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By P. O. Akinseye, F. T. Cawood

Mineral royalties are one of the oldest forms of mining taxation, and were initially introduced to extract economic rents from mining. Over time, the royalty regime has become more complex as it was identified as an important policy instrument that can achieve more multi-faceted outcomes. Such a multi-tiered approach in the use of the royalty instrument is also the case with South Africa. With South Africa’s new mineral royalty regime now in place for ten years, it is perhaps time to assess its impact and effectiveness. To carry out this assessment, an econometric evaluative study was undertaken using four major commodities in South Africa, namely gold, platinum, iron ore, and coal. The study explored five different policy options for government to consider and tested them to determine the most favourable one that will realize the regime’s policy objectives. After the assessment, two major options stood out. Hence, this paper seeks to highlight which of the two options is the most favourable for consideration by policymakers. Based on that study, we find that the current structure is effective, but also recommend that the factors in the formula for refined minerals be ‘modified’ to reduce the capped profitability ratio from the current 60% to 30% and the maximum royalty rate for refined minerals from 5% to 3%. The minimum rate of 0.5% during times of depressed mineral prices and no or low profitability will not be affected.

Dec 1, 2021

By G. E. Rencken, J. H. Potgieter, A. Narain, J. Smith

To conserve fresh water resources and comply with environmental regulations, DRDGOLD, a South African gold producer re-treating surface tailings, has transitioned to a fully closed water circulation system. Consequently, the accumulation of contaminants, as well as addition of reagents, has led to changes in water composition that have compromised leach performance and overall gold recovery. A two-sample t-test confirmed a significant difference in gold recoveries between the use of Rand Water, which was used as a benchmark, and untreated process water. Atomic absorption analysis of ERGO’s process water, confirmed the presence of iron, nickel, zinc, and manganese. A study of the effect of the identified contaminants on gold recovery showed that iron, nickel, and zinc have the largest negative effect on gold recovery, with iron and nickel being more detrimental than zinc. Sulphates were shown to have a possible passivation effect, which also influenced gold recoveries, although to a lesser extent than the heavy metals. Calcium, when present in excess, had a positive influence on gold recovery indicating the possible formation of a calcium aurocyanide complex. Lime softening successfully reduced the heavy metal and sulphate concentrations, and the gold recoveries obtained with the treated process water were similar to those as achieved with Rand Water.

Jul 1, 2021

By T. Dlokweni, M. Bester, C. Koegelenberg, I. Basson

Certain degrees of safety, economic, and financial risk are implicit in any mining operation. At Thabazimbi Mine, slope stability was one of the major sources of risk, largely due to data uncertainties. Consequently, a risk-based approach in slope design was followed. On 6 June 2015, a slope failure occurred in Thabazimbi Mine’s Kumba pit, involving approximately 65 million tonnes of rock failing into the pit and the valley below. Although the failed mass moved rapidly and resulted in a run-out distance of approximately 900 m, controls had been put in place to successfully evacuate all personnel. Risk assessment during the onset of failure supported the decision to not compromise the safety of personnel in any way, leading to unavoidable equipment loss. This contribution presents the failure as a case study in the context of a risk-based approach to slope design as well as the importance of implementing geotechnical controls to effectively manage slope instability risk. Furthermore, a comprehensive back-analysis was performed, on a fully constrained 3D model, utilising 3DEC software, to gain insights into the failure mechanism. In conclusion, lessons from the Thabazimbi slope failure are valuable as they demonstrate the importance of following a risk-based approach in slope design to effectively manage safety and financial risk in open pit mines.

Sep 1, 2025

By I. J. Kotzé, R. T. Jones

Conventional PGM matte smelting requires the presence of a certain quantity of base metal sulphides in order to collect the platinum group metals in a molten sulphidic matte phase in the furnace. Furthermore, the quantity of chromium oxide in the feed materials is controlled in order to avoid the build-up of high-melting chromite spinels in the furnace. Mintek has developed a process for smelting difficult PGM-containing feed materials that contain low amounts of sulphur and/or high amounts of chromium oxide. A DC arc furnace is used to provide the appropriate conditions to generate an iron alloy that collects PGMs very effectively, leaving extremely low residual quantities of PGMs in the slag. Various feed materials have been treated successfully in furnace campaigns running at power levels up to 1.5 MW. The longest of these campaigns was run continuously for more than four months, treating more than two thousand tons of materials such as low-grade concentrates, revert tailings, and converter slag. The campaigns demonstrated the robustness and versatility of the process, and proved that it is possible to sustainably produce a PGM-containing alloy and discardable slags containing an average of less than 1.4 g/t of PGMs over the entire campaign. Keywords: DC arc, smelting, furnace, platinum, PGM, revert tailings, converter slag, ConRoast

Jan 1, 2004

By B. Matsetela, S. Amos, V. Nkuna

"The Kamoa-Kakula copper project—a joint venture between Ivanhoe Mines, Zijin Mining Group Co. Ltd, and the government of the Democratic Republic of Congo—has been independently ranked as the world's largest undeveloped high-grade copper discovery by international mining consultant Wood Mackenzie. It is a very large, near-surface stratiform copper deposit with adjacent prospective exploration areas within the Central African Copperbelt, approximately 25 km west of the town of Kolwezi and about 270 km west of the provincial capital of Lubumbashi. A phased development approach is currently envisaged. The first phase of the project involves the development of a 6 Mt/a underground mine and surface processing complex (dual stream concentrator) at the Kakula deposit, a discovery announced in early 2016. The second phase involves an integrated 12 Mt/a two-stage development, beginning with initial production from the Kakula mine, to be followed by a subsequent, separate underground mining operation at the nearby Kansoko mine, along with the construction of a smelter. Project description and locationThe Kamoa–Kakula project comprises a newly discovered, very large stratiform copper deposit with adjacent prospective exploration areas, located within the Central African Copperbelt in Lualaba Province, Democratic Republic of Congo (DRC). The Kamoa–Kakula project lies approximately 25 km west of the town of Kolwezi and about 270 km west of Lubumbashi. Ivanhoe owns a 49.5% share interest in Kamoa Holding, an Ivanhoe subsidiary that currently owns 80% of the project. Zijin Mining owns a 49.5% share interest in Kamoa Holding, which it acquired from Ivanhoe in December 2015 for an aggregate cash consideration of US$412 million. The remaining 1% interest in Kamoa Holding is held by privately-owned Crystal River.The Kamoa–Kakula project consists of the Kamoa exploitation licences (exploitation permits 12873, 13025, and 13026, which cover an area of 397.4 km2) and one exploration licence (exploration permit 703 covering an area of 12.74 km2). The Kamoa exploitation licences, approved 20 August 2012, grant Kamoa Copper the right to explore for, develop, and exploit copper and other minerals, for an initial 30-year term, expiring on 19 August 2042. The permits can then be extended for 15-year periods until the end of the mine’s life."

Nov 1, 2018

By T. Chikande

"Falls of ground pose costly hazards to personnel and equipment and thus measures should be taken to prevent them. This study endeavours to improve the support systems used in geotechnically poor ground at a Zimbabwean platinum mine by analysing the status quo and recommending an effective support system. Various techniques were used to determine the quality of ground conditions, predict the rock mass behaviour, and to identify the appropriate rockbolt type. An analysis of the current ground control methods and their limitations was also undertaken.The results showed that the current support system and mining practices in poor ground need to be modified to improve safety and productivity. Stoping overbreak is influenced by poor ground conditions and the explosives currently used. The use of emulsion is recommended to replace ANFO. Redesigning of pillars is also recommended in poor ground conditions. An evaluation of the current roofbolt system indicated an opportunity for improvement. With new insight on the performance of the shorter length roofbolts currently in use, a new support system was recommended taking into consideration cost-benefit analysis. Barring down using pinch bars in poor ground was seen as a risky and time-consuming exercise, hence the use of mechanical scalers is recommended to achieve zero harm and to meet production targets. Smoothwall blasting is recommended in poor ground to minimize excavation damage. Other recommendations include the use of hydrological surveys to determine groundwater levels and implement corrective measures. Both empirical and numerical modelling approaches need to be utilized in determining the optimum support. IntroductionThe presence of geological discontinuities such as faults and joints weakens the rock mass. Adequate support is critical in achieving zero harm in underground mines. This paper reviews the current support systems used in poor ground conditions at a Zimbabwean platinum mine. The area of research is located on the Great Dyke of Zimbabwe. The mine exploits platinum group elements (PGEs) and base metals. It is shallow, having a maximum depth of less than 300 m. The Great Dyke is the second largest reserve of PGEs, following the South African Bushveld Complex (Oberthur et al., 2012). It is a linear layered intrusion that extends for about 550 km with a maximum width of 11 km (Prendergast, 1989). The generalized section of the Great Dyke is almost like a trumpet, comprising layers that dip towards the centre. The reef exploited at the mine, the Mineralised Sulphide Zone (MSZ), is located in the pyroxenite layer, which is hosted in the ultramafic sequence. The MSZ is a uniform layer about 2– 3.5 m thick, dipping at around 10–14° from surface outcrop towards the axis of the basin, and located between bronzite and websterite horizons. The visible disseminated sulphide mineralization shows a typical and consistent vertical distribution of platinum group metal (PGM) and base metal values. The research was undertaken to review the current support systems used in geotechnically poor ground conditions in a bid to improve both safety and productivity."

Jan 1, 2016

By V. Borissenkob, L. D. Ropera, M. J. Danielc

Eccentric High Pressure Centrifugal Comminution (eHPCC) is a novel comminution device that provides a single step to achieve a desired target grind size. The mechanisms within the unit mirror particle breakage that is akin to high-pressure-grinding rolls (HPGR) and high-intensity-attrition with air classification. eHPCC receives lump and can produce a product P80 such that the progeny are at or less than natural grain size of the feed. The unit operates in either closed or open-circuit. The grinding zone is dry and free of steel grinding media. This paper presents evidence of eHPCC-2 capable of selective and preferential mineral liberation. A recent test campaign on a blend of underground quartzgold- vein ore was completed. The feed to eHPCC-2 trial was SAG mill trommel oversize (low-grade pebble rejects). eHPCC-2 operated open-circuit with air-fluidisation in the rotating-grinding-chamber, classifying particles based on terminal velocity of the air-swept product particles, displaying size and mineral composition classification taking place at the same time. There is an opportunity for future industrial research targeting eHPCC as an advanced integrated comminution and classification technology. Keywords: High pressure, high intensity, compression, attrition, comminution, classification

Jan 1, 2020

By K. J. Craig, M. A. Swart, Q. G. Reynolds, L. Hockaday

A solar reflector soiling study was carried out at a ferromanganese smelter in South Africa to assess the soiling rates at different locations around the plant. Several meteorological parameters were monitored to give insight into the conditions that lead to increased soiling. Mineralogical characterization of dust samples collected from the reflectors and the atmosphere revealed that only a certain size fraction is of importance with regard to soiling, and that the dust can be attributed to both raw materials and smelter products. Proximity to the dust source was the primary driver for increased soiling. The site that experienced the most soiling was very close to raw material heaps; this was deemed an outlier and was excluded from the summary statistics. The secondary driver for increased soiling was location relative to the smelter dust sources and the wind’s direction and speed. The reflector set at the best location experienced 13.1% less soiling than the set at the ‘worst’ (but still feasible) location, represented by an averaged mean daily reflectance loss of 0.0186. The study revealed that while there are periods of intense soiling at this particular site, proper planning of reflector location in relation to the smelter dust sources can significantly mitigate the soiling rate.

Jun 5, 2023

By T. Fraszczak, U. A. Peuker, T. Mütze, O. Ortlepp

Dolomite is a calcium carbonate sedimentary rock that can be found all over the world. In its calcined form it is employed for water treatment or as an additive in iron production. Calcined dolomite is produced at the Wünschendorfer Dolomitwerk GmbH in shaft furnaces (kilns). Because of an expansion of the mined deposit, significantly higher extraction costs were expected. Therefore, the existing upgrading processes for the kiln stone fraction had to be adapted and improved. This paper presents a process optimisation which allows for an increase of the yield of calcined dolomite by 10 % due to a redesign of the crusher circuit and by an additional 5 % due to a comprehensive characterisation of the kiln stone fraction itself. Here the interdependency between the pressure drop in the furnace during calcination and the size distribution of furnace stones was used to increase the amount of fine size fractions in the furnace feed without deterioration of the calcination process. Keywords: Dolomite, crushing circuits, kiln stone production, flowability, calcination

Jan 1, 2020

By L. Cheng, Y. Liu, Z. Shen, H. Shang, Y. Li

The pre-concentration process of magnetic coarse particles can discharge waste rock or liberated gangue before milling, which is an effective means to reduce cost and increase the efficiency of the concentrator, but the weakly magnetic ore doesn’t have the effective separation method of coarse particle such as hematite, limonite, ilmenite and so on, Because the composite iron minerals contain both strong and weak magnetic elements, the pre-concentration process cannot be applied, or the existing pre-concentration process has problems of complicated configuration and high operation cost. By researching a new type of external magnetic separation technology, the pre-concentration process of composite iron ore was realised by single equipment, which can have a good recovery rate with simple arrangement. In this paper, the separation principle and structure characteristics of the external magnetic separator were researched, and the magnetic circuit characteristics of the external magnet were analysed. The laboratory tests of vanadium titanium magnetite were conducted, and the test results proved that the external magnetic separator can be applied for the pre-concentration process. The industrial application shows that a product of TFe 24.76% with 90.08% recovery, TiO2 10.10% with 91.78% recovery can be achieved from the feed of TFe 20.67%, TiO2 8.33%. Keywords: Coarse particle pre-concentration, composite iron ore, external magnet, magnetic separator

Jan 1, 2020

By R. E. Robinson

I shall present a concept for the development of the resources of this country and its neighbours that repre¬sents a fantastic challenge to our scientists and entre¬preneurs. This concept offers prospects of development that must make our previous achievements seem equivalent only to the first act in a drama enacted on the stage of Southern Africa. I hope to illustrate how, in Act Two, chemistry will play a dominant role, and chemists and chemical engineers will be among the principal actors.

Jan 1, 1980

By Turgay Gurun

"Digital simulation can be used as an analytical tool to optimize the design of crushing plants without need for large-scale experimental programs.General mathematical description of a crushing operation permits the simulation of a crushing plant flowsheet under various operating conditions. The process model encompasses multistage open- and closed-circuit crushing of hard and soft rock. Crushing balances are analyzed in the light of crusher and screen performance and a comparison of different closed-circuit arrangements is made in terms of process and layout criteria.The simulation model allows comparison of process alternatives to be made in terms of equipment selection and capital and operating cost estimation. It thus provides the pertinent practical information to maximize plant efficiency, and to minimize expenditures in such items as equipment, structures, power consumption, and so on."

Jan 1, 2014

By M. Handley

The Witwatersrand Basin contains by far the most gold ever found, and has hosted mining from its discovery in 1886 to the present. For many years, South Africa was the world’s largest producerof gold, nearly all of which came from the Witwatersrand. Since 2000, South Africa has fallen back several positions because of declining gold output. There are many complex and varied reasons for this; however, declining gold resources in the Witwatersrand Basin are not one of them. As far as the author knows, there are no qualified estimates in the literature of gold remaining in the Witwatersrand Basin. This paper collects mining data from several sources and then, using elementary gold accounting and error analysis, attempts to estimate the amount of gold remaining in the Witwatersrand Basin. It includes gold underground in existing and defunct mines, in evaluated ore resources, and dumps. Compiled data from 1887 to 2019 shows that 50 200 t of gold were produced by Witwatersrand mines, while it is estimated that a further 48 100 t remainunderground, both within and outside of mine leases, a further 1 600 t on the surface in tailings,and an unknown amount in rock dumps. Nearly all of this gold will remain inaccessible with current mining methods, and major technical developments in mining will be necessary before any of the gold can be categorized as a code-compliant resource or reserve. To win this prize, the mining industry will have to rethink its approach to mining, both in old mining leases and in the unexploited ground. It will also have to find effective means of preventing gold theft and informal mining, which are on the rise.

Apr 5, 2023

By T. Feroze, B. Genc

"The effect of some of the system variables in forcing and exhausting ducted fan systems on ventilation in an empty heading was investigated using computational fluid dynamics(CFD) and comparative analyses. The diameter of the duct, duct mouth to face distance, and the power of the fan (quantity delivered by the fan) were varied and their effect on ventilation determined through a comparative analysis of the flow rates calculated close to the face of the heading. Estimation models were developed, which can be used to calculate the flow rate close to the face of the empty heading for different settings of the system variables studied.The study showed that recirculation for a forcing ducted fan system can be reduced by increasing the duct diameter or increasing the duct mouth to face distance. For the exhausting ducted fan system, higher flow rates were achieved by reducing the duct mouth to face distance, andincreasing the fan design flow rate and duct diameter.The outcomes of this investigation will help ventilation engineers in deciding the optimum duct fan system required for sufficient ventilation.IntroductionThe ventilation of underground mines, irrespective of the type of mine and mining method, is divided into two broad branches, the primary ventilation and secondary or auxiliary ventilation. The primary ventilation is responsible for the total volumetric flow through the mine and the auxiliary ventilation is responsible for the ventilation of the development ends, production areas, and facilities disconnected from the main circuit with no through-ventilation connections. Auxiliary ventilation is the more difficult to achieve (Bise, 1996), and the disruption of this ventilation system is considered to be one of the primary factors contributing to methane and coal dust explosions (Creedy, 1996). A number of causalities have been recorded by many authors due to these explosions (Phillips and Brandt, 1995; Dubinski et al., 2011; Phillips, 2015). The ventilation of short headings, less than 10 m in depth, can be carried out without the use of any auxiliary equipment (Feroze and Phillips, 2015). However, for headings deeper than 10 m, auxiliary ventilation systems are required. These are generally classified into the three basic types, namely line brattice (LB) ventilation systems, ducted fan systems, and jet fans (Figures 1 through Figure 3 respectively)."

Jan 1, 2017

By M. B. Shongwe, G. Freemantle, M. Botha, S. Brill, J. D. Steenkamp

During steelmaking, one important factor for production efficiency is the free opening of the ladle nozzle during continuous casting. Free opening occurs when the well filler sand and the steel flow freely when the slide gate is opened. Well filler sands are used for the slide gate of a ladle to separate the slide gate refractory and the molten steel. The well filler sand is partially sintered by the heat of the molten metal, which can result in the ladle nozzle failing to open if the sand is not sintered to an appropriate extent. It is therefore of great importance that the sintering behaviour of well filler sand is understood. We studied the effect of the well filler sand chemistry on its sintering properties. Samples of well filler sand with various chemical compositions were sintered in a high-temperature chamber furnace. Quantitative X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICPOES), and wavelength dispersive spectrometry (WDS) by electron microprobe analysis (EMPA) were used to analyse the various well filler sand mixes. Points of analysis were indicated on backscattered electron (BSE) micrographs. Quantitative element mapping was undertaken by energy dispersive spectrometry (EDS). Thermodynamic calculations in FactSage predicted the percentage liquid phase present for the various well filler sand compositions at equilibrium conditions. The results of this work show that the degree of sintering of chromite-silica well filler sand depends strongly on the silica content. The amount of liquid phase formed increases with increasing silica content.

Feb 2, 2022

By H. Manurung, I. M. Bendiayasa, W. Astuti, and H. T. B. M. Petrus, F Anggara, K. C. Wanta

The leaching kinetics of cerium (Ce) and yttrium (Y) in sodium-hydroxide-digested non-magnetic coal fly ash using acetic acid were investigated. The variables analysed were pH, solid-to-liquid ratio (S/L), and temperature. The results show that cerium and yttrium's maximum recovery was 57.33% and 58.36%, respectively, under leaching temperature of 90°C for Ce and 60°C for Y at pH of 1,74 and 10 g/mL solid-liquid ratio in 240 minutes. Increasing the leaching time to more than 120 minutes did not significantly improve the results. After the magnetic separation process, the ICP-OES analysis shows a slight increase in the concentration of cerium and yttrium on nonmagnetic components. The XRD and ICP-OES analysis for the sample before and after silicate digestion shows that 40% silicate was dissolved. The calculation of apparent activation energies of leaching using the Arrhenius law for the leaching of cerium and yttrium gives 22.72 kJ/mol and 35.84 kJ/mol, respectively. The kinetic leaching model of cerium and yttrium all fit Dickinson's new shrinking core model. The calculation results show that the leaching reaction is controlled by combining interface transfer and diffusion across the product layer.

Nov 6, 2024

By M. Z. Emad, M. U. Khan, A. ur Rehman

The use of stemming plugs in surface blasting is gaining popularity because of the environmental, technical, and economic advantages. Although previous studies have established the operational effectiveness of different types of stemming plugs, evaluations of the economic and ergonomic impacts are lacking, thereby hindering their application in many mining operations. Consequently, a significant proportion of mining operations end up performing less efficient blasts. We evaluated the effectiveness of three types of stemming plugs by conducting multiple full-scale production blasts. The results show that stemming plugs reduce the need for secondary blasting and increase blast performance. An economicanalysis showed that the incorporation of stemming plugs can reduce blasting costs significantly.

Jul 1, 2021

By L. A. Cisternas, R. I. Jeldres, D. Calisaya

"Flotation of copper-molybdenum sulphide ores in seawater entails critical challenges such as selective recovery of molybdenite, effective pyrite depression, and reducing the lime addition required to reach highly alkaline conditions. It is essential that laboratory flotation tests aimed at solving these problems give reliable, reproducible results and indicate the correct approach for industrial operations. Rougher flotation of coppermolybdenum sulphide ores in seawater was investigated using two different cells: a modified Denver cell and a standard commercial cell. The effect of an organic reagent on the flotation performance was tested, and the fast/slow-floating model was used to describe the results. The modified Denver cell significantly improved the reproducibility of the flotation test results, due to technological enhancements such as the impeller being driven from below without a stator, which enables the whole froth surface to be scraped with a paddle at a constant depth and rate. Organic reagents are a promising alternative to inorganic reagents for depressing pyrite in seawater. However, further studies should be conducted to investigate their impact on molybdenite recovery, as well as to evaluate the possibility of depressing pyrite after molybdenite separation. The fast/slow-floating model was found to be appropriate for describing the flotation kinetics of the copper-molybdenum ores. The parameters are useful for comparing the performance at different conditions. IntroductionOwing to the increasing scarcity of fresh water, the use of seawater mining and mineral processing is becoming increasingly important (Cisternas and Moreno, 2014). Seawater can be desalinated by reverse osmosis, but this involves considerable costs, limiting it to the big mining companies (Akgul et al., 2008; Leidner et al., 2012; Ghaffour, Missimer, and Amy, 2013). Furthermore, desalination has environmental consequences (Lee, Arnot, and Mattia, 2011); for example, a desalination plant designed to process 2.5 m3/s requires an electrical energy supply of around 30 MJ/s. To supply this power demand, a thermoelectric plant burning bituminous/sub-bituminous coal mixtures at a thermal power generation efficiency of 35% might release around 1200– 1500 t of CO2 per day. Furthermore, the effluents from desalination plants are typically discharged into the sea, and their high temperature and ionic content inevitably modifies the marine environment, with unknown consequences. The direct use of seawater is, therefore, more attractive, but it also poses major challenges since seawater contains ions that adversely affect mineral recoveries. In particular, in the flotation of sulphide ores in seawater, the floatability of molybdenite is depressed (Castro, 2012; Laskowski, Castro, and Ramos, 2014)."

Jan 1, 2017

By Moraka N. V., van Rensburg M. Jansen

"SynopsisGoing beyond transformation claims contained in employment equity scorecards and industry compliance reports, this article provides qualitative insight into the initiatives employed and challenges experienced by mining companies in a quest to transform the mining industry. Perceptions expressed during in-depth interviews with 10 senior executives showed that the assumption that mining companies are reluctant to transform is erroneous. Results from this study suggest buy-in and commitment to transformation. This article describes specific initiatives undertaken by mining companies to transform. The most notable initiatives include staff recruitment efforts to appoint historically disadvantaged South Africans (HDSAs), staff development initiatives, as well as community development. The findings furthermore contextualize the challenges experienced by industry participants in their quest to transform. Despite accusations that industry participants are not taking responsibility for the implementation of the transformation agenda, government needs to recognize that they too have a role to play and need to appreciate and assist in the current challenges experienced by the industry.IntroductionWe need a mining sector that works. Mining employs over half a million people. It is the biggest earner of foreign exchange in our country. It also contributes about 20 billion rand directly to tax revenue. Mining also makes a far larger contribution as a buyer of goods and services, and a supplier of inputs to other sectors of our economy and other economies around the globe’ said President Jacob Zuma during the 2014 State of the Nation Address (Zuma, 2014). However, despite apparent commitment from government, enforced compliance with social and labour plans, regulations and Mining Charter targets, the South African mining industry is slow to gain local and international investor trust (Deloitte & Touche, 2013; Mashego, 2013).Industry players acknowledge that their context has changed – creating various challenges (Davis, 2014). In the past few years, such challenges included subdued commodity prices, increased working costs, constrained infrastructure, and high labour costs, coupled with poor levels of productivity, strained labour-management relations, an uncertain regulatory environment, and the inevitable maturation of the industry (Deloitte & Touche, 2013; Davenport, 2014). Mining affected communities also became more cognisant of their rights, and politicians more vocal in their expectations from their relationships with the mining giants (Davis, 2014). One of the main issues that contributed to the difficult operating conditions was claims from organized labour and Minister Shabangu that this industry is too slow to transform. Specific claims were made in terms of employment equity, fair salaries and wages for mineworkers, housing and living conditions, health and safety issues, and general working conditions (Limpitlaw et al., 2005; Miningmx, 2013; Shabangu, 2010). These claims were followed by what Gill Marcus, Reserve Bank Governor, explained as ‘unprotected strike action [that] has escalated into an uncontrolled, violent and unlawful landscape, led by a mob mentality in the absence of formal and recognised leaders’ (Mavuso,2013)."

Jan 1, 2015

By K. Wu, L. Li, D. W. Zhou, J. W. Yu

The presence of a fractured water-conducting zone (FWCZ) is of significant importance for the safety of underground mining under water bodies. When a coal mining area is covered with a thick layer of alluvial soil, the height, width, and distribution pattern of the FWCZ in the area shows unique features. The internal mechanism by which thick alluvial soil affects the FWCZ is still unknown. Using the Huainan coal mining area (HCMA) in China as a case study, we investigated the impact of thick alluvial soil on the height, width, and distribution pattern of the FWCZ through numerical simulation using the distinct element method, theoretical derivation, and data validation. The results indicate that a thick layer of alluvial soil inhibits the FWCZ height and increases the FWCZ lateral width. When the soil-to-rock ratio is greater than a certain value (the numerical result in this study is 15:18), the FWCZ height and width are affected by the thick alluvium significantly, and the thick alluvial soil alters the shape of the FWCZ from tall and thin to short and wide. The load exerted by the alluvial soil transfers downward to influence the FWCZ; however, this process is obstructed by the hard strata in the bedrock. Therefore, the vertical and lateral change trends show a similar step pattern. Our results can provide a basis for accurate calculation of the FWCZ height in mining areas with thick alluvial soil, to mitigate mine water hazards and increase the safety of underground mining in coal mines covered with a thick alluvium layer. Moreover, reducing the FWCZ height can help extend the upper extraction limit in coal mines covered with a thick alluvium layer, which reduces the thickness of the impermeable coal pillar and increases coal production.

Jan 1, 2016