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In their excellent paper, Milev and Spottiswoode have provided quantitative and definitive descriptions of an important phenomenon that hitherto has been largely the subject of conjecture. They convincingly show that ?site-response? can amplify the strong ground motions on the rock-wall of a stressed tunnel by a factor of 10 to 12 compared with the PPV in the solid rock mass (at the same distance from source). This knowledge gives us a firm foundation from which to begin to build an understanding of the mechanism of damage resulting from a rock burst. Regrettably this understanding is still far from adequate, in my opinion. The authors of this paper, however, have made some statements that are too reassuring and which tend to reinforce the sense of complacency that prevails among many members of the rock engineering community on the deep gold mines.

Jan 1, 2006

By Chris Ringas

The safe operation of gas transmission pipelines is increasingly coming under the spotlight. Increasing environmental pressure is also forcing pipeline owners and operators to ensure the integrity of their pipelines. The integrity of a pipeline is usually determined using intelligent pigging, often referred to as In Line Inspection (ILI). However, in many cases, gas pipelines cannot be pigged for a variety of reasons. The National Association of Corrosion Engineers (NACE) has recently published Recommended Practice (RP) 0502, referred to as the External Corrosion Direct Assessment (ECDA) Methodology to assist pipeline owners with assessing the condition of pipelines that cannot be pigged. 2. External Corrosion Direct Assessment - NACE RP 0502 The ECDA Methodology is conducted in four phases as follows: ? Pre-Assessment ? Indirect Inspection ? Direct Examination ? Post-Assessment In the Pre-Assessment Phase, all the relevant historical and current data relating to the pipeline in question is reviewed. This covers pipeline, construction, soils/environmental, corrosion control and operational data. The aim of the Pre-Assessment Phase is to determine whether ECDA is feasible, and if so, to define the ECDA Regions and finally to select the Indirect Inspection Tools that will be used for each region. Typical overline techniques used for overline surveys include the following: Voltage gradient surveys ? DCVG or ACVG

Jan 1, 2006

By E. Munnik

The Chambishi Metals Cobalt Plant in Zambia has recently installed a novel oxidation/precipitation pressure leach process as part of the COSAC (CObalt from Slag And Copper as by-product) Project. Aniron-cobalt-copper alloy, produced by the carbothermic reduction of slag, is atomized and pumped to the COSAC Leach Plant, where cobalt and copper are recovered as dissolved sulphate salts, andiron is rejected primarily as hematite. Cobalt and copper are subsequently recovered as cathode metal in the existing Chambish ioperation by conventional electrowinning. This paper examines the challenges faced during the design and subsequent successful commissioning of the COSAC Leach Plant. The challenges discussed include alloy handling, autoclave design, autoclave cooler design, residue liquor recovery and the water balance design. Keywords: Chambishi, Avmin, COSAC, Zambia, Copperbelt, cobalt, copper, alloy handling, pressure leach, autoclaves, cooling, filtration.

Jan 1, 2003

By A. H. Mokken

Failed attempts at amalgamation of a gold/osmiridium concentrate, recovered behind pebble mill liners during re-lining, led to the discovery that the gold particles were coated and that nitric acid only could remove the coatings. Following this treatment amalgamation was rapid and resulted in a complete recovery of the gold that otherwise would have been lost in plant residues. Investigations into the nature and formation of the coatings led to the realization that the coatings were impregnations of harder elements, associated with the gold during grinding and driven into the softer gold surface by high pressure, impact and attrition. It was further realized that this phenomenon could be part of gold ore milling, world-wide. With these thoughts in mind the question is asked whether concentration down to micron sizes prior to cyanidation, should not play a greater role in gold recovery.

Jan 1, 1999

By Nicholas Adrian Barcza

"What affects and influences one’s perspective of the mining and metallurgical industries?One’s perspective of the industry we work in changes over time as a function of our experience as well as from the interaction we have with colleagues locally and probably even more so with those internationally. Furthermore, the ever-changing environment continues to impact the context in which one sees things. Living mostly in South Africa through its changes in the past fi fty years but also having the opportunity to travel extensively and work on projects abroad adds an invaluable richness to this more global perspective. One of the greatest challenges is how best to use this experience to endeavour to support the many potential opportunities in southern as well as sub-Saharan Africa. However, one has also to face the realities of how the best interests of the country and its peoples are sadly often not well served for various unfortunate reasons. Investment, education, regional stability, and good governance are some of the most critical considerations for the prosperity and survival of the region.The mining and metallurgical industry in southern and sub-Saharan Africa changed significantly during the post-colonial and apartheid eras as a result of global and regional developments that have impacted the ownership of businesses, the technologies used, and products produced in a manner that was not envisaged even fi fty years ago. Southern Africa’s mining and metallurgical industry has progressed from one based mostly on diamonds and gold in the late 19th century to a much more diverse one that involves the production of a variety of other precious, base, and ferrous metals and minerals as well as coal and industrial minerals. The infrastructure and manufacturing capacity was largely developed to meet the needs of this industry during its growth phases, but even though the dynamics have changed there is still a need for more efficient and effective support systems in the region."

Jul 1, 2019

At Namdeb, submerged beaches are earmarked for sampling and future mining and various sampling configurations are tested for optimality through the use of spatial simulations. For the creation of these virtual orebodies, basic statistics and variograms are needed, but in this specific instance no data exists from which the necessary parameters can be determined. The best that can be done is to use proxy data from onshore beaches, with adaptations where needed. The reworking of raised beaches during periods of rising and falling sea levels in some cases destroyed the internal beach structures, and it is very difficult to determine the variograms. A method is proposed whereby simulated annealing is used to adjust the sample locations to align the data pertaining to beach crests or cliff lines, thus improving the variogram structure along the shoreline in the direction of the highest geological continuity.

Jan 1, 2014

By M. Abdellatif

Keywords: Magnesium, pyrometallurgy, Mintek Samples of crude magnesium produced by the Mintek Thermal Magnesium Process were refined in two stages. The first stage consisted of co-melting of batches of the crude metal and MgCl2-KCl flux (cleaning), followed by stirring at 30 rpm for 30 minutes and settling of the sludge (mixture of molten salt and solid impurities) from the magnesium melt. The operating temperature was 680?730°C. Most of the contained calcium and significant proportions of iron and silicon were transferred into the sludge phase, which left a metal containing, on average, 950 ppm Si, 470 ppm Fe, and 230 ppm Ca. In the second stage, small-scale refining tests were conducted on cleaned samples from the first stage, as well as on crude magnesium. FeCl3 was used as the refining agent. These tests were carried out at 715?760°C with various amounts of the refining agent. The refined metal was suitable for the production of various magnesium alloys, particularly AZ91D.

Jan 1, 2006

By J. Sjöberg, T. Savilahti, S. B. Umar

"Sublevel caving in Malmberget mine results in mining-induced surface deformation. One of the currently mined orebodies is the Printzsköld orebody. As mining deepens there is need to assess the behaviour of the cave formed in the subsurface above this orebody. Numerical analysis was used to assess the effects of extraction to deeper levels and perform strength parametric studies. Stress redistribution was studied, and the results showed high stress buildups in the hangingwall and the crown pillar. Two failure mechanisms have been identified – shear and tensile. Reducing cohesion by 50% increased the area of the yielded zone by more than 100% in the hangingwall.IntroductionThe Malmberget mine is owned and operated by the Luossavaara-Kiirunavaara AB (LKAB) mining company. Iron ore is extracted by large-scale sublevel caving. The mine comprises a total of 20 orebodies, about 10 of which are in production today (Figure 1). The mine is located in the municipality of Gallivare, about 100 km north of the Arctic Circle (Figure 2).Successful sublevel caving requires progressive caving of the orebody after initial blasting. This results in caving of the hangingwall, sometimes all the way to surface, resulting in surface deformation. As mining progresses to deeper levels a larger area is affected by deformation. Over the years, extraction from the Malmberget orebodies has led to deformation of the ground surface, affecting residential areas and existing infrastructure.Forecasting the caving process is not straightforward as it can be rapid or slow, depending on the rock mass conditions, stress conditions, the failure mechanisms at work, etc. Moreover, several of the orebodies in Malmberget are non-daylighting, which makes reliable caving analysis even more difficult, primarily since there is less available experience from such cases. The present study was designed to improve the understanding of the caving and deformation mechanisms at Malmberget, and in particularly for the Printzskold orebody"

Jan 1, 2017

By S. Adams, J. R. C. von Holdt, J. L. Broadhurst

Fugitive dust from mineral extraction and processing activities can significantly influence air quality, the environment, and the health and quality of life of workers and surrounding communities. Poor engagement and communication between experts and lay persons, disciplinary silos and polarised viewpoints have made it difficult to develop a holistic understanding of the complex health issues associated with environmental emissions of mine dusts, and consequently to design meaningful and integrated approaches to address such issues. The collaborative Global Challenges Research Fund (GCRF) Mine Dust and Health Network, hosted by Minerals to Metals at the University of Cape Town, serves as a collaborative think-tank to inform research directions within and across disciplines, government policy and regulations, health monitoring programmes at public clinics, industry best practice, community healthcare and impact prevention programmes. It focuses initially on the southern African region, but with the intention to expand to mining-intensive developing countries within the rest of Africa, South America and Asia. This paper outlines the approach and activities of this global transdisciplinary and intersectoral network and presents some of the key outputs and achievements to date. Keywords: Mine dust, Global Challenges Research Fund Mine Dust and Health Network

Jan 1, 2020

In recent years several mine researchers have studied the optimization of cutoff grade with the purpose of maximizing Net Present Value (NPV). The best and most popular one is the Lane algorithm. Based upon the Lane algorithm it is possible to calculate the optimum cutoff grade for mine, mill, and refinery capacities for single metal deposits with variable grades. The Lane algorithm cannot be used in multiple metal deposits. The reason is that, while in single metal deposits six points are possible candidates for the optimum cutoff grade, in multiple metal deposits an infinite number points are possible candidates for the optimum cutoff grades and objective function evaluation of these infinite points is impossible. In this study the Golden Section search method was used to calculate optimum cutoff grades of multiple metal deposits for the same conditions as Lane assumed in single metal deposits. Based on this method, grade-tonnage distribution uncertainty space of problem is guessed. In the next step, by selecting test points in uncertainty space and evaluating the objective function at these points, a part of uncertainty space will be eliminated. The procedure is then repeated until the uncertainty space has been sufficiently reduced to ensure that the optimum cutoff grades have been located to the required accuracy. Key words: Optimum cutoff grades, Optimization, Net Present Value (NPV), Golden Section search method

Jan 1, 2003

Control of flotation processes is mostly managed by plant operators, who assess the performance of the plant based on their own experience and other heuristic rules. These rules tend to be subjective or ill-defined, since most of them are concerned with the structure of the flotation froth, such as colour, bubble size and shape distributions, froth mobility and froth stability. These phenomena are very difficult to quantify objectively, and inexperience on the part of the operators, human error, etc., can lead to significant inefficiencies in plant operation. In this paper the development of a fuzzy system to support the control decisions of plant operators is described, which leads to significantly smoother control action and more stable plant operation than could be obtained with crisp sets of rules or manual control strategies. Keywords: flotation, fuzzy logic, image analysis, genetic algorithms, rule induction

Jan 1, 2000

By Mauri Kauppi, Pekka Niemelä

World HCFeCr production is 6.0 million tonnes. Correspondingly 1.1-1.6 t slag / t FeCr is produced depending on the raw material basis. Essentially all FeCr is produced in submerged arc furnaces, while the role of competitive technologies like DC is limited. In all furnaces fluxes are used to optimize the slag composition. Vital characteristics are smelting point, electric conductivity and viscosity. The main components of FeCr slag are SiO2, Al2O3 and MgO. Additionally it consists of Cr-, Fe-oxides and CaO. Granulated slag and/or classified slag products are produced depending on the production process. The slag products are mainly marketed in road and civil construction purposes but also in producing refractories. Normally crushed and screened slags are produced simultaneously when recovering alloy. The leachate of slag products is low and performance results are excellent. Slag products successfully replace natural sand and macadam. Generation of waste is essentially reduced. Producing and using slag products are described as BAT-technology and it is an essential environmental aspect. Outokumpu Tornio Works produces 320 000 t FeCr-slag/a. This paper deals with formation of slag in smelting process, its chemical composition, physical and structural characteristics, utilization and product specifications as well as environmental aspects. The slag products are standardized and CE marked. Additionally the role of slag in smelting and alloy recovery is reviewed in this paper.

Jan 1, 2007

By C. W. P. Finn

INFACON is of special significance to people in South Africa who are interested in ferro-alloys, because it was in South Africa that the idea of regular international congresses on ferro-alloys was conceived and developed. INFACON 74, the first-ever such congress, was held in Johannesburg from 22nd to 26th April, 1974, being organized by the South African Institute of Mining and Metallurgy, the National Institute for Metallurgy, and the Ferro Alloy Producers' Association of South Africa. Design Awards The Design Institute is inviting entries for the 1981 Shell Design Awards. Any product that falls into the three categories shown below, and that was designed in South Africa and is in production, is eligible for an award. Since their inception in 1970, the Shell Design Awards

Jan 1, 1981

By J. Daavittila

In the latter part of the 1980s Outokumpu Chrome in Tornio, Finland, was in a situation when its twenty-year-old ferrochrome plant was becoming too inefficient to sustain economically sound production. The company made extensive studies on the then available processing methods to find out the best possible processing route. As a result, the whole plant was practically rebuilt and expanded. When equipment was proven in practical operation, an application for FeMn production was developed. Now as the Tornio FeCr-plant is considering expansion, the same type of exercise is to be performed with today?s challenges, which will be discussed in the paper. These challenges include increasing costs or decreasing quality of raw materials, increasing energy costs, stricter environmental regulations and demand for better working conditions. The possibilities of resolving to these challenges will be discussed in the paper. The future and continuing development with FeCr includes the better utilization of process dusts and a lower consumption of energy. By adapting the latest automation tools to better control the process, even higher efficiencies can be achieved with present technology. New processes are considered for development in the future and some possible technologies will be described.

Jan 1, 2004

By C. Birch

"A ‘geologically constrained’ orebody model has long been hailed as vital for a Mineral Resource statement that is compliant with the South African Code for Reporting of Exploration Results, Mineral Resources and Mineral Reserves (SAMREC Code). In this paper, the requirements for geological modelling as contained in the outline for the SAMREC Code are considered, and whether the new modelling software available on the market is a ‘black box’ or is better for modelling than traditional methods of wireframe creation.Implicit geological modelling is a technique that uses a radial basis function to establish and update geological models relatively quickly and efficiently from borehole data, outcrop data, manually interpreted vertical or horizontal sections, and structural data. Assays and any coded drill-hole data, such as lithology and alteration, can be interpolated.Leapfrog Geo software is an example of this new approach to geological modelling. A case study of a short training course in geological modelling for non-geologists at the University of Witwatersrand, as part of the Higher Certificate in Mineral Resource Management, is presented. The benefits of this type of geological modelling software are considered for this type of assignment as well as for mining industry applications.The use of geological models in mine planning is reviewed and a case study is presented comparing the variations in mine plan design and financial output of 13 final-year Mine Design projects from the University of the Witwatersrand School of Mining Engineering. These designs were all based on the same geological model created in the traditional way, and yet the resultant mine designs were significantly different, with very different resulting financial outlooks for the project. This raises questions as to how significant a very detailed model in the pre-feasibility and feasibility phases of projects really is, considering the huge costs involved in gathering the required data to build a SAMREC-compliant geological model."

Jan 1, 2014

By A. M. Clegg

In general, overall experience has shown that the approach to the appointment of a project manager is given much attention, but little specific attention is given first to the risk associated with the project conceptual design and its overall executability within either the new legislative framework or the sustainability of the outcome. The risk in project executability and sustainability within the ?new age? legislative framework of the Mining Charter, etc, is itself however, of far greater importance. The degree of importance being defined by the intended projects impact on the business going forward. This is particularly the case where the intention of the implementation is effectively to turn around or even enhance a loss-making strategic investment like a mine or process plant operation in an ?old-order rights? or Brownfield?s operation. This paper attempts to highlight the importance of a ?pre-project project? (PPP) to mitigate the risk in the ?new age?, with specific reference to operational due diligence (ODD) and project conceptual design.

Jan 1, 2005

By A. C. Moorgas, J. Divall

This study investigates the feasibility of using waste iron slag, the by-product from a mineral sands processing works, in road construction. The study includes the different options investigated for the treatment of a leachate that is produced during the cooling of the iron slag, prior to processing. It also reviews the reasons for choosing the current treatment option that is being trialed. Cooling the iron slag with water results in the formation of a leachate with a high pH and high sulphide concentration. This leachate can seep into the ground and, over time, it will contaminate the ground water. A system was designed to collect and treat the leachate to prevent contamination of surrounding natural water sources. Numerous leachate treatment options were investigated to find cost effective method of treatment After cooling, the iron slag is passed through an iron recovery plant and the unsaleable product is placed on a dumpsite. Rain percolates through the dumpsite, which can result in the formation of a leachate that can contribute to a contaminated plume. After extensive testwork, it was found that the dumpsite, which was leached of contaminants, could be screened and used as a G5material (specifications in Table II) in road construction. The initial challenge was to establish that this material was environmentally safe for use in this particular application. Approval from the Department of Water Affairs (DWAF) was required for the testwork and then for the long-term use of this material in the construction industry. The following challenge involved establishing a market for the material. Construction companies in the area were reluctant to change to a new product that was not naturally occurring. The economics of this project are extremely sensitive to transport costs and hence only projects within a specified radius can be supplied with the Black Top Gravel (BTG). This project is not are venue generator, but it does save the money that would be required to manage the dump, and it reduces the closure costs.

Jan 1, 2003

By M. F. Handley

Sequential grid mining has been employed as the primary mining strategy at the AngloGold West Wits Elandsrand Mine since the inception of stoping operations from the sub-vertical shaft system in 1988. Little has been published on sequential grid mining as a mining strategy since, and the purpose of this paper is to describe sequential grid mining, its history, its implementation at Elandsrand, and the outcome to date. The results obtained using sequential grid mining have been evaluated from seismic data, productivity statistics, and rock related accident statistics. Comparisons with neighbouring mines namely Western Deep Levels and Deelkraal, have been made to substantiate the improved conditions observed at Elandsrand, and to compare sequential grid mining directly with longwall mining in similar conditions and at similar depths. Sequential grid mMining is shown to be cost-effective, more flexible, and safer than long wall mining in similar conditions, at least on the Ventersdorp Contact Reef in the western part of the Carletonville Goldfield. More work is necessary to establish it as the favoured mining strategy at depths exceeding 3000 metres, and for reefs other than the Ventersdorp Contact Reef.

Jan 1, 2000

By B. Zlender

ABSTRACT: The paper presents investigation of carboniferous slates from the Trojane hilly area performed on series of samples of equal material. The results of static loading tests show that carboniferous slate is heterogeneous and yields on slate layers. Where that kind of heterogeneity is distinctive the strength results are essentially lower of commonly tests results. The results of dynamical loading tests show that the slate surfaces have the essential meaning for the stability of the material. When those surfaces are moistened the material become unstable. RÉSUMÉ: L'article présente une épreuve des ardoises carbonifères de la région montagneuse de Trojane sur une série des échantillons des matériaux identiques. Les résultats des tests de charge statique montrent que l'ardoise carbonifère est hétérogène et qu'elle cède sur les couches d'ardoise. Quand l'hétérogénéité est distinctive, les résultats de stabilité sont essentiellement plus bas que les résultats obtenus par des tests ordinaires. Les résultats des tests de charge cyclique montrent que les surfaces d'ardoise sont très importantes pour la stabilité du matériel. Quand ces surfaces sont mouillés, le matériel devient instabile. ZUSAMMENFASSUNG: Der Artikel präsentiert die Forschung von Karbonschiefersteinen im Bereich des Bergland Trojane, ausgeführt durch Serien von Proben aus den gleichen Erdmaterial. Die Resultate der statischen Belastungsprüfungen zeigen, das die Karbonschiefersteine heterogen sind und die Schieferflächen nachlassen. Wo bei dieser Art der Heterogenität die Festigkeitsergebnisse wesentlich niedriger sind als bei gewöhnlichen Testergebnissen. Die Ergebnisse der zyklischen Belastungsprüfungen zeigen das die Schieferflächen eine wesentliche Bedeutung für die Stabilität des Erdmaterials haben. Wen diese Schieferflächen befeuchtet sind, wird das Erdmaterial unstabil.

Jan 1, 2003

By A. V. Pavlov, V. A. Grygorian, Kossyrev, A. E. Semin, A. Korostylev

A new way of producing low-silicon ferrosilicon from iron-ore materials in a new type of aggregate-oxygen reactor is presented. The oxygen reactor process is based on using the calorific combustibility and reducibility of carbon materials inside the aggregate. The key to the process is successful post-combustion of carbon monoxide above a layer of a solid coke bed. Initially the possibility of production of grades of ferrosilicon containing 20 to 25% Si (FeSi20-FeSi25) was studied on a laboratory model of the oxygen reactor. Quartz sand and iron ore concentrates (from Russia and India) were used in the laboratory tests. This test work demonstrated that a ferrosilicon grade FeSi15 could be obtained directly from raw iron ore (containing 75.9 % Fe2O3 and a maximum of 23.8 % SiO2) without using rich iron-ore concentrates. The process was successfully tested on a pilot furnace at Serovsky metallurgical plant. Very promising results and efficiency parameters were achieved. The consumption of materials for 1t of ferrosilicon (15 % Si) production was as follows: 1567 kg raw iron ore, 591 kg of coal (in a composition of ore-coal briquettes), 299 kg of coke (for coke bed formation), and 815 m3 of oxygen.

Jan 1, 2004