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By J. A. Theron

"This paper provides guidelines on performing mass and energy balance modelling involving coal and coal derivatives. Usually, the inputs to a pyrometallurgical process would be specified in terms of elements and compounds. Reliable thermochemical data is more widely available for species involving uniquely defined, relatively smaller molecules. However, in the case of coal, the molecules are extremely large and not uniquely defined. Consequently, modelling processes involving coal and its derivatives have several potential pitfalls. These are outlined in the present paper. The main findings are as follows:•,Coal proximate analysis should not be regarded as absolute; it could vary with several parameters, including heating rate •,For modelling, the use of ultimate analyses should be considered a preferable option to proximate analyses, where, ‘fixed carbon’ and ‘volatiles’ are not defined in terms of chemical composition •,Significant errors could be made if the larger molecules are neglected during calculation of the calorific value (CV) of coal gas (the gas liberated when coal is heated in the absence of oxygen) •,For elemental analyses, the oxygen content (which is calculated by balance) should be checked to ensure it is within the expected range •,For representation of sulphur in coal, double-counting due to SO3 in the ash analysis should be avoided •,Potentially, oxygen in coal could be represented as O2, H2O, CO, or CO2; however, use of some of these species without considering the experimentally determined gross CV results in significant errors in the energy balance. If coal enthalpy is calculated from elemental analyses without correction, representation of coal oxygen as H2O(l) gives reasonable accuracy (up to 6.9% error for a set of South African coals). Coal volatiles could be represented by a complex mixture of compounds, even using different oxygen-containing species than the abovementioned four, provided the enthalpy is corrected •,It is recommended that an ‘enthalpy correction value’ is incorporated in energy balances involving combustion, devolatilization, or conversion of coal and coal derivatives, e.g. coke, char, or tar. That would imply that proximate analysis, elemental analysis, as well as the gross CV would be required for all solid or liquid coal-derived substances being modelled. No other correction due to the form of carbon being different than graphite should be used, as that would imply doublecounting some effects."

Jan 1, 2014

By W. E. Stumpf

"SynopsisSouth Africa recently announced a resurgence in its commercial nuclear power programme. The implications for the development of the necessary high-level manpower within South Africa’s tertiary educational system and its national research and development (R&D) capacity in materials science and engineering, as well as in other engineering disciplines, are placed into perspective. An organized national process of developing this manpower by moving away from the previously high-risk and costly ’large programmes’ to rather a selection of ‘small and better’ research projects and a redefinition of what constitutes ‘nuclear materials’ are proposed as parts of this strategy.IntroductionSince 2008, and more particularly in 2014/2015, South Africa has woken up to the fact that significant steps need to be taken to ensure sufficient electricity generating capacity for the future, even beyond the coal-fired stations at Medupi and Kusile currently under construction. It is, therefore, encouraging to see some active large-scale wind farms in the Eastern Cape near Jeffrey’s Bay, in the Couga area, and others in the Western Cape already in operation. In addition, many solar energy projects are also progressing from the small localized scale to larger programmes in the Northern Cape, which may contribute some capacity on a national basis. South Africa needs to tap into its renewable resources of wind and solar much more, but will these projects solve the country’s long-term industrial needs? Unfortunately not. One cannot run mines and trains on solar cells. Industry needs reliable baseload capacity, and with very limited easily accessible hydrocapacity this leaves really only coal, possibly natural gas, and nuclear power as options. South Africa’s current over-reliance of about 90% on coal–fired power, however, places it in an internationally vulnerable position, and diversification into a more equitable energy mix should be a national priority for the medium to long term. South Africa cannot significant climate change confronting the human race, as the IPCC cautioned in 2013, and will have to adjust its future energy reliance to a more balanced combination of sources."

Jan 1, 2015

By B. P. von der Heyden, T. Blenkinsop, A. Mamuse

Zimbabwe hosts a varied array of coloured gemstones. With the exception of emerald deposits and several world-class pegmatites, few of the gemstone occurrences have received detailed attention from the scientific or mineral exploration communities. In the present contribution we summarize the status of knowledge of the gemstone deposits and occurrences in Zimbabwe, paying particular attention to the geological settings in which they were formed. Synthesis of this regional geological approach reveals that there may be significant exploration potential for further gemstone occurrences, particularly in the extensive pegmatite fields and in Al-enriched orogenic belts that have undergone greenschist to granulite facies metamorphism. Further socio-economic and developmental initiatives will aid in optimizing the value generation from this important sub-sector.

Feb 12, 2024

By T. Uysal

The increasing demand for rare earth elements (REE) in highly strategic sectors such as hybrid electric vehicles, renewable energy, communication technologies, and the defense industry has made REE production methods important. In recent years, studies on REE have increased rapidly; however there are many studies on REE, there are not enough studies in the literature on the economics of the beneficiation process. RE ores are generally leached after beneficiation by gravity, magnetic and flotation methods. In this study, direct leaching, attrition scrubbing and leaching, and flotation and leaching methods are evaluated economically based on the data for the Mountain Pass (MP) facility. According to the sensitivity analysis performed as a function of capital cost (CAPEX), operating cost (OPEX), and rare earths oxides (REO) recovery, REO recovery has the biggest effect on the process economies. Although the flotation method entails additional investment and operating costs, transportation and operating costs are significantly reduced result of the higher grade and recovery. The flotation method is more profitable, with larger NPV and IRR values and a shorter payback period.

Jul 2, 2022

By M. M. Oosterveld

"In South West Africa diamonds are mined from ancient beach deposits by the Consolidated Diamond Mines of South West Africa, Limited.To improve the control of mining production, a computer is used for the calculation of statistically more accurate and homogeneous ore blocks. Geological and sampling information has been digitized and stored on magnetic files.The figures derived for each block entail the calculation of the diamond size frequency distribution, the diamond density distribution and the ore reserve by using the density distribution.The diamond size frequency distribution is used for estimating the revenue in an ore block.A description is given of how a linear programming system can be used for production planning."

Jan 1, 2014

By V. Sheikhzadeh, M. R. Sheikhzadeh, A. Haratian, M. Zare

High Pressure Grinding Roll (HPGR) as an efficient grinding technology plays a major role in mineral processing plants. Investigating the effects of this technology on different parts of mineral processing circuits reveals this technology’s capability. In this paper, HPGR grinding effects on an iron ore beneficiation circuit, in comparison with conventional crushing systems were studied. A representative feed sample was taken from an iron ore beneficiation plant, then crushed to minus 6 mm in a laboratory by two methods: HPGR and cone crusher, and finally a concentrate plant circuit was simulated. Plant simulation was performed by doing laboratory tests consisting of grinding, magnetic separation, flotation and filtration on HPGR and cone crusher products, respectively. According to comminution tests results, in particle sizes smaller than 6 mm, a cone crusher product is coarser than an HPGR product. Also, the Bond ball mill work index of the HPGR product was 10% less than the crusher product. Therefore, based on the Bond formula in applying HPGR, ball mill power consumption decreased by 12%. After ball milling to minus 100 microns, magnetic separation tests results showed that the recovery of the cone crusher circuit output was 90.8% and the product Fe grade was 66.4%. For the HPGR circuit these figures were 87.6% and 67.3%, respectively. Therefore, by using an HPGR, a higher Fe grade of the final concentrate was achieved. A flotation test was then performed on the magnetic separation concentrate, where the results showed that the crusher circuit recovery and the sulfur grade of the product were 96.5% and 0.192%, respectively; whereas the HPGR circuit recovery was 97.2% with a sulfur content of 0.185%. Findings revealed that flotation performance in the HPGR circuit was more efficient than the crusher circuit. Vacuum filtration tests on concentrate produced through the HPGR circuit resulted in a moisture content of 12% that was 2% higher than the crusher circuit’s concentrate in the same condition. Keywords: High pressure grinding roll, power consumption, magnetic separation, flotation, filtration

Jan 1, 2020

By C. Yi, M. Onifade, B. Genc, S. Dineva, T. Zvarivadza, M. Khandelwal

Deep level hardrock mining faces increasing challenges from elevated in situ stresses and associated rockbursts. This study aims to develop a systematic framework for evaluating destress blasting effectiveness, with a focus on deep Swedish hardrock mines. The methodology integrates a critical review and adaptation of global best practices: advanced numerical modelling (static and dynamic simulations), field-based rock fracture monitoring using ground penetrating radar and borehole imaging, and application of rockburst prediction criteria including the strain energy storage coefficient (F), brittle shear ratio, and burst potential index. Geostatistical simulations, machine learning models, and industrial internet of things-based, real-time monitoring are proposed to enhance predictive accuracy, model calibration, and operational adaptability. Key findings show that effective destress blasting evaluation requires multi-modal integration of numerical outputs, field observations, microseismic trends, and uncertainty quantification, accounting for site-specific geological variability and dynamic stress redistribution. The study advances the field by proposing a predictive, feedback-driven evaluation framework tailored for deep Swedish mining conditions, capable of improving proactive rockburst risk management. It offers both practical tools for mining practitioners to optimise stress management, reduce seismic hazards, and enhance excavation safety, and academic foundations for future refinement of destress blasting models, geotechnical monitoring strategies, and adaptive design protocols. This research contributes to safer, more efficient deep mining operations by bridging gaps between theoretical modelling, empirical monitoring, and real-time, data-driven blast design optimisation strategies.

Jun 27, 2025

By A. Mainza, A. Mabentsela

A finite element model of a 5 m radius DC arc ilmenite furnace in idling mode was used to test the notion that the slag solidifies when it comes in to contact with colder pig iron, thus constituting the initial step in the formation of solid slag at the slag-pig iron interface. It was found that a slag that is 150°C hotter than the pig iron does not solidify at the interface. The 150°C temperature difference between the slag and pig iron is a result of solid slag at the slag-pig iron interface, not the other way around as suggested in the literature. Calculations show that the thickness of the frozen slag at the slag-pig iron interface is 1.7 cm for the furnace used. It is proposed that slag solidification begins with the slow co-current flow of molten slag and pig iron in the outer parts of the furnace. This provides enough time for molten slag to interact with molten pig iron without solidifying. As the reduction products form due to reduction of the slag by carbon in the pig iron, the slag solidifies. This approach negates the need for the slag to solidify by merely coming into contact with an inherently colder pig iron. Making use of a low thermal contact conductance between the slag and pig iron was found to be sufficient to numerically capture the presence of solid slag at the slag-pig iron interface and to preserve the 150C difference between the slag and pig iron phase.

Mar 30, 2023

By M. A. Reuter, N. J. Bartie

Metals make modern societies function, and increasingly, various high purity precious and special metals endow sustainability-driving technologies with specific functionalities. These metals become heavily intertwined within products, complicating end-of-life treatment. To counteract the resulting downcycling and potential depletion of scarce resources, maximising both the quantities and qualities of materials recovered during primary extraction and recycling, processes should be a priority in the pursuit of sustainable circular economy. Adopting a process simulation approach; a digital twin for the life cycle of cadmium-telluride solar photovoltaic (CdTe PV) modules was created. The system comprises an integrated metallurgical production system that produces, among others, cadmium, tellurium, selenium, zinc, copper, and lead, all of which are required to manufacture PV modules. System-wide resource efficiency and environmental impacts are assessed using exergy analysis and life cycle assessment, respectively. Simulation of this large and complex product life cycle at a high level of detail allows for the evaluation of potential system-wide effects of various production, recycling and residue exchange scenarios aimed at maximising the sustainability of the entire system. It diminishes the need to make arbitrary choices about allocation methods for the distribution of environmental impacts in multipleoutput production systems. Furthermore, it demonstrates the key importance of metallurgy in achieving circular economy. Keywords: Circular economy, sustainability, simulation, metallurgy, CdTe photovoltaics, life cycle assessment

Jan 1, 2020

By M. B. Díaz Aguado, I. Á. Fernández, C. González Nicieza, B. S. Menéndez

This paper summarizes the works that the Research “Group of Ground Engineering”, belonging to the Mining Department of the University of Oviedo, Spain, has been developing in close cooperation with the Regional Mining Department, since 2001, in order to control and monitor an experimental underground limestone exploitation by the room and pillars method. The aim of the current research is not only the geotechnical characterization of the rock mass (by means of laboratory and site tests) or the instrumentation of its displacements and stress changes (using convergence meters, INCREX probe, extensometers and rigid inclusion cells), but, moreover, to undertake intensive monitoring and control of such pilot mine, which is mined exclusively in order to accomplish this research. The data transmission was made on line via Internet, to achieve a full understanding of the behaviour of the experimental mine, to access data from remote locations and to visualize results from a website. All the collected information becomes input data for several numerical models using finite differences under a program developed in the research Group, ALMEC. The simulation and a final economical analysis lead to a design of an underground exploitation, at production scale, for a resource that is traditionally mined by means of open-pit process methods that could be worked underground with less environmental impact. The main purpose achieved by this exhaustive analysis is the technical and economic viability of such mine, for their optimisation for a future productive exploitation.

Jan 1, 2003

By J. Mothomogolo

Mining projects are capital-intensive and are also characterized by high technical and economic risks. These factors pose challenges to mining entrepreneurs when they seek to raise seed capital for mining start-ups. There are limited sources of mining investment funds in South Africa and each has shortcomings due to one reason or another. Another impediment is South Africa?s status as a developing economy, in which the standards of living ? which in turn influences the savings culture ? the limited GDPs and budget, the socio-political environment, and banking, mining, treasury and other regulations, determine the size of investments, particularly in mining ventures. The proposed funding mechanism was developed with the aim of filling the gaps identified in existing funding mechanisms that were developed by the government with the introduction of the Minerals and Petroleum Resources Development Act (MPRDA), 2002. The shortcomings identified were presented to the study participants as questions to obtain views that were used to define innovative ways of raising mining start-up capital. Most participants in the study supported the derived hypotheses and proposals, and these were used to refine the proposed mechanism for mining investment in South Africa. The proposed funding framework is aimed at encouraging interaction between mining entrepreneurs, government, and the investors to align goals and expectations when undertaking a mining investment.

Jan 1, 2012

By U. König, N. Norberg

Ore mineralogy defines the properties during processing and metal extraction. Fast and frequent monitoring of the mineral content and related process parameters brings value to the mining operation and material processing. Decreasing ore qualities and increasing prices for raw materials require a better control of processed ore and a more efficient use of energy. Traditionally quality control in mining industries has relied on time consuming wet chemistry or the analysis of the elemental composition. The mineralogy that defines the physical properties is often monitored infrequently, if at all. The use of highspeed detectors has turned X-ray diffraction (XRD) into an important tool for fast and accurate process control. XRD data and their interpretation make the difference in the identification of minerals, in describing their distribution in ore bodies and in their beneficiation during processing. The use of statistical techniques such as Partial Least-Squares Regression (PLSR) or Principal Component Analysis (PCA) on XRD raw data has been successfully trialled to determine raw materials and processed ores, in addition to well established methods for mineral identification and quantification. PLSR can be used to correlate process parameters directly from the XRD pattern without investigating the mineral content. Hidden information present in the XRD pattern but not determined with traditional methods can be used to improve the characterisation of the analysed materials. The practical use for the direct determination of process relevant parameters during exploration and ore beneficiation will be illustrated in several case studies from mining and ore processing. Keywords: Geometallurgy, mineral monitoring, X-ray diffraction, process efficiency

Jan 1, 2020

By B. Hart, B. K. Gorain, A. Chattopadhyay, S. Dimovc

This paper presents a detailed and systematic approach to metallurgy diagnostics using an integrated novel gold deportment technique for complex copper-gold and refractory gold ore bodies. This uantitative gold deportment for these complex ore bodies is a challenging task due to reasons such as lower grades, high variability of visible and invisible gold content in different sulphides and iron oxide phases, significant presence of disseminated and composite carbonaceous matters along with associations of various copper sulphide phases. Gold mostly occurs as "invisible gold" (sub-microscopic gold) as solid solution or as colloidal-sized particles in different sulphides and other phases. The dominance of invisible gold and presence of highly preg-robbing and finely disseminated carbonaceous matter adversely affects gold recovery in flotation and leach circuits. Studies were initiated on various complex ore deposits and also on samples representing various process streams. Some case studies are presented in this paper to demonstrate the value of a high confidence gold deportment methodology in developing insights for problem diagnostics and to identify opportunities for metallurgical improvements. A systematic and holistic approach involving different fields of expertise is critical for successful development and delivery of solutions for complex ore bodies. Keywords: Integrated gold deportment, complex copper-gold ores, double refractory gold ores, carbonaceous matter, diagnostic metallurgy, preg-robbed surface gold

Jan 1, 2020

By M. Z. Emad, Y. Majeed, G. Rehman

Massive deposits of rock salt are mined in the Salt Range area of Pakistan. The main export products of rock salt include salt lamps, blocks, and tiles, while local consumption includes the chemical industry and domestic use. The profitable production of salt for value addition depends on the quality, size, and shape of the block. Salt processing for value addition is easier when very few cracks are present in the blocks. The current salt mining practice involves drilling and blasting, which introduces undesired fractures in the material. This paper focuses on the extraction of rock salt blocks by applying conventional cuboidshaped block mining methods used in quarries. The techniques include wedges and feathers, expansion chemicals, and blasting with low-yield explosives. Experimental work involved both laboratory-scale and in-situ field testing. Laboratory experiments assisted with the determination of splitting force, loaddeformation curves, and other rock mechanics parameters. Regression analysis proposes a relationship for the estimation of radial strain from the load in the case of the wedges and feathers method. The splitting force obtained from the laboratory tests was used to confirm the accuracy of the already published empirical relationship. The results of the laboratory as well as in-situ tests showed that the wedges and feathers technique is the most suitable method for mining rock salt blocks of the desired size, shape, while minimizing cracking.

Mar 2, 2022

By A. Atta-Quayson

Since 2012, Ghana has been implementing local procurement regulations in the mining sector to broaden and deepen linkages between mining and other sectors of the economy. The regulations have been implemented in collaboration with the mining industry. This paper offers an in-depth analysis of how the local procurement regulations and related initiatives have been implemented so far. Primary data gathered with semi-structured interviews and secondary sources of data indicate a steady improvement in both in-country procurement and local manufacturing of inputs for the mining industry. There are, however, some challenges relating to tariff structure and support (financial and technical) for local suppliers and manufacturers to meet high standards and demands of the mining industry. This calls for a well-thought-out strategy and programme of activities to sustain and improve on progress made.

Feb 2, 2022

By T van Zyl

Some standards are being used by the corrosion industry on a daily basis. This talk will cover how a standard comes into existence, the different types of standards and the voluntary/ compulsory nature of different standards. The maintenance of standards is discussed This talk also looks at how standards should be referenced, what reference to the mark scheme can be made and which national and international standards might be of value in the corrosion industry.

Jan 1, 2006

By T. Lee

The mining industry, both here and internationally, is continually developing increasingly sophisticated software to compute mineral resource estimates, but these processes cannot compensate for a flawed geological interpretation of the geology of the economic commodity(s) concentrations. Quality assurance and quality control (QA/QC) is becoming increasingly common in association with the sampling and assaying practices within the industry. However, it is rare in the case of a geological interpretation associated with mineral resource estimation. Why? In the context of this paper, QA/QC relates to the use of statistical and graphical tools to show that the geological economic commodity concentrations have been appropriately domained. Domaining is essential to improve the chance of getting a mineral resource estimate right. Commodity value and acceptable concentration variation within a mineral resource can be ingredients that make mineral resource estimation difficult to get right. But it is possible to get it right a very high proportion of the time. It is more likely to occur when inappropriate data consolidation is minimised. In any case, inappropriate data consolidation is significantly reduced when the geological interpretation is strongly consistent with the data and it is demonstrable. To achieve quality global estimates of geological domain concentrations, it is essential that the geology of the prospect is understood sufficiently that the deposit is appropriately domained. Appropriate domaining occurs when sample populations are separated in such a way that only data in harmony with each other within the population contributes to the domain's concentration estimate. The paper will use four brief case studies to illustrate how QA/QC can be used to display data and validate the underpinning geological interpretation through its associated domaining to get it right when it comes to a mineral resource estimation.

Jan 1, 2007

By R. H. Matjie, J. R. Bunt, A. C. Collins, J. C. van Dyk, C. A. Strydom

South African discard coal fines and K₂CO₃ blends were heated in a laboratory-scale rotary kiln to produce ashes for H₂SO₄ leaching tests. The optimized H₂SO₄ leaching conditions of 6.12 mol.dm³ (M) H₂SO₄, solid to liquid ratios 1:5 and 1:10, and 80°C for 8 hours were used. K₂CO₃ was added to increase the dissolution efficiency of K. The objective was to determine if the Al present in metakaolinite (Al₂O₃.2SiO₂), the Al, K, and Ti in the alumino-silicate glasses, and the Ti in rutile (TiO₂) in the ashes could be selectively dissolved in H₂SO₄. XRF results show that the ashes formed at 700°C dissolved more efficiently (87% Al, 89% K and 23% Ti) compared to the ashes formed at 1050°C. This can be attributed to the presence of Al₂O₃.2SiO₂, K₂CO₃ melt, K₂CO₃ remnants, KAl(SO₄)₂, and K-aluminosilicate glass in these ashes. XRD results indicate that the ashes prepared at 1050°C contained anorthite (CaAl₂Si₂O₈), microcline (KAlSi₃O₈), pseudomullite (Al₂O₃.SiO₂), and silicon spinel (2Al₂O₃.3SiO₂), which are either insoluble or only sparingly soluble in H₂SO₄. These minerals resulted in the lower dissolution efficiencies of Al and K. Based on the high dissolution efficiencies of Al and K for the ashes produced at 700°C, coal fines blended with K₂CO₃ could possibly be utilized as feedstocks for the production of aluminium(III), potassium(I), and titanium(IV) and a sulphate-containing leach liquor. Furthermore, the environmental issues and costs associated with the handling and disposal of large volumes of coal fines will also be resolved.

Aug 2, 2022

By F. T. Cawood, C. C. Birc

The South African mineral resource royalty system, initiated in 2010, employs a hybrid ad valorem approach tied to profitability ratios. This rate is then applied to the total revenue from mineral sales. In this article we explore how the profitability ratio in the mineral resource royalty formulae interacts with the gold tax formula as applied to South African gold mines, devising a strategy for cut-off grade optimization. The study focuses on nine narrow, tabular-reef (Witwatersrand) gold mines. The approach involves a mixed-integer cut-off grade optimizer utilizing Excel Solver, incorporating relevant royalty and income tax formulae. Different mineral resource royalty cost scenarios were examined. Ignoring these costs in the break-even analysis lowers the cut-off grade but slightly boosts profits compared to considering expected costs. The developed optimizer model, recognizing the profitability aspect of the mineral resource royalty and income tax formulae, yielded a 6% lower cut-off grade than the base case. This is significant for increasing mine life. While the profit differences are marginal (0.2% compared to the break-even base case), substantial improvements were noted: a 6% increase in stope tons above cut-off grade, and a 4% rise in total revenue. Enhanced resource utilization (3% extra gold kilograms) reduces necessary development and overall costs, allowing for a reduction in the cut-off grade and ultimately, more profit.

Aug 8, 2024

By A. E. Voigt

Iron ore samples representing the input and output of several jigging experiments were analysed to determine the effect of particle size, shape, and density on jigging performance. Traditionally, the manual measurement of the size and shape of individual particles is very tedious and prone to inaccuracies and inconsistencies. Using a novel multi-view imaging technique the 3-dimensional representations of each particle in the sample was determined. From this representation several size and shape measurements were extracted, and these were correlated with the individual particle density measurements. A rigorous investigation into the confidence associated with density and the size and shape features as a function of sample size was conducted, thus allowing the significance of correlations in the data to be determined. The jig?s performance was seen to be clearly sensitive to density and markedly so to particle size, while the results for shape indicated the need for continued work in the definition of particle shape.

Jan 1, 2012