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By C. Chibwe, M. Tadie

Copper electrowinning models are useful for prediction of process performance, optimisation and improved understanding of complex phenomena such as current distribution without the expense of physical experiments. Recently, finite element models such as those generated in COMSOL Multiphysics have been developed for the electrowinning process. The predictive capacity of these models is improved by incorporating physical and chemical phenomena. Since physicochemical properties of electrolytes can have a significant effect on the quality of copper produced, this work was conducted to investigate the effect of such properties on electrodeposition at varying levels of copper, sulphuric acid concentration, iron concentration and temperature, in the presence of a smoothing agent. Tests were conducted at conditions similar to those for industrial copper electrowinning. Mathematical correlations were developed for the following properties; density, conductivity and diffusivity which were compared to existing models in literature and thereafter applied in a COMSOL generated model. The model predicts, current distribution at the cathode surface, deposit thickness (morphology), concentration of species within the cell and current efficiency. Current distribution output shows the impact of several phenomena on the deposit generated including the relationship between increasing copper concentration and current density and lack of influence of acid concentration on this property. Keywords: Electrowinning, physicochemical properties, electrolyte composition, modelling

Jan 1, 2020

By K. Premlall, R. M. Dire, H. Bissett, D. Delport

Tungsten carbide is a fine grey powder. It can be formed into shapes by compacting with the addition of a binder. Spherical particles are generally preferred in additive manufacturing as they pack together more efficiently than non-spherical particles, promoting a uniform powder bed density, better flowability, and elimination of internal cavities and fractures, resulting in a better quality of final product. The particle shape of powders can be transformed into spherical through the process of spheroidization. However, due to its high melting point, tungsten carbide could be difficult to spheroidize. Tungsten carbide was spheroidized using an inductively coupled radio frequency plasma at various plate powers between 9 and 15 kW. The influence of additional H2 in the sheath gas on the chemical composition of the tungsten carbide product was also investigated by means of XRD, which indicated that WC is converted to W2C at higher H2 concentrations. Optical analysis of SEM micrographs indicated that the spheroidization ratio increased with increased plasma energy.

Apr 1, 2021

By J. R. Percival, L. Ip, M. D. Piggott, S. J. Neethling

Component wear due to particle-laden flow is a significant challenge in the minerals processing industry in the handling and transportation of abrasive mineral slurries. Studying wear through experimentation is time-consuming and expensive; therefore possessing the ability to accurately simulate, understand and predict wear in these complex environments is highly desirable. The ability to predict wear is important in both the design of equipment in order to maximise the performance over the wear life of the components, as well in minimising potentially costly and dangerous failures and unscheduled maintenance.. Particle-induced wear is a complex problem, requring an understanding of coupled fluid-solid motion, geometry deformation in response to fluid-solid behaviour, moving geometries and wear modelling. Although the literature demonstrates that rebounding particles and changes to surface profiles can have a significant effect on subsequent wear rates and patterns, the challenge of implementing a model to account for this effect in complex geometries has been addressed by only a few authors in the literature. This paper describes a new wear simulator, leveraging fluidity, an open-source, massively parallel, finite element based CFD simulator capable of unstructured adaptive meshing. The wear simulator includes the ability to model particle-laden flow using representative Lagrangian particles and dynamic remeshing of geometry in response to wear and component movement. These capabilities are demonstrated using wear and the associated dynamically deforming boundaries within a Coriolis tester arm, with the results comparing favourably with the experimentally observed wear patterns. Keywords: CFD, wear, two-phase flows, anisotropic mesh adaptivity, boundary deformation

Jan 1, 2020

By Keith Rowley, Neal Harries, David Noon

The management of risks associated with slope instability is an essential process in the safe and economic operation of open cut mines. The ?slope stability radar? (SSR) has been developed to better manage those risks. The SSR remotely scans rock slopes to continuously measure any surface movement and can be used to detect and alert users of wall movements with sub-millimetre precision. The high level of movement precision and broad area coverage of the rock face can allow for a better understanding of the geomechanics of slope deformation, including magnitude of potential failures and additional warning time of impending instability. Additionally, radar waves adequately penetrate through rain, dust and smoke to give reliable measurements, 24 hours a day. SSR systems have been deployed in many mines in Australia, Indonesia, South Africa, Zambia, Chile and the United States. Greater than 70 rock falls and waste dump failures (from several to millions of tonnes) have been monitored, and on every occasion precursor ?warning? movements were recorded by the SSR. This technology enables a radical change in the management of risks in open cut mining. This paper will present recent case studies of the SSR operation in coal and metalliferous mines.

Jan 1, 2006

By D. A. Vetter

A novel mathematical model is presented which describes the behaviour of beds of particles, of uniform size and shape but different densities, during autogenous separations. The approach used in the formulation of the dispersion model is a phenomenological one based on a statistical view, which leads to a diffusion-like representation of the autogenous-separation process. Although the model currently considers only density-related phenomena, it accounts quantitatively not only for the density-segregation aspects of the process but for the interactions between the particles. Quantitative predictions of the dispersion model are compared with the results obtained in tests using a specially constructed experimental batch jig, and it is shown that the model provides an adequate quantitative description of the process for particles of uniform size and shape. It is pointed out that, for the description of more complicated autogenous separations, a more rigorous formulation of the particle drag and density-segregation terms will have to be incorporated into the dispersion model. Nonetheless it is concluded that the model as presented in this paper provides not only a novel insight into the mechanisms of autogenous separations but a means by which to analyse similar systems.

Jan 1, 1987

By S. Tu, Y. Yuan, H. Wei, Z. Chen, M. Jia

"To reduce production costs and increase efficiency in ageing coal mines, a system that utilizes two shearers in a fully mechanized longwall working face is proposed. Using theoretical and engineering experience, three issues pertaining to the system were determined: (a) the two-shearer mining technique; (b) matching and modifying the equipment; (c) and coal-cutting task allocation for each shearer. Two mining processes are proposed, with the two shearers travelling in either the same or opposing directions. To avoid breakage of chains and pan extrusion of the armoured face conveyor (AFC), the length of the AFC ‘snake’ was controlled. To ensure continuous cutting and transporting of coal, the cross-sectional dimensions of the AFC were checked and the shearer closer to the head drive was modified. Based on the assumption of equal cutting times for each shearer, the meeting position of the two shearers was obtained by using a theoretical model of mining task allocation. Application of this technique at No. 2 Jining Mine, China, has shown remarkable benefits: daily production capacity was increased by 54% and personnel efficiency was improved by 33 t/d per person. IntroductionAll coal mines aim to increase the unit output of the working face to reduce mining costs and improve the economic efficiency of the operation. To achieve this goal, a production model known as one mining face of the mining area has been adopted by most Chinese coal mines (Hu, Meng, and Zhu, 2008; Zhang, Zhang, and Wang, 2000). Under these conditions, the main technical approaches to maximize the output are increasing the width of the working face (Qu, Xu, and Xue, 2009) and accelerating the advancing speed (Robbins, 2000). In coalfields with shallow seams, the width of a fully mechanized face exceeds 300 m (Ju and Zhu, 2015; Fu, Song, and Xing, 2010); in coalfields with deep seams, the width of the face is usually greater than 240 m (Liu et al., 2016; Li et al., 2013). The term ‘super-long working face’ was proposed to describe working faces with a width of over 240 m (Zhao and Song, 2016; Xu et al, 2007) in China. To support these long working faces with rapid advancing speeds, high-powered mining equipment is required (Kulshreshtha and Parikh, 2001, 2002; Tu et al., 2009; Mishra, Sugla,and Singha, 2013). This is easily achieved in newly built mines, but is not a good choice for ageing mines because of the low return on a high investment on account of the limited remaining resources. It is therefore difficult for ageing mines to significantly increase their unit output with the existing mining equipment. This study focused on this problem: two shearers were applied to a longwall fully mechanized working face (LFMWF) to achieve increased unit output."

Oct 1, 2018

By S. V. Lukichev, O. V. Nagovitsyn, V. V. Laptev

In this paper the authors describe the developed algorithms of short- and medium-term planning of underground mining operations. The algorithms were developed using the example of the flat-back cut-and-fill method, and provide multifactor accounting of mining conditions, technical and technological limitations: state and properties of the rock mass; the current mining situation; mining rules; availability of safety pillars; properties of the filling; additional characteristics of technological objects that complicate the driving of workings; sufficiency of human and technical resources; employee specialisation; existing machinery and equipment; opportunities and limitations of the transport scheme of the mine, and work schedule. The paper is presented by means of a dynamic model of mining development, which shows the sequence of mining operations in the mine workings. Besides animation, the tool provides an opportunity to form tabular and graphical reports.

Sep 1, 2021

By M. Steyn

Until 2000, pricing involved profit taking and cost covering combined with limited global published information. Market information was mostly subjective in nature and large resource companies benefited exclusively from aggregated company information and data. The market constituted producers and consumers only. The nineties saw massive cost cutting drives and re-engineering initiatives and this underwrote the structural changes evident in the late 1990s? economy. This supported South African producers on the international FOB cash cost curve, and ensured profitable coal mining operations. As the debate on relative scarcity of fossil fuels ensued, producers and buyers looked to the developing terminal coal market for direction. The much needed direction was provided when the API coal indices were developed and derivative trading was embraced to include financial institutions, trading houses and hedge funds. The liquidity of coal trades increased rapidly and vastly and market information became obtainable on a daily basis. Interpretation of current and future coal prices became available to all market players and contributed to the sophistication of the market that is now able to participate in risk management of prices, capital expenditure and brownfield developments.

Jan 1, 2010

"Coal seam gas problems can adversely affect the safety and productivity of underground coal mines, leading to fatalities and financial losses. Conventional gas management technologies using ventilation and gas drainage are unable to deal with the high and irregular gas emissions associated with high-production longwall mining. New technologies need to be developed to supplement the traditional gas management techniques to minimize the hazard of coal seam gas. Thin spray-on liners (TSLs) have gained some success for rock surface support since their introduction to the mining industry. Due to their relatively low permeability and appropriate mechanical properties, TSLs also show potential to be used as a gas management tool in underground coal mines.In this paper we review the current gas management challenges and discuss the potential use of TSLs as a gas management tool in underground coal mines. This may involve reducing gas migration into the excavations/roadways, enhancing in-seam gas drainage, and preventing spontaneous combustion. Some potential areas for future research work are identified. IntroductionWhen a coal seam is influenced by mining activities, gas stored inside is liberated into the underground ventilation system. Gas emissions have created serious difficulties for the coal mining industry around the world. Therefore, coal mines have to develop effective strategies to control the gas concentration below the threshold value to meet statutory requirements. Ventilation has been the first solution in gas management for underground coal mining. When the emitted gas cannot be effectively diluted by ventilated air, gas drainage using pre- and/or post-drainage has to be introduced. However, even with ventilation and gas drainage, irregular gas emissions usually increase the gas concentration in roadways and slow down the development rate, thus causing significant economic loss to the coal mining industry (Thakur, 2006). Therefore, new technologies need to be developed to address this issue and mitigate the explosion risk."

Jan 1, 2016

By J J. Pretorius, G M. Hoffmann

Utilisation of lower-grade (<60 per cent Fe) resources, not utilised in the current products, is crucial to ensure optimal resource utilisation and maintaining/improving future profit margins by reclassifying low-grade material to ore. The purpose of the Sishen Expansion Project (?SEP?) is therefore to investigate the technical and financial viability of producing up to an additional 10 Mtpa of new products at Sishen from material currently classified as low-grade materials. Jigging technology has progressed to a point where Sishen?s 50 to 60 per cent Fe run of mine (?ROM?) material, once considered as waste, can be beneficiated to produce a saleable 64 per cent Fe product. This has been confirmed through appropriate beneficiation testwork. Consequently, Sishen can now produce saleable product from material not currently included in the resource definition, increasing the resource base of the mine significantly and ensuring higher resource utilisation. Mine Planning utilised the geological models to produce detail planning schedules, reflecting the current and SEP plants separately, optimised to comply with product specifications of both the current and SEP plants and to confirm the viability of the low-grade resources identified as SEP feed material. The SEP products specifications have been derived by optimally matching iron ore market requirements with the revised resource base. A 64.0 per cent Fe lump product and a 63.5 per cent Fe fine product are the optimal SEP products. The SEP plant will be able to produce 10Mtpa at an average yield of 60 per cent and a lump to fine ratio of 62 to 38. The plant consists of five major sections namely crushing, material preparation, beneficiation, final product handling and quality control services. Maximum integration with the current Sishen plant was considered. Kumba currently has an agreement with Transnet to rail up to 23.5 Mtpa through the Sishen Saldanha Iron Ore Export Channel (?IOEC?). Transnet and Sishen Iron Ore Company have signed a Definitive Agreement that deals with the expansion of IOEC?s capacity, which increases Kumba?s entitlement from 23.5Mtpa to 35.0Mtpa. The detailed enviro-legal impact assessments for the SEP indicated that the project has low enviro-legal risk as a result of it being a brownfields project incorporated into the current Sishen operations.

Jan 1, 2006

By K. C. Corin, M. S. Manono

The drive to reduce water usage globally has led to the mining industry reassessing its water usage - owing to past environmental degradation due to effluent discharge, tailings disposal and process water seepage into the water-table (Haggard et al., 2015). Factors such as water scarcity and environmental restrictions have created the necessity for recycling of process water in mining and other industries. Water recycling, however, causes an accumulation of ions in the process water, which may affect the strength of reagent action on the target mineral and in turn critical aspects of flotation may be impacted. Prior studies have shown that certain ions have specific effects on flotation: for example, calcium and copper have been found to enhance the adsorption of depressant onto gangue (Feng et al., 2013, Wang et al., 2016). Calcium and sulfate ions have been seen to give a higher concentrate grade than other ions present in process water (Manono et al., 2012). An increase in ion concentration will increase the mineral grade due to a decrease in entrainment (Corin et al., 2011). This study considers the impact of ion accumulation on reagent action and flotation response. Keywords: Flotation chemistry, water quality, ionic strength

Jan 1, 2020

By D. Sager

Middleburg Ferrochrome (MFC), a company in Samancor Chrome, commissioned a new ferrochrome smelter in March 2009. This is a 60 MW DC-arc furnace with a DC power supply for the smelting of Transvaal chromite ore fines. With the benefit of 12 years&apos; experience with this technology while operating a 44 MW DC-arc furnace, MFC mitigated all known challenges and considered up-scaling risk in the new plant, which had a rapid ramp-up to full power in 02 of 2009. Good operating practices, as made possible by robust equipment selection, including a thyristor rectifier set of proven technology, and operation with optimal slag chemistry, leads to a safe and effective plant operation. With the optimized furnace design and a correctly sized power conditioning system, using only standard (static) harmonic filters and a correctly sized smoothing reactor, the arc furnace is not a &apos;dirty load&apos; for the utility, staying well within IEC limits for power quality. A patented arc compensation system is installed and allows for full arc position control (to compensate for magnetic field induced arc deflection) so that a symmetrical crucible is maintained, significantly benefiting refractory life. The principal benefits gained from the MFC process is the fact that ore fines are processed, without metallurgical coke, and higher chrome recoveries are achieved compared to other smelting technologies when using a DC open arc for smelting. Keywords Samancor Chrome, Middelburg Ferrochrome, ABB, smelting, DC arc furnace, arc compensation, power factor correction, anode, harmonics, thyristor, reactor, maintenance, refractory, ores, reductants.

Jan 1, 2010

By Z Bagheri, E Moosavi

Identifying the exact borders of geological domains and assessing the uncertainty of these borders are crucial steps in resource estimation. This potential field method was designed to build 3D geological models from data available in geology and mineral exploration, namely the geological map and a digital terrain model, structural data, borehole data, and the geologist’s interpretations. The resource evaluation of a copper ore deposit is often performed in three steps: (i) delimitation of the boundaries of the units corresponding to the various geological formations or ore types; (ii) estimating densities; and (iii) estimation of grades within each unit. In simple cases (e.g., a series of sub-horizontal layers), the geometric model can be built using 2D geostatistical techniques (kriging or co-kriging of the elevations or thicknesses of the various horizons) which also quantify the uncertainty of the model. A 3D model of Cu grade is generated using ordinary kriging; however, the indicator kriging method is run to design a 3D model of rock types by incorporating the drilling results. Block models of geophysical and geological characteristics are included in a similar 3D mesh to investigate their relationships in copper mineralisation.

Sep 1, 2021

By G. C. S. Burns

"A system has been developed to simulate the mining of the Mufulira orebody. The main output from the system is a picture-gram from which the start date and effective life of all proposed mining faces can be measured. This information provides schedule dates for the completion of major capital development projects and stope preparation activities.The orebody must be divided horizontally into main levels and vertically into blocks of equal interval. Ore reserves are defined by specifying the tonnage contained in each block and main level. Mining faces are defined by their co-ordinates, and may themselves be split into sublevels. The simulation maintains an echelon between contiguous sublevels. Other face parameters control the speed of mining, the availability and relative priority of the face.The required production from each crusher/shaft system is specified. The technique of simulating the mining process in order to achieve the required production is described."

Jan 1, 2014

By S. C. Everett, I. S. Schache, P. A. Bannister, G. F. Balderson

The Pooncarie Project is located in the Murray Basin region of Australia. This region is a potential new mineral sands province. Due to the geological environment and the lithology of the deposit, these deposits have some technical challenges that need to be addressed prior to their successful development. Within the Pooncarie Project the Ginkgo deposit will be developed first. The technical challenges it presents include its geographical isolation, the requirement to remove substantial quantities of overburden as well as the processing issues raised by the highly weathered nature of the ilmenite family of minerals. Ore characterization bench scale testwork and bulk sample pilot plant programmes have been carried out and the data obtained used to design flowsheets for both the wet plant and mineral separation plant circuits with the flexibility to enable these plants to handle the variable heavy mineral assemblage. In addition to the solving of the processing challenges, technical issues such as removal of overburden for the minimum unit cost, the use of hyper saline water in the dredge pond and the provision of infrastructure, have had to be addressed. None the less, the orebodies making up the Pooncarie Project have many positive features including low slimes content, good rutile and zircon grades and the ability to recover most of the ilmenite family of minerals into acceptable TiO2pigment feedstocks. The development of the project is set to proceed with the establishment of mining operations on the Ginkgo orebody feeding a mineral separation plant at Broken Hill. The initial shipment of products is expected to occur in early 2005.

Jan 1, 2003

By T. Feroze, B. Genc

"The ventilation of underground coal mines plays an important role in minimizing the risk of methane and coal dust explosions. The ability of ventilation, with the use of line brattices (LBs), to remove methane and coal dust in empty headings is dependent on the amount of air leaving the LB and entering the heading. The quantity of this air depends on the associated system variables, namely heading dimensions, settings of the LB, and velocity of air in the last through road (LTR). However, the exact effect of these system variables on the flow rate at the exit of the LB in an empty heading is not known. The installation of LBs in South African coal mines is generally carried out based on experience. This can result in overor under-ventilation and may increase the cost of providing ventilation or cause accidents, respectively. In this paper, using computational fluid dynamics (CFD), the air flow rate at the exit of the LB in an empty heading was estimated using full-scale three-dimensional models. The CFD model used was validated using experimental results Firstly, the settings of these three system variables were varied, the flow rates at the exit of the LB were measured, and finally the results were used to calculate the effect of each system variable. The outcome is a mathematical formula that can be used to estimate air flow rate at the exit of the LB in empty headings for any practical scenario.This paper will help the coal mining sector in South Africa by providing estimation models based on scientific reasoning for the installation of LBs, and will also serve academia as part of the curriculum towards educating future mining engineers."

Jan 1, 2016

By G. P. Dyke

The MRMR classification system was developed specifically for mining applications, namely caving operations, and is one of three rock mass classification systems used in the South African mining industry today. Increased usage of the MRMR classification system has raised concerns that it does not adequately address the role played by discontinuities, veins and cemented joints in a jointed rock mass. To address these concerns, Laubscher and Jakubec introduced the In-Situ Rock Mass Classification System (IRMR) in the year 2000. Although the IRMR system is more applicable to a jointed rock mass than the MRMR system, a quantitative comparison of the MRMR and IRMR classification systems indicates that there is not a significant difference between the resultant rock mass rating values derived from the two classification systems.

Jan 1, 2008

By S. K. Murphy

A partial shaft pillar extraction project was embarked on at a mine in the West Wits mining region in South Africa. Prior to the extraction, a rock engineering assessment was conducted with the main objective being to establish which areas of the shaft pillar could be extracted without unduly affecting the stability of major infrastructure within the shaft pillar. Standard numerical modelling methods were used to conduct this assessment and several areas were identified for extraction. However, during the extraction process, it was found that the infrastructure was affected more than was originally predicted by linear elastic modelling. In addition to this, several large events resulted in far more large aftershocks than would normally be predicted. In order to gain an understanding of this phenomenon, seismic data was integrated with numerical modelling as follows: > The seismic data in the form of displacements was integrated in 3D space within the model to assess the effect of static stress changes associated with seismic activity > Data from large events was integrated onto specific structures, where displacements associated with large events were integrated onto the plane of structure in question. This paper describes the methodology and results obtained from each of the above processes and include insights into the mining process that were previously unfathomable using standard linear elastic numerical modelling. The way forward for this rock engineering assessment of partial shaft pillar extraction is also discussed.

Jan 1, 2012

By M. Pierce, E. Karampinos

"One of the main challenges in the numerical modelling of ground support in underground excavations is to reproduce the performance of the sequential installation of the reinforcement while capturing the rock mass behaviour of an advancing face in 3D. The 3D modelling approaches used to simulate the progressive advance of excavations are mostly continuum and often cannot reproduce the rock mass failure mechanisms. The 3D discrete element method (DEM) can better reproduce structurally controlled rock mass failure mechanisms and can explicitly represent the reinforcement elements. This paper builds on previous work that reproduced the structurally controlled squeezing conditions in an underground hard-rock mine using 3D DEM and the in situ behaviour of reinforcement under pull conditions. It addresses important issues on the way reinforcement is explicitly introduced in discrete element models. A pseudo-3D model is employed to overcome the computational restrictions and time limitations of a 3D modelling approach. The work focuses on the scaling of the material properties of the ground support elements when the thickness of the model is not equal to the out-of-plane spacing of reinforcement. It demonstrates the scaling methodology based on the type of the modelled reinforcement elements used and investigates the significance of this approach. The advantages and disadvantages of this approach with respect to 2D and 3D methods are discussed. The results are compared with field data and previous modelling work done at the mine. IntroductionNumerical models can provide significant insight into the anticipated behaviour of underground excavations. The modelling of ground support, however, is not a trivial exercise. An effective representation of ground support in underground excavations should capture the behaviour of both the rock mass and the support elements. When numerical models are used for design purposes, the complexity of the problem requires significant time and expertise (Sweby, Dight, and Potvin, 2016).At a laboratory scale, numerical models have successfully reproduced the results of laboratory tests on rockbolts by explicit modelling of the bolt, the borehole, and the grout. Chen and Li (2015) used a continuum FLAC3D (Itasca Consulting Group Inc., 2012) model to simulate the mechanical behaviour of D-bolts as observed experimentally. Grasselli (2005) used a 3D finite element code to model the behaviour of fully grouted rods and expandable bolts under shear."

Dec 1, 2018

By C. A. Preece

Finsch Diamond Mine, part of De Beers Consolidated Mines (DBCM), is situated between Kimberley and Postmasburg in the Northern Cape, South Africa. The kimberlite pipe was discovered in 1960 and De Beers assumed full mining rights three years later. Production commenced in 1966 from an opencast mine, and the operation moved underground in 1990 by developing and implementing a new mining method of blast hole open stoping. A mechanized block cave was brought into production in 2005. While block caving was not new to DBCM, with productive caves having operated in Kimberley and Cullinan, from the outset, the Finsch caving operation was designed as the most advanced with a semi-automated ground handling system. The extraction level was laid out as a single sided herringbone system due to the very poor ground conditions on the south side of the pipe. These factors combined to create a unique environment, which necessitated a completely new approach to draw control. The required system was developed by a team consisting of DBCM personnel from head office and Finsch, GEMCOM and Sandvik-Tamrock, the equipment manufacturers. It was essential that the system could be run quickly, provide daily updates and issue calls directly to the LHDs. It was also important that the base data were obtained from the resource model, which was to be depleted on a monthly basis, thus forming a close link between mine planning and draw control. A further requirement of the system was that it would form a central database for the extraction operation where all data pertaining to delays and changes in conditions, be they production or ground condition related, could be recorded and analysed. The design brought together empirical rules and tables developed at Cullinan plus concepts from programming developed for the front cave at Koffiefontein so that the new system was based on sound practical experience. These facets were incorporated into PCBC (GEMCOM) and CMS and PCS (Sandvik-Tamrock programmes). The system has now been operational for just under a year and while modifications have had to be made, it has proved itself as a practical and reliable tool with which to manage the draw control at Finsch. The system is unforgiving and has forced the production team to focus on the specified drawpoints. Problems have been encountered but most of these have been related to re-educating a workforce, familiar with a flexible mining method, to the strict discipline required for a modern block cave.

Jan 1, 2007