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By S. V. Rungan

The modern mining industry is increasingly being tasked to comply with various legal, industry and social prerequisites. In addition to complying with these, the mining industry is further expected to effectively report on their compliance. Although there are many models that aid the mining industry in compliance and reporting, it is perhaps opportune for a new model to be introduced. The Compliance Spindle is postulated as a new and alternative model which is easy to understand and has the possibility of implementation in South Africa and other jurisdictions as well. The Compliance Spindle is also an effective tool to educate future compliance officers. The new model provides for all aspects of compliance and reporting and can be easily modified to take account of new developments in the mining compliance and reporting arena.

Jan 1, 2010

By C. Chongo, F. X. Paquot, C. Ngulube

"Over the last six years, the Kansanshi copper-gold mine has continued to process significant quantities of complex transitional mixed ores. Initially, the ore treated came predominantly from accumulated stockpiles. Subsequently, the feed source shifted primarily to freshly mined ore that generally showed less tarnish with better flotation kinetics, but with the downside of lower concentrate grades. A number of changes were made to improve the efficiency of the rougher circuit and quality of concentrate produced. These changes were as a result of initial mineralogical studies and laboratory flotation test work that were discussed at length in a previous paper1. Salient among the recommendations adopted as a result of previous work were increased circuit capacity and a modified configuration to increase the residence time and the number of sulphidization stages. These modifications were completed and commissioned in 2011. This, however, resulted in significantly low rougher concentrate grades and a below-specification final concentrate product. This was due primarily to higher mass pulls from the extended rougher bank with multiple concentrate discharge streams, and which necessitated an enlarged cleaning capability. The extra cleaning capacity came on stream in 2014. Of note was the development of a recovery model, based on the strong correlation between the total copper and acid-soluble copper ratio, as a tool for monitoring plant performance. IntroductionThe Kansanshi mine, the largest copper mine in Africa, is 80% owned by Kansanshi Mining plc, a subsidiary of First Quantum Minerals. The remaining 20% is owned by the state through the parastatal Zambia Consolidated Copper Mines Ltd (ZCCM). The mine is located approximately 10 km north of the town of Solwezi and 180 km to the northwest of the Copperbelt town of Chingola. The mine has been in commercial operation since 2005."

Jan 1, 2016

By S. J. Moema, M. G. Maruma, L. A. Mampuru, M. E. Maja

"The most commonly used high-chromium white cast iron (HCWCI) is the hypoeutectic white cast iron that contains 2–3.5 wt.% C and 10–30% Cr. This type of material relies on hard, brittle M7C3 carbides to impart good wear resistance. Due to its good wear resistance, this material has found application in the mining industry and cement industry. However, it has low fracture strength and this challenge led to research aimed at refining the microstructure. This was done by the addition of niobium in the range between 0.1 and 0.6 wt.%. In the as-cast condition, the addition of niobium was found to increase the fracture strength due to the finer eutectic microstructure. The hardness was also found to have increased slightly compared to the reference alloy with no niobium additions. Low fracture strength after heat treatment was observed in the Nb-added HCWCI, which is believed to have been caused by the precipitation of secondary carbides and the transformation of the matrix from austenite to martensitic. IntroductionFor the past few years Mintek has been involved in a project in which a number of alloys have been identified for grinding media applications. The high-chromium white cast iron (HCWCI) alloys were among the alloys researched for this application. The knowledge acquired from the grinding ball media research has now been extended to mill liners, which have traditionally been made of manganese-, chromium- and chrome-molybdenum steels. The replacement of worn mill liners costs the mining industry a significant amount of money and this has led to a need for continuous research to prolong the life of the liners. During milling operations, liner wear has an adverse effect on the capacity of the mill, the energy efficiency and milling efficiency and finally leads to relining, to replace worn liners."

Jan 1, 2016

1. New books Extractionmetallurgy'81. London, Institution of Mining and Metallurgy, 1981. 441 pp. $40. Structures and properties of engineering alloys, by W. F. Smith. London, McGraw-Hill, 1981. 512 pp. R89,65. Rock and mineral analysis, by W. M. Johnson and J. A. Maxwell (editors). 2nd ed. New York, Wiley, 1981. 424 pp. $40. Mining methods and equipment, by Mining Information Services. London, McGraw-Hill, 1981. 218 pp. International directory of acronyms in library, information and computer sciences, by P. M. Vaillancourt. New York, Bowker Publishing Co., 1980.516 pp. 2. New journals Trends in analytical chemistry (TRAC), Amsterdam, Elsevier, 12 issues per year. Subs. for Volume I (16 issues) D.H 95.50. Engineering management international, Amsterdam, Elsevier, 4 issues per year. V.S. $32.50, D.H. 70.00. 3. Mineral policy sector publications Mineral Bulletin MR 188. Vanadium: an imported mineral commodity. $3.60. Mineral Bulletin MR 190. Canadian mines: 1980 perspective. $3.00. Canadian mineral survey 1980, by the staff of Mineral Policy and Energy Sectors. $1.00. 4. NIM reports Report 2090 Observations made during the dig-out of a 48 MV A ferrochromium furnace. Report 2110 The investigation of a fracture on one side of a skip bridle in a mine shaft. Report 2111 Pilot-plant tests for the recovery of chromite and the noble metals from the UG-2 Reef at Maandagshoek. Report 2112 The behaviour of UG-2 chromite concentrates during smeUing. Report 2113 M uUivariable control of a milling circuit at East Driefontein Gold Mine. Report 2115 Estimation of material variation in powdered materials Report 2116 Optimum operation of a direct-reading spectrometer with excitation by a 5 kW inductively coupled plasma torch. Report 2121 Five robust indicators of central value. Report 2124 The direct determination, by differential pulse anodicstripping voUammetry at the thin mercury-film electrode,of cadmium, lead, and copper. Report 2127 The preparation of a reference material of South African zirconium concentrate from Richards Bay. Report 2128 The determination, by differential pulse anodic-stripping voltammetry at the thin mercury-film electrode, of cadmium and thallium in six NIMROC reference materials Report 2130 The organizing of conferences. Research grant The Board of Directors of International Precious Metals Institute in conjunction with Gemini Industries, Inc., a California-based refiner of precious metals, recently announced a Gemini Research Grant of $3000 will be awarded annually to a graduate student who is pursuing studies in metallurgy, chemical processes as it pertains to precious metals, or materials sciences, and who is performing or planning research studies in the precious metals. Accidents and diseases The Third International Colloquium for the Prevention of Occupational Accidents and Diseases in the Iron and Metal Industry is to be held on 15th and 16th June, 1982, in Palma de Mallorca, Spain.

Jan 1, 1981

1. Journals Marine Geotechnology, edited by R.C. Chaney. London, Taylor & Francis (Rankine Road, Basingstoke, Hants RG 24 OPR, OK), 1988. vol. 8, $50. Published quarterly. Mineral Resources Engineering, edited by C.T. Shaw. London, Taylor & Francis (address as above), 1988. vol. 1, $99. Published quarterly. 2. New publication World mining map of non-ferous metals (with 4 regional maps and a booklet). Reinhard Ryborsch (Postfach 2105, D-6053 Obertshausen bei Frankfurt am Main, West Germany). International edition: bilingual, English and German. 7 colour-print: Size (unfolded) 138 X 100 cm. US$ 19 (excl. mailing) for folded map with hard cover (Order No. 61-4); US$ 25 (excl. mailing) for unfolded (flat) map with hanging strip (Order No. 62-2). 3. Mintek reports Report M326 Crevice corosion and other localized corosion behaviour of 3CR12 corosion-resisting steel in synthetic minewaters, by D. Howarth. May 1988. 28 pp.Report M332 The carbon-regeneration furnaces at Mintek, by P.M. Cole and P.J. van Staden. Nov. 1987. 31 pp. Report M344 The flotation of pyrite with amine colectors, by R.D. Hil, E.W. Giesekke, and P.J. Haris. Mar.'1988. 25 pp.Report M345 The substitution for chromium in steels: Progress and trends, by M.B. Cortie. Mar. 1988. 14 pp.Report M346 The direct reduction of sulphur dioxide to elementalsulphur, by I. Henderson. Mar. 1988. 30 pp.Report M349 The optimization of a process using weak-base resin for the recovery of gold from plant solutions and pulps, by A. Mehmet. Apr. 1988. 17 pp. Report M353 The determination, by ion-interaction chromatography, of sulphur species in cyanide solutions, by Pohlandt-Watson, M.J. Hemmings, D.E. Barnes, and a.w. PansL Jun. 1988. 7 pp. Report M355 A laboratory-scale continuous-feed resistance furnace, by K.P.D. Pery, A.S.E. Kleyenstiber, andC.T. Logan. May 1988. 9 pp. Report M357 The determination of minor and trace elements in activated charcoal, by RT. Eddy and G.J. Wal. Jun. 1988. 14 pp. Report M358 The sensitive determination of germanium by atomicabsorption spectrophotometry using electrothermal atomization, by G.D. Marshal. Jun. 1988. 11 pp. Report M92D The recovery of tin and tungsten from various zones of the Van Roois Vley deposit, including setling and filtration, by C.F.B. Coetzee. First issued Apr. 1983; reissued Apr. 1988. 40 pp. World Environment Day Symposium* Mintek auditorium in Randburg was the venue on Thursday, 2nd June, 1988, for more than 200 interested delegates at the annual World Environment Day Symposium, organized jointly by the Federation of Societies of Professional Engineers (FSPE), The Environmental Planning Professions Inter-disciplinary Committee (EPPIC), The Habitat Council, and The Associated Scientific and Technical Societies of South Africa (AS&TS). The theme 'Cultural and Historical Conservation' was adapted from the theme of the Department of Environment Affairs for the 1988 Environment Week.

Jan 1, 1988

By D. Vogt

South African underground hard rock mines are typically managed using measurements made daily, weekly or even monthly of key parameters such as face advance, readiness to blast, blast success, temperature or dust levels. Safety and health can be greatly improved if a real-time measurement system can inform decision making. To enable this vision of widespread sensing, communication and decision support, CSIR has developed an open standard architecture for communication of sensor data, and a reference implementation using that standard. The standard is called AziSA, which means ?to inform? in isiZulu. AziSA provides an architecture that allows for connection of any type of sensor and that is particularly suited to wireless sensing. On the safety side, the CSIR is developing a suite of sensors specifically around the risk of rockfalls. Sensors such as an electronic replacement for the barring tool, or a thermal sensor that can detect loose rock, can already be used to identify potential hazards in the hangingwall. When these sensors are combined with location and time information in a single database, it becomes possible to build maps of risk and to extrapolate risk into unmined areas. It is also easy to confirm that routine safety procedures like barring are actually taking place. In the future, it is proposed that entry inspections will be made using remote techniques that will not place an individual miner at risk. While miners will still be required to bar or place support, they will do so with a clear idea of which portions of the hangingwall are safe, and which present risk. On the health side, if a network such as AziSA is deployed in the stope, it becomes much easier to monitor the condition of individual miners. The work strain experienced by miners can be monitored through heart-rate sensors, and their core body temperature can be monitored using various novel techniques discussed in the paper. Additional sensors can be added to quantify worker exposure to hazards such as noise or dust. Individual sensors allow for people who are at an unacceptably high risk of developing heat disorders to be treated timeously, and they also allow for team management based on objective measures. Over a longer period, position sensing and environment monitors, or personal dosimetry, provide a powerful management tool to prevent workers from being overexposed to hazards, and to confirm that management instructions are being followed. Cost-effective sensing in the stope is a major challenge, but one that can be overcome through technology like that used in AziSA. Sensing provides opportunities both to make immediate interventions when workers are exposed to unacceptable risk, and to manage the long-term exposure of workers to hazard.

Jan 1, 2010

Alluvial diamond deposits covered with a thick overburden cannot be explored effectively and mined profitably with the available conventional techniques. A novel directional drilling technique has been developed and site trials have been conducted at the De Beers Namaqualand Mines situated at the western coast of South Africa. This paper describes the technique developed as well as the results of the site trials. The main task of the project is to develop a tool and a supporting system to achieve a remote exploration and ore extraction method for inaccessible alluvial diamond deposits. The project involves the acquisition of a system, commissioning on-site and evaluating the information obtained during assessment. The project consists of the design -of certain tools and instrumentation for the system, investigations and desktop studies as well as development of the system's logistics. The operating philosophy of the system is based on the keyhole surgery principle. In this study a pilot hole was drilled first, starting from the surface with an inclination to reach deeply seated diamondiferous gravel layers, followed by drilling into a more or less horizontal gravel layer for a certain length and finally pointing-upwards reaching ground surface at a predetermined exit point. The pilot drill bit was then replaced with a larger diameter reamer/mining tool and an HDPE tail pipe was attached behind the reamer. The drill string was retracted back to enlarge the guide hole and flush the excavated ore to the surface through the tail pipe. The material flow in between the sections of the system was' carefully measured to assess and record the gravel recovery rates. Several horizontal holes were drilled at preplanned drill paths to reach and follow the ore layer and the Ore extraction was achieved by means of a reamer/mining tool. Principles of the concept have been proven viable in this investigation.

Jan 1, 2010

High pressure grinding roll (HPGR) technology is used in an increasingly diverse range of applications, predominantly iron ore, gold and diamonds. KHD Humboldt Wedag HPGRs are applied world-wide, and consistently prove to be well designed and reliable operating units, with their performance meeting the pre-set standards. This publication summarizes some of the features and experiences for recent applications in treatment of copper ore, coarse iron ore, and gold ore. Summary data of roll surface wear life and operating data are given, together with operational observations. In addition, effects of feed segregation and truncated feed are discussed, as well as the implications of a product recycle flow sheet.

Jan 1, 2012

By P. T. Slatter

The role of viscometers for rheological characterization in the hydraulic transport of solids is discussed, and rheological models and phenomena pertinent to the hydraulic transport of backfill material are reviewed. The two main branches of viscometry (rotational and tube) for the measurement of mining slimes rheology are compared. The effects of solids concentration, particle size and chemical additives and the practical application of rheology in backfill system design are presented.

Jan 1, 1988

By L. A. Cornish, R. Süss, M. Sephton, N. B. Maledi, J. H. Potgieter, L. Chown

The gas turbine industry is faced with a challenge to improve the performance of engines, while simultaneously adhering to stringent environmental legislation. One way of addressing the problem is by further increasing the recipient working temperatures. Unfortunately, the use of nickel based superalloys (NBSAs) in the gas turbine industry has reached its limitations. Although coatings can be used for small increases, and air cooling is also incorporated by design, attention is towards developing stronger metallurgical materials having higher melting points, with acceptable creep and corrosion resistance. A series of ternary and quaternary Platinum-based superalloys were developed. Platinum was selected because of its higher melting points compared to nickel, similar fcc structure and better corrosion properties. Mechanical characterisation studies of Platinum-based superalloys alloys, which included oxidation, creep and hardness, demonstrated reasonable results, outperforming an oxide dispersed strengthening (ODS) Fe-based superalloy (PM2000) and a nickel based superalloy (MAR-M200). During any materials development where high temperatures are concerned, high strength is the primary property of interest. However, during the development of gas turbines, component life and reliability, which are influenced by temperature, need to be taken into consideration, and therefore creep as well as corrosion (both temperature dependant properties), are important. These properties become significant with increasing temperatures. With increasing demand for higher temperatures, it is becoming increasingly important to include hot corrosion properties of the alloy during the material selection process. A short description on hot corrosion and its degradation mechanisms are given in this paper. Coatings are currently dominating as the best practical solution to address temperature increases. This paper looks at benefits and shortcomings of coatings over Pt-based superalloys as candidates for applications under extreme conditions. Key words: Hot corrosion, Pt-based superalloys, Ni-based superalloys, Coatings

Jan 1, 2006

A modified germanium recovery process in conventional zinc metallurgy, based on the understanding that ferric hydroxide has strong ability to coprecipitate germanium element, was presented. The relaxed lab-scale experiments were conducted to evaluate its technological feasibility. The experimental results obtained show the new process has great competitive advantage over the conventional one.

Jan 1, 2008

By Timo Niitti, Antti Rinne, Janne Turunen, Klaus Schommarz, Sami Grönstrand

This paper captures the essential steps employed in developing Outotec?s new FloatForceTM mechanism. The development of a flotation mechanism essentially revolves around the efficient transfer of installed power, or capital cost, to optimum flotation performance. Optimum flotation performance will be achieved if a balance between metallurgical results, operating and capital costs is maintained. The development of the FloatForceTM mechanism was done by careful evaluation of each of these three areas. This paper focuses on how experience, CFD and laboratory equipment, pilot and plant tests are used to test and evaluate a new flotation mechanism. Validated variables include mixing profile, power draw and local air hold-up. Metallurgical and mechanical design considerations are not covered in this paper. Besides using the FloatForceTM mechanism in new flotation equipment, the FloatForceTM mechanism can be used in existing flotation cell installations, thus enabling improvements in the mixing profiles, solids suspension and metallurgical performance of operating flotation circuits. Results of several tests carried out in existing plant operations are presented.

Jan 1, 2007

By M. Kannenberg

When coal properties are estimated geostatistically for mine planning in the hardcoal industry, there is one important supposition which influences the reliability of prediction of economically profitable parts of the deposit. This is the fact that activities in hardcoal exploration and mine planning are characterized by distinct levels of information and knowledge upon which decisions of economic import must be based, for example, whether exploration should proceed or not, or which methods and strategies should be used to maximize search efficiency. To get more reliable results for mine planning, in particular, advanced kriging methods (e.g. conditional simulation) have to be introduced and checked for their reliability in historical analyses (post-mortem studies). By using this feedback, kriging results from underground samples or production data can be compared with results gained by advanced geostatistical methods from exploration boreholes.

Jan 1, 1987

By L. A. Sandham

Environmental impact assessment (EIA) in South Africa is administered by the Department of Minerals and Energy (DME) for the mining industry, and the Department of Environmental Affairs and Tourism (DEAT) for all other sectors. Thus far, EIA research has focused on the process under the auspices of DEAT but none has focused on the EIA process that has been mandatory in the South African mining industry since 2004. Using the Lee and Colley(Lee et al.13) review package as a basis, a review model specifically tailored to the needs of the mining industry was applied to review the quality of a sample of 20 environmental impact reports (EIRs)approved by the DME. Results reveal that 85% of the EIRs are of a satisfactory quality. Presentational and descriptive components generally achieved higher quality grades than the analytical components such as impact magnitude and alternatives. The results show that in spite of some areas of weakness, and in spite of being conducted in terms of different legislation, EIR quality in the mining sectors appears to conform to the overall standard of quality of EIRs in other sectors in South Africa, and is also on a par with quality abroad. Hence, despite the criticism that DME is usurping the role of DEAT, it is concluded that EIRs of comparable standard are being produced, and that the quality of EIRs in the mining sector do not provide supporting evidence for this criticism. However, EIR quality is only a single aspect of EIA effectiveness, others including action and implementation of EIA proposals and mitigation measures.

Jan 1, 2008

By W. J. Kempson

As a result of the rising electrical energy costs in South Africa, a method was sought to reduce the overall electrical consumption of typical shaft systems. A typical shaft configuration was analysed and the primary energy consumers were identified. The ventilation fans for this system were found to consume 15% of the total energy of the shaft system. It was calculated that more than 50% of this energy is consumed by the shaft itself, more specifically, by the pressure losses that occur in the shaft as the ventilation air passes through it. In order to ensure that the theory being used for the evaluation of these shaft systems is accurate, a total of five shafts were instrumented and the actual pressure losses over the shafts plotted against time. These shafts were then analysed from a theoretical perspective. Finally, in order to ensure a thorough understanding of the behaviour of the ventilation air in shaft systems, the systems were simulated using computational fluid dynamics (CFD) techniques. There were significant discrepancies between the theoretical analysis and the CFD simulation during the initial comparisons. This discrepancy lessened as the complexity of the CFD models increased, until when the complete shaft was modelled using the full bunton sets, the pipes, and the flanges, the difference between the theoretical evaluation and the CFD simulation was small. This result demonstrates that the theory is insufficient and that the interrelated effect of the buntons and fittings has not been fully appreciated by current theory. The final phase of the work presented here was to evaluate the costeffectiveness of using different bunton shapes and shaft configurations. It is shown that the increase in the pressure losses and therefore the direct operating costs of the shaft can vary by as much as 80%, depending on the bunton configuration chosen. The placement of the piping in the shaft can increase the pressure losses, and therefore the direct operating costs of the shaft, by as much as 12%, depending on the placement of the piping in the shaft; this effect includes the use of flanges. The use of fairings on a large cage can reduce the resistance that the cage offers to the ventilation flow by as much as 30%. This, however, does not translate into a direct saving because as the cage moves through the shaft, the overall effect is transitory. These savings can be significant when the items highlighted in this work are applied correctly. Keywords shaft design, ventilation, energy consumption, modelling, CFD.

Dec 1, 2013

By Z-B. Cheng, X-J. Liu

"Intensive mining of shallow coal seams tends to result in severe subsidence of the ground surface. Surface subsidence is a complex dynamic spatiotemporal process that constantly changes as mining advances. With Liangshuijing coal mine as a case study, 3DEC numerical software was used to simulate the development of the moving subsidence field from open-off cut to full subsidence on the working face. The results demonstrate that the formation of a subsidence field is directly related to the coal seam depth H and the extent of the mine workings. Taking the advance distance of the working face as the unit of scale, the process of surface subsidence can be divided into four stages: micro-change (H/ p), the development of surface subsidence (2H/ p), the formation of a movement subsidence field (3H/ p), and dynamic balance (4H/ p). The changing movement of a subsidence field can be fully described by the characteristics of surface subsidence value, curve slope, and the inflection position. The results provide important technical support for predicting surface subsidence and the temporal–spatial evolution features of mining subsidence. IntroductionChina’s coal output was about 3.52 Gt in 2017 (China National Coal Association, 2018), making it the largest coal producer in the world, accounting for almost half of total world coal production. Coal production and distribution play a vital role in the energy industry of China. However, entire overlying strata, from coal seam to surface, are disturbed as a result of long-term, high-intensity and large-scale mining, causing surface subsidence. This results in groundwater loss, surface desertification, vegetation loss, and mud-rock flows. These issues have become topics of common concern throughout society. According to related research results (Liu 2008), the area of surface subsidence caused by coal mining in China has reached about 600 000 ha, some 0.2 ha (and up to 0.42 ha) of surface subsidence for every 10 000 t of coal produced. Surface subsidence disasters not only damage buildings, water conservancy, transportation infrastructure, and farmland, but also cause adverse effects on individual and community lifestyles, environmental hygiene, and economic development. Deterioration of the ecological environment in mining areas has a long history and is very harmful (Lu, 2015)."

Feb 1, 2019

By H. Edinger

China?s engagement with the African continent has increased impressively in the past decade. Even though China is not the African continent?s largest stakeholder, the rapidly increasing engagement is evident in the huge number of Chinese migrants that have come to Africa in the wake of unprecedented trade and investment levels, as well as in increasing diplomatic and political interactions, which has taken most other commercial partners by surprise. All but four countries in Africa have adopted the ?One China?1 policy stance; and in so doing opened the door for new or strengthened commercial dealings with China, including increasing investments into Africa?s extractive industries. This has been particularly evident since the turn of the century, with a clear shift in China?s policy towards Africa elevating the continent in China?s foreign policy objectives. As such, Africa has become a strategic focus2 for Chinese outward bound and internationalizing companies, especially in the extractive industries. This planned shift in focus is based largely on geo-strategic and commercial needs and interests, rather than previous ideological ones.3

Jan 1, 2011

By N. Graham, C. Walker

The SORD Miner is a patented mining principle being developed to exploit mineral and energy resources that current technology can not access. SORD Miner is designed to operate in underground wet, granular, continuously collapsing geological environments such as alluvial and marine deposits. It is somewhat like a cutter suction dredge and should be capable of mining its way through any fine granular material like sand or gravel, pumping the slurry back to the surface. In areas where the target layer is covered, the SORD Miner is inserted below the water table and will tunnel its way to the mineral deposits at depth. This paper describes the development, concept testing and prototype construction of the SORD Miner.

Jan 1, 2007

By E. Dervaric

The main purpose of this paper is to introduce the main strategic restructuring aspects of companies that are directly (coalmines) or indirectly (companies that depend on coalmines) linked to coalmining. An attempt is also made to determine the principal factors required for the successful execution of a restructuring process in companies focused on the basic activities of coalmining, such as companies that provide supporting activities. The restructuring process exerts an influence on the whole area that relies on coalmining. So coordination of activities among the government, the local community, and the coalmine is very important. This is the major premise of this paper. The first section of the paper focuses on identifying and analysing the key factors in restructuring and a selection of key methods, drawing on past and present practice. The key factors to be considered in a model of enterprise restructuring in the coalmining sector are considered. The second section is dedicated to the actual design of the model of enterprise restructuring in the coal industry. The proposed model is based on positive experiences in the restructuring of coalmining companies in Europe, with an emphasis on Slovenia, successful approaches to crisis management in corporations, and identifying key areas in bringing about a strategic turnarounds in company operation. To support the argument for the key business areas, a brief summary of empiric findings has been included to demonstrate the applicability of the proposed model and the restructuring process. The summary is based on the survey done in both Slovenian coalmining companies (especially in Velenje Coal Mine) and their subsidiaries. The conclusion integrates key findings and outlines issues for further consideration and discussion. Keywords: restructuring, coalmining, Velenje Coal Mine, strategic factors, restructuring model.

Jan 1, 2008

By R. L. Castro

Currently, in several caving operations, the spacing between the drawpoints is determined by consulting Laubscher's design guide (Laubscher 1994, 2000), a methodology based on the gravity flow characteristics of the caved rock. Laubscher's methodology is based upon the height of interaction between adjacent flow zones, but does not allow calculation of primary recovery for a given layout. In this paper the authors present a technical and economic methodology based on the flow that occurs near the drawpoint and the associated development costs to estimate the optimal spacing. The flow model at the drawpoint was validated at the El Teniente mine, which extracts coarse caved rock. To validate the flow model, small-scale simulations using drawpoint clusters were conducted and results compared to extracted grades, marker recovery, and drill holes to determine ore remnants that are part of the production control programme at the mine. The results indicate that primary recovery depends on the height of interaction, which varies with the friction angle of the caved rock and the spacing between adjacent drawpoints. Primary recovery estimations indicate values from 85 per cent to 97 per cent depending on the drawpoint spacing used. Extrapolations were then conducted to estimate the primary recovery for different drawpoint configurations planned to be used in the New Mine Level of the mine. The results indicate that the optimal drawpoint spacing is 32 m x 20 m with a through length of 18 m. The methodology developed may be used to estimate optimal drawpoint spacing for block caving mines under different metal prices and mine cost conditions.

Jan 1, 2012