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The addition of binder to full plant tailings significantly affects the rheology of a backfill mixture and, consequently, the pressure gradients in the pipeline. The binder increases the yield stress and apparent viscosity of the mixture, and the transition velocity between the laminar and turbulent flow regimes. In a test conducted at a slurry relative density of 1,72 with binder addition, the mixture also exhibited time-dependent behaviour owing to the hydration of the binder.

Jan 1, 1993

By W. J. Van Den Berg, J. G. Taylor

The paper discusses the introduction of blindhole boring on the South African gold mines of Anglo American Corporation. It covers the boring trials conducted, and outlines the progress made in the development of blindhole borers. The operating costs, and performances, of the latest 1,52 m diameter borer are given. Future trends and requirements In the application and design of blindhole borers are discussed, as well as factors that are of importance in the design of future machines.

Jan 1, 1978

By N. Mangesana

The effect of high solids concentration and coarse particle sizes (d50 ranges 90?300 µm) on the viscosity of a suspension of water and silica sand was investigated. The experiments were designed to include conditions that have been tested by other authors and those encountered in the operation of tumbling mills. The rheological data was measured using a tube rheometer with operating pseudo shear rates of up to 1500 s-1. The rheograms obtained depicted dilatant behaviour. The Otswald-de Waele, Bingham, Herschel-Buckley and Casson models were fitted to the experimental data. The Herschel-Buckely model, which approximates the yield point and gives an indication of the shear thinning or shear thickening behaviour of the suspension, was found to provide the best description of the flow curves for all slurries. The Herschel-Buckely model was then used to determine the apparent viscosity of all the tests. The apparent viscosity and yield stress increased with solids concentration and particle size at the different pseudo shear rates. The increase in slurry viscosity with solids concentration was attributed to increased frequency of particle-particle interactions. The increase in slurry viscosity with particle size was attributed to increased inertial effects. At low shear rates the sand slurry exhibited shear thinning behaviour for all solids concentrations. At higher shear rates above 1000 s-1the high solids concentration suspensions exhibited a transition from shear thinning to a shear thickening behaviour.

Jan 1, 2008

On 8th August, 1973, 57 members of the Institute visited Prieska Copper Mine at Copperton in the North Western Cape. After tea, the group was welcomed by the Management of the Mine, and Mr Grobler, the General Manager, gave an introductory talk. After they had been taken on a bus tour of the property, the members split up into groups and proceeded underground or to the concentrator. Of special interest to the mining members were the rock-handling methods in use at the mine. The stoping method that has been adopted is the continuous, long-hole sub-level open stoping system. The broken ore is moved with rubbertyred front-end loaders from the stope drawpoints to the ore passes. On the main tramming levels, the ore is collected by electric locomotives and discharged into the main shaft system at the bottom. At the shaft ore-pass system, a gyratory crusher that can accept rocks up to 1 m in diameter has been installed. The crushed product (minus 150 mm in diameter) will then be hoisted by a Koepe winder, which has a rated capacity of 900 tons per hour. The mine is also served by a declined roadway from surface, which facilitates the movement of heavy equipment. The most striking aspect is the productivity that can be achieved by the use of a trackless-mining system. For the production of 230 000 tons per month, it is estimated that 6 stopers and 7 developers will be required. The total labour force will be approximately 2500-2000 Bantu, 200 Coloured, and 300 Europeans. Training of maintenance and operating personnel is of the utmost importance, and it was interesting to note the extent to which non-White labour is being used in these occupations. Lunch was served at the single quarters, after which the group proceeded to the airfield for the return trip to Johannesburg. On behalf of the visitors, Professor de V. Lambrechts thanked Mr Grobler and his staff for the most interesting morning and for their hospitality,

Jan 10, 1973

By M. A. de Ruijter

Bracken Gold Mine ceased mining operations during February 1993. The clean-up of the gold plant, which had already commenced in September 1992, was completed in January 1994. The mine had been in production since early in 1962 but, because of a decreasing ore reserve, increasing working costs, and a relatively low gold price, closure had become inevitable. The closure had been under consideration since August 1983, when the first estimate was made regarding the amount of gold that could be recovered from the clean-up operations. Until that stage, it had been accepted that Bracken would conform to the commonly accepted idea that 0.25% of the total gold produced by the plant would be recovered during the clean-up operation. This idea was dispelled when the initial estimates indicated that the gold recovery would vary between 0.049 and 0.095%. The actual figure realized was 0.036%, showing that there is no generalforl1ula for the calculation of the amount of gold to be recovered from such clean-up operations. During the clean-up operation, Bracken became an unexpected contributor to the State's Reconstruction and Development Programme by having al the mine and plant buildings purchased and converted into a community development centre. This shortene4 the time available for the clean-up, and several of the buildings remained intact. However, the foundations and sub-soils had been sampled extensively, and it is considered that no recoverable gold was left behind.

Jan 1, 1996

1. Book review Gold and silver handbook: On geology, exploration, production, economics of large tonnage, low grade deposits, published by S.W. Ivosevic. 227 pp. $29.50 + 3.25 for shipping and handling. Available from the publisher, 207 World Savings Building, 12211 West Alameda Parkway, Denver, Colorado 80228, D.S.A. Reviewer: D.G. Krige 2. New Canadian publications Canadian mines: perspective from 1983. Ottawa, Canadian Government Publishing Center, 1984. $4.20. The Canadian iron ore industry: current and emerging problems.

Jan 1, 1985

By B. P. Christos

The improved rate of stope-face advance at Buffelsfontein Gold Mining Company Limited by B. P. CHRISTOS (Associate) To achieve a higher rate of stope-face advance. it was necessary to examine al.1aspects of the stoping operation, to identify bottlenecks, and to eliminate them or reduce their effect. The cleaning cycle was fund to be the most significant bottleneck. and this problem was aggravated by long panel lengths. under-capacity winches In strike gullies. and excessively long strike scraping distances.

Jan 12, 1975

By T. J. Otto, C. Musingwini

"The objective of any mining company is to sustainably maximize the net present value (NPV) throughout the life-of-mine (LOM). The expected NPV over the LOM is calculated based on a mine plan, yet the actual value realized by the mining company depends greatly on the level of intertemporal execution against the mine plan. Consequently, a major key performance indicator (KPI) that is often overlooked in open pit mining, due to a greater focus on temporal KPIs, is the degree of spatial compliance to the mine plan. Such focus sometimes leads to short-term actions being detrimental to long-term plans. In this paper we describe the development and implementation of a spatial mine-to-plan compliance reconciliation approach for an open pit mine. Application to a case study open pit iron ore mine in South Africa indicated a significant improvement in the spatial mine-to-plan compliance, from 69% to 94% over a three-year period from 2014 to 2016. These results indicate that implementation of the proposed spatial mine-to-plan compliance reconciliation approach can contribute positively to improving the level of spatial execution and assists in improving the alignment between short-term, medium-term, and LOM plans.IntroductionThe objective of any mining company is to maximize the net present value (NPV) throughout the life of mine (LOM). However, this objective needs to be fulfilled in a sustainable manner that considers the needs of various stakeholders, including employees, shareholders, and local communities where the mines operate. The expected NPV is calculated using a mine plan as a basis. Mine planning broadly involves identifying a strategy to exploit the mineral resource in a way that maximizes value at an acceptable level of risk throughout the LOM (Tholana and Neingo, 2016).The mine planning process is a well-recognized component in the mining value chain of an open pit mine. Figure 1 reflects the relative position of mine planning within a typical open-pit mining value chain from the mineral resource to the market"

Mar 1, 2019

By A. Fouchee, N. Naudé, K. Schommarz

"This article presents laboratory test work conducted on an African haematite ore to determine the influence of the flotation pulp pH on the final iron grade and recovery. Results show that a combination of an isodecyl ether propylene amine/amino acetate and 1,3-propanediamine, N-(3-(C10-C16-alkyloxy)propyl)-derivatives collector is suitable for separating haematite from quartz. Higher iron grades were obtained at pH levels between neutral and pH 9. This underlines the importance of the surface charge effect of the ore on its flotation characteristics. The results serve as good baseline conditions for further optimization. IntroductionBeneficiation of iron ore by flotation is widely used in Brazil, India and China. In Africa, however, this practice is not yet commercially developed.The aim of this test work is to serve as a starting point by establishing suitable pH conditions for the development of a practically implementable reagent suite, which will then be included in a larger beneficiation circuit for producing high-grade iron ore sinter feed.In the literature, African iron ore types are graded as low-grade (60.0–62.9% Fe; 8.6– 12.5% SiO2 and insolubles), high-grade (66.0– 69.9% Fe; 0.8–4.5% SiO2 and insolubles), and meduim-grade as the remaining portion (Astrup et al., 1998). The low-grade ore used in this work contains less than 60% Fe.For Brazilian ores consisting of a combination of haematite and quartz, it is common to use corn starch as a depressant and ether amine blends as collectors with additional frothing characteristic (Araujo et al., 2005). Work by Turrer and Peres (2010) shows the possibility of using other depressants successfully as well.The main mechanism of the reverse flotation of quartz from iron ore is based on the electrostatic theory of flotation. This is due to the strong pH dependence of the zeta potential of the mineral edge planes on silicate particles (Fuerstenau and Pradip. 2005)."

Jan 1, 2016

By A. M. Venter

"SynopsisThe availability of advanced characterization techniques is integral to the development of advanced materials, not only during development phases, but in the manufactured components as well. At Necsa, two modern neutron diffractometers equipped with in-situ sample environments, as well as complementary X-ray diffraction instruments, are now available as User Facilities within the National System of Innovation in support of the South African research and industrial communities. Neutrons and X-rays, owing to their different interaction mechanisms with matter, offer complementary techniques for probing crystalline materials. Both techniques enable nondestructive investigation of phenomena such as chemical phase composition, residual stress, and texture (preferred crystallite orientation). More specifically, the superior penetration capabilities of thermal neutrons into most materials allows for the analysis of bulk or localized depth-resolved properties in a wide variety of materials and components. Materials that can be investigated include metals, alloys, composites, ceramics, and coated systems. In particular, depth-resolved analyses using neutron diffraction complements surface investigations using laboratory X-rays in many scientific and engineering topics. The diffraction techniques can add significant downstream value to the anticipated nuclear industry development activities.IntroductionMaterials characterization is central in understanding the relationship between the structure, properties, and performance in order to engineer materials that fit the performance criteria for specific applications. This is conveniently represented in the form of a tetrahedron, generally known as the material science paradigm (Figure 1).The availability of advanced characterization techniques is integral to the development of advanced metals, not only during development phases, but in the form of manufactured components. At Necsa (South African Nuclear Energy Corporation), modern X-ray and neutron diffraction instruments are now accessible to the South African research and industrial communities. These facilities enable nondestructive investigations of materials and components that could add significant downstream value to the anticipated nuclear industry development activities."

Jan 1, 2015

By H. A. D. Kirsten

Mining-induced seismicity is usually evaluated in terms of continuum elastic analyses, and is quantified in terms of energy release rate as state parameter and excess shear stress along particular features on which failure may be induced. Although both of these quantities are representative measures of potential seismic activity, elastic analyses do not enable the associated stresses and displacements in the rock in which failure occurs to be evaluated reliably. The paper compares the effect of depth, span, support stf1Jhess, field stress ratio, and discontinuity strength on mining induced seismicity determined from elastic analyses and from analyses in which discontinuities in the rock are allowed to fall. It is, accordingly, shown that the incidence and magnitudes of potential seismic events and the net excess shear as representative state parameter cannot be determined reliably from elastic analyses that do not account for the failure of ubiquitous discontinuities. The magnitudes of seismic events in rock in which ubiquitous discontinuities are allowed to fail are very considerably overestimated in elastic analyses. The extent of the seismic source region and the associated seismicity do not increase with depth, which, together with the improved containment of the concomitant rockburst damage by backfill is reassuring for mining at greater depth in future. For conventional support, the magnitude of potential seismicity increases for an increase in span in elastic rock, but remains unaffected in non-elastic rock. For backfill, the magnitude of potential sesmicity decreases substantially in elastic and non-elastic rock for an increase in span. Increases infield stress ratio very significantly reduce potential seismicity irrespective if the type if analysis, but effect the distribution if potential seismic events very differently in elastic and non-elastic rock.

Jan 1, 1994

By W. D. Grimsley, R. P. King, J. B. See

Samples (15 to 20 g) of pre-calcined Mamatwan manganese ore or pure Mn 304 smaller than 48 mesh were reacted at temperatures in the range 1000 to 1300°C with samples of spectrographically pure graphite smaller than 325 mesh. Samples (1 g) of ore or pure Mn02 smaller than 48 mesh were reacted at temperatures of 1000 and 1200°C with pure graphite fines in argon, with graphite in carbon, .'1onoxide, and with carbon monoxide alone. In each case, the loss of mass as a function of time was recorded with a hermobalance. The rate and degree of reduction were found to increase with additions of carbon and with increasing temperature up to 1300oC, when they reached their maximum. The shape of the reduction curves, together with the results obtained from examination of the products of reaction by microscopy and X-ray diffraction, were used as the basis for a postulated reduction mechanism. Some details are given of an initial kinetic model that was used to verify the proposed mechanism. It was found that the reduction of Mamatwan ore by graphite at temperatures in the range 1000 to 1300°C occurs in two stages: (i) an initial stage during which the higher oxides of manganese are rapidly reduced to MnO with concurrent formation of CaMn2O4 and (ii) a longer stage during which CaMn2O4 and MnO are reduced to carbides by carbon dissolved in the ferromanganese phase.

Jan 1, 1978

By J. H. van Laar, L. J. van der Walt, P. L. Crouse, H. Bissett, G. J. Puts

"SynopsisSilicon carbide nanopowders were produced using a microwave-induced plasma process operating at 15 kPa absolute and at atmospheric pressure. Methyltrichlorosilane (MTS) served as precursor, due to its advantageous stoichiometric silicon-to-carbon ratio of unity, allowing it to act as both carbon and silicon source. Argon served as carrier gas, and an additional hydrogen feed helped ensure a fully reducing reaction environment. The parameters under investigation were the H2:MTS molar ratio and the total enthalpy. The particle size distribution ranged from 20 nm upwards, as determined by SEM and TEM micrographs. It was found that an increase in enthalpy and a higher H2:MTS ratio resulted in smaller SiC particle sizes. The adhesion of particles was a common occurrence during the process, resulting in larger agglomerate sizes. SiC layers were deposited at 15 kPa with thicknesses ranging from 5.8 to 15 µm.IntroductionIt is well known that methyltrichlorosilane (CH3SiCl3 or MTS) decomposes to form silicon carbide (SiC) and hydrogen chloride (HCl) as shown in Equation [1]. The reaction kinetics and mechanisms for this reaction are thoroughly reported in the literature (Sone et al., 2000; Papasouliotis and Sotirchos, 1999; Kaneko et al., 2002; Wang et al., 2011)."

Jan 1, 2015

1. Books from Elsevier The folowing are available from Elsevier Applied Science, Crown House, Linton Road, Barking, Essex IGl 8JO, OK. . Driling wastes, edited by F.R. Engelhardt, J.P. Ray, and A.H. Gilam. 1989. 872 pp. £95. Geothermal resources, by R. Bowen. 2nd ed. 1989. 468 pp. £60. The fate and efects of oil in freshwater, edited by J. Green and M.W. Tret. 1989. 340 pp. £42. Mining and the freshwater environment, by Martyn Kely (with contributions by W.J. Alison, A.R. Garman, and C.J. Symon). 1988. 228 pp. £32. 2. Books produced by Metal Buletin The folowing are available from Metal Buletin PLC, Park House, Park Terace, Worcester Park, Surey KT47HY, England. Prices and data 1990. £41 (airmail). Foundry directory and register of forges 1989-1990. £52 (airmail). 2. Canadian Publications The folowing two publications are available from the Canadian Government Publishing Centre, Supply and Services Canada, Otawa, Canada KIA 059. Mining and mineral processing operations in Canada. Mineral Buletin MR 224. $23.70. Canadian minerals yearbook 1989. Review and outlook. Mineral Report 38. $47.95. Technology developments The Mintek Pyrosim Simulator Pyrosim is a computer program for the steady-state simulation of pyrometalurgical processes?.

Jan 1, 1990

By C. S. Northcote, I. F. Buchan, L. F. Baars

In 1969 the Coal Division of the Anglo American Corporation was awarded the tender to supply coal to the new 3000 MW power station to be erected at Kriel, which is situated midway between the towns of Ogies and Bethal in the eastern Transvaal. The coal was to be supplied from the No. 4 Seam in the Kriel Area of the Witbank Coalfield. The No. 4 Seam in this area varies in depth of overburden from 75 m to 6 m, with an average of 55 m. Initially, the mine was planned as an underground mine incorporating a three-shaft system for transporting some 8 million tons of coal per annum to the power station. As the result of negotiations between Anglo and Escom to improve the volumetric extraction of coal from the new mine, the Kriel Division of Anglo Power Collieries was finally planned to produce 4,1 million tons of coal from an underground mine and 4,5 million tons from an opencast mine, with a resultant increase in volumetric extraction. This paper describes the opencast operation at Kriel, with particular reference to the water problems encountered and to the operation of the draglines on sloping ground to a depth of 40 m to the top of the coal seam.

Jan 1, 1980

Contribution by F.S.A. de Frey The authors are to be congratulated on a job well done by making, in their paper, such a pool of information available to mining engineers. I would like to comment on the following statement: 'As an alternative to the commonly used deep-level mining methods, consideration should also be given to pillar mining at great depths as a logical extension of the current methods. For example, a 75 per cent extraction Or Ryder's discussion The moderate levels if average pillar stress (APS) (320 MPa) are consistent with pillar stability. Squat 10:1 pillars should never 'fail' in themselves, and foundation strengths are also not exceeded (the stresses are well below the 2 ½ x UCS rule-of-thumb provided the foundations comprise normal strong 200 MPa quartzites). Authors' reply We thank Dr de Frey for his contribution to our paper on shallow hard-rock pillar systems. To considerable extent, we share his enthusiasm the potential role of squat pillars in deep-level mining, although we harbour reservations concerning strata control, mining economics, other issues. We agree wholeheartedly that further research, together with carefully planned field trials, is warranted in pursuit of this potentially highly rewarding concept. .

Jan 1, 1995

1. Book review . Fundamentals of fracture mechanics, by J.F. Knot. London, Buterworths, 1981 (reprint). Reviewer: G. Leadbeater The present reviewer approached the above book as a relative novice on the intricate details of fracture mechanics. Thus, the review is based to a great extent on how easily the information presented can be assimilated and understood, and how the book's format and content facilitate this. Note was taken of the preface comments about jumping ahead, in chapters, to ease understanding, and this was found to be a common occurence. 2. New publications Mechanical testing. London, The Institute of Metals, 1988. 357 pp. £25 Mining potential in northern and southern Canada: Guidelines for regional development policy, by Leo J. Verleun and Brian W. Mackenzie. Centre for Resource Studies (Queen's University, Kingston, Canada K7L 3N6), 1988. 225 pp, $20 Pricing of metals, by Margaret E. Slade. Centre for Resource Studies (see previous item). 149 pages, $20 CRS Perspectives, no. 29.Nov. 1988. Issued by the Centre for Resource Studies (see previous item) Introduction to the modern theory of metals, by Sir Alan Cotrel. London, The Institute of Metals, 1988. 456pp. £18 Mine winding and transport, by S.C. Walker. Amsterdam, Elsevier, 1988. 546pp. Dfl. 275.

Jan 1, 1989

By P. J. van der Walt, P. J. F. Fourie, L. M. Falcon

Various methods for the beneficiation of minus 0,5 mm coal are examined briefly, and tests are described on a cyclone of 150 mm diameter operating with magnetite as the medium. It was found that, for sharp separations, at least 50 per cent of the magnetite should be finer than 1Oµm. At that size, the ash content of the product was about 7 per cent at yields of 59 to 64 per cent, and the loss of medium was reasonable (about I kg per ton of fines treated).

Jan 1, 1980

By T. Ono, B. Altansukh, S. Kawamura, K. Haga, A. Shibayama, Y. Takasaki

In recent years, the grade of silica in zinc concentrate has increased due to the degradation of zinc content and the increase in impurity content in natural ores. It implies that the development of silica removal technology from zinc concentrate is necessary to solve problems in the smelting process caused by the high content of silica in zinc concentrate. In this paper, the authors investigated the silica removal processes from silica-rich zinc concentrate by mineral processing approaches such as re-grinding and flotation. This study focused on the pulverisation process as a pretreatment for the investigation of individual minerals' liberation from the silica-rich zinc concentrates using different kinds of pulverisers. Flotation experiments were performed to separate silica and zinc concentrate from the pulverizsd feed sample using a pH regulator (NaOH), activator (CuSO4), collecting agent (PAX), and foaming agent (DOW froth 250). Results showed that the liberation rate of silica (SiO2) was reached 75% from 13% by pulverisation in an attritor with a 2 mm ball in diameter, while silica accumulated in a fraction over 20 mm in size. Flotation experiments indicated that silica removal efficiency was achieved by 44% from + 20 mm fraction obtained from pulverisation whereas the grade of silica in froth reached 1.85 mass% from 4.5 mass%. Results indicate that silica could selectively separate from silica-rich zinc concentrate, and 99.8 % zinc recovery is achieved under the studied conditions. Keywords: Zinc concentrate, silica, pulverisation, liberation, sieving, flotation

Jan 1, 2020

By M. Frenzel, K. Bachmann, M. Rudolph, R. Tolosana-Delgado, E. Schach, M. Buchmann, L. Pereiraa, K. G. van den Boogaart, N. Kupka

Geometallurgy - the science of predicting the behaviour of ores along the value chain based on their geological and mineralogical characteristics - has barely moved beyond process minerology studies. These studies typically link process behaviour to the mineralogical and microstructural characteristics of pristine or processed ores in a qualitative or semi-quantitative manner. Eventually, a trial-and-error optimisation of the operation is achieved. However, to deliver on its promise, geometallurgy should progress beyond this current approach to a fully quantitative understanding of process behaviour, including the various uncertainties involved, namely predictive geometallurgy. One of the barriers currently hindering this development is the neglect of most ore characterisation data obtained in geometallurgical studies. This is mostly due to the large extent of this information exceeding the capacity of conventional software. To address this challenge, we developed a data mining platform consisting of an SQL database, an R front-end in-house package, and back-ends to interpret data from several analytical instruments. This platform enables the use of the statistical and data mining power of the R open-source environment for any geometallurgical study. Potential applications range from ore characterisation to process understanding and forecasting, and from geostatistical prediction to operational control and optimisation. The scripting abilities of R allow for the: 1) processing of many streams in loops, thus freeing the user from repeating tedious click-and-drop tasks; 2) computation of virtually any derivate or aggregate quantity from the data; 3) distribution of the work among several processor clusters; and 4) keeping of a log file for the calculations done. This contribution presents the building blocks of this platform, and illustrates with several examples its potential to enable predictive geometallurgy. Keywords: Data mining, entropy, kernel methods, LASSO regression, predictive geometallurgy

Jan 1, 2020