (cassiterite, stannine, etc.). X-ray phase and spectral analysis, scanning electronic microscopy (SEAM), laser SIM and AFM microscopy helped to identify the selective fixing of sodium dibutyl dithiocarbamate (DBDTC) on chalcopyrite and galena, as well as the tall oil fatty acids (TOFA) and IM-50 on cassiterite. For the first time, collectors and flocculants of slurry fractions of silver and tin, thermomorphic polymers TMPF were used to isolate more than 80% silver from the tin tailings of the Solnechny mine into a copper-silver rough concentrate. It has been established that preliminary ultrasonic treatment and desliming according to the 0.02 mm class removes up to 20% of sludge material, which impairs the process of gravity separation. The combined flotation-gravity scheme using new reagent compositions helped to obtain tin concentrate with a tin content of 5.42%, which meets the requirements for further metallurgical processing (at least 5%). This work was supported by the RSF according to the research project No. 17-17-01292. Keywords: Flotation, flotation reagents, tin-sulfide ores, casiterite, adsorption, flocculation

Jan 1, 2020

By A. M. Engelbrecht

Paper written on project work carried out in partial fulfilment of B Eng. (Chemical) Membrane processes are vital to a diverse range of technical and biological systems, which also feature in mineral processing applications such as the treatment of mine effluent and extraction of metals. In this study, the use of cellular automata to model a semi-permeable membrane that separates two compartments is considered. Cellular automata are simple models that enable the analyst to represent well-understood local effects, such as the chemical or steric interaction between molecules themselves and between molecules or particles and their environment, which can lead to very complex behaviour on a macroscopic scale. Various physical phenomena, including reverse osmosis, were simulated. Initial results for the effect of temperature, membrane structure and chemical properties of the solutes on the performance of the membrane appear promising. Keywords: cellular automata, dynamic modelling, filtration, membrane fouling, osmosis.

Jan 1, 2007

By E. Kumar, L. A. Kumar

"A methodology is proposed to develop an optimization model to understand the impact of transporting minerals, from mines to the final destination, on air quality. Recently, there has been increasing concern about the combined effects of multiple activities over many years, and the regional environmental changes brought about by a single project. Environmental issues in the iron ore industry have highlighted the need to broaden the cumulative impact assessment. In this study, we simulated the optimal routes and quantity of materials needed to meet the destination plant demand based upon environment constraints (level of air pollution), as well as the cost of transportation and availability of materials. Multiple scenarios were developed to analyse the effects of changes in routes, alternative transport system (or multi-modal split), traffic congestion, and the cumulative impacts on air quality. The air quality impact zones of the study area were demarcated using a GIS technique. The expected outcome of the study is the selection of a suitable transport system for a particular site with the least impact on air quality, including the transportation route, relative to the minimum cost of transportation of the minerals from the mines to their final destination. The proposed methodology is evaluated with a case study. IntroductionIn India, the process of environmental impact assessment (EIA) has been focused primarily on the local impacts of projects, without considering regional environmental effects. Environmental clearances for proposed projects are based on reports of local impacts. However, any developmental project poses a potential risk to the environment as a whole, and not just in the immediate vicinity of the project. Recently, there has been increased concern about the combined effects of multiple activities over many years—the regional environmental changes due to development of a single project (Dutta, Mahatha, and De, 2004). Environmental issues throughout the country, particularly in the iron ore industry, have emphasized the need to broaden the analysis to include the combined impacts, or those forecast for a proposed region, on an existing environment. The most significant adverse environmental consequences of iron ore transportation are the deterioration of biodiversity and air quality (Kumar and Ajay, 2015)."

Jan 1, 2017

By R. M. G. Machunter

The use of testwork to establish an economically feasible separating plant has been a long established practice in the mineral processing industry. However, uncertainties in orebody characteristics and equipment/plant operation can have a significant impact on the separation performance of a given project. This paper explores the impact of uncertainties derived during testwork at key processing stages on the overall performance of mineral processing flowsheets. Case studies for both mineral sand and iron ore projects will be used to illustrate the concepts studied in this paper.

Jan 1, 2007