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By L. A. Maseko

"As part of the mining engineering curriculum, students are required to be placed in industry for vacation work or work-integrated learning (WIL). In this paper we review work-based placement as done at the four South African mining schools: the University of Johannesburg, the University of Pretoria, the University of the Witwatersrand, and the University of South Africa.Key aspects of past and current WIL (pre- and post-graduation) practices that may need attention are highlighted for consideration by all universities that provide professional qualifications. Work-directed theoretical learning, problem-based learning, project-based learning, workplace learning, and simulated work experiences are discussed as legitimate approaches to WIL.Regardless of the choice each institution makes, commitments of universities, preparedness of university teachers, and the desire for equity and excellence will play an important role in the provision of WIL.DefinitionsAccredited Qualification: a qualification awarded on successful completion of an accredited programme.Advisory Boards (or Committees): are essential infrastructure for a WIL curriculum that is built on the integration of the workplace and the university. This requires the collaboration of experts from both environments. Workplace advisors are critical to the success of the academy as they embody expert knowledge of the ‘real world’.Assessment: the process of determining the capability or competence of an individual against standards by evaluating performance.Category: a mode of registration defined in or under the ECSA Act which has a distinctive purpose, characteristic competencies, defined principal routes to registration, and educational requirements.Experiential learning: (in South Africa sometimes used synonymously with work placement or cooperative education) is a term used with a great variety of meanings in the international literature. More broadly, it may refer to learning that has meaningful learner involvement. It is the process of generating meaning from direct experience. In the international literature, experiential learning is learning through reflection on doing, which is often contrasted with rote or didactic learning."

Dec 1, 2018

By Y. Y. Jiao, J. G. Cai

To investigate the dimensional effect on shock wave propagation in jointed rock masses, a 2-D and a 3-D calculation of a site test are performed respectively by using Discrete Element Method, the simulated results are compared with test data. It shows that, in modelling shock wave propagation and attenuation in jointed rock masses, when the explosive along explosion chamber is long enough and the joints are dense enough or uniformly distributed, the model can be considered as plane-strain problem, 2-D results are good enough to fit with test data. 2-D modelling, with much more details of rock masses taken into account, can be applied to make critical engineering judgements instead of 3-D modelling in some cases.

Jan 1, 2003

By I. Hague

Support liners for underground applications include steel and timber sets, meshing and lacing, screen/mesh, shotcrete and thin support liners (superskins). Over the past few years, major advances have been made in the design and application of liners; especially shotcrete and thin support liners. For shotcrete in mines these advances include the common use of slick-lines to solve logistics problems, the design of alkali free accelerators, the use of synthetic fibres and the new generation application equipment. The field of thin support liners is a new one but advances have been dramatic. This paper discusses the progress made and the need for standardization in definitions and testing for thin support liners. It concludes that the newer technologies have a huge potential positive impact on the industries, from both safety and cost points of view. Le chemisage de soutènement pour extraction souterraine comprend des cadres d’acier ou de boisage, mailles et chapeau, cribles/mailles, béton projeté et des chemisages minces de soutènement (super-peaux). Dans les dernières années, des progrès considérables ont été fait dans la conception et application des chemisages, en particulier les chemisages de soutènement en béton projeté et les chemisages minces. Pour le béton projeté dans les mines, ces progrès comprennent l’utilisation courante de lignes de minerais broyés fin pour résoudre des problèmes de logistique, la création d’accélérateurs sans alcali, l’usage de fibres synthétiques et d’une nouvelle génération d’outillage. Le domaine des chemisages minces de soutènement est très récent mais les progrès ont été rapides. Cette étude présente les progrès accomplis et discute du besoin de standardisation dans les définitions et les tests pour chemisages minces de soutènement. La conclusion est que les technologies nouvelles présentent un énorme impact potentiel positif sur les industries, du point de vue à la fois de la sécurité et de la rentabilité. Unterstützungsverkleidungen für Untertaganwendungen inkludieren Flecht und Seilwerk, Gitter/Geflecht, Spritzbeton und dünne Unterstützungsverkleidungen (superskins). Während der letzten Jahre wurden grosse Fortschritte im Design und in der Anwendung der Verkleidungen gemacht; besonders bei Spritzbeton und dünnen Unterstützungsverkleidungen. In Bezug auf Spritzbeton in den Gruben schließen diese Fortschritte den allgemeinen Gebrauch von Rutschbahnen ein um Logistikprobleme zu lösen, das Design von alkalifreien Akzeleratoren, den Gebrauch von synthetischen Fasern und die neue Generation von Anwendungsausrüstung. Der Bereich der dünnen Unterstützungsverkleidungen ist neu, aber die Fortschritte sind drastisch gewesen. Diese Arbeit behandelt den erzielten Fortschritt, die Notwendigkeit der Normierung in den Definitionen und in der Prüfung dünner Unterstützungsverkleidungen. Sie kommt zum Schluß, daß die neueren Technologien, sowohl vom Gesichtspunkt der Sicherheit als auch der Kosten, eine sehr große potentielle positive Auswirkung auf die Industrien haben.

Jan 1, 2003

By Md. Amanullah

A novel triple action load cell assembly (LCA) was developed to determine three index parameters reflecting compressive, tensile and shear characteristics of mudcakes. The results indicate that the tensile, compressive and torsional behaviour of mudcakes are strongly influenced by the physics and chemistry of the mud additives. Eine neuartige dreifach wirkende Druckkammer zur Bestimmung der drei Indexparameter Druck, Zug, und Scherung von Spülungskuchen wurde entwickelt. Die Ergebnisse weisen auf einen starken Einfluss der physikalischen und chemischen Spülungszusätze auf Druck, Zug, Scherung hin. Un assemblage d'une nouvelle cellule a triple action (LCA) a été développée pour déterminer trois paramètres caractérisant la compression, la contrainte en traction et la résistance á la fracture des cakes. Les résultats indiquent que les comportements tensile, compressif et de torsion des argiles sont fortement influencés par la chimie et la physique des additifs des boues.

Jan 1, 2003

By W. V. Mutler

Present day capital costs are analyzed for a 2,000 metric tonne per day (MTPD) pyrite burning plant and compared with a sulphur burning plant of the same capacity. Power, raw material and steam production rates are then compared for the two facility types. A sensitivity analysis is conducted to highlight the impact changing sulphur, pyrite, capital and operating costs have on the relative economics of these feeds. Technological improvement effects on capital cost and energy recovery are also discussed. Besides the steam produced from the burning of pure sulphur or pyrite, plants using an advanced form of heat recovery can produce up to 10 bar steam using heat from acid formation. The quantity depends on the overall water balance which is influenced by such factors as gas strength and product acid concentration. Modern materials and innovative process design also improve the ability to increase the high pressure steam from the roaster boiler in pyrite plants above the traditional 1.25 kg of superheated steam per kg of acid produced.

Jan 1, 2009

By A. Fahimifar, H. Soroush

Abstract: Triaxial tests were conducted on the schist specimens with various anisotropic angles under confining pressures of 0, 7 and 15 MPa, and axial stress-axial strains, were measured and plotted for various conditions. The results obtained reveal the effects of schistose on the strength and deformability of the rock very clearly. Peak strength of the specimens for 00 and 900 schistose orientations are nearly the same. Modulus of elasticity of this rock varies with anisotropic angle. For 0 orientation modulus of elasticity increases to a maximum. Confining pressure increases the peak strength and improves the rock deformability. However, this effect is not the same for various orientations, and there are no similar trends for each anisotropy direction. Analysis of the results shows that consideration of a linear failure criterion such as Mohr-Coulomb is appropriate for the prediction of rock behaviour up to 10 MPa, rather than a non-linear one. The analysis also reveals that the friction angle and cohesion are affected by the anisotropy orientation, and this effect is more important for the cohesion than the friction angles. Resume: Les esseys triaxiales sur les echantillon d un roch schist avec les differents angles non-isotrop sous les tension lateral zero et sept et qoinze mega pascal (mpa) est fait et les covtraite et allongment unitaire sont mesure et leur curues est destine sous different condition les resultats obtenues montre les effets du schistosite sur le resistance et le ductilite vissiblement. Le resistance final sur les echantilions pour les angles o degre et 90 degree est equivalent. Le modoule d elasticite de ce roch sera difere par a port de l angle de stratification. Pour l angle o degree le valeur de modoule est le maximum. le pousse lateral augmenterai le resitance final, et sera amilterai le toleran le de ductilite. Mais cette effet bn est pas unigue pour les different stratification, et pour les diferents directions no– isotrop it n y a pas le meme solution. L analyse des resulitats montre que le criterre de ruin comme mohr–colomb est moderate pour le pousse lateral jusq av lo mega pascal , et ce n est pas neccesaire d utiliser de criterre no–linear . Cette analyse aussi montre que l angle de frottement et cohsion est en relation de la direction no–isotrop, et cette effet est olus important pour le cohsion par a port de l angle de frottement . Abriß : Dreiachsige Prüfung wurde auf den schist Exemplaren mit verschiedenen anisotropic Winkeln unter Bestätigen von Drücken von 0.7 und 15 MPa geleitet, und axiale Spannung axiale Spannungen, wurden gemessen und für verschiedene Bedingungen wurde geplant. Die Ergebnisse haben die Wirkungen von schisocity auf der Kraft und dem deformability des Felsen sehr deutlich erhalten offenbart. Maximale Kraft der Exemplare für 0° und 90 sind° schistos Orientierungen beinahe das gleiche. Modulus der Elastizität von diesem Felsen ändert sich mit anisotropic Winkel. Für 0° vermehrt Orientierung modulus der Elastizität zu einem Maximum. Einschränkender Druck vermehrt die maximale Kraft und verbessert den Felsen deformability. Aber ist diese Wirkung nicht das gleiche für verschiedene Orientierungen, und es gibt keine ähnlichen Tendenzen für jede anisotropic Richtung. Analyse der Ergebnisse zeigt jener Überlegung Kriterium eines linearen Ausfalls wie zum Beispiel Mohr Coulomb passend für die Voraussage von Felsen Verhalten bis zu 10 MPa, anstatt eines nicht linear ist. Die Analyse offenbart auch, daß der Reibung Winkel und Bindekraft werden beeinflußt von der anisotropic Orientierung, und diese Wirkung wichtiger für die Bindekraft ist, als der Reibung Winkel

Jan 1, 2003

By J. P. Garnier, T. Bhambhani, J. A. Garcia, N. Renaud

Most flotation plants use a static reagent scheme, i.e., a set combination of collectors, frothers, and modifiers. This scheme is usually developed and refined over time to deliver optimal (not necessarily the highest) performance when the major ore types are fed to the plant. However, when ore types or mineralogy coming to the plant change substantially (and this often happens as different areas of the pit(s) are mined and crushed at the same time), there are upsets in the process, typically leading to lower recoveries. Adapting to this variability is usually done only when performance drastically suffers, and the changes made may be too late and bring additional variability in performance. The premise for SmartFloat™ is that the reagent suite needs to be dynamic, adapting continuously to changes in the ore and operating conditions. Solvay has combined advanced analytics and data science techniques with its expertise in flotation reagent chemistry to systematically and automatically achieve the above, and in real time. Thus, SmartFloat™ is optimizing the reagent suite continuously, removing the additional variability created by belated human interactions resulting in a better and more stable process. In addition, this advanced approach allows for continuous improvement by identifying poor performing ore domains and improving the reagent suite using Solvay’s FM-100 approach to design appropriate solutions.

Jan 1, 2023

By A. Dienenthal

"The casthouse floor has always been one of the most dangerous working places on a blast furnace or a ferro-alloy/nonferrous furnace. Apart from working in an atmosphere including toxic gases, fumes, and dust, the workers have to perform hard and heavy manual work close to runners and ladles filled with hot liquid metal and slag.Before the invention and installation of tapping equipment the tap-holes were opened and closed manually. Opening was done by means of steel bars and sledgehammers, whereas the tap-hole was closed by repeatedly ramming small amounts of clay or refractory material into the tap-hole, again with the help of long, heavy bars. In addition, on blast furnaces the blast had to be stopped, since it was impossible to close the tap-hole properly against the blast furnace pressure. This stoppage of the blast resulted in regular losses of production. Around 1900 a major change in technology occurred. Samuel W. Vaughen, superintendent of the blast furnace department of the Cambria Iron company at Johnstown, Pennsylvania (USA), invented the first clay gun in 1895 (Wiley, 1896) (Figure 1)."

Jan 1, 2014

By Jannie Maree, Dieks Theron, Ryneth Nengovhela, Patrick Hlabela

In extracting base metals from ore bodies, sulphide as well as oxide, the main environmental concern is sulphur, whether in the form of sulphurous gases or sulphate in liquid form. Generally sulphur is in over supply in developed countries mainly because of strict legislation to capture it. In developing countries on the other hand there is usually a shortage of sulphur because of less strict environmental legislation. Africa falls in this second category and the African continent imports substantial amounts of sulphur despite the fact that large quantities of sulphur is emitted by smelters, thermal power stations, coal mines, fertilizer manufacturers and others. Other than making acid from gaseous emissions, existing methods to capture sulphur from gaseous and liquid effluents are uneconomical and it ends up in the environment either as ammonium sulphate (from gaseous effluents) or as gypsum (from liquid effluents). The CSIR?s Environmentek and Pyroserv has developed a process whereby gaseous sulphur emissions and sulphates in liquid effluents can be economically captured and converted into elemental sulphur and metal carbonates. The elemental sulphur is of high purity as it is precipitated from a gas stream and is readily marketable. The metal carbonates (barium or calcium) can be recycled back to the process or marketed. The only harmful byproduct of the process is carbon dioxide. Should natural gas or methane be available the carbon dioxide could be reduced by about one third. Should solar, wind or hydro energy be available to generate hydrogen the carbon dioxide emissions would be zero. Employing this technology could make Africa independent of sulphur imports and furthermore reduce the impact of acid rain and seepage of sulfate from gypsum and other waste dumps into the environment.

Jan 1, 2005

For the past 12 years, the Universities of Stellenbosch and Cape Town have hosted an annual symposium to discuss research topics in Minerals Processing. Since 1987, this meeting has been held under the auspices of the Western Cape Branch of the South African Institute of Mining and Metallurgy, and has enjoyed much national and international support. In 1993, in place of the usual Symposium, the Branch and Universities collaborated with CSM Associates Ltd and Minerals Engineering Journal is organizing the international Minerals Engineering '93 Conference in Cape Town.

Jan 1, 1993

By F. T. Cawood

Inauguration of the new political dispensation in South Africa in 1994 initiated a dynamic shift in the ownership, management and development of the country’s affluent mineral heritage. The process of substituting the old South African regime with a new equitable system, started soon after the 1994 election of the African National Congress (ANC) to parliament. The Congress’ Freedom Charter revealed the intent of the new dispensation when it called for radical transformation of mineral development. However, since 1955 there have been important changes affecting the rules of mineral development. These are: •Firstly, a drastic change in politics ushered in by negotiation, a spirit of reconciliation and a desire to settle disputes peacefully •Secondly, the globalization of the South African mining industry in tandem with the opening of domestic mineral resources to foreign capitalists; and •Thirdly, the introduction of sustainable development as a holistic approach to mineral development in order to replace traditional narrow-minded environmental management. Each of these significantly shaped the new mineral investment environment of South Africa. This paper represents a summary of the historical developments leading to the current Mineral and Petroleum Resources Development Act No. 28 of 2002, its Regulations, the much-publicised Broad-Based Socio-Economic Empowerment Charter and its associated Scorecard.

Jan 1, 2003

By M. C. Bekker, T. Govindasamy

The potential benefits of implementing the Last Planner System (LPS) on mining infrastructure projects were explored through two case studies in the South African mining industry. The first part of the study involved measurement of the impact of LPS through earned value techniques on secondary project data. The second part sought to establish the lean construction success factors leading to improvements in construction performance. This was done by means of a research questionnaire distributed to the project owner’s teams, contracted parties, and the LPS facilitators. The results revealed a positive correlation between LPS application and planned percentage complete. However, the performance achieved during the LPS pilot was not sustained. The success factors and benefits considered most evident in the case study pilot differed among the three stakeholder groups. The findings are expected to guide construction stakeholders to better define performance measures and focus on factors required to make LPS implementation more effective in the South African mining sector.

Feb 12, 2024

By R. Armstrong

The stability of rock slopes is significantly influenced by their curvature in plan view. The importance of this in open pit mining is indicated by the fact that, in a deep pit, steepening of the slopes by 1° may save as much as $100 million. It is considered that there are two significant factors that play a part in the influence of plan curvature. These two factors are the effect of stress, and the effect of geological structure. The scant literature that pertains to this aspect of rock slope design was reviewed. The geometrical influence of the plan curvature was then investigated. It was seen that it has a parabolic effect on the maximum possible wedge that can fail into a circular pit, where the tighter the concave curvature the smaller the wedge. The plan curvature also affects the volume of a particular wedge, where concave slopes result in an exponential decrease in the volumes and convex slopes have exponentially increased wedge volumes. A change in the strike of the wedge did not affect the curvature’s influence on the volume, but the volumes of shallower dipping wedges were affected more by the influence of the plan curvature. La stabilité des talus des roches est très influence par la courbure de celles ci dans la vue en plan.Son importance de l peut arriver à sauver même $100 millions. Il est considère qu il y a deux facteurs importants qui jouent une influence sur cette courbure. Il s’agit de l’effet des contraintes et l’effet de la structure géologique. La brève littérature qui se réfère à cet aspect du conception sur le talus des roches a été revue. L’influence géométrique de la courbure des plans a été investiguée. Il a été vu que cela un effet parabolique sur la bosse ou le su relèvement maximum possible qui peut faillir dans un puits circulaire, ou le plus resserre est la courbure concave, le plus petit est su relèvement (bosse). La courbure plane aussi affecte le volume d’un particulier su relèvement ou les talus concaves résultent dans une décroissance exponentielle en volume alors que les talus convexes accroissent la volume de ces su relèvements (bosse). Le changement de l’orientation de la bosse (su relèvement) perpendiculairement ou obliquement n’ a par affecte l’influence de al courbure sur le volume mais les volumes des bosse (su relèvement) peu profonds étaient affectes par la courbure des plans. Die Stabilität der Felsensteigungen wird erheblich durch ihre Biegung im Plan beeinflußt. Der Wert von diesem in der Tagebaugrube wird durch die diese Tatsache, in einer tiefen Grube, steepening der Steigungen durch 1° angezeigt; kann soviel wie $100 Million speichern. Es wird betrachtet, daß es zwei bedeutende Faktoren gibt, die eine Rolle im Einfluß der Planbiegung spielen. Diese zwei Faktoren sind der Effekt des Druckes und der Effekt der geologischen Struktur. Die dürftige Literatur, die diesen Aspekt des Felsensteigungdesigns betrifft, wurde wiederholt. Der geometrische Einfluß der Planbiegung wurde dann nachgeforscht. Es wurde gesehen, daß es einen Parabolischen Effekt auf dem maximalen möglichen Keil hat, der in eine kreisförmige Grube ausfallen kann, wo, das fester die konkave Biegung, das kleiner der Keil. Die Planbiegung beeinflußt auch das Volumen eines bestimmten Keils, in dem konkave Steigungen eine exponentiale Abnahme an den Volumen ergeben und konvexe Steigungen exponential Keilvolumen erhöht haben. Eine Änderung im Schlag des Keils beeinflußte nicht den Einfluß der Biegung auf das Volumen, aber den Volu

Jan 1, 2003

By C. A. F. Sweet

The inter-relationship between these parties and the effect on the outcome of the project is often grossly underestimated. There are numerous success stories where the parties have worked as complementary teams aiming at the best outcome for the client company and achieving significant success. While there are a good number of occurrences where either the roles of the parties were unclear or perceived to be different from what others in the team believed or required them to be and the results were less than desired. This usually resulted in ongoing conflict, incorrect focus, working to different agendas and the result being a less than optimum result to Client Company. Mining, by its very nature of exploring where you cannot see, be it a shaft being sunk, tunnel being developed or other excavation that needs to be made, requires a very special working relationship between the parties. To understand this, and it applies equally well to mine and plant construction and other multiple function projects, one needs to start by describing the relationship of the parties. Often people believe that because they manage ongoing complex operations and large numbers of people that they can manage projects and as such the participants will ?fall into line.? At the outset it needs to be stressed that ?Project Management? is a specific type of management and needs to be understood as such. There are enough Colleges and Universities that teach project management, not only as a subject but also as a Master Degree. As you start up your project the relationship you establish between the client, project team (C.P.T) and the Engineering, Procurement, Construction and Management team (EPCM) will largely determine how successful your project will be. It is essential that from the outset a spirit of co-operation, support and respect be nurtured, and that it be actively carried through the project life cycle. There are several methods to facilitate this including team building exercises right at the start. This time and money will be well spent and recouped many times over during the project life cycle.

Jan 1, 2005

By X. M. Prévost

The reassessment of coal reserves has become a matter of urgency and has come as a result of the present situation of the industry, in the context of globalized coal economies, as well as new mining legislation and the advantages and difficulties of domestic coal suppliers. The de Jager report concerning coal reserves, released twenty years ago, can no longer be used as an estimate for accurately forecasting South Africa’s future coal production. The new reserve and resource study will promote the diversification of energy sources and provide a clearer view of the future of coal mining in the country. With plans to increase South Africa’s coal export capacity to approximately 84 million tons by 2005, it is uncertain whether the country really has sufficient reserves to meet this expansion, as well as satisfy the projected increase in inland demand. The face of South Africa’s coal industry and by association, the economy of our coal-dependent country, are both set to change. This is mainly due to factors such as the demise of most of the large collieries over the last approximately twenty years, growing numbers of economic empowerment producers, the emergence of strong competition in the export market, the dawn of Clean Coal Technologies (CCTs) and the Kyoto Protocol The paper will attempt to dispel some of the current myths about coalfields and reserves and highlight potential areas of high quality coal reserves, available mainly to new entrants in the industry. Keywords: Central Basin, Clean coal technologies, Coal combustion, Coal exports, Coalfields, coalLink, Coal reserves, Coal resources, Coal processing, Colliery, Economic empowerment, Discards, Fluidized bed combustion, Low-ash coal, Metallurgical coal, Power generation, Pulverized fuel, Reserve blocks, Richards Bay Coal Terminal, Run-of-mine production, Saleable production, SAMREC Code, South Dunes Coal Terminal, Steam coal, Synthetic fuels.

Jan 1, 2003

By W. V. Mutler

Present day capital costs are analyzed for a 2,000 metric tonne per day (MTPD) pyrite burning plant and compared with a sulphur burning plant of the same capacity. Power, raw material and steam production rates are then compared for the two facility types. A sensitivity analysis is conducted to highlight the impact changing sulphur, pyrite, capital and operating costs have on the relative economics of these feeds. Technological improvement effects on capital cost and energy recovery are also discussed. Besides the steam produced from the burning of pure sulphur or pyrite, plants using an advanced form of heat recovery can produce up to 10 bar steam using heat from acid formation. The quantity depends on the overall water balance which is influenced by such factors as gas strength and product acid concentration. Modern materials and innovative process design also improve the ability to increase the high pressure steam from the roaster boiler in pyrite plants above the traditional 1.25 kg of superheated steam per kg of acid produced.

Jan 1, 2009

By S. J. Thomas, P. A. Lilly, J. A. L. Napier

An industry research project has been established to examine the issue of rock mass failure in large open pit slopes. The approach began with numerically modelling failure at the laboratory scale with a displacement discontinuity program. The interim results from the program suggest the output failure mode is dependent upon the input parameter cohesion weakening. Es wurde ein Forschungsproject mit unterstützung von Bergbauindustrie bearbeitet. Die Zielsetzung der vorliegenden Arbeit war die Analysierung des Böschungsgefähr im größen Festgesteinstagebauen. Das Verfahren besteht aus der numerischer Modelierung mit Ansatz einen sonderen Rechnerprogram. Die erste Ergebnis zeigt, daß die Aufgabe am Angabendaten (cohesion) abhängig sein wird. Un project de recherche industriel fût conduit avec le but d’examiner les éboulements de roche dans les mines a ciel ouvert. La premiere étape a été de modelliser numériquement les éboulements dans un laboratoire en utilisant un programme de déplacement discontinu. Les resultants préliminaires du programme indiquent que la prédiction des ébouliements est directement reliée à la magnitude de la cohesion.

Jan 1, 2003

By D. R. Arnold

Discussion of the above paper by D. R. ARNOLDt This paper is the result of an excellent piece of work performed as a service to hyUrometallurgy in general and to the South African uranium industry in particular, and the authors are to be congratulated, Authors' reply Dr Arnold is correct in saying that the present Senbrix resins, which are based on the experimental heavy resins first developed at the National Institute for Metallurgy (NIM), need not necessarily show the same poor performance with respect to cobalt poisoning as the NIM prototypes. Oceanology International The next 01 World Conference is to be held Brighton, England, from 2nd to 7th March, 1980. The programme will concern technical advances in the offshore oil and gas industries, and is expected to include 140 papers from 20 countries.

Jan 1, 1979

By B. Kweto, W. Legodi, C. van Buuren, R. F. Sandenbergh

Biooxidation, and especially the BIOX® process, is a viable, economical and environmentally attractive process to liberate gold hosted in refractory sulfides by oxidatively leaching the sulfides as soluble sulfates. The moderate to high cyanide consumption during the subsequent cyanidiation of the washed biooxidation residue is probably caused by the retention on the solids of labile sulfur species formed during the multi-electron oxidation process of sulfide to sulfate. In this work the nature and mode of transport of the cyanicides in the products from the mesophile BIOX® process, as well as that of the combined mesophile and thermophile bioxidation process, were considered and strategies to reduce cyanide consumption evaluated. It was found that labile sulfur species were the major cyanide consumers in the mesophile biooxidation product, forming predominantly thiocyanate during cyanidation. The transfer of labile sulfur species was only marginally decreased by more intensive and thorough washing of the biooxidation products with warm and hot water, intense stirring and warm caustic leaching. A major reduction in cyanide consumption was however achieved by using a combined mesophile and thermophile biooxidation process. Keywords: Biooxidation, refractory sulfide gold ores, cyanide consumption

Jan 1, 2020

Most processing plants use automatic samplers to extract ore aliquots along a producing shift. These aliquots are combined into a sample normally sent to lab analysis. The sampler used in the extraction of an aliquot from a continuous flow of ore, i.e. a belt conveyor is required to be both precise and accurate. Surprisingly, not all commercial automatic samplers exhibit these two mandatory properties. Consequently, it is recommended the development of a procedure able to check sample assays reproducibility obtained using a given sampling protocol. This paper uses the Gy’s sampling theory to evaluate coal quality control practices at a washing plant using an automatic sampler extracting coal increments from the ROM feeding belt conveyor. Gy’s theory provides the means to establish the precision limits for a given sampling protocol. Various ore properties are required to be determined in combination with sample mass and mass of the lot sampled. All this information leads to the definition of the precision limit. The precision limit obtained was checked via an experiment mimicking what happens in situations where both miner and consumer use the same and appropriate sampling practices. The experiment demonstrates that sampling theory precision limits were valid if unbiased samplers are used by both parties, i.e. miner and consumer. Keywords: sampling, quality control, coal

Jan 1, 2003