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By J. Martinovic

The large proportion of gangue minerals present in platinum bearing ores in South Africa provides challenges to the flotation and down stream processes. In order to take effective measures to reduce their recovery in flotation an understanding of the mechanisms and factors influencing their behaviour is needed. Typical gangue minerals are pyroxene, feldspar, quartz, chromite and talc. Of these, talc is a naturally hydrophobic mineral and although it is present in relatively small quantities, it has a disproportionate effect as it has a strong froth stabilizing effect, increasing the recovery of other gangue minerals by entrainment. Talc recovery is effectively reduced with the addition of polymeric depressants. Although the other gangue minerals are assumed to be hydrophilic and their recovery by entrainment is expected to follow the water recovery, there is some evidence that they may be activated by the typical reagent suites used. Reagents such as copper sulphate, added as an activator, and collectors are used to selectively induce hydrophobicity on the sulphides. It has been shown that some of these gangue minerals can be activated. This research work investigates whether inadvertent copper activation is mineral specific and evaluates the mechanisms and factors affecting the reversal of activation with the addition of the depressants using electrokinetic measurements, adsorption and microflotation tests. Results are presented that show that the selected minerals do respond differently and that the reversal of activation is dependent on mineral type, depressant type, dosage and ionic strength of the electrolyte.

Jan 1, 2004

By W. C. Joughin

Modern soil mechanics is generally considered to have begun in 1925, when Karl Terzaghi published his book Erdbaumechanik auf bodenphysikalischer Grundlage (Earthwork Mechanics based on the Physics of Soils). These theories were applied to rocks more than 20 years later and the science of rock mechanics became established. Methods of analysis and design have been introduced and applied, and have evolved over time. More recently, the rapid growth in computing power has resulted in more sophisticated analyses, and together with improved monitoring techniques, our understanding of geomechanics has grown considerably. Despite this, geotechnical failures with major consequences still do occur. This is partly due to failure to transfer and apply the knowledge that has been gained, but also there are aspects of geomechanics that are not well understood.

Sep 1, 2023

By F. H. Touwen, N. C. Joughin

"Simulation is a technique for studying the operation of systems by synthetic experimentation. With digital computers it is possible to simulate even the complex production processes in gold mining. This has great potential in that it enables the investigation, analysis and comparison of mining systems to be done accurately, rapidly and at low cost. Two programs have been developed to simulate the principal underground production processes in gold mining.These are the simulation of any stope contract and the simulation of underground transport operations. The programs synthesize these mining activities from a large number of small unit operations. The stope contract program simulates rockbreaking by drilling and blasting and the cleaning of the panels by face and gully scraping. The transport program simulates the functions and movements of all vehicles running on rails on one underground level. The simulation programs provide an effective means for experimenting with mining activities."

Jan 1, 2014

By L. G. Snyman

"South Africa is well endowed with a plethora of valuable minerals, as well as being of world renown for its significant ecological and cultural resources. The unfortunate reality is that these two important attributes often come into collision when developmental decisions are made. Robust environmental planning tools are required to guide such development in areas of heightened sensitivity. Environmental management frameworks are one of the tools that can attempt to achieve the desired developmental and ecological balance by utilizing early identification and mapping of sensitive ecosystems and resources to assist in pre-empting potential future land use conflicts. This paper unpacks the characteristics of environmental management frameworks and further investigates their potential, as well as its current design and implementation challenges. The findings show that environmental management frameworks have the potential to provide meaningful resource information to decision-makers on the opportunities and risks of developments in sensitive areas. They further provide a platform and process through which local stakeholders can voice their opinions and collectively drive the developmental priorities of the identified area.IntroductionAt the core of a harmonious and prosperous society is the balancing of a broad spectrum of needs, rights, and imperatives. As South Africa’s resource and energy needs expand, it becomes increasingly important to safeguard environmental rights and ensure sustainable development through creative measures. The State’s drive for accelerated development to meet the targets in the National Development Plan 2030 is contributing to the growth of invasive developments in previously undeveloped areas. The unfortunate reality is that the heightened tensions between rapid economic growth and environmental sustainability are threatening sensitive areas."

Jan 1, 2017

By J. H. French, O. E. Lissner

S. J. Venning (Member): The authors should be congratulated on producing such concise data from the plethora of experimental report results. Their observations on the cost of liners calls for some comment however, as the really unique feature about liners in South Africa is that they can be obtained so cheaply. Attention has been focussed on the 1961 cost of white iron at R50 per ton for chill cast block liners while manganese steel liners are reported as costing as much as R250 per ton. The former are however, a relatively heavy, simple casting with a low labour content and reasonably high percentage productivity, made from metal melted in a cupola. The capital investment to produce this type of casting is low compared with that required to produce manganese or other alloy steels. The chill cast liner block is always a production item and is cast in a permanent mould. Almost all manganese mill liners, except perhaps small aperture screens, are sold for considerably less than the R250 per ton quoted by the authors. Where a price of this nature is asked it would be because the design of the casting demanded is complicated or leaves little metal to carry the labour and other costs of production. As reference has also been made in the paper to liner costs in America, prices for similar types of liners obtained during a visit to Canada and the U.S.A. in 1961, could be of interest: Material Price per Location short ton Ni-hard R250 Elliot Lake Body liners block type Ni-Hard R300-310 FAS New York Mn Steel R280-290 FAS New York Screens (grids) slotted Cr.Mo. Steel R600 FAS New York hole Ni-Hard R320 Elliot Lake At this time the price of comparable manganese steel block type liners on the Witwatersrand was between R145/R155 per short ton. White iron in Canada was then quoted at about R150 per ton, but as Ni-Hard gave a life of at least two to twoand-a-half times that of white iron, it was a much more attractive proposition particularly when relining and down time costs were taken into consideration. There is little doubt that most foundries would welcome clear and complete specifications of the customers requirements and systematic checks to ensure that these specifications are being met. B.S.S. or other accepted standards should form the basis of these, and periodic inspections should be undertaken to ensure that only those foundries capable of complying should be included as suppliers. The authors have referred to new designs, but can the industry really call the grid and plate new when the patents were taken out during the second world war and the sawtooth block has been used for at least 35 years. Unfortunately, far too little thought and consideration are normally given to the ultimate mill liner design while the mills themselves are on the drawing boards. The position and size of the door opening, which is the key to the ultimate shell liner configuration, the drilling of the

Jan 9, 1968

By A. O. Filmer

An account is given of a study on the non-oxidative dissolution in aqueous acidic solutions of nickel sulphides of different stoichiometric composition, in which a rotating ring-disc electrode was used. The rate of dissolution was found to depend on the potential of the sulphide and the nickel-to-sulphur stoichiometric ratio. A maximum rate for the dissolution of nickel from nickel sulphides containing an excess of nickel was recorded at potentials around -0,2 to -O,3V. The rate decreased markedly at more anodic potentials. For nickel-deficient nickel sulphides, the nonoxidative dissolution rate increased with a cathodic shift in potential. Under open-circuit conditions, a nickel sulphide of a composition approximating Ni ,S. reacted most rapidly. The dissolution rate was controlled by either a chemical or an electrochemical reaction at the electrode surface, had an activation energy of between 50 and 65 kJ.mol-1, and was independent of stirring speed.

Jan 1, 1980

By C. Musingwini, M. Woodhall

An often overlooked factor in the analysis of mine layouts and schedules is technical operating flexibility, mainly due to its nebulous nature. If one glosses over technical operating flexibility the resultant mine layouts and schedules tend to be sub-optimal. The need to incorporate technical operating flexibility into the analysis and comparison of mine layouts and schedules is increasing in importance. This paper illustrates the nature of technical operating flexibility, reviews previous work on valuing operating flexibility and proposes how technical operating flexibility can be quantified for tabular reef mines by using a platinum reef deposit as a case study. Once technical operating flexibility is quantified it becomes possible to explore its incorporation into the analysis of mine layouts and schedules and subsequent optimization processes. The work described in this paper is part of a current PhD study at the University of the Witwatersrand. Keywords: mine plans, layouts, schedules, technical operating flexibility, ore availability.

By Bert Woodhouse

The excursions - Symposium on Ancient Mining and Metallurgy in Southern Africa by BERT WOODHOUSE Excursions add much to any symposium. They enable the participants to see something of the subject matter, and provide an opportunity for informal discussion and for the creation or renewal of friendships. In this respect the Ancient Mining Symposium was well provided for. There were two excursions and both were repeated to cope with the large number of participants.

Jan 1, 1974

By F. L. D. Cloete

The Relix process is based on direct contact between an ion-exchange resin and undiluted pulp, thus avoiding prior solid-liquid separation. The resin particles float near the surface of the pulp, forming an inverted fluidized bed with the pulp flowing downwards. The basic idea was demonstrated on a full-scale pachuca tank at Stilfontein Gold Mine in 1970, followed by a small-scale demonstration run in a laboratory at the National Institute for Metallurgy. A pilot plant based on a throughput of 60 tons of ore per day was subsequently operated at West Driefontein Gold Mine for several periods over two years. Although the plant proved operable from a mechanical point of view, the metallurgical performance was not up to expectation. The basic cause of the poor metallurgical performace was shown to be backmixing of both the resin and the pulp between stages. The values obtained for resin losses were inconclusive. Further development of resin-in-pulp processes for the recovery of uranium should be focused on the performance of various techniques for the screening of resin from pulp.

Jan 1, 1981

By K. Basaure, S. Palma, R. L. Castro

"Mud rushes are sudden inflows of fine wet ore within underground mines; they can harm people and equipment as well as cause production delays. Block and panel caving mines are prone to mud rushes in their production levels, with mud flowing from the drawpoints. Different mines have developed methods to control drawpoint conditions and thus perform safe ore extraction. The aim of this study is to develop a decision matrix and apply it to samples from drawpoints for the Diablo Regimiento mine, Codelco, El Teniente Division (Chile). The Abrams’s Cone was used to perform slump tests on mud samples and characterize their consistency by setting the saturation degree and packing. The unconfined strength for different saturation degrees and packing was then evaluated. The results show that conditions for fluid response in slump tests correspond to conditions for low strength in unconfined compression tests. We also found the water content value at which the flowing consistency changes from plastic to soft behaviour according to the slump test classification for each sample. This value varied between 12.2% and 16.9%, depending on the sample tested. Finally, a fluid security factor was defined in order to design an extraction pattern for the samples tested, based on the water content. We conclude that a very densely packed ore is not prone to flowing. The flow properties depend strongly on the specific properties of the ore tested, and consequently a specific criterion should be developed for different types of ore at a particular mine. The criterion developed for Diablo Regimiento ore provides critical water content values from 11% to 15%, depending on the ore type. IntroductionBlock/panel caving has the lowest cost and the highest production rates of all underground methods (Heslop, 2000; Hubert et al., 2000). Good management of the risks is important to ensure the security of personnel and infrastructure. Operational risks for the method include rockbursts, air blasts, and mud rushes (Hubert et al. 2000). A mud rush is defined as a sudden inflow of mud from a drawpoint or other underground opening into the mine (Butcher, Joughin, and Stacey, 2000; Butcher, Stacey, and Joughin, 2005). Mud rushes can cause dilution, production delays, and damage to equipment as well as injuries and fatalities. The elements necessary for mud rushes are mud-forming material, disturbances, a discharge point, and water (Butcher, Joughin, and Stacey, 2000). All these elements are present in block/panel caving mines. Mud-forming material comes from ore milled by the caving process; water comes from underground and surface sources. Drawpoints in the production level are discharge points for the mud. Finally, several types of disturbance could trigger the mud rush phenomena: blasting, earthquakes, operation of equipment (Call & Nicholas, Freeport McMoRan, and Hydrologic Consultants, 1998; Jakubec, Clayton, and Guest, 2012), arch collapse above drawbells (Butcher, Joughin, and Stacey, 2000; Butcher, Stacey, and Joughin, 2005; Jakubec, Clayton, and Guest, 2012) and ore drawing (Butcher, Joughin, and Stacey, 2000; Butcher, Stacey, and Joughin, 2005; Call & Nicholas, Freeport McMoRan, and Hydrologic Consultants, 1998; Jakubec, Clayton, and Guest, 2012)."

Jan 1, 2017

By D. D. Howat, J. van der Colf

Slags of the system CaO-MgO-AI2O3-TiO2-SiO2at had been reduced in graphite crucibles for selected time Intervals were fully re-oxidized so that an assessment could be made of the rate and extent to which the titanium oxide had been reduced. The derived kinetic parameters were studied as functions of slag composition and temperature. The extent of reduction after selected Intervals of treatment could be correlated with the physical behaviour of the melt (in terms of viscosity and electrical resistivity).

Jan 1, 1979

By W. O. Ortlepp

This note considers the most fundamental concepts of support design for deep underground openings and discusses them briefly in the context of tabular stoping and deep hard-rock tunnelling. It concludes that the conventional re-bar, mesh, and lacing methods that have been widely used in deep gold mines are quite inappropriate for the support of highly stressed tunnels. The following is suggested as the criterion for adequate dynamic support: the energy absorbed by a support unit (yielding through some acceptable limited displacement) should exceed the kinetic energy generated by the mass of rock that is intended to be retained by that unit.

Jan 1, 1995

By P. Kind

Design criteria and recent developments in large-capacity Wemco flotation cells by P. KIND, Ph.D. (Clausthal), B.Sc. (Visitor) The scaling-up of the large flotation cells that have been developed during the past few years has been based on hydrodynamic considerations and has resulted in a 500 ft3 cell unit. Plant results on a porphyry copper ore show that the 500 ft3 unit is equivalent to the previously used 300 ft3 model.. . Plant tests on the use of 300 ft3 flotation cells for the recovery of phosphate, particularly from the coarse size fractions, are also described.

Jan 3, 1976

By H. D. Mtegha

The Southern African Development Community (SADC) aims to harmonize mineral policies and regulatory regimes in the minerals sector. This paper provides a review of the progress made towards harmonization of mineral regimes in the region. It singles out only the mining fiscal environment, as this is normally one of the key issues of interest to potential investors as well as the host state. Indications are that the region is slowly progressing towards a more harmonized approach, and there is evidence that the ?race to the bottom? has been prevented, which is the basis for an integrated mineral sector that the region aspires to.

Jan 1, 2011

By J. M. Stewart, C. H. Wyndham

Suggested thermal stress limits for safe physiological strain in underground environments by J. M. STEW ART M.Sc. (Eng) (Witwatersrand) (Visitor) and C. H. WYNDHAM M.B., D.Sc. (Witwatersrand), F.R.C.P. (Land) (Fellow) A comparison of safe temperature limits, based on Mitchell and Whillier's equations for specific cooling power (SCP), with similar limits determined experimentally shows the SCP-based limits to be unnecessarily conservative. It is argued that, while a small part of this conservatism may be attributed to an erroneous extrapolation of the heat transfer dependence on wind speed, the major part is probably due to the use of too Iowa limiting mean skin temperature in the calculation of SCP. A combination of Mitche/l's basic data with results available in the literature permits the derivation of modified heat transfer equations based on data that fully cover the range of wind speeds of interest. These equations, using a mean skin temperature of 36°C as the basis for the calculation of safe temperature limits, are then shown to agree favourably with those determined empirically. Furthermore, values of SCP based on these equations are shown to correlate reasonably well with wet kata readings, giving positive support to the wet kata thermometer as a heat stress meter.

Jan 8, 1975

By B. P. Watson

The Bushveld platinum group metal deposits in South Africa are the largest in the world. These deposits occur as two distinct stratiform tabular ore bodies and strike for many hundreds of kilometres. Mining is extensive, with depths ranging from close-to-surface to 2300 m. The mining method is a variation of planar open stoping. Crush pillars are widely used to support the open stopes. These pillars are designed to fail and the residual strength provides the required support resistance to stabilize the stoping excavations. This paper describes the in situ measurement, of stress within a Merensky pillar from Impala Platinum. These measurements were used to derive a stress-strain curve that includes pre and post failure behaviour. 2D FLAC modelling, with strain softening, was done to investigate how damage expands into the hanging- and/or footwall. Although the so-called ?squat? effect is always present, the modelling suggests that it does not dominate the pillar system behaviour at larger width to height ratios. Punching of the pillar into the hanging- and/or footwall increasingly controls the pillar system behaviour with larger width to height ratios. The paper investigates the behaviour of a system that incorporates the immediate hanging- and footwall, as well as the pillar itself.

Jan 1, 2009

By A. Koursaris, J. B. See

The influence of Iscor coke and Delmas coal on the reduction of Mamatwan manganese ore to ferromanganese was examined by use of a variation of the 'stationary charge in controlled environment' (SCICE) technique. The charges of Mamatwan ore and the appropriate reducing agent were heated to temperatures between 1300 and I600 °C and either allowed to cool immediately the required temperature had been reached or held at that particular temperature for periods of up to ... hours. The heating rate was 350°C per hour, the particle size of the ore was between 2,83 and 12,7 mm, and the particle size of the reducing agent was between 2,83 and 6,35 mm. After being allowed to cool in air, the reacted charges were examined by optical microscopy, X-ray-diffraction analysis, scanning electron microscopy, and electron-microprobe analysis. No significant difference was found between the changes observed during the reduction of Mamatwan manganese ore by Iscor coke and by Delmas coal. A hypothesis is advanced to explain the mechanism of formation of the Fe-Mn-C alloy.

Jan 1, 1979

By E. Barnea

This paper simplifies and provides a strict mathematical proof for an equation developed by R. J. Woody for the c alculation of solute recoveries in countercurrent decantation. The equation offers a convenient method for the optimization of flowsheets involving a simple countercurrent-decantation circuit.

Jan 1, 1978

By R. H. O?Connor, B. N. Soutar

The paper reviews the introduction 01mechanical shaft drilling into the sinking 01shafts in the Gold Fields Group. A comparison is made between the operating costs 01the drilling rig and those of conventional hand-held machines, and it is concluded that, despite certain disadvantages, mechanical drilling is preferable.

Jan 1, 1988

By W. C. Mather

The Witbank/Middelburg Branch of The South African Institute of Mining and Metallurgy hosted a colloquium entitled 'Recent Mining and Metallurgical Developments in the Eastern Transvaal', at the Witbank Civic Centre on Wednesday, 25th September, 1985. An attendance of close on 300 delegates bore testimony to the popularity of the theme. Two well-attended cocktail parties were held at different venues on the evening prior to the Colloquium. These were hosted at the South African Coal Estates Recreation Club and Middelburg Country Club.

Jan 1, 1986