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This publication is provided on an "as is" basis without warranties of any kind, either expressed or implied including, but not limited to warranties of title or implied warranties of merchantability of fitness for a particular purpose. The information contained in this publication is for general information purposes only. It does not constitute professional, technical, financial or other advice to the user of this publication and must not be relied upon as such by any person whatsoever. The use of this publication is at the users own risk. The authors/creators of the information contained in this publication have tried to ensure that the information contained herein is correct, but errors or inaccuracies may exist or the information may be incomplete, unreliable or no longer up to date. Therefore, no warranties of any nature whatsoever are given and any liability to any person in respect of anything and in respect of the consequences of anything done or omitted to be done, wholly or partly in reliance upon the whole or any part hereof, are disclaimed, including and without limitation any contractual, dialectal, direct, consequential or financial damages or losses. On no account will Organisers and/or any of the contributors or any person or entity involved in creating, producing or distributing the information and or software available in this publication be liable for any such damages arising out of the use of or inability to use this publication. Copyright Reserved The South African Institute of Mining and Metallurgy P O Box 61127, Marshalltown 2107, South Africa www.saimm.co.za All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical photocopying, recording or otherwise without the written permission of the copyright owner. Although the greatest care has been taken in the compilation of the entire contents, the editors and publishers do not accept responsibility for errors or omissions. First Edition Copyright February 2004 Proceedings ISBN: 0-9584663-5-1 (1 volume and CD-ROM)

Jan 1, 2004

By T. A. Ngcobo

Paper written on project work carried out in partial fulfilment of BSc Eng (Mining)degree The purpose of this report is to assess the risks faced by mines in dolomitic compartments in particular Kloof 8 shaft. The dolomites of the West Rand comprise one of South Africa?s most natural water resources, and overlie the reefs of the richest gold mines in the world. The pumping of water from the dolomitic aquifers to prevent flooding has caused the natural water table to subside, and the resulting cavities within the dolomite rock formations that overlie many gold deposits sometimes collapse, causing sinkholes. These impacts of the mining industry could worsen over time if preventative measures are not taken. This report discusses these impacts in detail, more specifically the risks to which operations in dolomitic compartments are exposed. A risk analysis was carried out to access the risks that the organization could face and it was this analysis that allowed one to examine the best methods to combat the problems. Other factors such as geological features and seismic events were also considered for the evaluation. To aid with the completion of this work various resources were utilized. A literature study was undertaken, information was gathered from various experts who specialize in dolomitic studies, evaluations were conducted and conclusions reached. The results from the project indicated that preventative measures should be implemented and correct procedures put in place to prevent any disasters.

Jan 1, 2006

Council for 1999/2000 President J.R. Dixon President Elect M.H. Rogers Vice Presidents Senior Dr L.A. Cramer Junior A.A.B. Douglas Immediate Past President R.P. Mohring Honorary Treasurer J.A. Cruise Members of Council B.C. Alberts Dr N.A. Barcza N.J. Barkhuysen R.D. Beck M.J.P. Bierman Prof. A.N. Brown D. Cockcroft Dr M.B. Cortie Dr L.A. Cramer J.A. Cruise E.G. de Villiers J.R. Dixon A.A.B. Douglas F.M.G. Egerton J.P.W. Fisher C.E. Fivaz K.J.R. Ford Prof. G.A. Fourie R. Graham Dr R.G. Gürtunca Dr R.V.R. Handfield-Jones* M.C. Harris J.P. Hoffman H.E. James P.J. Knottenbelt R.P. Mohring H.G. Mosenthal G.Y. Nisbet N.M. O'Brien R.G.B. Pickering Prof. R.P. Plewman S.J. Ramokgopa Prof. R.E. Robinson M.H. Rogers D.A.J. Ross-Watt Prof. R.F. Sandenbergh Dr H. Scott-Russell C.B. Sheppard D.A.A. Smith Dr T.R. Stacey Dr O.K.H. Steffen D.J. van Niekerk J.C. Viljoen J.N. Wallington

Jan 1, 1999

By C. Musingwini

Traditionally, mineral reserves management at most underground mines in Zimbabwe focus on maintaining large mineral reserves so that the time between development and production is as long as possible. Historical data at Shabanie mine, a Zimbabwean sub-level caving underground mining operation, confirms this practice. However, the high cost of underground development means that the luxury of large buffer mineral reserves cannot be justified. Furthermore significant increases in the costs of production, exacerbated by the current unfavourable economic climate, make the wisdom of extending development workings well ahead of use questionable. Poor ground conditions at Shabanie mine, mean that some development ends have to be re-mined two or three times due to partial or complete closure between the time they are mined and the time they are utilized. In order to reduce the inordinately high support costs associated with closure of development ends a new ?just-in-time? (JIT) approach that provides development ends as and when they are needed, has been adopted. Accordingly a model to determine an appropriate ?just-in-time? rate of development has been created. The JIT development model indicated that the mine could reduce development rates from 330 m/month in 2001, to 160 m/month in 2002 and achieve savings of about 50% on annual support costs, but still assure customers of a long-term product supply. The mine accepted the model in November 2001 and began implementing it in 2002. Results of the implementation will be reviewed in 2003.

Jan 1, 2003

By R. Dass

Paper written on project work carried out in partial fulfilment of B. Sc Eng (Extractive Metallurgy) degree Screening is an industrial process that splits material at a specific cut size into one fraction of particles larger than the cut size and another fraction of particles smaller than the cut size. Particles are vibrated to increase the probability of them being accurately classified and to move the oversize particles off the screen surface. In conventional screening, the screen mesh vibrates with a single frequency and the particles on the screen are all exposed to this same frequency. The Ultimate Screener (see Figure 1) is a new screen technology that imparts multi-frequency vibrations to the screen mesh so that different parts of the screen surface vibrate at different frequencies. The Ultimate Screener incorporates an additional deck that holds the multi frequency adapters as shown by Figure 2. These special adapters can transform single frequency vibrations into multi frequency vibrations. When the screen motors are switched on they begin to vibrate. This vibration is transmitted to the adapters via the body of the machine. The adapters then modify the vibration to have multiple frequencies, which are transmitted to the screen surface via resonating rings.

Jan 1, 2004

By J. M. Lottering

Paper written on project work carried out in partial fulfilment of B Eng (Chem) degree Operational factors influencing the electrostatic separation of mineral sands were investigated in a laboratory separator. Measurements were collected online by means of an optical sensor using diffused reflectance spectroscopy to determine the mineralogical composition. The results have shown that the roll speed and potential were the dominant operating variables, collectively explaining more than 83% and 68% of the product grade and yield, respectively. In contrast, the feed rate, temperature and position of the plate did not affect separation. The effect of the ambient relative humidity, ranging from 10% to 45%, could not be assessed conclusively and at best appeared to have a weakly beneficial effect on the product grade. Keywords: process modelling, high tension roll separator, mineral sands

Jan 1, 2006

By B. Das

he flotation studies on hematite were carried out using di (2-ethylhexyl) Phosphoric acid (D2EHPA) as the collector. The possible mineral reagent interaction was studied through electrokinetic and dissolution studies. The shift in zeta potential (PZC) and decrease in dissolution of iron in the presence of D2EHPA indicated that D2EHPA was specifically adsorbed on hematite surface. The adsorption imparted necessary hydrophobicity for flotation of hematite. Hematite could be floated selectively from hematite and quartz synthetic mixture. Key words: Hematite, D2EHPA, flotation, electrokinetics, dissolution.

Jan 1, 2003

By R. P. H. Willis

Uranium is back on the radar. Uranium has always been a controversial metal, from its role in the arms race to its claim to be the only viable alternative to fossil fuel. This paper will cover its properties and use, its occurrence and production in South Africa, the current market drivers and its future role as a primary energy fuel. It will highlight the difference between uranium used to make a bomb and uranium used in a power station. The recent significant uranium price rise will be put into context of the market drivers including geopolitical issues. Planned expansions in nuclear power station capacity will be reviewed, as will new mine production. Future demand will also be speculated on.

Jan 1, 2006

By G. S. Littlejohn

In anticipation of the flooding of an adjacent dolomitic groundwater compartment, five rough parallel sided boundary plugs at 58 and 50levels have been designed to resist safely hydrostatic heads of 1500and 1250 metres, respectively, over a service life of 100 years. Following a description of the engineering properties of the surrounding rocks, the paper details the design considerations relating to structural length and strength, hydraulic gradient, rock mass watertightness, constituent materials of mortar intruded concrete, pregrouting of permeable discontinuities within the surrounding rock mass, a bentonite barrier to resist aggressive mine water, plug tightening and design performance requirements. Routine quality control tests include permeability of the rock mass, fluidity, bleed and strength development of the intruded mortar, and temperature of the intruded concrete during curing. A special test programme includes determination of strength and stiffness of cored concrete and rock samples, shear strength of the rock/plug interface and associated in situ contact stress in order toe stimate the load safety factor against plug failure by shear.

Jan 1, 2006

By L. Bircumshaw

Paper written on project work carried out in partial fulfilment of BSc (Eng) (Chemical) degree This paper details the formulation of a mathematical model for the simulation of a primary bioleach reactor, with specific reference to the leaching of pyrite. The model is based on the direct reaction mechanism, where the leaching of pyrite is said to occur via a two-step process. The process involves the formation of ferrous?iron through the chemical leaching of pyrite and subsequent bacterial oxidation of ferrous-iron back into ferric-iron. At steady state the rate of chemical leaching and bacterial oxidation are linked by the ratio of ferrous-iron to ferric-iron in solution. The extent of conversion of pyrite in the reactor system is described using the segregated flow model, with the exit age distribution of the solid phase being described by the Tanks-in-Series model. The final phase in model formulation involves the inclusion of steady state material balances on the bacteria and fluid phase components. The model is compared to pilot plant data and laboratory data for two different types of pyrite concentrates, with simulation results showing that the model is in good agreement with the data. Author key words: Bioleaching; pyrite; primary reactor; modeling; segregated-flow model; tanks-in series model.

Jan 1, 2006

By K. Moxham, R. G. B. Pickering

Over the last few years Lonmin Platinum and Sandvik have embarked on a unique partnership of collaboration through a systematic approach to developing equipment to mechanize and automate narrow reef platinum mining. After the initial design and manufacture of the equipment the key aspect is the integrating equipment, people and method into a mining system. Another key a spec of mechanization is the optimization of equipment utilization and this philosophy has ensured continual evolvement of mining methods. This paper describes the trials and development that have resulted in the mining method described as Lonmin mechanized breast.

Jan 1, 2006

By A Weber, L MacNamara, H Schreiber

Design and development of the world?s largest flotation cell was completed in 2002. This was the first 257 m3 flotation cell installed in the mineral industry and represents a major development in the design of larger flotation cells. This cell has a 50% increase in volume over the widely installed 160 m3 WEMCO® Smartcell? flotation machine. In the next few years it is anticipated that 257 m3 flotation cells will be incorporated into rougher-scavenger flotation circuits in many more world class copper sulphide concentrators. The prototype 257 m3 cell, No.250 Smartcell? flotation machine was installed at Minera Los Pelambres in the front of Row 1 in the existing rougher flotation circuit. This cell is followed by nine No. 130 Smartcell? flotation cells. After the successful development phase, this unit has been incorporated as part of a row of No. 250 Smartcell? flotation machines at Minera Los Pelambres. A key to the successful development of the equipment has been the emphasis placed on fundamental hydrodynamic scale-up criteria. Hydrodynamic factors include superficial gas velocity, water (pulp) circulation through the draft tube, and pulp mixing (distribution) characteristics. This paper will review the scale-up criteria of the No. 250 flotation cell, and present a case study of the in-plant equipment testing. The case study will document the metallurgical and hydrodynamic performance of the machine. It will also illustrate the economic benefits derived by incorporating larger flotation cells in a modern copper sulphide concentrator.

Jan 1, 2007

By C. E. Doran

Since the early 1990s the underground mining industry has embarked on a vigorous program of improving process and eliminating costs. A leading development in this program has been the implementation of leaky feeder radio systems as an enabling infrastructure for future automation. El-Equip Inc. has led this development with more than 175 mines implementing mine-wide radio infrastructures for voice and data. In this paper, we describe the implementation of a digital radio network which supports existing installations through to an automation infrastructure employing full digital cellular communications with mobile video roaming capabilities. We outline the evolutionary path from existing low speed data communications links through to 155 Mbps and beyond.

Sep 1, 2001

By D. Tesh

The mining industry worldwide is facing a tremendous shortage of minerals engineers in all fields of specialization. For instance, in Australia the skills shortage in the mining industry has been identified as one of the top risks facing the mining industry. In Namibia most minerals engineers employed are expatriates, with some being Namibians who studied abroad. The minerals engineering programmes at the Polytechnic of Namibia are still in their infancy. These programmes were designed to meet the mining industry skills needs. Being young has its advantages in that lessons can be learnt from older minerals education institutions that went through similar challenges. However, this does not imply just copying and implementing their approaches, since the context differs and, to ensure sustainability of the minerals education programmes, curricula have to be customized to the local context. This paper reviews the interventions made by the Polytechnic of Namibia in order to ensure the sustainability of its minerals education programmes. The methodology consisted of an extensive literature review, a status quo analysis of the mining and process engineering department, identifying the gaps between the current state and desired state, and mapping the goals and strategic actions required to progress to the desired state. The following factors were identified as major threats to the sustainability of minerals education at the Polytechnic of Namibia: the quality of students, low student enrolment rates, low pass rates in science and mathematics, shortage of academic staff, dwindling government funding, and limited involvement of the mining industry. The major outcomes of this research comprise the detailed strategic actions employed by the Polytechnic of Namibia to address the threats to sustainability of its minerals education programmes.

Jan 1, 2014

The slags produced by the Imperial Smelting Process (ISP) are based on the system ZnO-?FeO?-Al2O3-CaO-SiO2. The slag chemistry is important to the process since it determines the fluxing practice and the operating temperature of the furnace required to produce fluid slag. The paper presents the results of the first systematic experimental investigation of these ZnO-containing slags in equilibrium with metallic iron, and provides information on the primary phase fields and liquidus temperatures in these slags over the range of compositions used in ISP practice. A feature of the slags is the presence of alumina, which has a major influence instabilizing the spinel phase. This information presented in the form of pseudo-ternary sections ZnO-?FeO?-(Al2O3+CaO+SiO2) enabling the data to be readily used by plant engineers. Keywords: liquidus temperature, ISP, EPMA, ZnO-?FeO?-Al2O3-CaO-SiO2, phase equilibria.

Jan 1, 2004

By O. F. Oxtoby, J. E. Olsen, M. W. Erwee, Q. G. Reynolds

"The extraction of molten products and wastes through smelting furnace tap-holes during the tapping process is a complex procedure involving many coupled thermophysical effects. Insight into the fluid flow behaviour in such systems can be gained by using computational mechanics tools to build highfidelity models of the fluid flow and other relevant physics. Previous work using such models indicates that the nature of the flow in the tap-hole, as well as operational parameters such as the tapping flow rate, depends strongly on the properties of the material being tapped and the geometry of the tap-hole channel. Additional complications arise when multiple fluid phases (for example, slag and metal) are present simultaneously, when porous coke beds hinder flow to the tap-hole entrance, and when the geometry of the tap-hole changes over time due to cycles of wear and repair. In the present work, challenges with the coupling of phenomena such as multiphase flow and porosity into computational fluid dynamics methods for tap-hole modelling are discussed in the context of electric furnaces used for ferromanganese production. Qualitative and quantitative results of computational models of flow through tap-holes are presented and compared as a function of material parameters to determine sensitivity effects, and in response to operational parameters to determine typical process behaviour over the duration of a tap. IntroductionPyrometallurgical production using electric furnaces accounts for substantial portion of the world supply of ferroalloys and other strategic materials (Degel et al., 2015). A range of different furnace designs may be used depending on the metallurgical process, with circular three-electrode submerged arc furnaces (SAFs) powered by alternating current being the most common for commodities such as ferromanganese and silicomanganese (Olsen, Tangstad, and Lindstad, 2007).As shown in Figure 1, manganese furnaces typically operate with a deep charge consisting of an upper layer of loose burden (onto the upper surface of which is fed solid raw material), a molten slag layer partially or completely filled with unreacted carbonaceous reductant (generally metallurgical coke), and a molten metal layer which settles to the bottom of the furnace due to its high density. The solid particles present in the slag and burden layers form porous beds which hinder the fluid flow of molten process material and gases inside the furnace (Olsen, Tangstad, and Lindstad, 2007).In order to remove material from the furnace during normal operations, a single tap-hole is built into the sidewall of the vessel near to the level of the hearth. Tapping involves removing both slag and metal phases through the same tap-hole channel, which makes tap-hole design, operation, and maintenance particularly complex. In the case of processes such as ferromanganese, which operate with no external gas injection or open arcs present at the furnace electrodes, flow of material out of the tap-hole is driven primarily by the hydrostatic pressure generated by the weight of the solid and liquid phases above the tap-hole."

Jun 1, 2019

By J. Martinovic

The large proportion of gangue minerals present in platinum bearing ores in South Africa provides challenges to the flotation and downstream processes. In order to take effective measures to reduce their recovery in flotation, an understanding of the mechanisms and factors influencing their behaviour is needed. Typical gangue minerals are pyroxene, feldspar, quartz, chromite and talc. Of these, talc is a naturally hydrophobic mineral and although it is present in relatively small quantities, it has a disproportionate effect as it has a strong froth stabilizing effect, increasing the recovery of other gangue minerals by entrainment. Talc recovery is effectively reduced with the addition of polymeric depressants. Although the other gangue minerals are assumed to be hydrophilic and their recovery by entrainment is expected to follow the water recovery, there is some evidence that they may be activated by the typical reagent suites used. Reagents such as copper sulphate, added as an activator, and collectors are used to selectively induce hydrophobicity on the sulphides. It has been shown that some of these gangue minerals can be activated. This research work investigates whether inadvertent copper activation is mineral specific and evaluates the mechanisms and factors affecting the reversal of activation with the addition of the depressants using electrokinetic measurements, adsorption and microflotation tests. Results are presented that show that the selected minerals do respond differently and that the reversal of activation is dependent on mineral type, depressant type, dosage and ionic strength of the electrolyte.

Jan 1, 2005

Escalating energy and electricity costs have become one of the largest drivers of expenditure in mining operations. Over the last eight years, energy costs have tripled when expressed as a percentage of total expenses in South African mines. In an effort to manage and reduce electricity costs, energy management strategies can be developed, inefficient operating units replaced, and the operation of energy-consuming components of ventilation systems optimized. Power consumption on mines is controlled mainly by three strategies, namely load clipping, by which energy use is reduced for certain parts of the day; load shifting, by which energy use is shifted to other parts of the day; and energy efficiency, by which energy use is reduced permanently. In this paper several projects that were implemented using the first two strategies of load clipping and load shifting are investigated. The actual and potential savings that can be achieved by implementing such energysaving interventions are presented. To reduce the operating costs of ventilating and cooling underground mines permanently, system optimization studies must be completed. Methods that can be used to reduce energy usage by optimizing cooling and ventilation systems are described, and network simulation models that accurately reflect the current and planned ventilation conditions are discussed. These models are then used to examine various options for improving the overall ventilation and cooling strategy. Different optimization scenarios can be simulated, and this assists the design engineer in obtaining the most energy-efficient system that will satisfy design workplace conditions. The final outcome is a reduction in operating costs, which can result in better operating margins and an extension of the life of mine.

Jan 1, 2014

By Huang Zhiwei, Paul Skayman, Kevin Holley

In 1989 The First Brigade for Geology and Mineral Exploration of Qinghai Province discovered gold at Jinlonggou and Qinlongtan, Tanjianshan. Between 1992 and 2002 small scale mining was carried out at these sites using underground mining methods at Jinlonggou and an open pit at Qinlongtan. During 2003 and 2004 geotechnical investigations were carried out in support of a bankable feasibility study. An important objective of this investigation was to meet both internationally accepted standards and codes of practice, and also to satisfy the Chinese requirements. Extensive use of local experience was utilised. Where possible geological drilling information was incorporated into the assessment. Extensive geotechnical mapping of surface and underground exposures, and index testing to gain an appreciation of rock intact strength were used to characterise the sites. Rock mass classification (MRMR) was used to assess indicative overall slope angles and appropriate bench stack heights for the proposed pits at Jinlonggou and Qinlongtan. Measured discontinuity orientations were used in kinematic analysis to assess stability of possible pit slope geometry at a batter and overall scale to provide preliminary recommendations for the pit slope configuration. Numerical modelling was also carried out to improve the understanding of anticipated pit behaviour. Site investigation and preliminary geotechnical design details, that incorporate site specific conditions for the formation of open pits at Tanjianshan, are discussed in this paper.

Jan 1, 2006

By Ö. Uysal

This study deals with the presentation of the mechanized longwall mining project introduced some years ago to increase productivity and output of Aegean Lignite Establishment (ELI) owned by Turkish Coal Enterprises (TKI.) and the comparison of this method with a planned alternative new mining method called ?shortwall mining? where continuous miners will be introduced as primary coal excavation machines. Following the planning phase, production costs have been calculated for both mining methods on the basis of a panel having a height of 7.5 m. In addition to cost analysis, both methods have been evaluated using ?the multi-dimensional objective system?. In this evaluation the value synthesis has been carried out according to scoring models. Lastly, the advantages and disadvantages of both production methods have been stated by analysing them according to related criteria. In the light of outputs gathered from the analyses, it has been determined that the shortwall mining method will out perform the longwall method. Keywords: continuous miner, shortwall mining, longwall mining, multi-dimensional objective system.

Jan 1, 2006