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By A. de Souza

On Thursday, 6th February, 1992, D. Jan Visser, the Executive Director, NPI (National Productivity Institute), addressed the Productivity Breakfast of the SAIMM-Vaal Triangle Branch in Vanderbijlpark. The Breakfast was held at the Riverside Holiday Inn, and was attended by 50 senior and middle managers in organizations in and around the Vaal Triangle, as well as by Richard Beck, the President of the South African Institute of Mining and Metallurgy.

Jan 1, 1992

By K. Aoki, Y. Mito, S. Shirasagi

The authors developed the TBM Excavation Control System (the TBM Navigator), in order to realize the advanced observational construction. During the excavation using this system, the rock strength value is immediately calculated from the TBM driving data as an index of rock properties, and the drill energy coefficient is also calculated from the drill logging data that is carried out using the probe hole ahead of the tunnel face. In this study, a new, geostatistical simulation-based method is proposed for the automatic prediction of the rock properties ahead of the tunnel face with good precision, using both the drill logging data and the TBM driving data. The applicability of this method is validated through the prediction at the actual tunnel excavation that passes through the faults. Les auteurs ont mis au point un Système de Contrôle de forage avec la machine à pleine section (Navigateur de la machine à pleine section), en vue de réaliser un système de surveillance plus efficace. Avec ce système, la résistance de la roche est immédiatement calculée, au cours du forage, à partir des données de conduite de la machine, comme indice des propriétés de la roche, et le coefficient d'énergie de la foreuse est également calculé à partir des données de log de forage collectées dans un trou de sonde foré dans le front de taille. Dans cette étude, on propose une nouvelle méthode basée sur la simulation géostatistique qui permet de prévoir d’une manière automatique, des propriétés de roches se trouvant derrière le front de taille avec une précision satisfaisante, à l’aide des données de log de forage et celles de conduite de la machine à pleine section. Cette méthode s’est avérée suffisamment précise au cours du forage d’un tunnel réel qui traversait une zone de failles. Die Autoren entwickelten das TBM Ausschachtungssteuerungssystem (den TBM Navigator), um noch besser überwachte Bauarbeiten zu ermöglichen. Unter Einsatz dieses Systems wird die Gesteinsfestigkeit während der Ausschachtungsarbeiten unmittelbar aus den TBM Antriebsdaten als ein Index für die Gesteinseigenschaften berechnet. Gleichzeitig wird auch der Bohrenergiekoeffizient aus den Bohrlogdaten berechnet, die an Hand der Probebohrung am Stirnende des Tunnels erhalten wurden. In der vorliegenden Studie wurde ein neuartiges, auf geostatistischen Methoden basierendes Verfahren für die automatische und angemessen genaue Vorhersage der Gesteinseigenschaften am Stirnende des Tunnels vorgeschlagen, für das sowohl die Bohrlogdaten als auch die TBM Antriebsdaten verwendet werden. Die Anwendbarkeit dieser Methode wird durch die Vorhersage bei einer tatsächlichen, durch Verwerfungen verlaufenden Tunnelausschachtung bewiesen.

Jan 1, 2003

By S. Kauchali, J. van Dyk, J. Feris, S. Pershad, M. van der Riet, D. Love, J. Brand, C. A. Strydom

"This paper offers an introduction to and strategic context for the other papers included in this special UCG edition of the Journal of the Southern African Institute of Mining and Metallurgy. South Africa is facing long-term energy security challenges, brought about by a myriad of factors that are somewhat unique or exacerbated in the global context. Underground coal gasification (UCG) is a process used to produce synthesis gas from coal in situ, that is, in the coal seam. UCG is an emerging, advanced clean coal technology that offers a potential solution for these challenges, as it can cost-effectively and cleanly liberate vast coal resources in the country that currently cannot be economically exploited using traditional mining technologies. One of the tasks of the South African Underground Coal Gasification Association (SAUCGA) is to advance the development of UCG in South Africa by compiling a technology roadmap. This paper presents the initial findings of the SAUCGA Roadmap (Draft), and contextualizes the technology opportunities and challenges, stakeholders, and provides a basis from which to progress further plans for technology development. Firm development plans and deadlines are not yet possible due to the reliance of the UCG Roadmap on the higher level South African energy policy and regulatory framework. However, the draft roadmap has taken the first step of identifying these policies and stakeholders, and should be seen as the seed from which this embryonic technology and industry can be further developed. IntroductionSouth Africa’s long-term energy security challenges include energy access and affordability, dwindling reserves of accessible bulk primary energy, mounting environmental concerns with all forms of energy generation (especially coal and nuclear), balancing the electricity grid by incorporating an increasing proportion of non-despatchable renewable energy sources, mounting environmental liabilities regarding defunct mining operations, and lastly but by no means less important, fluctuating exchange rates and energy commodity prices.Correctly managed underground coal gasification (UCG) is an emerging, advanced clean coal technology that offers a potential solution for these challenges, as it has been shown to have the potential to cost-effectively and cleanly liberate vast coal resources in the country that currently cannot be economically exploited using traditional mining technologies."

Jan 1, 2019

By W. Newcomen, G. Dick

"Effective management and mitigation of pit slope instability in open pit mines begins with a comprehensive slope monitoring programme. The ability to differentiate between non-critical pit wall movements due to rebound or relaxation of the excavated slopes and movements that may be indicative of slope failure is important for maintaining a safe working environment and maximizing production. Slope failure prediction methods using velocity, acceleration, and strain criteria have been introduced and put into practice over the past few decades. Forty-eight slope failures with surface monitoring data are presented and assessed using the strain-based failure prediction approach, with consideration of the quality of the rock mass and the potential failure mechanism. The results indicate that the strain-based approach can be used to provide general guidance regarding strain thresholds for pit walls for a variety of failure modes in diverse geological environments. The advantages and potential drawbacks of the strain-based and other slope failure prediction methods are discussed. The importance of implementing a pit slope monitoring and performance evaluation system early in mine development is also emphasized. IntroductionThe successful prediction of the Manefay Slide pit slope failure at Bingham Canyon at 9:30 am on 10 April 2013 (Engineering and Mining Journal, 2014) highlighted the importance of having a comprehensive slope monitoring system that provides an accurate prediction of the time of failure of an open pit slope. Using most of the geotechnical monitoring tools available, the time of the failure was predicted within hours and equipment and personnel were evacuated from the pit well in advance of the failure. From a time to slope failure perspective, the monitoring system in place was a success.There are two general groups interested in monitoring pit walls, with slightly different objectives in mind when the monitoring system is being set up. There are those at the mine site that have to implement the pit slope design, monitoring protocols, and the action response plans, and there are those designing the slopes (often consultants) who regularly visit the mine but may not be responsible for the day-to-day activities. was a success.There are two general groups interested in monitoring pit walls, with slightly different objectives in mind when the monitoring system is being set up. There are those at the mine site that have to implement the pit slope design, monitoring protocols, and the action response plans, and there are those designing the slopes (often consultants) who regularly visit the mine but may not be responsible for the day-to-day activities."

Jan 1, 2016

PREFACE During the past year, the Council of the SAIMM undertook a major strategic-planning exercise to review all its current activities, and to redefine its scope and objectives in the light of changing circumstances. The following are the four main concerns that prompted Council to take stock of the situation. (1) Over the past five years, the SAIMM has become heavily involved in a variety of new activities. (There are many examples, of which the expansion in book publications and the establishment of physical metallurgy as a third major discipline with its own colloquia and schools are perhaps the most important.) While these new activities have considerably broadened the SAIMM's scope, they have resulted in a significant increase in the day-to-day workload of the President, Office Bearers, and Council members, and of the secretarial staff based at Kelvin House.

Jan 1, 1986

By Jacolien P. Wyethe

Zincor uses a Roast-Leach-Electrowinning circuit to process zinc sulphide concentrates. It also processes zinc oxide fume, originating from a slag smelting operation in the Democratic Republic of the Congo (DRC). Zincor achieved an average zinc recovery of 90.3% during the period January 2006 to May 2007. The bulk of the losses occurred in the iron and lead silver residues, both as soluble and un-dissolved losses. The un-dissolved losses in the iron residue constituted around 33% of the total zinc lost from the circuit, and were largely attributed to the presence of zinc-ferrite in the calcine used for neutralization during iron removal. As part of Zincor?s continuous improvement programme, the un-dissolved zinc losses in the iron residue were targeted by: the partial replacement of calcine with zinc oxide fume (from the DRC); and the preferential use of ?low-ferrite content calcine? as neutralizing agents in the iron removal circuit. These initiatives, coupled with other operational factors, resulted in a marked improvement in recovery to 92.6% during June to December 2007. The zinc oxide fume, directly fed to the circuit, required investigation of the halide rejection capacity of the Zincor circuit. Rejection of chloride via the magnesium bleed operation was considered adequate. Fluoride was mainly rejected via the iron (~70%) and lead silver (~27%) residues. Fluoride rejection via the lead silver residue varied significantly, probably as a result of variations in the sparingly soluble CaF2 content in the feed. The mechanism for fluoride rejection in the iron residues is uncertain. The fluoride rejection capacity of the Zincor iron residue (comprising of mainly jarosites, schwertmannite and ferrihydrite) at 2 ? 4 mg/L F in solution, was estimated at 0.14 ? 0.19 kgF/tFe residue.

Jan 1, 2008

By I. du Plessis

The metallurgical response of a difficult to treat coal and an easy to treat coal orebody were investigated in terms of the coal yield and the coal quality in a basic coal recovery flowsheet. The purpose of this paper is to show trends and derive principles for the treatment of different coal types. This investigation entailed using the LIMN simulator to simulate the metallurgical response by varying the plant operational parameters. The controllable plant variables investigated were: ?Cyclone size ?Screen and hydro-cyclone cut points ?Medium cut density ?Feed particle size distribution.

Jan 1, 2010

By Martin Banda, Gift C. Chisakuta, Moses Chabinga

KCM made a major modification to the Nchanga Tailings Leach Plant (TLP) changing the circuit from feeding post leach thickeners in parallel with leach discharge for solid ?liquid separation to a Counter Current Decantation (CCD) configuration utilising most of the existing equipment. The new circuit is aimed at improving copper recovery from approximately 70% to 79% through enhanced wash efficiency. The re-introduction of CCD circuit at elevated throughput of 46 000-tpd design was made possible due to the EIMCO E-Duc technology design which is an auto-dilution system that enhances solids settling rate. Commissioning (manual operation) which accommodated on-going operational requirements was phased and completed in January 2004. The circuit stabilised in subsequent months and in March alone an all time record copper recovery of 81.8% was achieved which contributed an extra 779 tonnes copper above the plant?s projected production plans. 100% of the project cost was paid back by end of April 2004 This paper discusses the work involved and the challenges faced during the re-commission

Jan 1, 2005

By A. M. Neale

Kriel Colliery has experienced some sub-standard blast results on the overburden. Blast results are considered poor when the fragmentation is too big, back break into the new highwall, capping is experienced and/or excess overburden material is thrown into the void. Poor blasting leads to lower productivity, equipment breakdowns, and poor drilling and blasting results on the adjacent blast, contamination of coal or loss of coal. A simulation was developed in Microsoft Excel to model blasting results while changing various parameters. From the simulation results, it could be seen that a change of blast design could be beneficial. As an example, smaller drilling patterns were simulated (10 m x10 m to 8 m x8 m, and 8 m x8 m to 7 m x7 m in Pit 5 and Pit 6 respectively) in combination with changes in explosives (P700 emulsion vs. ANFO) and drill bit diameter (311 mm vs. 251 mm). The results show that each of the options has a specific scenario that will be most beneficial to the mine. These results are quite specific and subject to variable inputs. The purpose of the example is to demonstrate how the simulation can be used as a tool to asses blast design variations.

Jan 1, 2010

By Z. Leng

"After detonation of the explosive, the final blast-induced damage area around the blast-hole falls into three categories, namely crushed zone, fractured zone, and elastic deformation zone. This paper presents a modified model to calculate the size of crushed zone around a blast-hole in drill-and-blast, with the hoop compressive stress and cavity expansion effect taken into account. The material in the crushed zone was assumed to be a granular medium without cohesion, but with internal friction. On this basis, the formula for crushing zone radius was derived. The proposed approach was verified with tests reported in the literature and the simulated results from SPH-FEM coupled models. A full statistical analysis was also carried out, and the predicted values were found to be in better agreement with the test results compared with other models. A sensitivity analysis of the modified model showed that the size of the blast-induced damage area is mainly affected by the following factors: rock mass properties, in situ stress, and borehole pressure. In particular, the roles of borehole pressure and in situ stress are discussed. Finally, suggestions are made on how the size of the crushing zones can be decreased. IntroductionOver the past decades, drill-and-blast has become the most commonly used technology in rock excavation. It is well known that in rock mass fragmentation with explosives, the annular rocks around the blast-hole are converted into fines. The formation of these fines consumes a significant part of the energy of the detonation, which in general is ignored in the determination of the efficiency of detonation (Glatolenkov and Ivanov, 1992; Furtney et al., 2012). Many studies show that only 20–30% of the total explosive energy is effectively used in fragmenting the rock, and up to 50% of the energy generated by conventional charges is wasted in overcrushing of the crushed zone and the inner part of the fractured zone (Ouchterlony et al., 2004; Sanchidrian et al., 2007). How to control the crushed zone to enhance the effective utilization of explosive energy, reducing the unit explosive consumption and the engineering cost, is therefore of great significance."

Jan 1, 2016

By D. F. Sinclair

It is often said in business that if you don't have a customer you don't have a business. The same rule applies to project evaluation; if you don't have customers you really don't have a viable project. It is therefore essential that in the early stages of project evaluation the following fundamental questions are addressed: ? What products will this project produce? ? Who are the potential customers? ? What are the customers' requirements with respect to grade and impurities? ? Do they have adequate capacity to take the production from the proposed project? ? Will the products introduce adverse effects in the customer's process circuits? ? Will additional waste streams requiring disposal be produced? In the past the attitude has been along the lines of the customer will take whatever we produce at the mine site. Times have now changed with customers now operating under much tighter environmental regulation with waste disposal becoming increasingly difficult. It would therefore be prudent that the principles of product stewardship be used as a tool in project evaluation. This paper will provide a general discussion on customer requirements and provide detail on case studies of the impact of mine products on smelter process circuits. It will provide examples where there were synergies between the mine product and the smelter circuit and where the mine product had adverse impacts on smelter performance.

Jan 1, 2007

By J. Glazewski

The mining industry in South Africa has developed its own environmental guidelines in the form of an Aide-Mémoire1,which is an extension of the previous rehabilitation provisions to include all aspects of the environment and all phases of a mining operation. This development, at the time, recognized an international trend towards the formalization of environmental management in mining practice, which resulted from the realization of the large environmental liabilities that mines could face, particularly on closure. Over the past decade the international environmental focus in the mining industry has moved from operational management, to the reduction of liability on mine closure. Mine closure guidelines are being developed internationally by nations (for example, SRK, 19982) and by large mining groups (for example, Rio Tinto, 19983). In South Africa the Department of Minerals and Energy (DME) is presently reviewing the Aide-Mémoire to bring it in line with international and local developments and a separate mine closure plan is being considered.

Jan 1, 2000

Fig. 4 and 5 of the paper 'The analysis of ventilation and cooling requirements for mines' by J. van der WaIt, E. M. de Kock, and L. K. Smith are positioned incorrectly in the February issue (J.B. Afr. Inst. Min. Metal., vol. 83, no. 2, Feb. 1983). Extractive metallurgy of zinc At a professional development seminar to be held in Montreal (Canada) from 18th to 22nd April, 1983, specialists from industry and university will discuss the extractive metallurgy of zinc from ore to finished metal with special emphasis on the theory and practice of modern technology.

Jan 1, 1983

By W. Peters, W. A. H. Poppmeier

An overview is given of the present state of traditional and new steelmaking equipment and techniques, and one of the direct steelmaking methods that are currently being developed is described. In steelmaking processes, coal is used to supplement the energy input and to reduce iron oxides in the slag. Foamy slag practice is discussed, and the most widely used types of ladle recarburizers, their properties, and manufacture are described. It is concluded that the use of carbon sources, mainly for supplementing energy and as reductants, will increase in the future, but that demands on the purity of the materials will probably become more stringent. If hydrogen were manufactured at a competitive cost, it could become an alternative fuel and reductant in the field of iron and steelmaking.

Jan 1, 1993

By G. Dhakal, J. -I. Kodama, K. Neaupane, T. Yoneda

ABSTRACT Durability tests and evaluation of sub-zero temperature effects to some argillaceous clastic rocks were carried out. Welded tuff, limestone, sandstone and schist samples collected from different parts of Japan were tested and results are presented. Schist and dolomite from Ganesh Himal area along the higher Himalayas of Nepal were also tested, and the results are compared. The slaking tests were performed on all samples in pure water. The results reveal that the slaking index of schist from Japan is lower than that of schist from Nepal. Regarding carbonate rocks, the slaking index of limestone from Japan is higher than that of dolomite from Nepal. A tendency of decrease in slake durability with an increase in porosity is also observed. Freezing and thawing experiments conducted on welded tuff and schist reveal that crack initiates earlier but extends slower in schist than in welded tuff. It is also observed from the freeze-thaw experiment that the welded tuff deteriorates and wears faster than the schist. However, sandstone remains relatively intact for a long run of freeze-thaw cycles. Zusammenfassung Beständigkeitstests sowie die Bewertung der Auswirkungen von Minusgraden auf Tonschiefer Trümmergestein wurden durchgeführt. Dabei wurden geschweißter Tuff, Kalkstein, Sandstein und Schiefer aus verschiedenen Gebieten Japans sowie Schiefer und Dolomitgestein aus dem Ganesh Himal Gebiet, dem höheren Himalaya Nepals, untersucht und die Resultate verglichen. Für alle diese Gesteine wurden Slaking-Tests in reinem Wasser vorgenommen. Die Resultate zeigen, dass das Slaking von Schiefer aus Japan höher als das von Schiefer aus Nepal war, wohingegen bei kalkhaltigem Gestein das Slaking von Kalkstein aus Japan niedriger als das von Dolomitgestein aus Nepal ausfiel. Es wurde dabei auch eine Tendenz zur Löschbeständigkeitsverringerung bei gleichzeitig erhöhter Porosität beobachtet. Gefrier- und Tautests an geschweißtem Tuff und japanischem Schiefer zeigten, dass Risse in Schiefer schneller auftraten, aber sich langsamer ausweiteten als in geschweißtem Tuff. Bei Gefrier- und Tautests wurde ebenfalls beobachtet, dass geschweißter Tuff schneller verfällt und verschleißt als Schiefer. Sandstein hingegen blieb über lange Tau- und Gefrierzyklen intakt Résumé Des tests de solidités et l’évaluation de l’effet des températures en dessous de zéro sur les rocs argileux ont été effectués. Les rocs d’origine volcanique (cendre), les rocs calcaires, sableux et les schistes de différentes régions du Japon, ont été étudiés. Les schistes et les dolomites de la région de Ganesh Himal le long du haut Himalaya (Népal) ont été étudiés et comparés à ceux du Japon. Les tests de désintégration sur les rocs ont été effectués dans l’eau pure. Les résultats montrent que l’index de désintégration des schistes du Japon est inférieur aux schistes du Népal. En ce qui concerne les rocs carbonyles, l’index de désintégration des rocs calcaires du Japon est supérieur à ceux des dolomites du Népal. Une décroissance de la résistance à la durabilité est observée avec une plus grande porosité des rocs. Les tests de congélation-décongelation sur les schistes et les rocs d’origine volcanique (cendre) du Japon montrent une apparition précoce des fissures mais l’expansion des fissures est plus rapide dans les rocs volcaniques. Des tests similaires montrent que les rocs volcaniques (cendre) se désagrégent plus rapidement que les schistes. Cependant, les rocs sableux restent intacts après plusieurs cycles de congélation-décongélation.

Jan 1, 2003

COUNCIL FOR 1989/90 President Dr O.K.H. Steffen President-elect Mr H.G. Mosenthal Senior R.D. Beck Vice Presidents Junior ].P. Hoffman Immediate Past President C.E. Fivaz Honorary Treasurer Dr H. Wagner

Jan 1, 1990

By E. Dzingayi

Keywords: Pyrometallurgy, furnace, Bindura, nickel The smelter at Bindura Nickel Corporation processes concentrates from its own mines and other external sources. Concentrates are dried, smelted, and converted to a desulphurised matte (leach alloy) for further processing at the refinery. The smelter comprises a drying plant, submerged arc electric furnace, electrostatic precipitator, and three Peirce-Smith type converters capable of treating 150 000 tonnes of concentrates per year. Concentrates are dried in a rotary coal-fired kiln, blended with fluxes, and smelted in a six-in-line submerged-arc 15MW electric furnace. Slag is tapped and granulated for disposal, and matte is tapped at regular intervals for blowing in Peirce-Smith converters. The paper details the 37-year history of the smelter, including furnace rebuilds and operating parameters as they have evolved in response to changing feed compositions. Special challenges, particularly relating to the treatment of high talc concentrates, are also described.

Jan 1, 2006

By G. F. Balderson

In response to the written contribution made by G. J. C. Young to the above paper, I would like to make the following points. Paragraph 1 The build-up of oxidized coatings on cone surfaces has not been a problem in other applications similar to that at President Steyn. The following companies have commented.

Jan 1, 1982

By T. Nishi, D. Teguri, K. Saitoh

In recent years the requirement for high carbon ferro-manganese (HCFeMn), which is the key product of our company, has increased due to bullish demand for steel products. In our Tokushima works, we have 2 closed types of electric furnaces (1F and 2F), with which we are manufacturing HCFeMn. In order to meet the increase in demand, we made various modifications to these furnaces and we tried to increase the furnace operating loads. Especially for 1F, we deepened the furnace. In this paper, we report the results of this modification. The operational situations of the above-mentioned two furnaces are different because they have different individual profiles. As for 1F prior to modification, the depth of the furnace was one meter shallower than2F, because 1F was designed for the manufacturing of SiMn. On the other hand, our Tokushima works specialized in HCFeMn 14 years ago. However, the profile of 1F was not optimized for HCFeMn. In comparison to 2F, 1F was more difficult to stabilize due to the smaller tolerance for the adjustment of the electrode length, the metal / slag level, and the coke-mixing ratio. We deepened 1F by 770mm by disposing of the furnace rolling mechanism. We consequently achieved a 10% increase in production capacity. This meant the operating load was enhanced from 24.5MW to 27MW, the furnace became more stable and the tapping speed of both metal and slag increased, all which made the tapping easier than before.

Jan 1, 2007

A wide range of drill holes and process streams are sampled for resource estimation, grade control and contractual purposes in the minerals industry. However, despite the availability of training courses, conferences and both national and international standards on correct sampling practices, it is still surprising how often little attention is given to ensuring that representative samples are collected for analysis. The reason for this is that the responsibility for sampling is often entrusted to personnel who do not appreciate the significance and importance of sampling, with cost being the main driving force rather than whether the sample is representative of the material from which it was extracted. This seriously undermines the precision and accuracy of the analyses subsequently generated and can render the analysis process a total waste of time and money and expose mining companies to serious, potential, financial losses. Company management needs to reverse this situation and ensure that sampling is given the attention it deserves to generate representative samples for analysis.

Jan 1, 2009