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By M. S. Smith

Paper written on project work carried out in partial fulfilment of B. Eng (Mining Engineering) degree The condition of tunnels at Premier has deteriorated to such an extent that an objective viewpoint on what leads to poor condition was required. Poor and untimely development results in schedule deviation, rehabilitation, and increased working costs. The project focused primarily on quality, and not on efficiency. The project gave management guidelines that need to be focused on in order to produce quality infrastructure. The conclusions were reached by doing literature searches, underground site investigations, benchmarking and computer simulations. From the results we can see that, in order to produce good quality tunnels, we have to have the basics working. This was found to be one of the major problems. Firstly, tunnel profiles are not to the design specification and no fixed blast designs existed. After revising tunnel profile statistics, over break increased to 10% (previously 7%) and development metres were 50 m short of target. Blasting was not monitored and designs not optimized for the conditions. Furthermore, geological factors are the main contributor to tunnel failure, although this process is initiated and aided by poor development (overbroken tunnels, incorrect profiles, direction and location) and blast damage. Continuing to develop tunnels in the current manner will cost R 1.5 million in additional costs for loading and supporting overbreak, whilst an additional 1 800 man-shifts will be required. Blast patterns were designed as a starting point for trials, while the implementation of a blast management system, development statistical database, tunnel hand-over procedures and a revision of the bonus system were proposed.

Jan 1, 2004

By Y. F. Bulgakov, Y. V. Melnikova, V. S. Zakharov

A new technology of atmosphere in inertization of fire section with the help of gazeous nitrogen is presented in the report. This technology is based on membrane air subdivision into two streams, concentrated with nitrogen (up to 99%) and with oxygen correspondently with subsequent giving them into the place of fire. This technology belongs to environmentally friendly ones and it has a great number of technical, mobile and economic advantages comparing with the rest of well-known methods of fire extinguishing. This technology application in Ukrainian coal mines allowed to reduce the member of isolated places of fire at the expense of their extinguishing efficiency.

Jan 1, 2003

By M. D. Seke

The flotation response of a Pb-Zn sulphide ore from the Rosh Pinah Mine (Namibia) was studied in the presence of inorganic depressants such as sodium cyanide and zinc sulphate. Poor flotation selectivity was observed in the rougher concentrate of the galena circuit despite the use of a large amount of sodium cyanide. Batch flotation tests have shown that the use of cyanide alone is not efficient for the depression of sphalerite from the Rosh Pinah ore when milling is carried out according to the current plant particle size distribution. The use of both cyanide and zinc sulphate improved the selectivity between galena and sphalerite much better than cyanide alone. Flotation selectivity is limited by the mineralogical texture of the Rosh Pinah ore sample. Microscopic analysis has shown that the presence of sphalerite in the galena concentrate is also due to poor liberation between galena and sphalerite, especially in the middlings. Hence, selectivity could be improved by regrinding the rougher concentrate prior to the cleaning stage. Keywords: sulphide ores, flotation, flotation depressant, mineralogy.

Jan 1, 2005

In constructing a financial model of a project significant effort is expended on capital and operating cost estimation, commodity price forecasts, and choice of discount rates while uncertainty in the primary input, the reserve, is often completely overlooked. The aim of this paper is to highlight the impact of uncertainty in the resource/reserve estimation process on the assessment of the financial performance of a project. Four qualitative processes have an impact on resource/reserve uncertainty. These stages are: 1.Ore definition 2.Geological interpretation 3.Resource estimation 4.Ore reserve estimation and mine planning. Each stage contains a number of tasks that may be considered as key performance activities (KPAs). Optimizing the manner in which these KPAs are completed can remove a great deal of uncertainty and error from the resource/reserve process. Examination of these KPAs within a company can also provide an insight to the quality of the information underlying the project. This will allow the company to identify any shortcomings in the data and to assess the resulting risks (Gilfillan, 1998). A hypothetical financial model based on a gold operation has been used to estimate the potential effect of resource/reserve uncertainty on revenue. Monte Carlo simulation has been employed to simulate a number of hypothetical scenarios: 1.a base case scenario which assumes no major errors or biases, but contains realistic margins for uncertainty that would exist in any project where work is being completed to the limit of best endeavours 2.a poor sampling scenario which assumes poor sampling practice and lack of understanding of sample preparation 3.a poor resource estimation scenario which assumes poor modelling and inappropriate choice of interpolation technique, and 4. a ?typical? scenario which represents a project where the majority of KPAs are not performed as best as they could be. The results show that realistic uncertainty ranges can generate changes in the estimate of potential revenue of plus or minus 30%.Therefore, it is important to allow for errors in these processes in any financial analysis or feasibility study. It is recommended that, when building a financial model, are view of relevant resource/reserve KPAs be carried out and appropriate ranges for uncertainty be applied to provide a range of potential outcomes. These outcomes can then be factored into the detailed cash flow analysis in order to ensure that technical uncertainty is built into financial decisions.

Jan 1, 1999

By H. H. Einstein

This paper reviews how uncertainty has been dealt with over the past 40 years using the decision making cycle as a frame of reference. The review of the phases of this cycle, as applied to rockmechanics and rock engineering, namely characterization, performance analysis, updating and decision making shows that in each, progress has been made over the past 40 years, although most of the basic concepts existed already in the 1960’s. Characterization is the area in which the greatest scientific steps were taken, this phase and performance analysis also gained from the tremendously expanded computational capabilities which allow one to use both more complex and more practically oriented models. The greatest practical advance is without using any doubt in risk based decision making although its acceptance shows interesting differences between different professions. Dans l’article suivant on utilise le cycle de décision pour illustrer le développement du traitement des incertitudes en mécanique des roches et en construction en roche dans les quarante années passées. La revue des phases du cycle de décision montre qu’on a fait du progrès dans chaque phase du cycle de décision, c’est à dire dans la caractérisation, dans l’analyse et la prédiction du comportement, dans l’actualisation et dans l’acte de décision, même si les concepts fondamentaux existaient déjà dans les années 1960. Les plus grands avancements scientifiques se trouvent dans le domaine de la caractérisation tandis que l’analyse prédictive profitait du développement de l’informatique qui a mené à des modèles plus complexes mais aussi plus pratiques. Le plus grand progrès est sans doute dans le domaine de l’acte de décision sur la base des risques. Ce procédé est devenu assez commun même s’il y a encore des différences d’acceptation entre différentes professions. Im vorliegenden Artikel wird der Entscheidungszyklus gebraucht, um darzustellen wie sich derUmgang mit Unsicherheiten im Felsbau während der letzen 40 Jahre entwickelt hat. DerÜberblick über die Phasen des Entscheidungsprozesses zeigt, dass bei der Anwendung in derFelsmechanik und im Felsbau, in allen Phasen d.h. bei der Charakterisierung, bei der analytischenVorhersage, beim Aktualisieren und bei der Entscheidungsfindung Fortschritte gemacht wurden,obwohl die grundlegenden Konzepte bereits in den 1960er Jahren existierten. Im Gebiet derCharakterisierung gab es wohl die grössten wissenschaftlichen Entwicklungen, während dieanalytische Vorhersage vor allem von den Fortschritten der Informatik profitierte, welchekomplexere wie auch praktischere Modelle möglich machte. Der grösste Fortschritt ist ganz sicherin der Entscheidungsfindung zu beobachten, wo Risikobetrachtungen gang und gäbe sind, obwohlhier noch einige Unterschiede zwischen verschiedenen Berufsgattungen zu finden sind.

Jan 1, 2003

By A. J. Van Der Merwe, J. F. Erasmus

One of the valuation approaches applied to Advanced Exploration Areas and Pre-Development Projects is the so-called ?in situ Mineralization Method? or the ?Yardstick Method?. This method is based on the concept of a known undeveloped Mineral Resource being worth a certain fraction (the ?Yardstick?) of the contained commodity value (?metal in ground?), using commodity prices ruling at the date of valuation. The Yardstick value is derived usually from an average market-based figure obtained from an analysis of recent transactions and is expressed as a monetary value per ounce or per tonne. It maybe modified to accommodate the quality (e.g. grade) and category (e.g. confidence level) of the Mineral Resource/Reserve involved and the time, effort and expenditure expected to be involved in bringing the project to fruition. Some eighteen recent and relevant transactions were analysed, allowing the following general conclusions to be reached: ? a Yardstick with which to value undeveloped PGE mineral resources is likely to range between 0.5% and 2.5% of the in-ground contained metal value ? the expected method of mining (especially with regard to mining costs) and the grade of the mineralization both have a strong influence on the Yardstick ? the status (classification) of the Mineral Resource has some influence on the Yardstick and ? the ruling price of platinum and the regional location of the deposit appear to have insignificant influences on the Yardstick.

Jan 1, 2006

By A. T. Haile

Detailed monitoring of the response of the rock mass between rockbolt reinforcement units subjected to a simulated seismic source has been successfully conducted. This work has shown the increase in amplification of the Peak Particle Velocity (PPV) with distance from a rock bolt unit, and, a minimum PPV for rockburst damage for the given site characteristics. This understanding, at this site, will allow the design of a suitable rock bolt spacing to prevent unravelling of the rock mass between the rock bolt units for a given level of seismicity. Or, alternatively, an estimation of the requirement for a suitable fabric support system, for the anticipated level of seismicity, can be made.

Jan 1, 2001

By K. Collett

Elandsrand started shotcreting back in 1991. This paper will share the experiences of the mine by looking into the past, the present situation and the way Elandsrand plans to approach the future. It looks at the application of drycrete and discusses the factors that led to the introduction of wet fibre reinforced shotcrete. The logistical constraints of getting shotcrete material underground will be solved by the development of an underground batch plant, using run of mine waste rock as an aggregate.

Jan 1, 1998

By B. Amadei, F. Tonon

Rock stress measurement is cast in the more general context of the determination of boundary conditions for rock engineering. A study on the effect of elastic anisotropy on underground excavations reveals that this effect is actually controlled by the imposed boundary conditions. Applications to tunneling and to the Underground Research Laboratory (URL), Canada, exemplify a procedure for boundary condition estimation formerly developed by the authors. The procedure displayed fast convergence despite the complex geometry, and the high degree of non-linearity of the models. In the URL application, the 3-D model was able to completely reproduce the complex measured stress pattern, and the 90° rotation of the principal in situ stresses with depth. In order to reliably estimate the boundary conditions reproducing the current in situ state of stress, response measurements of the rock mass to current disturbances are necessary as input data. La mesure des contraintes in situ tombe dans le domaine général de la détermination des conditions aux limites pour les problèmes de mécanique des roches. Une étude sur le rôle de l’anisotropie élastique sur les excavations souterraines montre que ce rôle est contrôlé par les conditions aux limites qui sont imposées. L’application aux tunnels et au Laboratoire Souterrain de Recherche (URL) au Canada, nous permet de présenter une méthode de détermination des conditions aux limites. La méthode converge rapidement bien que le géométrie soit complexe et que le problème soit non-linéaire. Pour le URL, le modèle 3D est capable de reproduire la distribution des contraintes qui ont été mesurées ainsi que la rotation de 90 degrés des contraintes in situ avec la profondeur. Afin de déterminer avec précision les conditions aux limites responsables pour la distribution actuelle des contraintes, la réponse du massif rocheux doit être connue et mesurée. In der Felsentechnik sind die Spannungsmessungen in Gestein an die Bestimmung der Randbedingungen gebunden. Eine Studie legt dar, dass der Effekt elastischer Anisotropie in unterirdischen Aushoehlungen von den Randbedingungen kontrolliert ist. Eine von den Authoren entwickelte Methode zur Bestimmung der Randbedingungen wird an Beispielen im Tunnelbau und im Underground Research Laboratory (URL) in Kanada illustriert. Auch bei komplexer Geometrie und einem hohen Grad an Nicht-Linearitaet zeigt diese Methode ein schnelles Konvergenzverhalten. Ein 3D-Model und dessen 90° Drehung der lokalen Hauptspannungen mit der Tiefe, kann bei einer URL Anwendung vollstaendig reproduziert werden. Um mit dieser Methode die Randbedingungen zuverlaessig abschaetzen zu koennen, werden der gegenwaertige lokale Spannungszustand sowie die Antwort des Gesteins und die resultierenden Stoerungen als Eingabedaten benoetigt.

Jan 1, 2003

Cokriging uses a sparsely sampled, but accurate and precise primary dataset, together with a more abundant secondary data-set, for example grades in a polymetallic orebody, containing both error and bias, to provide improved results compared to estimation with the primary data alone, as well as filtering the error and mitigating the effects of conditional bias. The method described here may also be applied in polymetallic orebodies and in other cases where the primary and secondary data could be collocated, and one of the data-sets need not be biased, unreliable, etc. An artificially created reference data-set of 512 lognormally distributed precious metal grades sampled at 25×25 m intervals constitutes the primary data-set. A secondary data-set on a 10×10 m grid comprising 3200 samples drawn from the reference data-set includes 30 per cent error and 1.5 multiplicative bias on each measurement. The primary and secondary non-collocated data-sets are statistically described and compared to the reference data-set. Variograms based on the primary data-set are modelled and used in the kriging of 10×10 m blocks using the 25×25 m and 50×50 m data grids for comparison against the results of the cokriged estimation. A linear model of coregionalization (LMC) is established using the primary and secondary data-sets and cokriging using both data-sets is shown to be a significant improvement over kriging with the primary data-set alone. The effects of the error and bias are filtered and removed during the cokriging estimation procedure. Thus cokriging using the more abundant secondary data, even though it contains error and bias, significantly improves the estimation of recoverable reserves.

Jan 1, 2014

By H. C. de Wet

The predevelopment and preparation of a total infrastructure in a deep level mining environment, prior to the shaft system being commissioned has major advantages. This paper intends to indicate these advantages and outline an understanding of the disadvantages. These benefits can be classified in three basic groups: the financial and timing advantages, a knowledge of the ore body and the development of required technology to meet the design parameters. The required technology in many aspects was still to be developed prior to successful application. Stemming from the technological evolution are some secondary advantages which will be described in each of the groups. Safety and health considerations and some practicalities made some of the new technology redundant prior to the actual application. In each case the actual achievements and the anticipated benefits will be indicated to allow the reader to distinguish clearly between planned and actual achieved advantages.

Jan 1, 1997

By A. Cichowicz

In this study, techniques used to design earthquake-resistant structures are applied to the deep-level mining environment. Earthquake engineers seek to identify the cause of potentially damaging resonance, and design or reinforce structures to reduce these effects. Similar techniques have been used to analyse the dynamic behaviour of the rock mass surrounding a stope in a deep South African gold mine. A three-dimensional seismic array installed in a stope at TauTona Mine (previously Western Deep Levels, East Mine) provided an opportunity to examine the evolution of the wave field close to an underground opening. A set of three-component geophones installed in a borehole above the panel revealed the development of surface waves as wave fronts reached the excavation, and an array of vertical component geophones fixed to the hangingwall provided a two-dimensional map of site effects. While the collected data do not include damaging seismic events, quantitative analysis enabled phenomena which could lead to damage, to be recognized. In the vicinity of the excavation, the energy of the seismic signal is generally transformed from high frequency to low frequency. It was found that seismic events with relatively high corner frequency (150 Hz?200 Hz) usually excite several modes of vibration (30 Hz to 110 Hz), while events with low corner frequency (30 Hz?50 Hz) do not always excite higher modes of vibration in the structure. This implies that the rock mass around the excavation is a complex medium, and should be studied using the multi-degree-of-freedom model. A strong structural effect (due to the excavation shape) was revealed as a low frequency coda wave (at 40 Hz and 60?70 Hz), well developed on the skin of the hangingwall. A strong site effect was revealed by changes in signal properties between hangingwall geophones, exhibiting strong resonances around 160 Hz and in the range 200 Hz to 300 Hz.

Jan 1, 2000

As the world continues to face the turmoil of the economic environment, legislative prerequisites and physical conditions the intervention of technological development is vital for the continuation of the ancient source of revenue: mining. The Palabora underground mining project is a state-of-the-art shaft mining system that will prove to be a benchmark in its field for years to come. An integration of modern technology?both in application and development?has resulted in a shaft system that is intrinsically holistic. Every aspect of the mining and production process has undergone thorough investigation, simulation and innovation to ensure that every component is selected by design and not simply conforming to past practice or trends. The process philosophy includes proven technology such as to promote the lowest operating cost and process time with the highest yield. The underground mining system is in the final stages of commissioning and will shortly be producing a nominal 30 000 tons per day with a predominantly automated system. This paper discusses the complete state-of-art shaft system developed for the Palabora underground mine, and refers particularly to the headgear, the winders, the conveyances and the shaft guide system, as well as the loading system developed specifically for the high performance requirements of the mine.

Jan 1, 2000

By J. H. Viljoen, C. H. Graan, N. B. Strydom, J. S. Greyson

M J Martinson (Fellow) There is everywhere a lamentable dearth of quantitative information on occupational factors affecting the health and safety of mineworkers, and as the authors point out in their introduction underground lighting is one of the factors which has received little attention in South Africa prior to this welcome paper. Since the authors are to some extent pioneering, it is perhaps inevitable that the paper should raise more questions than it answers, but nevertheless it provides a provisional yardstick against which the need for, and success of, remedial action may be judged. Before commenting in detail on a few aspects of the paper it may be worthwhile to summarize the statutory provisions relating to underground lighting, contained in Chapter 15 of the Regulations promulgated in terms of the Mines and Works Act 27 of 1956. Chapter 15 is entitled `Lighting, Safety Lamps and Contraband', but in the context of the present paper only four simple regulations need be noted: firstly, no person shall work or travel in an unilluminated part of a mine unless he carries a light ; secondly, adequate stationary lights shall be provided at stations and certain other localities in shafts, winzes and places used for winding; thirdly, mechanically propelled conveyances shall be provided with an effective bright light shining in the direction of travel; and fourthly, moving machinery to which personnel have access shall be illuminated so as to be clearly visible. In all four regulations the standard of lighting to be provided is wholly subjective, and under these circumstances the wide inter- and intra-mine variations in light intensity disclosed by the study are hardly unexpected. Nevertheless the data presented in the authors' Table I raise three points (1) Is there any evidence that the 19 mines visited during the survey are representative of the 45-50 large gold mines in South Africa, or that the shafts selected are representative of the respective mines? Mine managers would scarcely be human were they not to offer better lit working places for the survey; perhaps the use of a scaling factor (e.g. tonnes or transit mineworkers per shift, kilowatts, etc.) for each working place might have helped to put the figures in perspective. (2) Looking at two of the more numerous - and probably important - of the ten working places included in the survey, i.e. stations and tips, one is struck by the marked. skewness of both intensity distributions (with higher frequencies at the lower intensities) and the abrupt cut-off in both cases just short of pitch darkness. Thus, of the 45 meaned readings recorded at 26 tips no less than 19 fall in the lowest range of 0,1-0,9 1m/ft2, with but one tip in total darkness; of 46 readings on 26 stations, 7 fall in the lowest range and none is in total dark-'1 ness. Although a light with an intensity in the range 0,1-0,9 1m/ft2 may satisfy the regulations, it is certainly arguable that in some situations it may be safer to have no light at all. (3) In view of the skewness referred to above, one wonders how meaningful are the `total average light intensities for (the gold mining) industry' quoted in Table I, which the authors compare with illumina¬tion levels found in other countries. Looking at tips again, one notes that 34 out of 45 meaned intensity readings fall below the `total average' for tips, and only 10 exceed it. From this it may be concluded that a few well-lit working places included in a `total average' may conceal a plethora in Stygian gloom. In their discussion the authors make fleeting reference to the effect of underground lighting on productivity and accident rates, without however quoting any South African experience in this regard. Intuitively it seems highly likely that better lighting (in the widest sense) would improve productivity and reduce accidents, and of course it is in these areas that the mining industry might seek economic justification for providing better lighting. It is all the more regrettable therefore that these factors were not studied simultaneously with the present investigation, especially at the Psychological Division of the Human Sciences Laboratory has recently published a study on underground accidents in the gold mining industry without making any reference whatsoever to lighting as a causal factor. In the event neither of the two studies enables us to make an economic appreciation of the situation, and this seems to be a classic example of a situation where some dovetailing of research effort would have greatly increased the useful return. On the effect of lighting on accidents, it may be noted that in 1939 Mickel presented some very interesting statistics to the Mine Managers Association of the Transvaal2, on the improvement in accident rates which followed the random issue of electric cap lamps to native mineworkers in the Hercules Section of E.R.P.M. the previous year. Based on a 12 month trial period in which 250 000 shifts were worked with carbide lamps and (contemporaneously) 307 000 shifts with cap lamps, the incidence of major accidents (at least one day in hospital among men using carbide lamps was 1,15 accidents per 1000 shifts, while the incidence of minor accidents (requiring dressing only) was 11,52 per 1 000 shifts. The corresponding figures for men using cap lamps were 0,79 and 7,31 accidents per 1 000 shifts respectively, representing a reduction of over 30 per cent in both major and minor accidents. While these figures are obviously dated - only men using cap lamps were issued with hard hats, for instance - they do indicate a need for similar research today.

Jan 1, 1971

By I. McDougall

The matte/slag tidal zone in a nickel-copper-iron-sulphide matte smelting furnace is subject to severe process conditions that can lead to premature failure of the lining. The MgO-FeO-SiO2 slag is aggressive to refractory bricks, while the Ni-Cu-Fe-S matte is aggressive to water-cooled copper cooling elements, and can penetrate and sulphidize refractory bricks. A novel approach to the lining design was taken at a PGM smelting furnace, where an indirectly-cooled graphite ring was applied in the matte/slag tidal zone, with refractory bricks on the hot face. The graphite was cooled by the copper cooling elements in the slag zone, obviating the need for copper cooling elements in the tidal zone. In this paper the effectiveness of different lining designs utilizing varying degrees of cooling in the slag zone and slag/matte tidal zones is compared. In comparison to water-cooled copper in various configurations, cooled graphite shows promise as an indirect refractory cooling system in the tidal zone area of furnaces. Keywords PGM smelting, graphite, refractory lining, copper cooling elements, submerged arc furnace.

Aug 1, 2013

By V. Mathebula

Paper written on project work carried out in partial fulfilment of B. Tech (Mining Engineering) degree The purpose of this study is to establish whether to mine the Bottom of Pit (BOP)/TOB 4 reserve before the commencement of the Block Cave or whether this should be disregarded and the reserve be extracted at the end of the life of the Cave. The primary goal of this report is to investigate and propose a practical mining method to safely extract the reserve given the set constraints. This report quantifies the additional revenue the TOB 4 will contribute to Finsch?s overall NPV thus enhancing Finsch?s business case and strategically enhancing the SBP. Several underground mining options have been investigated. The proposed mining method includes the installation of a series of extraction tunnels below the TOB 4 reserve from 53 level, with a slot access tunnel system. Ground will be loaded by LHDs from the draw points and tipped into 50-ton dump trucks at a transfer point, from there the ground will be transported to 53 level No. 1groundpass where it will join the existing ground-handling system. Primary development is scheduled to begin October 2002 and last for a period of approximately 7 months until early April 2003.The production is broken into 4 phases. Phase 1 is scheduled to begin mid-April 2003. The final production phase will be completed by November 2005. The production scheduling has been designed in order to remain ahead of the Block 4 undercut in order to ensure stability and safety. Due cognisance was taken of the health and safety of all employees concerned during the design of the mining and ground-handling processes for the Bottom of Pit. As far as is reasonably practicable, the BOP was designed and will be constructed and equipped to provide conditions for the safe operation of machinery and a healthy working environment for people underground. Relevant requirements of the Mine Health and Safety Act regulations pertaining to mining operations have been identified and adhered to during all phases of the design process.

Jan 1, 2004

Mr Colin M. Spence took office as President of The Federation of Societies of Professional Engineers on 1st July, 1984. Colin Maynard Spence was born in November 1921, and was educated at the Durban Preparatory and High Schools, in both of which he was a Dux Scholar. He graduated from the University of Natal in 1942 with a B.Sc. degree in civil engineering. In 1958 he received a Diploma in Town Planning from the same university. Cessation of Membership In accordance with Clauses 7.6.1 and 12.1 of the Institute's Constitution, Rules and Policy, the following members have been struck off the Membership list.

Jan 1, 1984

By J. Kuijpers

Failure and fracturing are often regarded as synonymous. While this is obviously true in an environment dominated by tensile stresses, it is still not clear how failure and macro fracturing are related in a compressive stress environment. Excavations at great depths are typically subjected to compressive stresses only. The fracturing observed around such excavations is therefore commonly assumed to be induced by such compressive stresses. The physics of such a phenomenon have unfortunately never been explained properly, so that the formation of these so-called extension fractures still remains a mystery. As the presence of fractures is an important factor affecting the stability of underground excavations, it is of practical relevance to understand their formation. In this paper, a possible explanation is proposed. It is argued that fracturing in a compressive stress environment is a secondary effect. Primary failure, in the form of micro fracturing and associated damage is assumed to precede the major fracture processes. The fractures are thus generated in response to material failure and may not directly be the cause of failure. The implications for material response and behaviour are discussed. Keywords: micro fracturing, macro fracturing, extension fractures, failure, compressive stresses, damage, excavations.

Jan 1, 2000

By H. Appiah

Small scale mining (SSM) has been going on for a long time in Ghana. SSM was legalized by the PNDC Law 218, 1989. Since then there have been numerous gains from the SSM industry. The SSM is organized locally by the concession owner who engages people to work for the gold which he buys. Small scale miners (SSMs) use crudely made sluices in Ghana and, therefore, their production falls below what is expected. The SSMs work in groups and not as cooperatives, as they do in Brazil and other Latin American countries. Legalization of SSM has curbed gold smuggling considerably because a gold marketing entity is available. SSM poses certain environmental problems like pollution of water bodies and soils by mercury and indiscriminate digging of pits.

Jan 1, 1998

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