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By L. Mpolokeng, J. P. Labuschagne, H. Yilmaz

"An investigation into pillar cutting was carried out at a platinum mine on the western limb of the Bushveld Complex. The focus was on crush pillar design and implementation in order to ultimately improve the compliance percentage for pillar cutting. The major findings from the investigation suggest that the pillar cutting problem lies with the implementation of the design rather than the design itself. Observations of the practical issues underground that prevent good pillar cutting were made. After these issues had been identified, recommendations to rectify these problems and a few other issues identified during the investigation were provided. The recommendations are aimed at improving the pillar cutting compliance and reducing the likelihood of pillar bursts or pillar runs, which will ultimately create a safer mining environment. Paper written on project work carried out in partial fulfilment of BSc. Eng. (Mining Engineering)"

Jan 1, 2015

By P. N. Lategan

Mining companies are challenged with increased difficulty in delivering capital projects on schedule and within budget. In 2005, PricewaterhouseCoopers global review of major capital projects in the mining industry only 2.5% of projects could be defined as successful when assessed across the four critical dimensions of scope, cost, schedule and business benefits. Thus 97.5% of major mining capital projects were not successful according to the criteria PricewaterhouseCoopers used. Normally if a project fails on all these criteria it indicates scope creep. Scope creep refers to the change in a project's scope after the project work has started. As a result, the projects drift away from their original design, timeline, and budget, and as a consequence destroy business benefits. The major reasons for scope creep are poor change control and the lack of proper front end loading. Change control and front end loading are based on project processes in the planning and monitoring & control process group of the Project Management Body of Knowledge1 (PMBOK). This paper will focus on key factors to consider during project scheduling/planning with special reference to cost and schedule (using Microsoft Project as a tool although the principal is universal)

Jan 1, 2009

By N. B. Devi

The extraction of copper(II) from sulphate solution was investigated using LIX®984N in kerosene. The parameters that could affect the extraction, such as equilibrium pH, extractant concentration, salt concentration, various diluents, and temperature, were separately investigated. On the basis of slope analysis, the complex formed in the organic phase is proposed to be CuR2, where R is the anionic part of LIX®984N. The extraction equilibrium constant and Gibbs free energy ( G) of the extraction process were determined. The positive value of H obtained from temperature variation studies showed that the extraction process is endothermic. The extraction of copper was lowest when chloroform was used as the diluent. Separation and recovery of copper from a synthetic copper-nickel solution containing 6.35 g/L Cu(II) and 0.58 g/L Ni(II) was carried out using 20%(v/v) LIX® 984N. The separation factor ( = DCu/DNi) was found to be pH-dependent. A two-stage batch countercurrent extraction was carried out at an O:A ratio of 3:4 at equilibrium pH 1.05 for extraction of copper from copper-nickel solution, followed by copper stripping from the loaded organic phase with 15% H2SO4 at an O:A ratio of 3:1.

Jan 1, 2014

By F. T. Cawood

The distinction between real estate ownership and that of interests in the property is fundamental to the appraisal of mineral properties. This distinction affects the nature and understanding of security of tenure and, consequently, the perception of what constitutes fair value. Legal matters are a particular concern because of their influence on security of tenure, ownership definition and use restrictions. The dynamics of the market and the complex interrelationships between the factors of production define value at a specific point in time for the bundle of rights, interests and assets that constitute a mineral property. Because each mineral property is unique, physically immobile and of a wasting nature, its usefulness to its owner and society must be optimized. The US Appraisal Institute (2001) classified the forces that affect land use as the cultural, political and economic attitudes of society. These forces culminate in laws that often dictate the purposes for doing appraisals. Once the legal definition of the asset is understood, valuers can decide on the valuation process that will support the final valuation approach.

Jan 1, 2004

After the closure of collieries, they naturally start to fill up with water. As a result, hydraulic gradients develop between them and different hydraulic pressures are exerted onto peripheral areas or compartments within mines. This results in water flow between mines, or onto the surface. This flow is referred to as intermine flow. The collieries in the Witbank Coalfield have geometries such that there are several areas where this intermine flow is possible. Since the Department of Water Affairs and Forestry has declared intermine flow as one of its greatest concerns for granting closure to South African mines, much research into this phenomenon is required. The challenges in determining intermine flow are numerous, and attention has focused on identification of areas where these flows can take place. The quantification of these flows is problematic due to the uncertainties in exact geometric configurations and the variation in site-specific hydraulic properties of thecoal and overlying lithilogical layers. During this study, use has been made of numerical flow modelling and several analytic solutions to test the applicability of the flow models as well as to predict groundwater flow directions, filling times of voids and flow volumes. The numerical modelling methodology entailed a downscaling approach starting with a broad regional model covering the entire area, followed by modelling the interactions between interconnected mines, and finally looking in detail at the major areas of interaction.

Jan 1, 2005

By N. Sutcliffe

Refractories and slags play a vital role in the production of stainless steel. They are in intimate contact with the steel at temperature, and chemical reactions between the three can and do occur. These interactions can be beneficial, in the case of active tundish and ladle slags, and negative in the case of refractory erosion and slag entrapment. This paper presents the results of both plant trials and laboratory investigations of steel/refractory and slag/refractory interactions. The interaction mechanisms observed are described leading to selection criteria for new refractory products. Keywords: slags, steels, refractories, reaction mechanisms.

Jan 1, 2004

By D. M. Walters

To achieve safe and healthy working conditions in shaft sinking operations, ventilation, and where necessary cooling, must be provided. These requirements are considered for sinking vertical, sub-vertical and decline shafts. Regulatory requirements, determining air volumes and amount of cooling required, the various ventilation methods used such as force, exhaust, twin columns, air reversal using four gate systems and the equipment required to achieve this, are discussed. Consideration is also given to the sinking of single and twin declines using diesel equipment, calculating the air volumes required to dilute pollutants and the various methods for achieving this. Also discussed is the importance of having early ventilation design input to the overall design of the mine. In many cases ventilation can be the prime determinant for the size and configuration of the shafts or declines that have to be sunk.

Jan 1, 2009

By M. M. Valenta

A number of challenges face platinum concentrator plant operators. These challenges include the increase in operating costs, the increase in smelter cost for the processing of concentrate, the shortage and cost of power, and the tightening of specifications on concentrate quality by the toll-smelting operations. Over the years the focus has moved from extracting the platinum group metals (PGM) from the Merensky Reef to the UG2 reef. This has a number of advantages, including the higher ?basket price? for UG2 concentrate, reduced mining cost per unit volume as a result of the higher density of UG2, and the reduction in overall concentrate tonnage to be smelted. In many cases the Merensky ore has been fully exploited and it makes sense for the focus to shift to the UG2 ore that can be accessed through the Merensky shaft infrastructure. The presence of relatively high levels of chromite in UG2 concentrate is, however, a major disadvantage due to the problems associated with smelting such a concentrate in conventional submerged arc furnaces. In addition to increasing the specification on the minimum PGM grade of concentrates, smelters have had to impose strict specifications on the levels of chromite in the concentrate. The threat of high penalties has forced concentrators to change their modus operandi, often resulting in a significant loss in recovery. The final concentrate grades and PGM recoveries are shown to vary significantly throughout the industry. The reasons for this include varying ore mineralogy and different operating philosophies. This would therefore imply that the opportunity exists to optimize the operations by considering fundamental aspects such as the PGM mineralogy and the application of appropriate technologies. By returning to the fundamentals of flotation and applying the findings of detailed process reviews, it has been possible to increase the concentrate PGM grade, reduce the concentrate chromite grade, and in some cases increase the recovery of PGM to concentrate. This paper presents case studies where this approach has been used to successfully optimize concentrator performance, resulting in lower operating cost and higher PGM production. Keywords Process optimization, platinum concentrator, milling, flotation, grade, recovery

Jan 1, 2011

By F. N. F. le Roux

This paper describes the method used for excavating the upper 33m of emergency access shaft E2 for the underground single track tunnel running between Park and Rosebank station of the Gautrain Rapid Rail System. The soil was decomposed shale and diabase from the Witwatersrand Supergroup. The location was in the car park of The Wilds (a public park) in Johannesburg. The method proved very simple and required less complex plant and equipment than normal when excavating the shallow soil sections in shafts. It involves driving steel sheets ahead of the shaft sump into the soils and then excavating inside the ?tub? created by the sheets whilst supporting the sheets above with regularly spaced circular Steel Rings. It is the intent of this paper to discuss the method and design approach to the method. This will be done at the hand of experiences at E2 shaft..

Jan 1, 2009

Instability in rockpasses at deep levels often initiates as a result of stress induced fracturing of the rock on the walls of the pass. This may then progress to a stage at which the geological structure of the rock mass becomes dominant and permits large joint-defined blocks and slabs to become unstable. In this paper, a technique is described in which jointing parameters and their variabilities?orientations, spacings and lengths?are taken into account in estimating the extent of failure that may develop around a typical unsupported deep level gold mine rockpass. The results of this prediction are compared with the results obtained from a review of pass performance in the gold mining industry.

Jan 1, 2005

By P. Dennis, T. Pieters, A. De Kievit, S. Ganguly

TEMCO has been producing manganese ferroalloys in submerged arc electric furnaces for over 40 years. The furnace linings all along have been of conventional insulation type until 2001 when a freeze lining of UCAR concept was installed for a 20 MW Furnace. Continuous improvement of furnace lining performance has been a key component in improving the business competitiveness of TEMCO. The expected minimum campaign life of the freeze lining is fifteen years as compared to the ten years of the conventional linings. The success of the freeze lining is very critical to the quanta and direction of heat flow through the lining that control the freeze protection. Under freeze protection can lead to reduced lining life and over freeze protection, on the other hand, can lead to operating difficulties and loss of smelting efficiency. It was, therefore, necessary to develop a computer based system to monitor and control the freeze protection. The computer based monitoring and control system uses the basic principles of heat transfer, activeX object and heat flux from dual thermocouples and that is reviewed.

Jan 1, 2004

By F. N. F. le Roux

This paper describes the method used for excavating the upper 33m of emergency access shaft E2 for the underground single track tunnel running between Park and Rosebank station of the Gautrain Rapid Rail System. The soil was decomposed shale and diabase from the Witwatersrand Supergroup. The location was in the car park of The Wilds (a public park) in Johannesburg. The method proved very simple and required less complex plant and equipment than normal when excavating the shallow soil sections in shafts. It involves driving steel sheets ahead of the shaft sump into the soils and then excavating inside the ?tub? created by the sheets whilst supporting the sheets above with regularly spaced circular Steel Rings. It is the intent of this paper to discuss the method and design approach to the method. This will be done at the hand of experiences at E2 shaft..

Jan 1, 2009

By M J. Van Der Merwe

The mining industry is facing a serious skills resource shortage, growing commodity demand and cyclical prices. This makes focus and allocation of resources in the early stages of project development very important. To assist with these six key elements in the project prioritization process is proposed, namely: 1) Define the project vision, objectives and business case, 2) Determine the potential show stoppers, 3) Determine the key value drivers, 4) Track changes and provide regular feedback, 5) Evaluate the alternatives and, 6) Ensure proper gate management governance at the decision point. Incorporating these elements in the project development process will assist in resource allocation and focus on the high value aspects of projects and alternatives during the early stages of the project development lifecycle. Keywords: Resource allocation and focus, vision, show stoppers, value drivers, project prioritization, linear programming, business case modelling, management decision.

Jan 1, 2008

By C. Legote

"This paper investigates the conditions leading to the indefinite termination of production in four critical primary panels at an underground coal mining operation, the observed shortcomings in the mining approach, and the proposed strategy to mine through the affected panels. Initial assessment of the abandoned panel conditions indicated time-dependent strata failure,(i.e. bolted roof failure overrunning intersections), which occurred from mere minutes to up to four weeks post-production, with and without prior warning of failure. This prompted the constant re-supporting of back areas, which raised safety and productivity concerns. Investigation of the initial mining conditions revealed that the failures were due to a critical combination of factors, the chief of which was isolated horizontal stress. Other factors that were initially overlooked by the mine (i.e. influence of hydraulic stress, misinterpretation of borehole data), resulted in the conditions being described as abnormal. Remedial actions were determined, and in so doing, a new strategic approach was formulated to thoroughly address all failure concerns. The four panels were explicitly planned to serve as the main intake and return airways for the recently commissioned secondary ventilation shaft, as well as providing access to millions of tons in proven coal reserves. It is thus imperative to mine the panels. A feasibility study showed that the proposed strategy set for implementation would be financially viable. Paper written as project work carried out in partial fulfilment for BEng(Mining Engineering) degree"

Jan 1, 2015

By S W. Robertson, A Vercuil, P Craven

Mintek is currently developing a design approach for the heap leaching of low-grade primary copper sulphide material. Since the leaching of chalcopyrite requires elevated temperatures, the generation and management of heat within the heap is crucial. Furthermore, the precipitation of iron needs to be managed to prevent premature blinding of the heap, and acid consumption needs to be limited to contain cost and limit the dissolution of gangue impurities. Standard column tests using jacketed 1-m and/or 6-m columns do not allow accurate prediction of temperature changes and heat generation in an actual heap. Mintek therefore utilizes a computer model to calculate the energy balance and heat generation with time, based on the measured sulphide oxidation rates in the column. The temperature in the column is then adjusted to reflect the computer-predicted temperature in an actual heap. Using this approach, an overall copper extraction of 70% was achieved in 120 days, using 1-metre columns, when treating an ore blend containing 1.36% chalcopyrite, 0.23% chalcocite, 0.07% covellite, 3.8% pyrite and silicate gangue (92%). The chalcopyrite contribution to the total copper content in the feed was 75%. This was followed by 6-m columns using a similar approach, and the column results will be validated on a 23,000 tonne test heap. Key Words: heap; bioleach; chalcopyrite

Jan 1, 2005

By J. Krzyzanowska

Paper written on project work carried out in partial fulfilment of Bachelor of Engineering-Mining Venetia Mine, an open-pit diamond mining operation in the Limpopo Province of South Africa, currently has a mixed haul truck fleet consisting of Caterpillar 785B and C; 789C; modified 793D and 793D. Even in an ideal situation these trucks have different cycle times, which causes queuing at the loading area and their different speeds cause bunching on the ramps, leading to higher overall cycle times and lower productivity. This problem was identified but the root causes of the problem were not investigated and quantified. A time and motion study on the haul trucks was thus undertaken to measure actual cycle times and compare them to ideal cycle times as well as to observe any reasons for deviations. Ideal cycle times are partly evaluated on the basis of simulation and partly from production optimization expert input. Several areas that affect production were identified and these include: haul road conditions, the control room, dispatching programme and dispatching data management, as well as truck-shovel matching. The investigation was important in establishing control parameters for haul fleet operation since time spent queuing is production time lost, which defers waste tonnes to later in the life of mine, thus decreasing the tempo at which kimberlite is exposed.

Jan 1, 2007

Excavations in rock are commonly supported with wire mesh, shotcrete, wire mesh and shotcrete in combination, and shotcrete reinforced with various types of fibres. Wire rope lacing and various types of straps are additional forms of support installed over the above types, to cope with severe conditions. These support systems are very important items of ?membrane? rock support. With the recent development of several types of thin sprayed linings, the importance of membrane support is likely to increase in the future. In this paper, a wide range of mechanisms of membrane behaviour and mechanisms of loading of membranes, is described. The concepts of membrane components, which are single membranes that may be used on their own as rock support, and membrane systems, which are combinations of more than one membrane component, are introduced. Different situations have different requirements of membrane support, and differences between civil engineering and mining requirements are highlighted. With the different basic requirements in these two areas, the requirements of rock support are correspondingly different. A thorough understanding of the mechanisms of behaviour of the different types of membranes, and the different mechanisms by which the membranes are loaded, is essential before a selection of appropriate support can be made, before appropriate design methods and calculations can be determined, and before appropriate performance test methods for membranes can be defined. The material in this paper contributes towards the understanding of membrane support behaviour.

Jan 1, 2001

By C. Kloppers

The aim of this investigation was to reduce the cost of primary steel de-oxidation by substitution of aluminium primary de-oxidation with a practice that uses carbon. The cost of carbon is four times lower than that of aluminium. The application of carbon would directly result in raw material cost savings. Investigations were conducted at Iscor?s Newcastle steel plant on various steel grades. Specific production aspects were emphasized to ensure that the cost savings accrued would not create secondary expenses. These production aspects entailed: ?Yields on de-oxidation elements ?De-oxidation capabilities ?Alloying yields (Mn and Si) ?Carbon-pickup ?Nitrogen-pickup ?Temperature loss during tap ?Steel cleanliness ?Slag morphology. This project proved that carbon de-oxidation, apart from reducing de-oxidation raw material cost due to cheaper raw materials being used and lower consumption rates, resulted in steel that is cleaner and has lower nitrogen concentrations. Carbon primary de-oxidation has been implemented at Iscor?s Newcastle plant on a large range of steel grades, ranging from ultra-high carbon (> 0.60% C) to ultra-low carbon (< 0.03% C) grades. A net saving of between R100 000 and R200 000 per month was achieved.

Jan 1, 2001

By H. Gumede

The occurrence of fracturing due to high stress levels is a major factor in hangingwall stability in deep level gold mine stopes. However, rock falls cannot be the result of these fractures alone. Rock falls can result only from the occurrence of unstable rock blocks defined by the interaction of the stress induced fractures and naturally occurring geological planes of weakness. These planes include bedding planes and joint set planes. However, there is a general lack of information on the characteristics of these planes (orientations, spacings and lengths)?it does not appear that any such systematic and quantified information, if collected, has been published. To remedy this situation to some extent, joint mapping exercises have been carried out in several geological environments in two gold mines. The data collected on joint geometry included orientation, spacing and length, and this information is included in the paper. In addition, the paper describes the use of the data collected to evaluate the potential for rock falls and the probability of failure of stope support

Jan 1, 2007

By C. S. Chenga

Sustainable development is currently an extremely relevant concept worldwide, especially in developing countries like South Africa. Mining and metals companies are also directly affected by the sustainable development agenda. The Mining Charter?s requirements as well as new legislation (Mineral and Petroleum Resources Development Act) expect, among others, for mines to support infrastructure and poverty eradication projects in the communities surrounding the mines. The aim of this paper is to, against the background of a qualitative study of mining communities in the North-West Province of South Africa, put forward some critical factors for the sustainability of social development projects in the mining sector.

Jan 1, 2006