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By G. Lyman

The cross-belt sampler is a device that is very widely used even though it has not been ratified by the Standards associations. This paper is concerned with the bias testing of two cross-belt sampler designs against stopped belt samples and a cross-stream cutter at the belt end. The bias analysis is carried out using size distribution as the analyte and conventional t-testing and the Hotelling T squared test, which are compared for their effectiveness. The paper considers the issue of detectable bias and the statistical planning of bias tests.

Jan 1, 2009

By L. H. Lindstad

The paper reviews the tapping process and the major wear mechanisms on the tap-hole, including wear from tapping tools. Measured temperatures in different tap-holes are related to choice of binder and material for repair pastes. The strength and disadvantage of carbon and silicon carbide materials are compared. Normal daily and weekly maintenance of tapholes is described, together with the major repairs that are done during longer furnace shutdowns. The objective is to show that the type of repair and repair material needs to be adapted to each individual furnace.

Jan 1, 2014

By X. Jia

The ability to perform three dimensional imaging at micron-scale resolution of real mineral floc sediments and structures using commercially available Micro X-ray Tomography (XMT) instrumentation can be used for the analysis of aggregates and granules, liberation and dewatering of sediments. This paper presents are view of recent work by the authors relevant to the mining and minerals industries. It covers three main topics: X-ray imaging of agglomerates and multi-component mineralic particles,, permeability of sediments, and dissolution of granules with potential application to heap leaching.

Jan 1, 2008

By P H. Ferreira

The mechanisation of mine development is becoming increasingly important in our South African and Southern African mines with increased emphasis on safe and efficient mining. Raise, blind and shaft boring offer mechanised solutions for excavations such as:- [reef raises stope boxholes and shaft ore passes ventilation passes and shafts chairlifts large vertical hoisting shafts (in excess of 1200 metres in depth) angled hoisting shafts (from small to large diameter bored holes)] These techniques will be discussed with reference to relevant applications and the author?s comparison between conventional drill and blast techniques.

Jan 1, 2005

By Bosman

Medium suspensions play an integral part in the successful application of dense medium separation for both static and dynamic separators. Although models exist to predict particle movement as a function of medium density and viscosity, these models have been derived on the assumption of Newtonian rheology. Viscosity measurements of medium suspensions have shown that they are non-Newtonian, with a yield stress, and as such cannot be used in the existing models. As a result, medium selection remains an art based upon practical experience and indirect measurements of viscosity such as stability and cyclone differentials.

Jan 1, 2014

By J. H. Zietsman

It has previously been observed that industrial high-titania slags display a compositional invariance, remaining close to stoichio-metric M3O5. The present study focuses on this invariance and the phenomena which may cause it. The invariance was studied using thermochemical calculations and a mechanism is proposed for the observed behaviour. The mechanism suggests that a combination of thermochemical equilibrium and transient slag solidification and melting results in the observed compositional invariance. The proposed mechanism provides new insights and prompts questions about other mechanisms in the smelting process.

Jan 1, 2004

By A. B. Fox, R. P. Thackray, K. C. Mills

The role of mould fluxes in continuous casting is reviewed. The main functions of the flux are described and the importance of the flux in providing lubrication and the right level of heat transfer between the shell and the mould is described. The major problems of longitudinal, transverse and star cracking, gas and slag entrapment and deep oscillation marks in the steel product and ?sticker breakouts? are analysed. The important physical properties of the flux in combating these various problems are identified. Physical property data for the fluxes are given.

Jan 1, 2004

By J. H. Zietsman

It has previously been observed that industrial high-titania slags display a compositional invariance, remaining close to stoichio-metric M3O5. The present study focuses on this invariance and the phenomena which may cause it. The invariance was studied using thermochemical calculations and a mechanism is proposed for the observed behaviour. The mechanism suggests that a combination of thermochemical equilibrium and transient slag solidification and melting results in the observed compositional invariance. The proposed mechanism provides new insights and prompts questions about other mechanisms in the smelting process.

Jan 1, 2004

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

This paper reports on recent field observations on the performance of support systems under different corrosion environments in Canadian underground mines. Phenomenological data are used to gain a better understanding of the main causes of corrosion in underground metal mines. Preliminary field data collected from five metal mines have been complemented by atmospheric and water sample analysis as well as fractography and metallographic studies. This has identified dominant factors that control the corrosion of support systems. The data are analysed in order to develop a support strategy for mines operating in corrosion environments.

Jan 1, 2008

Keywords: Pyrometallurgy, Pretoria University Substantial research in pyrometallurgy at the University of Pretoria started in 1980 with the appointment of Rian Dippenaar to the Iscor Chair, a position that he held until 1996, when Chris Pistorius became the leader of this pyrometallurgy group. This paper reviews the main research themes over the quarter-century from 1980 to 2005, as well as some of the industrial developments that have shaped the research approach. The main topics have been the use of electrochemical sensors for equilibrium measurements, ilmenite smelting, steel processing, and reduction.

Jan 1, 2006

By F. Bonnet, J. Lehmann, H. Gaye

A review of thermodynamic information and models of slags, including associated software when available, is presented. The pertinence and accuracy of these models is discussed by comparison of their predictions for various slag thermodynamic properties with the available experimental data. Practical industrial applications will be illustrated by a literature review of the dephosphorization process of ferromanganese alloys and by the description of Ti behavior during silico-manganese alloys production. This latter example will show how the thermodynamic models have been used to propose a flotation treatment at low temperature to enhance TiC removal.

Jan 1, 2004

The newly implemented mineral law framework exacerbated the need to clarify the roles and responsibilities of mine and land surveyors in the preparation and registration of plans and diagrams. The main concern is that survey tasks may be performed by persons who are not considered competent under the different laws. The methodology used was to analyse historic and present legislation on the issue in order to formulate a narrow interpretation of the current requirements. The major findings are tabulated to present a summary of who is responsible for which areas of survey.

Jan 1, 2010

By N. Reddy

The influence of local geology and rock mass characteristics on deformations during a rockburst caused by a controlled blast was studied. This was done by means of visual examination, mapping and photography both before and after the blast. We found that the ejected material was bounded mostly by fractures associated with the bow-wave fracturing and bedding surfaces and that existed prior to the blast. Most of the damage was caused by shake-out. This information is important input for the design of rockburst resistant support systems under conditions of moderate stress.

Jan 1, 2001

Using the philosophy that 'change cannot be introduced through memos-you have to get people emotionallyinvolved', SRK's Environmental Group in South Africa is helping clients communicate their environmental management objectives more effectively through the powerful medium of interactive industrial theatre. Existing and pending environmental legislation, international pressures, and growing awareness of the environment have led South African industry to the point where responsible care, for both the environment and the health and safety of those affected by the activities of an industry, is now a focus of management policies.

Jan 1, 1995

By J. Kempken, R. Degel, J. Kunze, R. König

The FeNi technology is currently dominated by high-power submerged arc furnaces, often designed as smelter as "two-inline-solution". To achieve the intended high efficiency, state-of-the-art design in good correlation with ores and reductants and an integrated layout of the whole plant is of great importance. An introduction will be given to general aspects in the production FeNi, plus a detailed overview of design principles for large FeNi smelters and finally some examples of innovations and research projects concerning Fe-Ni.

Jan 1, 2007

By J. L. Viljoen

t has long been the drive of the industry and all operations to create an environment that is free of injury and illness. We have come a long way; the leaders, executives, managers, supervisors and workers are to be commended for relentlessly driving to create, what I call a ?White Flag Day Every Day?. Yet I am also aware of the huge shift we still need to create in the industry, on the operations and in the workplaces to have them free of injury and illness. Keywords People, values, care, trust, belief.

Jan 1, 2011

By G. Lyman

The cross-belt sampler is a device that is very widely used even though it has not been ratified by the Standards associations. This paper is concerned with the bias testing of two cross-belt sampler designs against stopped belt samples and a cross-stream cutter at the belt end. The bias analysis is carried out using size distribution as the analyte and conventional t-testing and the Hotelling T squared test, which are compared for their effectiveness. The paper considers the issue of detectable bias and the statistical planning of bias tests.

Jan 1, 2010

By P. R. Jochens, D. D. Howat, R. B. Atmore

INTRODUCTION The Miller chlorination process has assumed a preeminent position in the refining of gold bullion, a position it has maintained for over half a century. In the early sixties considerable interest was aroused by the idea of producing a consistently high grade bullion at the mine smelthouses themselves. However, as the use of chlorine in industrial plants is associated with considerable hazards, oxygen was considered a natural alternative, apart from bing less expensive than chlorine. Partial refining at the mine smelthouses would considerably decrease the requirements made on Rand Refinery Limited as well as indicating the possibility of reducing final refining costs. An added factor would be the purer silver chloride obtainable, after prior removal of the base metals by oxygen injection, which would facilitate the production of high-purity silver. The free energies of formation of the oxides of the metals;- silver, copper, lead, zinc, iron and bismuth indicate that, with the exception of silver, these metals should be capable of removal as oxides by oxygen injection. Rose1 had shown that during injection of gold bullion, considerable loss of silver to the boraxsilver slag occurred and, furthermore, that copper removal was not efficient and oxide attack on the refractories was severe. Plant test work2 had confirmed the difficulty of copper removal, but had shown that zinc and lead were almost completely removed. The difficulty of copper removal by oxygen injection warranted further investigation. Also, the high decomposition pressure of silver oxide suggested that by suitable control of the slag composition it might be possible to reduce to very small proportions the silver carried into the slag as oxide. The oxidation of copper by oxygen injection and subsequent dissolution of the oxide in a slag may occur according to the following reactions; Reactions 4 and 5 were considered because of the relatively high solubility of oxygen in molten silver and silver alloys. Thermodynamic data indicate that there is little possibility of any reaction involving the formation of CuO occurring at temperatures above 1 000 °C. To ensure that the operative reactions 1 and 4 take place to the maximum extent, the following factors He significant. (a) an increase in the activity of the copper in the bullion, (b) an increase in the partial pressure of oxygen in the system, (c) an increase in the activity of the oxygen in solution in the metal, (d) a decrease in the activity of cuprous oxide in the slag. From practical considerations, the operative variable most easily susceptible to control is the composition of the slag. SOLUBILITY OF COPPER OXIDES IN BOROSILICATE SLAGS Very scanty information exists on systems containing copper oxides but the indications are that slags containing considerable amounts of boric oxide would possibly prove to be the best solvents for cuprous and cupric oxides. This is attributed to the fact that the activities of copper oxides are much lower in boric oxide slags than in slags in which silica is the main network former. The number of possible slags containing boric oxide was limited by consideration of liquidus temperature, viscosity, corrosive action on refractories, volatilization, and ultimately cost (for industrial application). Slags in the systems soda-boric oxide-silica and lime-boric oxide-silica were selected paying due attention to the above limitations. Additions of 5, 10 and 15 per cent cupric oxide were made to the finely ground, premelted slags. These mixtures were then reground and 2g quantities held in re crystallized alumina crucibles at temperatures of 1150°C and 1 250°C respectively for 30 minutes. The crucibles were removed from the furnace, rapidly cooled, cut in half longitudinally, and a thin section taken from one half was subjected to microscopic examination.

By C. H. Wyndham, N. B. Strydom

INTRODUCTION Acclimatization of the labour force to heat is an integral aspect of gold mining in South Africa. A recent survey revealed that about 250,000 Bantu mine workers require to be acclimatized to heat each year. Until 1965 men were acclimatized by means of one of the Chamber of Mines methods (introduced by the Human Sciences Laboratory in 1953). This type of acclimatization was carried out underground where men shovelled rock in hot stopes under careful supervision. However, it has become increasingly difficult in the last few years for mines to provide underground the conditions of work and environmental heat required for adequate acclimatization to heat. In examining an alternative to acclimatization in underground hot stopes, the Human Sciences Laboratory carried out a trial in 1965 of acclimatization in an air-conditioned climatic room on the surface of a mine. The new procedures developed from this trial have been so successful that there are today 26 climatic rooms on different mines. These rooms have been built following a design proposed by Mr Hodgson of the National Mechanical Engineering Research Institute1. Approximately 85 per cent of the total number of men being acclimatized each year are put through the new procedures in these climatic rooms. This paper gives an account of the problems which arose and how they were solved, the inter-relationship between physical conditioning and climatic room acclimatization, the prodecures developed for elimination of labourers with low maximum oxygen intakes, and the advantages of climatic room acclimatization. CLIMATIC ROOMS The majority of the climatic rooms (twenty) have been built on the surface, but a number (six) of mines preferred to establish their acclimatization centres underground in order to decrease the initial costs involved in the construction of such facilities. These underground climatic rooms are usually located near shaft stations in redundant haulages and they can accommodate from 200 to 400 labourers, thus eliminating the need for multiple acclimatization shifts. Figs. 1-4 illustrate various aspects of a surface climatic room. PROBLEMS WHICH AROSE IN INTRODUCING CLIMATIC ROOM ACCLIMATISATION There were four main problems which arose in connection with the introduction of the new method. These were: (i) The type and rate of work to be used. (ii) The air conditions required to obtain optimum acclimatization. (iii) The duration of exposure to heat each day and the total number of days of acclimatization. (iv) The methods of cooling labourers with high body temperatures. Shovelling rock would have been the desirable type of physical work to employ, but the air-conditioned space required to accommodate large numbers of men and the difficulty in standardizing the work rate in shovelling led to the decision to employ instead the work procedure used by the Human Sciences Laboratory in acclimatizing men in the Laboratory. This is the lifting of the body weight against gravity when men step on and off a bench. It has the advantage that large numbers of men can work physically at the required rate in a relatively small space (120 men can be accommodated in an area of 70 ft by 21 ft) and the cost of construction and ventilation of the climatic rooms is thereby reduced. Also the work rate can be standardized by varying the height of the stepping benches in relation to the individuals' body weights. The next problem was the air condition to be used in the climatic rooms. The Laboratory's research experience in acclimatization led it to choose an air temperature of 89°F (with the air almost saturated with water vapour) and an average velocity of air movement of 100 fpm. This air condition was combined with a work rate of 1,560 ft lb/min (oxygen consumption 1.0 litre/min) on day 1, and the work rate was increased gradually over the period of acclimatization to reach a work rate of 3,120 ft lb/min (oxygen consumption 1.6 litres/min) on day 9.