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By F. Yang, T. Pan, T. Zhao, Z. Shao, D. Zuo

In this paper, the development and applications of robot technique is summarized, and the status and developing direction of China coal mine robotics. A description of the research meaning, frame and key technology of underground salvage robot is given. Keywords: coal mine, robot, special robot, salvage robot.

Jan 1, 2003

By A. K. Das, S. Pathak, C. Bhanu, P. K. Tripathy

Ferroalloys are integral part of steel melting process. The purpose of using ferroalloys is three fold e.g. killing of steel, modifying the slag composition and steel alloying. Amount of ferroalloys used for alloying is subject to requirements of steel properties e.g. yield strength, ductility, formability etc. Variety of ferroalloys (some-times pure metal) is used by steel industries depending upon their techno-economic feasibility. Size, chemistry and modes of addition of ferroalloys are suitably engineered to bring in operational consistency and cost benefits. Of late, Tata Steel has tried out a few ferroalloys for the first time with interesting results to meet the specific requirements of high strength interstitial free (IF) and micro-alloyed steels. Some of these ferroalloys have been put into regular use with complete or partial replacement of ferroalloys used earlier. Size of one of the ferroalloys has also been modified without any other adverse effects. This paper summarizes requirements of ferroalloys for the steel industry with special emphasis on recent trials.

Jan 1, 2007

By D. Farrow

Future development of kimberlite mines is now focused on mining at deeper levels. The consequences are increased difficulty and costs of the mining operations. The decisions on investments require accurate resource evaluation and quantification of the risk. In the decision process the first step consists in choosing the number of boreholes sampling the pipe relative to the level of uncertainty that can be accepted. The uncertainty in the volumes of rocks of different types can be assessed as soon as we can estimate these volumes from a given borehole layout and calculate the error by means of its variance for instance. In theory this can be achieved by using geostatistical techniques (‘transitive theory’), but in practice the calculation of the error on volumes can be achieved in very particular cases, assuming some regular sampling patterns. A different approach has been chosen based on simulations, giving maximum flexibility to reproduce the reality of the sampling procedure. The idea is to simulate the geometry of several ‘possible’ pipes with their internal geology and estimate them by kriging. Several experimental errors are obtained on which risk analysis can be performed. The aim is to find a feasible method to perform the simulations with reasonable chance to correctly represent the reality, without data on the pipe extension. The methodology applied is based on some hypotheses that can be assessed by the geologist as well as by the geostatistician. The procedure assumes a geological model based on current knowledge including appropriate geostatistical variation. What make these simulations specific and powerful in this case comes from the fact that the boundaries between the different rock-types can be simulated using a transformation of the real 3D space into a 2D space defined by means of polar coordinates. Ultimate transformations to account for smoother variations with morphological transformations allow the generation of realistic pipe geometries on which sampling pattern can be used to evaluate the estimation errors. By estimating the simulated pipe geometries with different boreholes layouts a risk curve expressing the uncertainty in the volumes of the different rock-types versus the number of holes can be developed.

Jan 1, 2003

By M. J. Nicol, G. Cromberge

An account is given of the development of a relatively simple model that describes the kinetics of the absorption of gold cyanide on activated carbon. The model is based on the treatment of the carbon solution interface as a homogeneous boundary across which gold is transported at a rate determined by the rate of mass transport to and from the interface. Rate equations derived from this model describe the results of various kinetic experiments under continuous or batch conditions in the laboratory and on operating pilot and full-scale plants.

Jan 1, 1983

By W. J. Cruise

This paper reports on a test that was conducted underground in a mine for two years on the following: pipes coated with paint, fusion-bonded powder, metal, or impregnated tape; and aluminium, stainless-steel, 3CR12, and plastic pipes. It was found that the degree of corrosivity and mechanical damage increases substantially from the shaft of a mine towards the stope. Thus, the range of coatings that can be used successfully is fairly large in the shaft and haulageways, but corrosion-resistant materials, especially corrosion-resistant steels, need to be used close to the stope. A study of the relative costs involved showed the costs of pipes of low-carbon steel and unplasticized polyvinyl chloride to be lowest, and those of epoxy-coated steel pipes to be highest.

Jan 1, 1985

By B. C. Alberts

Rapid and effective handling of run-of-mine, waste, and treated materials is vita.! to every step of resource development and recovery. Modern mine managements have planned and engineered systems for the handling of ever-larger tonnages. Where traditional methods have not proved to be costeffective and adequate, managements have pioneered the development of new materials-handling systems in the mining industry.

Jan 1, 1983

By J. Gilliland

The Grootegeluk coal-beneficiation plant was erected in the Waterberg coalfield, near Ellisras in the Transvaal, to supply Iscor's steelworks with a predetermined tonnage of coking coal in accordance with strict quality requirements. This plant has to handle a high tonnage of raw coal, which is not easy to beneficiate, in order to produce 1,82 X IQ6t of coal. Extensive tests were conducted on borehole cores and a mass sample of coal obtained from the area. These tests were carried out on a laboratory and pilot-plant scale, and were aimed at the establishment of the most effective beneficiation methods and the choice of suitable equipment. This led to the completion of a full set of design and manufacturing drawings that resulted in the project approach . described in this paper.

Jan 1, 1982

By J. C. Vreugdenburg, W. A. H. Poppmeier

An overview of methods of manufacture is presented, as well as the results of laboratory experiments on the making of stainless clad steels. , It is concluded that stainless clad steel can be made in South Africa with existing rolling equipment, and that good bonding between the two materials depends on clean mating surfaces, proper edge welding, and a minimum reduction of 25 per cent at a rolling temperature of 120O"C. In practice, a minimum reduction of 70 per cent at 1100cC is recommended. : Suggested applications for clad steel include parts and equipment for the chemical, petrochemical, marine engineering, and mining industries, for the building sector, and for household appliances.

Jan 1, 1991

By M. J. Nicol

The results are reported of experiments on the influence of a number of variables on the rate of loading of gold cyanide onto activated carbon and the equilibrium capacity of the carbon. These variables include the concentrations of gold and free cyanide in solution, the pH value and ionic strength of the solution, the concentration of organic compounds in the solution, the temperature, the particle size of the carbon, and the mixing efficiency. The experiments were carried out under approximately steady-state conditions to simulate the conditions in a countercurrent carbon-in-pulp absorption plant. In addition, the results are reported of experiments to establish whether the absorption of gold cyanide onto activated carbon is a reversible process.

Jan 1, 1983

By R. E. Gundersen

Hydro-power-the use of high-pressure water as an energy source-offers tremendous benefits for environmental control in deep, hot mines. The extent of these benefits depends on the mining method, the selection of equipment to be hydro-powered, and the efficiency with which the coolth is extracted from the water and into the working environment. The engineering of hydro-power systems continues to receive much attention. However, this paper considers the environmental implications of using hydro-powered equipment, particularly with regard to positional efficiency. The integration of hydro-power with developments such as backfill, mechanization, and higher face-advance rates is discussed. Layouts are proposed that attempt to minimize the quantity of water in circulation by extracting the maximum coolth from the water.

Jan 1, 1990

By R. H. Steel

Ingot casting and wire drawing In Iron Age Southern Africa by R. H. STEEL (Visitor) This paper describes the experiments that were conducted in 1974/1975 on two related aspects of Iron Age copper technology in Southern Africa: ingot casting and wire drawing. Three types of ingot were successfully cast: the St Andrew's Cross ingot, the marale ingot, and the musuku. It is suggested that the 'studs' on the musuku are not the remains of broken-off rods as previously proposed by other investigators, but that the ridged pattern is an ornamental feature. Copper wire was successfully drawn with similar tools and according to the procedures described in the literature on African Iron Age wire drawing. It is concluded that these accounts are generally accurate and that the pre-European metal workers are worthy of respect for the results they achieved with primitive methods.

Jan 11, 1975

By F. N. F. le Roux

This paper describes the method used for excavating the upper 33m of emergency access shaft E2 for the underground single track tunnel running between Park and Rosebank station of the Gautrain Rapid Rail System. The soil was decomposed shale and diabase from the Witwatersrand Supergroup. The location was in the car park of The Wilds (a public park) in Johannesburg. The method proved very simple and required less complex plant and equipment than normal when excavating the shallow soil sections in shafts. It involves driving steel sheets ahead of the shaft sump into the soils and then excavating inside the ?tub? created by the sheets whilst supporting the sheets above with regularly spaced circular Steel Rings. It is the intent of this paper to discuss the method and design approach to the method. This will be done at the hand of experiences at E2 shaft..

Jan 1, 2009

By B. X. Huang

Hydraulic fracturing technology is presented as a solution to improve permeability and thus solve the extraction problem of coal seam gas in low-permeability gas-bearing coal seams. Given an existing group of original cracks, the propagation of main hydraulic cracks and hydraulic wing cracks was simulated using realistic failure process analysis software. The process represents the structural transformation of hydraulic fracturing and permeability improvements caused by it. In addition, a field test for improving the permeability of gassy coal seams by hydraulic fracturing was also conducted. The propagation of the main cracks and wing cracks by hydraulic fracturing forms a network of original joint cracks, hydraulic wing cracks, and main hydraulic cracks, which improve the permeability of the coal seam. High-pressure water in the drill hole and in the main hydraulic cracks permeates the two flanks of the hole, forming the permeating water pressure. With an increase in drill water pressure and an extension of the main hydraulic cracks, the permeating water pressure on both sides of the main hydraulic cracks in the coal mass also increases. Hydraulic cracks tend to form connections through rock bridges. The extension of hydraulic wing cracks through connections in the rock bridges between the cracks transforms the rock mass to a fractured structure and improves its permeability. Hydraulic fracturing technology for improving permeability in underground conditions can increase the amount of gas drainage by a factor of 15. A stress relief area develops at a radial distance of 10-2.0 m from the hydraulic fracturing drill hole, while an area of rising stresses, called the pressurized area, develops a further 15 m away from the pressurized hole. Practice has proved the existence of the stress transfer phenomenon and the high stress area after fracturing. This kind of hydraulic fracturing technology is more effective in holes drilled from underground than in surface drill holes, with respect to costs and controllability, and is therefore the major trend in gas drainage development in coal mines.

Jan 1, 2012

By P. R. Jamisch

The limitations of gold-mine evaluation by P. R. JANISCH, B.Sc. (Sur.) (Natal) (Visitor) Inherent uncertainty in the choice of parameter values places theoretical and practical limitations on the interpretation of a gold-mine valuation that are not necessarily removed by comparison of two valuations on the same assumptions. These limitations arise mainly in the estimates made of cost inflation and gold-price escalation, and lead to inconsistencies in the 'league table' method of investment analysis. The choice of discount rate is also critical in many cases. An approach to the overall problem that takes these limitations into account is suggested.

Jan 6, 1976

By Cade Mweemba, Alex Mwanza, Jackson Sikamo

"The Zambian Copper mining industry as we know it today has its genesis from early in the 20th century in the 1920s. Consistent private sector-driven investment in the industry over a period of over 50 years in exploration, mine development and operation, development of minerals processing facilities, building of infrastructure for pyrometallurgical and hydrometallurgical processing, with attendant support facilities, including building of whole new towns, resulted in copper production going from zero to a peak of 769 000 tons of copper in 1969. At the same time, the industry created jobs to the extent that in 1972 the industry had over 62 000 direct jobs. The industry was nationalized in 1973 and remained in government hands for just over 24 years. During this period, the industry experienced a serious decline in production levels, reaching the lowest level at the dawn of the 21st century in the year 2000 when production was 250 000 tons. In terms of jobs, an average of just under 2000 jobs were lost every year in the 24-year period, reaching just over 22 000 direct jobs in 2000. Following the return of Zambian politics to pluralism and liberalized economic policies, the government decided to privatize the mining industry. The process started in 1996 and by the year 2000 all the mining assets had been privatized. The new investors embarked on serious investment to upgrade the assets and to develop greenfield mining projects. Fourteen years later and investments of over USD 12 billion, the industry production levels increased year- on-year to reach a peak of 763 000 tons in 2013 with direct jobs reaching 90 000. This paper discusses the impact of the mining industry in Zambia on the economy in areas such as employment, support to other industries, direct contribution to the national gross domestic product (GDP), foreign exchange earnings and social amenities. The paper also focuses on the performance of the mines during these periods vis-à-vis mineral availability, mineral grades and complexity, new technologies and human capital. This is looked at particularly in the light of current challenges the industry is facing and makes suggestions on how the industry can be nurtured to continue being a major driver for the Zambian economy and a major player in the international copper mining business."

Jan 1, 2015

By P. Stevenson

Correlations for the critical velocity needed to hydraulically convey particles in horizontal, or near-horizontal, pipes are either explicitly dependent upon the shear stress imparted by the fluid upon the surface of the particle bed, or require a velocity and hydraulic diameter. Often such approaches are modified to account for pipe inclination by the introduction of simple factors. However, we assert that the physics that underpins the hydraulic conveying of particles in steep pipes (such as a directionally drilled oil well) is dissimilar to that which governs particle behaviour in horizontal pipes. In steeply inclined systems, a sliding sediment induces an upward counter flow and hence an autogenous contribution to the shear rate. The physics underpinning particle hydraulic conveying in steep systems is explored using the separation results of Laskovski et al.10

Jan 1, 2007

By Y. H. Suh, H. C. Lee, D. S. Kim

A progressive karst formation and its influence upon engineered structures in the ‘phil-karst’ rock mass draw a tunnel engineer’s special attention to a long-term stability and the maintenance issues. Karst sinkholes of any size beneath the railway bed cause train wrecks or long interruptions in train traffic during rehabilitation work. The collapse of cave roof, called a ‘doline’, is in general connected to the cave by the gradual dissolving of the rock, developing into subsidence and sink-holes. The principal conclusions obtained from the field experiments are as follows: It is found that the development of karst cavity shows a relationship with a structural geological line and it is necessary to define the dominant directions of joint and geological layer (formation). The relation-ship between the water flow and joint direction can be used as an indicator of cavity presence in their direction. In addition the direction of in-situ stress can play a role in the development of karst cavities. A risk map of karst scenario is produced for the tunnel supporting systems with rock type classifications in water-soluble karstic rock mass. Eine fortschrittliche Karst-Formung und sein Einfluß auf angelegten Strukturen in der Phil-Karst-Felsenmasse wecken einem Tunnelingenieur eine besondere Aufmerksamkeit zu einer langfristigen Stabilität und der Wartungsausgaben auf. Karstensinkhöhlen in irgendeinen Größen unter dem Eisenbahnbett sind die Ursache der Zugeszerstörung oder der langen Unterbrechungen in Zugverkehr während Rehabilitationsarbeit. Der Zusammenbruch von Höhlendach, d.h. ein “doline”, ist im allgemeinen an die Höhle, die durch das allmähliche Auflösen des Felsen zu entstehen ist und sich in die Subsidence und Sinkhöhlen entwickeln, angeschlossen. Die Hauptschlüsse, die von Feldenprüfungen erhalten wurden, sind folgendermaßen: es wird gefunden, daß die Entwicklung von Karstenhöhlung eine Beziehung mit einer strukturellen geologischen Linie zeigt und es notwendig ist, die vorherrschenden Richtungen von Gelenk und geologischer Schicht (die Formung) zu definieren. Die Beziehung zwischen dem Wasserablauf und der gemeinschaftlichen Richtung kann als ein Anzeiger von Höhlungsanwesenheit in ihrer Richtung benutzt werden. Zusätzlich kann die Richtung von In-Situ-Spannung eine Rolle in der Entwicklung der Karstenhöhlungen spielen. Für das Tunnelunterstützungssystem, welches mit Felsentypenklassifizierungen in wasserlöslicher Karstic-Felsenmasse, ist eine Risikokarte von Karstenszenar hergestellt. Une formation progressive de karst et son influence sur les structures tracées dans la masse de roche "phil-karst" retiennent l'attention particulière des ingénieurs de tunnel aux problèmes de la stabilité à long terme et du maintien. Les creux de karst de toute la taille sous le chemin de fer causent les accidents de trains ou de longues interruptions pendant le travail de réhabilitaion. L'effondrement du plafond de caverne qui s'appelle "doline" s'est, en général, connecté à la caverne par dissolution progressive de la roche, en devenant l'affaissement et les creux. Les conclusions importantes venant des experimentations sur le terrain sont suivants: d'abord, le développement de la cavité de karst montre le rapport avec la ligne géologique de la structure et il est nécessaire de définir les directions dominantes du joint et la couche(formation) géologique. La relation entre l'écoulement de l'eau et la direction du joint peut être utilisé comme un indicateur de la présence de la cavité dans leur direction. De plus, la direction sur place peut contribuer au développement des cavités de karst. Le plan risqué de karst s'est produit pour le système d'appui du tunnel avec les classifications du type de roche dans la masse de roche karstique qui est soluble dans l'eau.

Jan 1, 2003

Mineral sand beneficiation plants comprise a complex combination of electrostatic, magnetic and gravity based separation techniques. These are combined and replicated in ways that provide the most efficient and cost effective separation of the valuable components. On line instrumentation has been developed at the JKMRC (eg. conductor/non-conductor(CNC) ) to measure the properties of the dry plant process streams. This paper provides results from the recent development of a novel low cost mass flow meter and discusses their combined use with the CNC instrumentation for the control of dry separation circuits.

Jan 1, 2003

By A. L. Hinde, P. J. D. Lloyd, A. R. Atkins, J. G. MacKay

The control of milling circuits by A. R. ATKINS, M.Se. (Elee. Eng.) (Visitor), A. L. HINDE, S.Se., Ph.D. (London) (Visitor), P. J. D. LLOYD, S.Se. (Chem. Eng.), Ph.D. (Cape) (Fellow) and J. G. MACKA Y, S.Se. (Chem. Eng.) (Visitor). The general behaviour of mills is described in an attempt to find a control philosophy that will permit milling circuits to produce a constant particle size. Although the experimental work has been confined to a single section of the milling circuit of one mine, it is felt that the findings are applicable to other milling circuits.

Jan 6, 1974

By N. Naude, W. P. Roux

Fine particle beneficiation plays an ever-increasing role in mineral processing plants and it seems that technology can’t keep up with the challenges involved in the treating of these fines. The REFLUX™ classifier has proven itself able to treat high tonnages of fine material, especially in the coal industry. There are various fine ore applications that can benefit from such a process, yet laboratory and pilot-scale tests on many of these ores show poor efficiencies and recoveries. A better understanding of the design, operation and mechanisms of the REFLUX™ classifier is required to determine if and how it fits into these applications. The mechanisms in gravity separators are very complex due to the complex hydrodynamics, and the REFLUX™ classifier is no exception. The mechanisms of these systems are usually described through theoretical single particle-models that are hard to verify through analysing the feeds and products of these processes. To verify these models the movement of individual particles must be measured, which is not an easy task. In this paper the separation mechanisms in the incline channels of the REFLUX™ classifier were investigated with high-speed videography. A small lab scale model of the incline channel was constructed for this purpose. It was possible to capture and track the trajectories of particles under certain conditions and match these trajectories with theoretical models. The resuspension of particles, clustering and streaking was also observed and captured. Keywords: REFLUX™ classifier, particle trajectory, beneficiation, high-speed videography

Jan 1, 2020