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By Wayne Burmeister, Danie Benade, Louis Meyer, Hugo Joubert

What is not measured cannot be managed. This is true of most things, including a furnace lining. This paper describes a Lining Management System used for this purpose. It provides the operations staff with a management tool to predict long term lining life and acts as a process optimisation tool. It alarms and records upset furnace conditions. Outputs from the system are described as presented through a specially developed software package and interface. It includes vertical and horizontal furnace sections showing estimated isotherms through the lining as well as the furnace bath. It also shows calculated heat flux values, estimated lining wear and the freeze layer profile. A novel three-dimensional display is described which provides the operator with a big picture view of the furnace crucible profile under real time operating conditions. The powerful trending facility for analysing both measured and calculated values is discussed. The required instrumentation hardware as well as the installation thereof is described, with special reference to an electrically insulating thermocouple socket design. Finally feedback is provided on the first year?s performance of the system installed on an open ferrochrome furnace at Assmang Chrome, Machadodorp, South Africa.

Jan 1, 2007

By A. V. Peake

Continuous Mining presents an opportunity to extract reef in the stope ?continuously? by integrating the drill and blast activity using propellants or low energy charges. To date, the majority of effort spent on Continuous Mining systems has focused on developing an effective rock breaking process (micro breaking process), and to some extent, eliminating fumes and dust. The perceived benefits of applying low energy charges have been identified as: ?Concentrated mining yielding face advances of 40 to 60 m per month ?Lower stoping widths through better-controlled breaking ?Increase in the advance per blast ?Increase in labour productivity ?The potential to mine reefs where specific conditions make conventional mining uneconomic e.g. reefs with shales in the immediate hangingwall. However, the ability to successfully use low energy charges to create a ?Continuous or Semi-Continuous? mining method is dependent on overcoming the following challenges. ?Improving reliability of rock breaking. This is dependent upon achieving:? Improved drilling accuracy, and? Successful stemming or gas confinement, particularly in fractured rock ?Reducing gas and dust levels ?Reducing high costs. Through the research carried out in Future Mine, many different low energy rock breaking methods and systems were investigated. Whilst detailed results cannot be published here, the guidelines for overcoming low energy rock breaking challenges are discussed.

Jan 1, 2003

By Elizma Ford, Vincent Sithole

"Two shortened test procedures for estimating the Bond ball work index are compared for suitability of use on Zambian/DRC-type copper–cobalt ores. The first procedure is based on a batch milling test while the second procedure is based on a limited locked-cycle test. Both procedures were conducted using a standard Bond test mill. INTRODUCTION The Bond ball work index is widely used in the field of minerals processing as an indicator of ore grindability. The work index is determined by means of a locked-cycle test procedure that typically requires seven to eight cycles to stabilise at a re-circulating load of 250%. A typical test requires between three to four kilogram of ore sample and around eight hours of operator time. For geometallurgical test work applications, where a large number of variability samples are to be tested, it would be highly beneficial to use a test procedure that requires less sample mass and operator time. Certain test work laboratories, for example SGS and JK Tech, are already offering various types of shortened test procedures for estimating the Bond ball work index. This paper discusses a comparison of two shortened test procedures that were evaluated for suitability of use on Zambian/DRC-type copper–cobalt ores. EXPERIMENTAL Test Procedure 1 – Batch Milling The first test procedure is derived from a batch milling approach proposed by the University of Hacettepe (Aksani, 2000). Some modifications were, however, made to the data analysis method from that originally proposed. During this test procedure, a 700 mL volume of sample is milled in a standard Bond test mill for a pre-determined number of revolutions. The feed and product particle size distributions are measured for each test. These results are then used to back-calculate a cumulative breakage rate parameter (k) for each particle size, according to the following formula:"

Jan 1, 2015

By S. Vujic

The exploitation of stone (trachyte) at the ?Srebro? open pit mine, located on the northern slopes of the Fru?ka Gora National Park (Serbia) central area begun in 1964. Stone exploitation in this locality does not endanger the environment in an ecological sense, does not pose a threat to plants and animals, and apart from the terrain configuration changes, it did not leave behind permanent consequences to the environment. Projects for permanent cessation of mining operations and for land reclamation and spatial arrangement were completed in these circumstances. The paper gives a short review of the condition at the open pit mine; furthermore, the key problems and basic demands are presented, together with a concept of technical and biological land reclamation and the spatial arrangement of the mining complex. Keywords Open pit mine, land reclamation, spatial planning, spatial arrangement, National Park, Fru?ka Gora, Srebro.

Jan 1, 2011

By J. B. Oosthuizen

Mechanical rock breakers are used in block caving operations to reduce the size of ore fragments which are too large to pass through grizzlys at the load-haul-dumper tipping points. Several layouts of grizzly, rock breaker and ore pass are possible. The authors evaluated three different layouts at the Premier Mine Division of De Beers Consolidated Mines. The first layout consisted of a 15m surge bin before the breaker, which was located 15 m below the production level. The second layout had a 43 m longs urge bin, with the breaker located 43 m below the production level. The third layout did not have a surge bin, the breaker was located on the production level and operated at the tip. The ore throughput, availability and utilisation, delays, costs and operational experience with each system are discussed. It was found that the rock breakers did not represent a bottleneck in the ore transfer system and a surge bin did not significantly improve the production capacity. The mine has decided to make use of rock breakers situated on the production level, breaking rocks at the tip.

Jan 1, 1997

By J. G. Bruwer

Paper written on project work carried out in partial fulfilment of B Eng Met Surface coatings persisting on zircon particles, after being leached in an acidic solution, are believed to be the cause of zircon misplacement during the electrostatic separation of heavy mineral beach sands. Electrostatic separation is employed to separate non-conductive zircon particles from more conductive rutile particles. Surface coatings on zircon particles are believed to render the non-conductive zircon particles more conductive, resulting in the contamination of the more conductive rutile stream with zircon particles. Resistivity measurements, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were performed to compare the surface characteristics of zircon particles found in the different product streams following electrostatic separation. XPS analysis showed that no significant difference exists in the outermost layer of the zircon particles found in the different streams. SEM analysis showed the existing surface coatings on zircon particles from different product streams to have similar chemical compositions. Resistivity measurements confirmed the results obtained from both the XPS and SEM analysis; no significant differences in the resitivities were observed. From the results obtained it suggests that surface coatings present on zircon particles are unlikely the primary cause of zircon misplacement. Zircon losses can possibly be a result of machine related aspects. Key words: XPS; SEM; resistivity measurements; electrostatic separation; heavy mineral sands.

Jan 1, 2007

By J. P. Harrison

ABSTRACT: The significant effect of fracture surface morphology on the mechanical behaviour of rock masses is well known and has been studied by many people. For linear profiles taken from fracture surfaces, short- and long-period variation has traditionally been described using the descriptors ‘roughness’ and ‘waviness’, with Fourier series analysis being perhaps the most commonly used technique to distinguish between the two attributes. However, the mathematical procedure is involved and the assumptions that have to be made may not be appropriate for rock fracture surfaces. In this paper, an alternative method is presented that enables us to distinguish between roughness and waviness of a linear profile by performing only one straightforward analysis. In our technique, surface morphology is studied in terms of the distribution of unit normal vectors to the profile. The statistical analysis of the distribution is performed using Riemannian, rather than the customary Euclidean, geometry, and from this the 1D Riemannian dispersion parameter (DR1) is obtained, which quantifies the geometry of the profile. The method is applied at different scales to both synthetic sinusoidal profiles and real rock profiles. The results show how periodic behaviour of the profile is revealed at scales where DR1 is substantially equal to zero. RESUME: L’influence significative de la morphologie des épontes sur le comportement mécanique des massifs rocheux est bien connue et a fait l’objet de nombreuses études. Pour les profils lineraires, les variations de courtes et longues périodes sont traditionnellement décrites par les indicateurs “rugosité” et “ondulation” qui sont le plus couramment distingués à l’aide d’une analyse en series de Fourrier. Cependant, la méthode de calcul utilisée et les hypothèses faites ne sont pas appropriées dans le cas des épontes rocheuses. Cet article présente une méthode alternative qui permet de distinguer la rugosité de l’ondulation d’un profil en réalisant une seule analyse directe. Avec notre technique, la morphologie de l’éponte est étudiée comme une distribution spatiale de vecteurs normaux au profil. L’analyse de cette distribution est réalisée à l’aide de la géométrie Riemannienne plutôt que la géométrie classique Euclidienne et permet d’identifier la dispersion Riemanienne en 1D (DR1) qui quantifie la géométrie du profil. Cette méthode est appliquée à différentes échelles sur des profils artificiels sinusoïdaux et des épontes naturelles. Les résultats montrent que le comportement périodique du profil est révélé à des échelles où DR1 est essentiellement égal à zéro. ZUSAMMENFASSUNG: Der signifikante Effekt von Bruchoberflaechen Morphologien auf das mechanische Verhalten von Gesteinsmassen ist gut bekannt und von vielen Bearbeitern untersucht worden. Traditionel lineare Profile von Bruchflaechen sind mit kurz und lang periodischen Variationen, die auch als “Rauhigkeit” und “Welligkeit” bezeichnet worden sind, beschrieben worden. Hierbei ist wohl die Fourier Serien Analyse das wichtigste Hilfsmittel zur Unterscheidung der beiden Attribute gewesen. Hierfuer wird jedoch ein mathematisches Prozedere verlangt und Vorraussetzungen gemacht, die vielleicht nicht fuer Gesteinsbruchflaechen zutreffend sind. In dieser Publikation wird eine andere Methode vorgestellt, die uns mit Hilfe nur einer einfachen Analyse erlaubt zwischen “Rauigkeit” und “Welligkeit” bei einem linearen Profil zu unterscheiden. In unserer Methode wird die Gesteinsoberflaeche unter zu Hilfenahme der Verteilung von Einheitsnormalvektoren beschrieben. Die statistische Analyse der raeumlichenVerteilung dieser Vektoren wird mit Hilfe der Riemannschen, anstatt der ueblicherweise benutzten Euklidischen, Geometrie durchgefuehrt. Von ihr wird der Riemannsche Dispersions Parameter (DR1) abgeleitet, der die Geometrie des Profils quantifiziert. Diese Methode ist bei verschiedenen Masstaeben sowohl auf rein harmonische (sinusoidale), syntetische Profile als auch auf Gesteinsprofile angewendet worden. Die Ergebnisse zeigen, dass bei Masstaeben bei denen DR1 nahe Null ist periodische Characteristika der Profile hervortreten.

Jan 1, 2003

By J. Daavittila, P. Jokinen, M. Honkaniemi

In the latter part of the 1980?s Outokumpu Chrome in Tornio, Finland, was in a situation when its twenty-year-old ferrochrome plant was becoming 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 when Tornio FeCr-plant is considering the 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 of better working conditions. The possibilities to respond 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 of 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 J. Gómez-Hernández, P. K. Kaiser

Abstract The process of stress-induced fracturing around underground excavations in brittle rock is associated with dilation or volume increase of the failed, fractured rock. Different attempts to account analytically for this dilation have been made within the framework of plasticity theory. This theory has been developed mostly for metals, strain-hardening materials or soils, but brittle failure of rock-like materials is characterized by strain-softening behaviour and the volume change is dominated by geometric factors, which may violate stability principles of plasticity. In this work a semi-empirical Rock Mass Bulking Model (RMBM) was developed, using as starting concepts: dilation angle, plastic strain rates, effective deformation modulus, effective Poisson's ratio, Griffith locus, and the definition of a bulking factor BF introduced by Kaiser et al. (1996). The model was calibrated in order to obtain bulking factors that are consistent with experimental data and case studies of measured bulking around underground excavations. Résumé La fracturation provoquée par le stress autour des excavations souterraines dans le minéral friable est associée à la dilatation ou à l’augmentation du volume de la roche en rupture. Dans le cadre de la théorie de la plasticité, différents essais ont été faits dans le but de trouver une justification analytique pour cette dilatation. Cette théorie a d’abord été élaborée pour les métaux, les matériaux ou les sols d’écrouissage, mais la rupture fragile de matériaux d’aspect rocheux est caractérisée par un comportement d’amollissement et le changement de volume est dominé par des facteurs géométriques, ce qui pourrait ne pas être conforme aux principes de stabilité de la plasticité. Dans le présent ouvrage, un Modèle semi-empirique de masse rocheuse a été élaboré, dont les concepts initiaux sont les suivants : angle de dilatation, vitesse de fluage plastique, module effectif de déformation, coefficient effectif de Poisson, locus de Griffith, et la définition d’un facteur de foisonnement FF apportée par Kaiser et al. (1996). Le modèle a été calibré afin d’obtenir des facteurs de foisonnement qui soient conformes aux données expérimentales et aux études de cas sur le foisonnement mesuré autour des excavations souterraines. Kurzfassung Der Prozess von Brüchen in unterirdischen Abgrabungen in sprödem Gestein ist mit der Ausweitung oder der Volumenzunahme des gebrochenen Gesteins verbunden. Verschiedene Versuche im Rahmen der Verformbarkeitstheorie haben versucht, diese Ausweitung analytisch festzustellen. Die Verformbarkeitstheorie wurde hauptsächlich für Metalle, kalthärtende Werkstoffe oder Böden entwickelt, da sprödes Versagen von Gestein ähnlichen Werkstoffen von kaltenhärtendem Materialverhalten gekennzeichtnet ist, und die Volumenveränderung von geometrischen Faktoren beherrscht wird, die die Stabilitätsprinzipien der Plastizität übertreten. In dieser Arbeit wurde ein halbempirisches Rock Mass Bulking Model (RMBM) (Modell für das Aufgehen der Gesteinsmasse), entwickelt, für das die folgenden Anfangsprinzipien benutzt wurden: Ausweitungswinkel, plastische Fliessensätze, wirksames Verformungsmodul, leistungsfähiges Poissons Verhältnis, die Griffith Ortskurve und die Bestimmung eines Aufgehensfaktor BF1 der von Kaiser et al. (1996) eingefürt wurde. Das Modell wurde so kalibriert, dass es die Aufgehenfaktoren erzielte, die mit den Vesuchsangaben und den Fallstudien von Aufgehensmessungen in unterirdischen Abgrabungen übereinstimmen.

Jan 1, 2003

By C. F. Strydom

Paper written on project work carried out in partial fulfilment of B. Eng (Mining Engineering) degree The Self-directed work team concept is the product of relentless performance pressure on American industries during the late eighties and early nineties from other world industrial leaders like Japan. The concept proved to be a successful vehicle by which the Americans could increase their production and improve their safety statistics. The aim of this study is to evaluate the concept as a means to improve the overall performance on South African goldmines. he study is directed by a historical research section, answering questions like: ?Why do we need to change? ?What is a Self-directed work team? ?What are the principle advantages of the concept? ?What are the essential requirements for the concept to succeed? The study also includes an empirical research section that focuses on the current Self-directed work team situation in the South African gold mining industry. The empirical research section is limited to three case studies within Anglogold due to a study period of only six weeks. The mines chosen for the case studies have been labelled Mine 1, Mine 2 and Mine 3. The latter being the base mine allowing for a more in depth study. This includes a perception analysis towards Self-directed work teams within the mine. The study proves the truth of the Latin proverb ?Tempora mutantur, nos et mutamur in illis? meaning ?The times are changing, and we are changing with them?. The chief change catalysts identified are a dwindling gold price and a projected labour crisis. From the study it is evident that the Self-directed work team concept disposes of the critical parameters required for a dramatic improvement in performance. The study also indicates that for the concept to succeed, certain factors like top-level commitment and management-employee trust have to be in place. Sadly, the concluding part of the study proves that very few of the identified critical success parameters are present in the South African gold mining industry. This can serve to explain why the industry only has success with the concept when monetary gain is the chief motivator. The study only focuses on the reasons why the concept is not performing to its full potential and does not wander into explaining the reasons for the current unsupportive milieu in the industry. Self-directed work teams could well rescue the South Africangold mining industry but currently we are driving a square pin into a round hole! [Terminology SDWT?Self-directed work teams AEL?Adventure Experiential Learning ISW?In-stope worker POLC?Plan, organize, lead and control TEC?Total employee costed Silo?The confinement of departments preventing networking JCI?Johannesburg Consolidated Investment Co. Ltd]

Jan 1, 2002

Council for 1999/2000 President M.H. Rogers President Elect Dr L.A. Cramer Vice Presidents Senior A.A.B. Douglas Immediate Past President J.R. Dixon Junior S.J. Ramokgopa Honorary Treasurer J.A. Cruise

Jan 1, 2000

By A. L. Edwards

A two-year study focused on current noise exposure levels in the South African mining industry, aimed at helping the Mine Health and Safety Council of South Africa meet its milestones for eliminating noise-induced hearing loss (NIHL). Methods A multi-task methodology was adapted from international baseline studies to determine the exposure to noise in both large-scale and small- to medium-scale mines. Results On average, 66.7 per cent of the employees sampled in year 1 and 78.4 per cent in year 2 were exposed to noise levels of above the 85 dB A legislated occupational exposure level. Conclusions Information obtained through the study could be developed into a national personal noise exposure database, including audiometric results, equipment noise emission levels and initiatives for noise engineering control by mines and equipment manufacturers to facilitate targets of eliminating NIHL. Keywords Noise exposure levels, mining industry, noise-induced hearing loss

Jan 1, 2011

By Andrew Jones

This paper discusses the worldwide market and cost environments for the bulk ferroalloys namely manganese alloys (ferromanganese, silicomanganese), ferrosilicon and ferrochrome (high-carbon ferrochrome, charge chrome). Annual average market prices since 1993 are presented graphically and analysed, and the main supply and demand trends for manganese, ferrosilicon and ferrochrome are summarized. The paper shows carbon and stainless steel output data for 1995, 2000 and 2005, mainly to demonstrate the rising importance of China as a ferroalloys market. Developments in ferroalloys capacity worldwide from 1991 to 2007 are discussed (plant start-ups and closures, ownership changes). Finally, the paper examines developments in the main cost factors for the bulk ferroalloys, i.e., chrome and manganese ore, electricity, carbon reductants and labour. Note that data for 2006 are estimated based on information available in November 2006.

Jan 1, 2007

By S. Kahraman

The correlations between the modulus ratio and penetration rate of rotary and percussive drills were statistically investigated using the raw data obtained from the experimental works of different researchers. An inverse power law was found between the modulus ratio and the penetration rate of rotary and diamond drills. The penetration rate of rotary drills and diamond drills decrease with an increasing modulus ratio. The penetration rates of percussive drills increase with an increasing modulus ratio. There are significant linear correlations between the penetration rates of percussive drills and the modulus ratio. In one of the cases of percussive drilling, a strong correlation between the penetration rate and the modulus ratio was found for the rocks having a porosity value lower 1.23 %. It can be concluded that the modulus ratio might be a representative measure of rock drilling efficiency. However, further study is necessary to check the validity of the derived equations for other rock types. The effect of porosity on the correlations between the modulus ratio and penetration rate needs to be further investigated.

Jan 1, 2003

By W. Kotze

The gold mining industry has mainly relied upon the use of highly polluting chemicals, such as mercury and cyanide to recover gold from its ores. The Coal Gold Agglomeration (CGA) process was developed some years ago and has the advantage in that gold is recovered by a procedure which has little or no negative impact on the environment. A gold ore containing liberated gold particles is contacted with coal-oil agglomerates, where by the gold is recovered into the coal/oil phase. Laboratory scale batch tests were performed on an artificial mixture gold slurry and gold recoveries of up to 85% were found under optimized conditions. By recycling the coal/oil phase, it was found that the gold loading onto the agglomerates was increased. Tests performed on an industrial ore yielded slightly lower gold recoveries, and X-ray Diffraction (XRD) analysis on the coal/oil phase showed that minerals other than gold was recovered into this phase. A comparative study was conducted whereby the CGA process was compared to mercury amalgamation. Gold recoveries obtained through amalgamation were 15% lower than by the agglomeration process, which indicates that this process can be considered favourably as an alternative to amalgamation.

Jan 1, 2000

By P M. Bradbury

The nature of aggressive process chemical requirements typically in the Platinum Refinery Industries, lend themselves to the use of Polymer Composite Glass Reinforced plastics for pipework and other associated equipment in these types of Plants. This paper discusses the basic characteristics of a Polymer Composite glass reinforced piping system and gives sample examples of applications in current present day use.

Jan 1, 2006

By W. Dziurzynski, S. Nawrat, A. Krach

The paper presents research on the influence of the goaf methane inflow on a fire. The problem was investigated by a computer simulation of a fire developing in a goaf. A relevant mathematical model of the fire was selected, which considered both burning of coal and methane. The combustion process is very sensitive on the oxygen and methane concentrations, which was indicated on graphs of the fire temperature evolution. Examples of computer simulation for various location of the fire were considerd. Analysys of results confirms the influence of the content of the goaf methane on development of fires.

Jan 1, 2003

A large number of brittleness concepts have been used in very different studies in the literature. One of them is the B1brittleness concept. In this study, the objective is to criticize the B1 brittleness concept on rotary blast hole drills. The B1 brittleness concept, the ratio of uniaxial compressive strength (sc) to tensile strength (sT), are widely used as a rock brittleness concept in the literature (Inyangand Pitt, 1990; Verhoef, P.N.W. 1993; Neil, D.M. et al.1994;Becker, et al.1984; Evans and Pomeroy, 1966; Göktan, R.M.1992; Kahraman, S. 2001; Yamaguchi, U. 1970; Verhoef, P.N.W. et al.1996; Bilgin, 1982; Howarth and Rowlands,1987; Howarth, D.F. et al. 1986). So, it was used as a rock brittleness concept in this article. The value of the B1brittleness concept is equal to the tangent of ß angle in the following graph. It was seen that more meaningful relationships could be obtained with the B2 brittleness, the under ?Area?(= 1/2(scxsT) = B2) under the curve, instead of tangent ß, (=B1), of the curve.

Jan 1, 2003

The modern theory of sampling of particulate minerals essentially consists of a recent generalization of the procedures for applying and calibrating the formula usually known as ?Gy?s Formula? for sampling variance control, in which the central concept is a parameter called the liberation factor l. A model which can be experimentally adjusted was proposed by one of the authors several years ago, based on geostatistical considerations. This new model, which relates the liberation factor to the sizes of the fragments and mineral grains, solves the usual difficulties faced in the past, and permits predictions that are well verified in practice. Unfortunately, an older, arbitrary and less general formula is still widely used. The vast majority of today?s misapplications of Sampling Theory of Particulate Materials can be traced back to the use of this antiquated and generally incorrect model. Following a brief history of the models used for the liberation factor and a description of its main variable, the liberation size, and to illustrate the importance of proper modelling of l, this paper presents demonstrative calculations of the absurdity of the incorrect model using the particular case of gold mineralization as an example, followed by some more positive examples of application.

Jan 1, 2002

In this study, the effects of slag compositions, slag amount, temperature, and carbon content of steel on the manganese and phosphorus distribution ratios during converter steelmaking were analysed using the classical regular solution theory, and industrial tests were performed using two 80 t top-and-bottom combined blown converters (duplex melting process). The results indicate that the slag amount, temperature, and carbon content in steel are the main factors affecting the manganese yield when converter slag compositions remain constant. The FeO content of the slag has a strong impact on the manganese distribution ratio, while the slag basicity and MgO content have no obvious effect. The calculations and experimental results show that the phosphorus distribution ratio increases sharply with increasing slag basicity R, but then decreases with the increase of MgO and MnO contents in the slag. The final slag in converter steelmaking should have the following characteristics: 3.5 < R < 4.5, 15% < (FeO) < 20%, and 6% < (MgO) < 8%. The slag amount should be controlled appropriately at the same time. The results of this investigation would be useful in deciding on the application of manganese ore in alloying and identifying the slagging regime in converter steelmaking.

Jan 1, 2014