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By X. Gumede

Mud houses are common structures in most South African rural homes closer to the mining operations. Fulltime dwellers in these properties are often the elderly. The mine codes of practice and the South African legislative instruments attempt to define the damage criteria to limit the effect of the blast-induced noise and ground vibrations to different structures. All these assessment criteria are based on the peak particle velocity and noise generated during blasting. The South African safe limit criterion that was adopted was initially derived from the international standards, which were then used as a local guideline. This paper evaluates the currently adopted safe limit criteria used in South Africa for a mud house, currently rated at 6 mm per second and 120 decibels to134 decibels, for blast-induced seismicity and noise, respectively. Further, a study was performed on a residential house near a coal mine (5.26 km) based in Mpumalanga following numerous complaints by the owner, launched at the mine and to the Department of Minerals and Petroleum Resources. The aim of the study was to measure the magnitude of blast-induced triggers experienced at the aggrieved homestead and to establish if there is a likelihood that an irritation or damage may be caused by these triggers. The seismometer was installed at about 2 m from the mudhouse, from 1 July 2022 to 31 of July 2022. Five blast-induced triggers were recorded during the period showing an average of 0.09 mm/s and 121 decibels for blast-induced seismicity and noise, respectively. The results obtained indicated a maximum seismicity of 0.15 mm/s. This seismicity was below the perceptible vibrations obtained from daily home activities such as walking, jumping, and door slamming, which produce 0.8 mm/s, 7.1 mm/s, and 12.7 mm/s, respectively. Seismicity was therefore not likely to have caused any annoyance and or damage. For noise, the results indicated a maximum of 123 decibels and an average of 121 decibels from five events recorded. A literature review suggests that slight damage may occur when airblast frequencies match the natural frequencies of structures at 120 decibels. Based on these results, it can be concluded, therefore, that the noise, rather than seismicity, is more likely to be the cause of damage to the structure assessed. For improvement, a new approach is proposed based on relating the safe limits to the structural and human response.

Dec 15, 2025

By H. G. Denkhaus

Comment on ?The evaluation of rock brittleness concept on rotary blast hole drills? in the Journal of SAIMM, vol 102. no. 1. pp. 61?66 Comment on ?Correlation of specific energy with rock brittleness concepts on rock cutting? in the Journal of SAIMM, vol 103. no. 3. pp. 163?171by R. Altindag Foreword Some thirty years ago it was almost customary that articles in South African technical and scientific journals were followed up by discussions in which the reader(s) expressed criticism and/or added to the information contained in the article. This custom has obviously died out, be it that the articles are nowadays of such a high standard that nothing can be added or be it that the receivers of the Journal suffer from an information inflation and do not read the articles anymore. I now have the temerity to offer a discussion to an article that recently appeared in the journal, namely ?The evaluation of rock brittleness concept on rotary blast hole drills? by R. Altindag (J.S. Afr. Inst. Min. Metall., vol, 102(2002), pp. 61?66.

Jan 1, 2003

By M. L. Baharani

Looking for an idyllic paradise that has investment and business potential as spectacular as the stunning views of mountains, the rich Ganesh Himal zinc-lead deposit exposed between 4,050 m and 5,000 m is the answer. Arising from the sea floor in a span of 55 million years, the enchanting Himalayas had remained one of the most potent factors influencing the Asian region. The challenges of the mighty Himalayas notwithstanding, it continues to provide opportunities for the humankind in optimum usage of the natural resources and sustainable development. Optimal management of natural resources in mountain areas through decision support tools offered by remote sensing will go a long way in realization of the Ganesh Himal Zinc-Lead Project. The authors have a real life endeavor spanning over 37 years in developing a mining industry in a mountainous region of Nepal and an attempt to integrate with the development of other natural attributes of the region. With rapid acceleration of science and technology, humankind has acquired power to transform his environment countless ways and on an unprecedented scale. While mineral resources are the pillars on which we have built industry and infrastructure, industrial countries in the North have been in the forefront of technological advancements, the developed countries of the South have been at the receiving end of exploitation of mineral resources worldwide. A relationship with natural environment, re-crafted by the civilizing impulse, to meet human demands are upcoming challenges for management of natural resource in sustainable manner for a livable world.

Jan 1, 2008

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 S. J. Ramokgopa

The development of the modern State and the growth of capitalism involves a complex process of interaction between cross-cutting structural dimension: first between politics and economics and, second, between market and hierarchy. Central to such developments are political economies of scale. Mineral specialization in the Third World developed within the framework of an international extension on oligopolistic structure of the advanced capitalist economies of Western Europe and North America. Up to the late 1960s, the world mineral and metallurgical industry was closely controlled by a handful of Western mining and industrial groups. To the extent that, foreign control of the mining sector was seen in the Third World producing countries both as the essence of foreign domination and as its major symbol. In some newly industrializing countries, the State took a more direct role in tying the economy and society together. Central to this process was the growth of large-scale finance capital. From early 1959to the mid-1970s, metal consumption in industrial countries expanded well beyond their domestic mineral endowments. And a free access to Third World minerals was a major element of the economic dynamism of these countries throughout that period. With the change in the characteristics of international investment, Africa has become less important as an outlet for capital exports of European countries. Actually, the African continent now receives only a very minor share of direct foreign investments of Western enterprises. International political economy is concerned first of all with the relationship between the economic and political domains across territorial boundaries. Second, attention should be drawn to the role of the State as the focus of decision-making in a system of competitive States, that is in turn, interdependent with a trans-national market economy in which mining and metallurgy are essential activities that affect the politics of the State, and how this in turn, rebounds on the politics of the international system. Understanding the role of the State must go beyond the glib pronouncements on the ?national interest?. How, and whose interest, the ?national interest? is determined, is precisely the problem. This implies a third theoretical problem that must be addressed: the linkage between the domestic and international domains (or levels of analysis), given that political-economic processes clearly cut across the lines of political decision-making constituted by the institutional structures of the State. Situating the State and economic interests within this vast ?state-society? complex that we call the global order will be a crucial problem for any theoretical approach that involves mining and metallurgy.

Jan 1, 2002

By J. E. McGill

The junior and small-scale mining sectors in South Africa play an important role in the livelihoods of numerous communities. Mining presents an opportunity, in the post-1994 democratic era, for many individuals to obtain access to much required empowerment and socio-economic development. These sectors are, however, not without numerous characteristics that pose problems for operators, legislators, and other role-players. Mining is inherently risky, with operators experiencing frequent difficulties and challenges throughout the life of mine. Opportunity exists, and needs to be enhanced, for junior and small-scale prospects and operations to include technical risk assessment techniques in documentation presented in search for funding, and in optimizing monthly planning and longer-term functioning. The focus here is to explore how the risk management cycle may currently be applied to a mineral resource suitable for exploitation by the junior and small-scale mining sectors. No management process can create additional value in the ground, but various available mechanisms can go a long way to quantifying the inherent risk that exists, highlighting the need to manage the risks and hopefully allowing the entrepreneur access to the intrinsic opportunities of the emerging mining sector in South Africa.

Jan 1, 2006

By Ch. Schroeder, F. Collin, R. Charlier, Y. J. Cui

The paper proposes two numerical models ot the mechanical behaviour of chalk. First, an elasto-plastic constitutive law reproduces the different plastic mechanisms of the chalk and the influence of pore fluids by introducing the concept of suction. Secondly, a model able to reproduce time dependence behaviour. Eventually, the paper gives a simulation of an academic reservoir during depletion and waterflooding phase. Der Artikel stellt zwei numerische Modelle des mechanischen Verhaltens der Kreide vor. Das erste ist ein elasto-plastisches Modell, das verschiedene plastische Mechanismen der Kreide und den Einfluss von Porenflüssigkeit, unter dem Begriff der Suktion, reproduziert. Das zweite Modell berücksichtigt darüberhinaus das zeitabhängige Verhalten. Schliesslich zeigt die Veröffentlichung eine Simulation einer theoretischen Lagerstätte während der Entleerung und der Wasserinjektion. L'article propose deux modèles numériques du comportement mécanique de la craie. Le premier est une loi élasto-plastique qui reproduit les différents mécanismes plastiques de la craie et l'influence du fluide interstitiel par l'introduction de la notion de succion. Le second est un modèle prenant en compte les effets différés. Enfin, l'article présente une simulation d'un réservoir académique durant les phases de déplétion et d'injection d'eau.

Jan 1, 2003

By S. Heukelman

Zincor uses O2 enrichment (up to 26% O2 in the fluidizing air) to increase the processing rate of zinc concentrates in the fluidized bed roasters. The aim of this study is to determine whether O2 enrichment can be reduced by introducing micro-pelletized concentrate into the feed blend, while maintaining current roaster feed rates and calcine quality. It was found that, with a load of 20% micro-pellets introduced into the feed blend, that O2 enrichment could be reduced by 60%. It was determined that entrained particles spend on average between 0.46 hour and 2.44 hour in the roaster, compared to particles remaining between 3.93 hour and 4.00 hour in the bed overflow. This compares well with a radioactive tracer test performed by Spira. The required reaction time for micro-pellets was found to be less than the residence time inside a Zincor roaster. The result achieved indicated that the average particle residence time inside the roaster was increased successfully in order to compensate for the longer reaction time required to roast micro-pellets at lower levels of O2 in the fluidizing air.

Jan 1, 2011

By S. Dessureault

Computer Integrated Mining (CIMG) is a process of using computer networks to transform islands of enabling technologies into a highly interconnected mining system. CIMG involves the integration of advanced technologies at various levels in the mine business to achieve higher flexibility, better quality of processes and control, and improved profitability. Justifying the benefits of CIMG are difficult as many of the advantages are derived from improved flexibility, quality, and control. Justification is based on the evaluation of the benefits to be gained, compared to the required capital investment. Management tools used in mining are currently inadequate in assessing the value of advanced technology whose benefits are primarily qualitative. A key aspect of successful implementation is management acceptance, which has to be won through the capability to justify the technology?s financial costs and the true value of all of its benefits. The manufacturing industry faced similar justification difficulties when adopting advanced technology in factories. A significant amount of funding and research was invested in developing management strategies and approaches to justification. Many of the problems that faced the transformation of the manufacturing industry in the late Eighties and early Nineties are now facing mining. The solutions derived for manufacturing may help mining in its transition to an increased reliance on integration technology. Reviewing the industrial history of computer integrated manufacturing identifies several tools and strategic frameworks that can be adapted for mining. Keywords: Computer integrated mining, justification techniques, CIM, information technology.

Jan 1, 2004

By G. T. van Rooyen

The susceptibility of a low-alloy steel that has been hardened and tempered-826 M40 (EN26)-to embrittlement by strain aging during service was simulated by artificial aging of specimens at 100°C. It was found that the brittle transition temperature of both monotonic and cyclically strained material was increased by only about 25°C as a result of strain aging. It is concluded that the susceptibility of low-alloy steels in the hardened, tempered condition is less than that of low-carbon steel, and that such steels qualify for exemption of the periodic 'annealing' required by the Mines and Works Act.

Jan 1, 1986

The mathematical models of semivariograms can be classified according to whether or not they correspond to situations where the second order stationarity conditions are satisfied (§ 3.3.4). If second order stationarity exists, the a priori variance s2 of x (z) also exists and is finite. For large distances h such that x (z) and x (z + h) are not correlated, the semi- variogram ? (h) will reach a value equal to s2 [this is a consequence of (3.27) above]. This limiting value is called the sill C of the semivariogram, and the distance at which ? (h) reaches the sill is called the range. The range of the semi- variogram obtained from a given type of sample corresponds to the distance of influence of these samples. If only the intrinsic hypothesis is satisfied, the sample variance is an increasing function of the size of the area or volume in which the samples are located, and the semivariogram ? (h) will be a continuously increasing function of h. Remark: It will be shown in Chapter 7 that the variance s2 of x (z) in the ore body O is equal to the average value of ? (h) in O. If ? (h) is a non-decreasing function with sill C, the average value of ? (h) in O will be less than C. s2 and C will be equal only if for some values of h in O, ? (h) exceeds C. In practice, if the range of the semivariogram is small with respect to the dimensions of the ore body, the difference between C and s2 will be negligible.

Jan 1, 1978

By C. E. Hales

In an effort to improve efficiencies and reduce costs, AngloGold has embarked on a process to develop and deliver consistent, high quality, tailings based support or construction products to stopes and tunnels on request. A three-phase approach of product conceptualisation, design and delivery has been adopted. To date a substantial amount of laboratory development has taken place with promising results, indicating that the project aims are achievable. Dans un effort pour améliorer le rendement et réduire les coûts, AngloGold s’est embarqué dans une opération qui vise à développer et fournir aux chantiers d’extraction et tunnels, sur demande, des produits de construction ou de support basés sur rejets qui sont réguliers et de haute qualité. Une méthode à trois volets a été adoptée : conception, création et livraison. A ce jour, un développement important en laboratoire s’est produit, avec des résultats pleins de promesses, qui semblent indiquer que les buts du projet peuvent être atteints. In der Bemühung, die Effizienz zu steigern und Kosten zu verringern, hat AngloGold begonnen ein Verfahren zu entwickeln welches auf Anfrage konsistent hochqualitative auf Haufwerk basierender Unterstützung oder Bauprodukte für Abbaustellen und Tunnels entwickelt und liefert Eine Dreiphasenplan zur Produktkonzeptualisierung, Design und Lieferung wurde adoptiert. Bis jetzt hat eine substantielle Anzahl an Laborentwicklung mit vielversprechenden Resultaten stattgefunden und aufgezeigt, daß die Projektziele erreichbar sind.

Jan 1, 2003

By J. Engelbrecht

South Africa?s re-entry into the fast moving and competitive global economy calls for some careful strategic planning and a good deal of co-operation between suppliers and end-users. The issues that need addressing are generally well known and include: ?South Africa was ranked 45th out of 46 i.r.o. productivity ?SMMEs contribute 1% to exports compared to 40-60% for the ?tigers? ?High unemployment ?Limited skills of the majority of workers ?Slow growth rate of the economy ?The vast majority of suppliers are not world-class ?The vast majority of suppliers are not export or marketing orientated. In order to survive, all parties, i.e. government, labour and business, will have to play their part.

Jan 1, 1999

Council for 1996/97 President Dr N.A. Barcza President Elect R.P. Mohring Vice Presidents Senior J.R. Dixon Junior M.H. Rogers Immediate Past President D.A.J. Ross-Watt Honorary Treasurer J.A. Cruise

Jan 1, 1997

By P. Lenegan, R. Masethe, R. I. L. Ferreira

Underground mining in high rock-stress environments can induce unanticipated dynamic rockmass deformation, posing a serious risk to the workforce. Data collected by seismic networks are imperative for the design-as-you-mine process. Often an inappropriate assessment of the seismic hazard is done when unnecessary data are included in analytical techniques, particularly short-term time frames. Depending on the methodology or application of data analysis and interpretation, some of the information may not be relevant and even detract from the objective. By using the spatial event clusters associated with active workplaces to define the shape and size of the polygons for data selection for subsequent analysis, a problematic subjective component can be eliminated. The mining of tabular reefs in South Africa, be they gold- or platinum group metals, is very extensive, and underground workplaces are often widespread. Production stoppages are very costly, especially for marginal mines, so there is just cause not to evacuate an entire operation’s workforce following the occurrence of a large mining-induced seismic event. A rationale based on the damaging peak particle velocities (PPV) of the past seismicity can exclude the unaffected underground personnel and allow a quick orderly withdrawal where required. Micro-deformation may precede rockbursting, which can occur on-shift close to the workface. A mine-wide array of geophones suitable for the accurate location and analysis of seismicity may not be able to detect these higher-frequency emissions. Inexpensive but fit-for-purpose accelerometers, providing real-time, continuous measurement of acoustic rockmass deformation near the workplace, integrated through underground and surface communications networks, are shown to record ‘rock-talk’, clearly distinguishable from the instrument background noise, which can be in the order of hours leading up to an imminent damaging seismic event.

Jan 12, 2025

By P. He

Abstract This paper introduces the test results of dark-gray calcium-shale, discusses the infection of strength characteristic and deformation characteristic due to the angle between structural planes. Keywords calcium-shale, failure form, strength, deformation characteristic, structural planes. Zusammenfassung: basier auf der Anwendung von Problematik des Felsenbauprojektes und Beschaffenheit Felsen unter Beaugnshme auf den Zustand des Druckes von einzeler Welle legt dieser Text dar, wie der Winkel der Schichtstrukturflaeche des schwarzgrau kalziumhaltigen Schieferblocks auf die Zerstoerungs-, Intensitaets- und Deformationseigenschaften einwirkt. Schluesselwoerter: schwarzgrau kalziumhaltigen Schiefer, Zerstoerungseigenschften, Intensitaetseigenschften, Deformationseigenschaften, Flaeche dar Schichtstruktur. Résumé – En fonction de la configuration du massif rocheux sous l’état de la contrainte de pression axiale simple et de la pratique de l’ingénierie de roches, le présent article fait la déscription concernant l’influence de l’inclinaison ? de la couche de structure stratifiée du bloc de schiste calcaire gris noir sur ses caractéristiques de destruction, sa spécificité de résistance ainsi que sa nature de déformation. Mot clés – Schiste calcaire gris noir, Caractéristiques de destruction, Spécificité de résistance, Nature de déformation, Couche de structure stratifiée

Jan 1, 2003

By PC Pistorius, DR Groot

The South African base metals industry has been one mainly focused on the production of metals or metal compounds from primary ores. This is true for metals such as titanium, vanadium, chrome, manganese, cobalt, nickel, copper, zinc and aluminium. The steel making industry has traditionally used a substantial portion of scrap steel, and could thus be considered to be somewhat of an exception. Secondary sources have played much less of a role, possibly due to at least some of the following factors. Scrap material is often of unknown composition, and thus it requires additional chemical analysis, and possibly special treatment. Tonnages are relatively small, and the incorporation of secondary materials is possibly seen to carry undue risk and inadequate benefit. South African consumers are still not very conservation and recycling conscious, which limits the amount of scrap made available. This attitude might also be expected to influence decision makers in these industries. Finally, pressure from environmentally motivated activists locally has not been unduly large. This landscape has been changing, and is continuing to do so. Various municipal authorities such as those of Pretoria, Johannesburg and Cape Town are reporting increasingly limited landspace for waste (Bondolfi, 2007). There are increasing concerns regarding the leaching of hazardous metals such as chromium, mercury and cadmium from landfill waste, especially electronic and electric wastes ? the so-called eWastes. In more developed countries such as the United States of America and Western Europe the problem of eWaste has grown to the extent where legislation has been enacted, such as the Waste Electrical and Electronic Equipment (WEEE) legislation of the EU (European Union Directive 2002/96/EC). The 19th and 20th centuries have seen major technological advances. Relevant to this paper is the availability of centrally generated electrical power, telecommunication, entertainment through recorded and transmitted music and images, the growth and pervasive influence of electronics, and the handling of digital data by computers and microprocessors. These developments have placed ever increasing demands on resources for the manufacture of electrical and electronic equipment, as well as on the generation of electrical power. Most of the resources required are non-renewable: copper, steel, aluminium and other metals, various thermoplastic polymers such as PVC (polyvinyl chloride), polyethylene and ABS ( acrylonitrile-butadiene-styrene), thermosetting polymers such as epoxies, elastomers such as butyl rubber, glasses and ceramics, and composites such as fibre reinforced plastic (fibreglass). The conservation of non-renewable resources inevitably includes recycling. To a certain extent, recycling of materials locally is well established. Thus glass, paper, used oil, car batteries, ferrous scrap such as beverage cans and non-ferrous scrap such as

Jan 1, 2007

By C. J. Cutler

Metallurgical accounting for toll treatment smelters pose a number of challenges. Multiple feed stockpiles have to be accounted for as part of the monthly recovery estimation. Moreover, multiple metallurgical intermediates make up part of the in-process inventory, which also influence the monthly recovery calculation. Errors propagate from the measurements of volumes, assays, moisture fractions and bulk densities in the various material types through multiple steps up to the point where the final recovery is calculated. These errors contribute non-linearly to the variance in the final recovery estimate. This paper develops the mathematical formulation for variance propagation in toll smelting operations, including the effect of in-process inventory, assuming measurement biases have been eliminated beforehand. Operational data from a Southern African copper smelter is used for a case study. The method of propagation of variance showed that uncertainties in stockpile assays were the main contributors to variance in the recovery estimate. Variance in the volume and bulk density uncertainties contributed a secondary, yet significant, proportion to the overall recovery variance. It was determined, for the given case study, that the recovery variance depended on the calculation method used and that variance propagation via the two-product formula was smaller than recovery variances calculated via the standard recovery formula. However, the probability that the two product formula will give inaccurate (versus imprecise) results is significantly more due to the practical difficulty of equiprobable sampling of tailings streams from smelter plants (which includes materials such as slags and flue dust). Recommendations are made on how to achieve a reduction in overall uncertainty for toll treatment smelters. Keywords: metallurgical accounting, copper smelters, pyrometallurgy, variance propagation, errors, precision, sampling

Jan 1, 2006

By S. Mundike

A scraper-based block cave method has been successfully applied to extract the Lower orebody at Nchanga since the 1950s. Since inception, scraper drifts and service ways have been supported using steel arch sets fabricated to a specific design from high strength manganese steel To reduce costs and to improve productivity, trials commenced in 2002 using fibre reinforced shotcrete as an alternative support method. One of the areas, the 2420 8E 1C trial drift, was subjected to abutment loading for several months prior to undercutting and cave mining. Shotcrete installed exhibited minor cracking shortly after application but very little deterioration thereafter. Following the success of the trial, the application of fibre-reinforced shotcrete was extended to other drifts. This paper describes the application of fibre-reinforced shotcreteat Nchanga and outlines design and quality assurance methods employed.

Jan 1, 2005

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