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The paper deals with the importance of design and of codes of practice in ensuring safe working conditions in mines. The design principles involved in the design process are dealt with, and the importance of a logical design process is emphasized. The links between the requirements for developing a code of practice, embodied in the existing guidelines for the preparation of such a code, and the design principles and process are considered in some detail. Finally, suggestions are included, which may provide improvements to the code and hence, ultimately, lead to further improvement in safe working conditions.

Jan 1, 2004

By D. A. Bruce

The paper describes the construction of 5 plugs to resist high water heads at depth within the South Deep Gold Mine, Randfontein, South Africa. A total of 20 segments were involved to create these plugs, which were 7.5 m long at the 58 Level and 6.25 m long at the50 Level. Emphasis is placed on the QA/QC and verification methods, which were developed and governed all phases of the work, from initial rock preparation and pregrouting through to the final grout tightening of the rock/plug interface and the surrounding rock. This paper is one in a series of papers detailing other aspects of the project, which was constructed largely between May 2001 and August 2003.

Jan 1, 2006

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 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

By R. Altindag

The rock brittleness is one of the most important rock properties that affect the drill-ability of rocks. It is supposed that the increase in rock brittleness causes the increase in penetration rate. The drill-ability of rocks depends on many factors. These factors can be separated as two parts depending on a machine, bit type, rotational speed, thrust, blow frequency, flushing, and rock properties, brittleness, compressive strength, structure, hardness, etc. In this paper, the relationship between brittleness and drill-ability index, which is used in the prediction analysis of the penetration rate of rotary blast hole drills, were examined using regression analysis. It is also seen that significant correlations exist between brittleness and the drill-ability index.

Jan 1, 2002

By D. Boldini, R. Lackner, H. A. Mang

ABSTRACT: In this paper, the strong interaction between the hardening shotcrete lining and the surrounding ground in NATM tunneling is investigated by means of axisymmetric analyses, accounting for the three-dimensional nature of the excavation process. The effect of the hydration of shotcrete on strength, stiffness, chemical shrinkage as well as microcracking and creep are accounted for. For the description of the mechanical behavior of the ground, a multi-surface plasticity model is employed. The performed analyses of the excavation process provide insight into the influence of each phenomenon accounted for in the material model for shotcrete on the response of the ground-shotcrete compound structure. ZUSAMMENFASSUNG: In diesem Beitrag soll die Interaktion zwischen dem erhärtenden Spritzbeton und dem Boden auf der Basis axisymmetrischer Berechnungen untersucht werden. Derartige Berechnungen ermöglichen die Berücksichtigung des drei-dimensionalen Charakters des Vortriebprozesses. Die Auswirkung der Hydratation auf die Entwicklung der Festigkeit, Steifigkeit und der chemischen Schwindverzerrungen, sowie das Reißen und das Kriechen des Spritzbetons wurde berücksichtigt. Das mechanische Verhalten des Bodens wurde mittels eines Mehrflächenplastizitätsmodells simuliert. Die durchgeführten Berechnungen des Vortriebprozesses geben Einblicke in die Auswirkungen der Spritzbetoneigenschaften auf das Tragverhalten des Boden-Spritzbeton-Komposits. RÉSUMÉ: La stricte interaction entre le soutènement en béton projeté durcissant et le terrain dans un tunnel creusé avec la NATM est étudiée par des analyses axisymétriques, compte tenu de la nature tridimensionnelle des processus de creusement. Les effets de l’hydratation du béton sur la résistance, la rigidité et la contraction chimique, ainsi que sur la micro-fissuration et le fluage, sont mis en compte. Pour la description du comportement mécanique du terrain on emploie un modèle de plasticité multi-surface. Les analyses conduites mettent en évidence l’influence de chaque phénomène considéré dans le modèle constitutif du béton projeté sur la réponse de la structure composite terrain-béton projeté.

Jan 1, 2003

By P. J. Lloyd

There are few data on the composition of discard coal in South Africa, and no overall view of the discards for the entire industry. As a result of work on coal qualities in South Africa, a database was established which enabled a good estimate to be made of the composition of the discard from every mine. The data are presented in the form of histograms of ash, volatile matter and fixed carbon content of the 43 million tons of material which were discarded in 1990. The results are discussed in terms of the closeness of the composition of much of the discard material to presently used power station coal. It is concluded that it is mainly developments in equipment, particularly fluidized bed boilers, which inhibit the wider use of discard coal. However, other factors must be noted, including the relatively high sulphur content of the discards, and the fact that even with the most careful storage the material ages and may become unusable after about 15 years.

Jan 1, 2000

By J. F. Curtis

In the synopsis, the author concludes that ?high levels of seismicity do not coincide with high rockburst rates?. Implicit to an appreciation of this statement is the necessity of a common understanding of what is understood by the terms: ?high level of seismicity? and ?high rockburst rates?. With respect to the former term there is no difficulty in that the level of seismicity is traditionally measured in terms of the Richter Scale. The latter term however presents a problem in that the author defines it as a particular sort of seismic event?viz: ?Rockburst? is understood as a seismic event that causes damage to an underground excavation with subsequent injury, loss of material/equipment or production shifts? (p. 322). No scale is given of the amount of: ?excavation damage ?level of injury ?material/equipment loss ?production shifts lost whether separate or cumulative, for a particular seismic event to be classified as a rockburst. A further difficulty arises in that in common usage the words ?rockburst?, ?seismic event? and ?earthquake? are all used to describe the same event.

Jan 1, 1999

By M. Gous

Namakwa Sands is a heavy minerals mining and beneficiation business in the Anglo Base Metals Division, and operates along the West Coast of South Africa. The business encompasses mining, mineral concentration, separation, and smelting operations. The smelting process comprises the carbonaceous reduction of ilmenite to produce titania slag with a TiO2 content of 86%, and iron with a carbon content of 2.5%. The Namakwa Sands smelter, situated near the Saldanha Bay harbour, commenced smelting operations in 1994, when a 25 MW DC-arc furnace was commissioned. The smelting operations were expanded in 1999, with the commissioning of a second 35 MW DC-arc furnace. Despite the fact that ilmenite smelting poses a technical challenge in terms of the high temperatures required, the physical characteristics of the slag, the constraints placed on the feedstock, and the tight product specifications, Namakwa Sands has continually increased slag production since 1995. High furnace feed-on utilization and furnace stability, complemented by continuous improvement drives, will be thevehicle to drive performance in the short-term, with longer-term performance enhancements due to strategic process development. Keywords: Pyrometallurgy, Namakwa Sands, ilmenite, DC-arc furnace, titania slag, pig iron

Jan 1, 2006

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 R. Butcher

Mud rushes are hazardous occurrences that have occurred frequently in mines in South Africa, and have been the cause of numerous fatalities in the past. Mud rush incidents not associated with accidents are believed to be common occurrences that are not generally reported. Many such incidents are probably associated with the operation of chutes and box fronts. This paper describes the conditions necessary for mud rush occurrences, postulated mud rush mechanisms, and methods of combating the mud rush hazard.

Jan 1, 2005

By J. R. Menasce

Mechanization in low-stope panels situated in hard rock infers roof support by tensile bolting to allow free passage of trackless mining equipment in the production areas. This is in sharp contrast to conventional mining, where compressive roof supports?such as timber and grout packs?have traditionally been used, up to 1.5 metres from the production face. Bolting is a hazardous operation because material is dislodged from the roof during the drilling activity. Even with temporary roof support installed, small pieces of rock are dislodged by the percussive action of the drifter. Operations with the man situated directly under the drill, during the drilling activity, are hazardous. The only way to remove the hazard is to move the man away from the machine for as much as possible throughout the complete cycle Costs associated with safety cannot be quantified, but need to form part of the decision-making process. Machine selections based on purchase and running costs alone do not justify the investment cost of mechanized bolters. The equipment selection process needs to take into account the total cost of mining as well as the human safety impact and loss of production costs from having to re-bolt roofs in a production panel to prevent falls of ground. Labour costs in mechanized low-stope bolting are between one-quarter and half the labour costs of non-mechanized bolting. This paper reviews the mechanized bolting option versus handheld bolting from a mining process and cost perspective in a hard rock, low-stope room-and-pillar mining operation in the platinum and chrome industries.

Jan 1, 2006

Plant survey data has shown that gold recovery through a specific copper concentrator was significantly lower than copper recovery. Size-by-size analysis revealed that this was due to poor recovery of+75 µm and ?23 µm gold containing particles. In order to further investigate the nature of the gold losses, experiments were conducted at laboratory scale. Gold deportment studies on the laboratory flotation products revealed that coarse gold (+75 µm) reporting to the rougher tailing was predominantly associated with non-sulphide gangue. Further grinding of the plant rougher tailing improved recovery of gold and copper, while not affecting iron recovery, due to improved liberation of gold from non-sulphide gangue in coarse size fractions. EDTA extraction to remove surface contaminants showed a similar improvement for fine, liberated gold flotation.

Jan 1, 2003

By R. E. Robinson

A novel variation of the GYPCIX process for the treatment of the acid mine effluent water from Grootvlei is described, in which a number of valuable by products can be obtained and the product water can be used for a variety of different purposes. A conceptual case study is presented in which the important cost parameters are described and certain critical path activities are indicated in order to derive a Return on Investment evaluation according to methods previously published. The study indicates that the treatment costs can be dramatically reduced, provided that proper utilization of the by products is taken into account. There are many possible uses for the water. However, by far the most advantageous contribution to the RDP and the best return on capital is derived if the water is used to establish small-lot farming activities providing work opportunities for thousands of people and contributing several hundred million Rands to the GDP. Vastly improved social conditions will be generated in an area of Gauteng that is in danger of rapid deterioration and a contribution will be made to maintaining mining activities in this area. The environmental impact is positive.

Jan 1, 1998

By R. L. Lawson

I?ve been asked to appraise the global role of coal and mining, and the best place I can think of to begin is with the World watch Institute, which purports to monitor all things global. Last fall the institute?s magazine, entitled World Watch, in a cover story called for a worldwide campaign to outlaw the use of coal before this century?s end. To my mind the article began the campaign. However, the institute had to admit that no such ban will be possible unless there is special help and heavy intervention?that is, novel policies and punitive taxes. I?ll quote directly from the magazine to underscore the point: ?without them the market will continue to deceive us into thinking coal is cheap, abundant and irreplaceable?.

Jan 1, 2001

Ongoing rockpass problems on mines within the South Africa region, prompted AngloGold Ashanti to embark on a risk assessment of major rockpasses. This commenced with the collection of relevant data to identify gaps in the available knowledge and identify existing problems. This was followed by an assessment of rockpass layouts to determine existing and potential interactions with other excavations. An initial risk assessment has been completed and the rockpasses have been ranked in terms of their risk profile. The lack of geological data and an easy and reliable method of surveying rockpasses have been identified as problem areas. Shortcoming is terms of rockpass management procedures have also been identified. Further work is required to quantify the risk in terms of probability of occurrence and consequences.

Jan 1, 2005

By J. P. Harrison, J. A. Hudson

ABSTRACT: Given the current widespread use of numerical models for rock mechanics and rock engineering, and the ‘Technology Road Map’ theme of the Congress, it is timely to consider the key issues in matching numerical models to rock engineering problems. The three main aspects are: a) identifying the mechanisms, variables and parameters that are relevant to a particular rock engineering project; b) establishing the content and mode of operation of a particular code; and c) deciding whether a particular code provides an adequate model for a particular project. We summarise the key issues, highlighting the concept of rock mass domains, validation and the ability to present the results of a modelling exercise. We include three compact numerical modelling case examples to illustrate the points. Finally, we also present a ‘roadmap’ to assist in the process of matching a numerical model to the rock reality. RESUME: Considérant l’utilisation généralisée des modèles numériques en mécanique des roches et en ingénierie au rocher ainsi que le thème du congrès ‘technology road map’, il est opportun d’aborder les problèmes essentiels liés au choix des modèles numériques dans les problèmes ingénierie au rocher. Les trois aspects principaux sont : a) l’identification des mécanismes, variables et paramètres appropriés au projet considéré, b) la définition du contenu et du mode de fonctionnement d’un code numérique donné, et c) la possibilité de décider si un code donné fourni un modèle approprié au projet considéré. Les points clés sont résumés en mettant en évidence les notions de “massif rocheux”, de validation et de capacité à présenter les résultats d’une approche numérique. Nous présentons trois brèves études de cas qui illustrent ces points. Enfin, nous proposons aussi un logigramme pour aider au choix d’un modèle numérique approprié pour représenter la réalité d’un problème au rocher. ZUSAMMENFASSUNG: Im Licht der augenblicklich weitverbreiteten Nutzung von numerischen Modellen in der Felsmechanik and im Felsingenieurbau und unter Beruecksichtigung der Themenstellung des Congresses “Technology Road Map”, erscheint es an der Zeit die Kernprobleme, die sich mit Fragen der Abstimmung der numerischen Modele mit Hinblick auf ihre Anwendbarkeit im Felsingenieurbau beschaeftigen, naeher zu befassen. Die drei wesentlichen Aspekte sind: a) Identifizierung der Mechanismen, Variablen und Parameter, die fuer ein bestimmtes Projekt im Felsingenieurbau von Bedeutung sind; b) die Festlegung des Inhalts und des Modus Operandi eines bestimmten Codes, und c) die Entscheidung darueber ob ein bestimmter Code ein hinreichendes Model fuer ein bestimmtes Projekt ergibt. Wir fassen die wichtigsten Punkte zusammen, heben dabei das Concept der Gesteinsmassen Domaenen (Rock mass domains) hervor, und erarbeiten ihre Beurteilung und die Moeglichkeit diese zu praesentieren in den Ergebnissen einer Model Uebung. Wir schliessen drei Beispiele von numerischen Modellen ein in denen diese Punkte erlauetert werden. Zuletzt schlagen wir eine “Roadmap” vor, um dem Prozess der Abstimmung des numerischen Modells mit der “Felsmechanischen Wirklichkeit” zu unterstuetzen.

Jan 1, 2003

By M. J. Nicol

The kinetics of the dissolution of colloidal silver in aerated cyanide solutions has been investigated with the aim of developing a relatively rapid and convenient method for monitoring the ?leaching power? of solutions typically used in the cyanidation process. Experimental results obtained are consistent with an electro-chemical model, in which the mixed potential is set up in the active region of the polarization curve for the anodic dissolution of silver, giving rise to a rate of dissolution which is controlled by the rate of mass transport of either cyanide or oxygen to the surface of the silver. The rate of dissolution of colloidal silver was found to respond to variations in the reactant concentrations in a similar manner to gold (and silver) in a typical free-milling ore. The use of this technique for the monitoring and control of the cyanide leach process is discussed.

Jan 1, 1998

By E. Kuipa, J. N. Lekunze

The selection of an underground mining method stems from a multivariate analysis that considers geomechanical, geological, economic, and operational parameters. Even after identifying the most compatible method, there is no assurance that the mining company will achieve the best performance. The geological complexity of some deposits requires adaptations of methods described in the literature to obtain more selectivity and reduce mining waste. There are some studies on geometry of underground structures, but a methodology that describes an adaptation of a room-and-pillar mining method for ore bodies with down-dip varying from 20° to 25° is novel. The present work aimed to reduce dilution by adapting the traditional room-and-pillar mining method (TRP) to inclined ore boLittle attention has been paid to the rehabilitation of derelict and ownerless mines in South Africa after their lifespan. This paper aims to explore management gaps in legislation that have resulted in the non-rehabilitation of derelict and ownerless mines in South Africa. There is growing evidence that supports the distressing effects of mining on people living around these mines in the North West Province. This paper was motivated by the current socio-economic status quo of old mining towns, the influx of illegal miners (Zama Zamas), severe environmental damages, and the violence associated with derelict mines. Underpinning this research was an ecosystem approach and integrated resources management principles, which formed the foundation for the decision-making process.The researcher used a mixed-method approach and employed convergent techniques. A semi-structured instrument was used to collect data from 200 respondents. The results indicated that there is a dire need for community-based consultative processes, and an absence of clear guidelines for derelict and ownerless mines to pressure mine management to adhere to rehabilitation standards. Moreover, the mining charter is ambiguous regarding policy implementation, budgetary allocation, and duration of the rehabilitation of these mines. The paper concluded that management challenges associated with derelict mines can be reduced if all stakeholders follow the guidelines as outlined in the environmental legislative framework (NEMA) of South Africa while being open to innovations in line with international best practices. It also contributes towards the development of guidelines for the management and implementation of legislation related to derelict and ownerless mines in South Africa from a philosophical, theoretical, and policy perspectivedies. This new method is entitled short-hole room-and-pillar (SHRP). The equations that measure the dilution are defined according to the geometry of stopes and openings. The results comprise comparative analyses of the operational and planned dilutions to measure the performance of the SHRP method. The average operating dilution of the SHRP method was more than five times lower than the planned dilution according to the TRP method. Low operational dilution indicates high selectivity of the method and its potential to reduce underground mining tailings.

Oct 9, 2024

The 103rd Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Gold Room, Transvaal Automobile Club, 60 5th Street, Lower Houghton, Johannesburg on Wednesday, 16th August, 2000. Welcome The President extended a special welcome to the guests and representatives of our sister institutes and other associations. Also to recipients of awards, senior members of industry, Honorary Life Fellows, Past Presidents, our Members and other guests, among them the following: Reinie Meyer, President, The Geological Society of South Africa Dr Nielen van der Merwe, Chairman, The South African Institute of Rock Engineering Chris Fourie, President, Institute of Mine Surveyors of South Africa

Jan 1, 2001