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By J. C. Zachariades, D. M. Fraser

The leaching of pyrolusite in acidic ferous sulphate solution was studied so that the important factors governing the kinetics of the reaction could be determined. The reaction is very rapid, and was monitored by continuous measurement and logging of the redox potential in solution by use of a microcomputer. The relationship between redox potential and manganese extraction was established empiricaly for each set of conditions by the use of a technique in which a calibration run was conducted in paralel with each leaching run. The study involved a number of batch leaching runs, and demonstrated that, of the variables investigated, only the initial ferous ion concentration and the reaction temperature afect the rate of manganese extraction. The final extraction did not vary. The reaction was modeled from the results by use of the shrinking-core model and Britan's activation-energy model. The later was found to provide a significantly better fit to the data.

Jan 1, 1991

By W. T. Ruhmer

Slimes-dam construction in the gold mines of the Anglo American Group by w. T. RUHMER. Pr.Eng.. B.Sc. Eng. (Met.) (Fellow) Current practices generally in accordance with the principles of design and operation of slimes dams within the Gold Mining Division of the Anglo American Corporation are described. Although many of the details given are either obvious or have been amply dealt with elsewhere, these have been included for the sake of completeness. The selection of suitable ground for the deposition of slimes, the initial design and construction of a slimes dam, and its consequent operation are presented in logical sequence. Emphasis is placed on the code of practice for the construction of slimes dams issued by the Chamber of Mines of South Africa, and draft regulations (Water Act of 1956) dealing with pollution. Operating costs are included, and possible future trends are discussed.

Jan 2, 1974

Acid heap leaching has been extensively applied to the processing of copper oxide ores, with recovery of copper by solvent extraction and electrowinning. Heap leaching has also been extended to the treatment of secondary sulphide copper ores, where oxidative conditions are generated in aerated heaps by the bacterially-assisted oxidation of ferrous iron to ferric iron. The treatment of low-grade chalcopyrite ores has recently been the focus of research, with Mintek playing a prominent role. When processing chalcopyrite ores, more complex column test work is performed, which incorporates the prediction and simulation of temperature behaviour in pyrite-containing heaps. Mintek has devised a trade-marked column leaching apparatus (SmartColumn?) for the simulation of the natural temperature profile development in pyrite-containing heaps. As heap leach applications are becoming more complex, the parameters that need to be built into the design and operation of heap leach plants are growing in number, and the amount of data to be collected and processed, and the number of decisions to be taken daily, are also increasing. Mintek has therefore developed the HeapStar® administrative advisory software, as a guidance system to ensure that the correct protocols are implemented at various stages of the leach cycle.

Jan 1, 2012

By P. S. Turner

After a brief account of the differences between the control of underground fires and those on the surface, the paper describes the analogue detection system used on the mines of the Anglo American Corporation of South Africa Limited. The system comprises Spanair gas analysers, Becon combustion-particle detectors, a telemetering system, a surface signal-recording and-processing system, and an alarm system. The use of the system is described and illustrated.

Jan 1, 1982

By M. J. King, W. K. B. Loftus, H. S. Simpson

SYNOPSIS The history of the early diamond fields and primitive methods of diamond recovery are traced, giving a brief description of the improvements made in final diamond recovery processes and techniques up to the present day. In particular the emphasis is on the effect of improved equipment in reducing final hand sorting time and labour, better security and greater recovery of fine diamonds.

The Floatability Characterisation Test Rig (FCTR) is a self-contained, highly instrumented, mobile pilot plant. It was developed as part of the AMIRA P9 project, primarily to determine ore floatability characteristics and to develop and validate flotation plant modelling, scale-up and simulation methodologies. This paper describes the use of the FCTR in validating the AMIRA P9 flotation model and modelling methodology. In 2001 the FCTR was installed and operated in parallel with WMC's (now BHP Billiton's) Kambalda Nickel Operation. The FCTR was operated using four different circuit configurations of increasing complexity. Metallurgical surveys, cell characterisation measurements and batch flotation tests were performed around each circuit. This allowed the calibration of a number of flotation models using a combination of data from one, two, three or four circuit configurations. The calibrated flotation models were then validated using predictive validation. To do this, data around a further five FCTR circuit configurations were collected (three of which are presented in this paper). The performance of each of the five circuit configurations was predicted using JKSimFloat V6.1 and the parameters from the various calibrated flotation models. The predicted performance was compared to the experimentally determined performance of each circuit. The validation of the AMIRA P9 model was shown to be largely successful except in the case where the reagent addition (depressant) to the validation circuit was different to that in the calibration circuits. The results also provided information regarding the required complexity of the calibration circuit and how many calibration circuits are required to obtain an accurate prediction of circuit performance. These results have increased the confidence in the AMIRA P9 flotation modelling methodology and have provided important information on what data must be collected to allow the accurate prediction of plant performance using the floatability component modelling approach.

Jan 1, 2007

By L. A. Cornish, I. A. Mwamba, R. A. Couperthwaite

"In previous work by the authors, it was established that additions of 0.2 at.% Ru to an Fe-40 at.% Al alloy improved the corrosion and oxidation resistance of the alloy. The alloy was produced by mechanical alloying and spark plasma sintering and the work showed that nonequilibrium processing was able to significantly refine the grain size of the material. The sintered material had a higher hardness than the as-cast material and the change in grain size did not significantly affect the oxidation and corrosion. In the present research, the mechanically alloyed powder was coated onto a mild steel substrate using cold-spray coating at a gas pressure of 10 bar and a temperature of 500°C. The coatings were found to be 5–10 um thick, although thicknesses of up to 30 um were observed. The coated materials were subjected to oxidation and corrosion tests to determine the effectiveness of the coating in increasing the oxidation and corrosion resistance of mild steel. This was done to determine the effectiveness of cold-spray coating as a technique to coat these mechanically alloyed powders. IntroductionPrevious work conducted by Mintek (Couperthwaite et al., 2013, 2015) investigated the effect of precious metal additions on the structure, oxidation and corrosion properties of an Fe-40 at.% Al (Fe- Al) alloy. Initial work determined that additions of more than 0.5 at.% precious metal did not improve the oxidation and corrosion properties of the materials and in some cases even decreased the resistance to corrosion. Further work identified Pt and Ru as beneficial additions to the FeAl alloy. Four alloys were then produced by mechanical alloying and sintering (FeAl–0.2 at.% Pd, FeAl–0.2 at.% Ru, FeAl–0.5 at.% Ag, FeAl–0.5 at.% Pt). These alloys were all successfully produced by melting and casting and mechanical alloying sintering and it was found that the nonequilibrium processing greatly decreased the grain size of the materials compared to the ascast materials. It was found that the additions of Ru and Pt were still the most beneficial to the oxidation and corrosion properties, with Ru being considered the most beneficial."

Jan 1, 2016

By W. Wilmans

Electrokinetic dewatering of kimberlite slime under constant direct curents of 0,5 to 2 A and dewatering under constant applied potentia Is of 16,5 to 46,5 V are considered. The combined efects of electrophoresis and the addition of 8,3 x 10-3 M Mg2+ ions on the one hand, and 1 to 10 p.p.m. of the anionic polyacrylamide flocculant Praestol 2935 on the other, were investigated in a 3-litre Perspex electrophoretic cel. .The electro-osmotic dewatering experiments were conducted in a 3-litre Perspex electro-osmotic cel at various electrode spacings, as well as with a moving anode (top electrode). During electrophoretic dewatering, the zeta potential of the kimberlite particles did not change significantly, whereas the pH and temperature showed marked increases with time. The addition of Praestol 2935 enhanced the setling of the sludge bed owing to the additional effect of flocculation. The addition of electrolyte Mg (CIO4)2 retarded the separation process, partly as a result of gel formation in the slurry. During the electro-osmotic experiments, the rate of dewatering was found to be approximately proportional to the applied constant direct current, and to be independent of the electrode spacing. In general, electro-osmotic dewatering seemed to be more energy-efficient than electrophoretic dewatering.

Jan 1, 1987

By C. Debek, A. Wasilewicz, T. Czysz

"Both Polish and European hard coal mining nowadays faces the need of deepening shafts (significantly in some cases) or extending mining hoists, due to the exploitation of deeper coal deposits.In order to protect the crew working within a shaft, rope safety platforms (artificial shaft bottoms) are employed. Old solutions, based on rigid steel constructions with the external damping layers made of e.g. slag and up to several tens of metres long, are intended to absorb the energy of approximately 5 t mass falling a distance of 700 m. However, current requirements often assume a drop of 20 t to a depth of 1000 m or even more.More modern safety platform structures, made of one or more support rings with steel ropes stretched on them (rope platforms), are more compact (up to 3 m high) and lighter than traditional solutions. Multi-ring rope platforms with additional damping layers filling the empty spaces between the ropes are able to absorb sufficient energy to meet the current requirements.Single- and double-ring platforms have been employed in Poland to absorb the energy of approximately 5 t dropping to a depth of 900 m. They have been developed (and some have already been implemented) by SADEX Ltd. and are protected by various patents and patent applications.This paper presents a design for a triple-ring platform structure with six rope nets. FEM analysis was used to model the performance of the platform. According to the simulation, a 20 t mass falling from 1000 m (>100 m/s) will destroy all the nets, breaking most of the ropes and deforming the support steel boards placed on the nets, but will ultimately be stopped by the platform, as its kinetic energy falls to zero."

Jan 1, 2017

By G. Coetzer, J. C. Davidtz

The substitution of functional groups in covalent trithiocarbonate collector molecules influences the selective and non-selective bonding of collector molecules to mineral surfaces, as well as flotation efficiency in a mixed sulphide ore. These effects were concluded to be related to the metal-sulphide solubility products and electron densities on the sulphur atoms in the collector

Jan 1, 1989

By H. C. Voges

The use of heavy-medium separation in the processing of iron ores by H. C. VOGES. B.Sc. (Visitor) The paper discusses various aspects of the application of heavy-medium separation to the processing of hematite ore at Sishen and Thabazimbi. The two main factors to be borne in mind in the design of a plant for such beneficiation are the Iow unit value of the iron ore produced and the high separation densities required. The four factors of importance in the avoidance of high viscosity in the ferrosilicon medium are discussed in turn.

Jan 6, 1975

By C. Botha

The South African democratically-elected government instituted policies and legislation that are intended to bring about change and transformation in the country and have drastically affected different industries, among others, the mining industry. The Mineral and Petroleum Resources Development Act 28 of 2002 (MPRDA) and the Broad-based Socio-economic Empowerment Charter (Mining Charter) were introduced in order to redress previous inequalities and to promote women?s employment in the mining industry. This research evaluates the practical implementation of the MPRDA and the Mining Charter with specific reference to women in underground mining. A quantitative research paradigm was used. Data were collected through a process of a face-to-face interview surveys utilizing a structured questionnaire. The research setting was limited to the platinum-mining industry in the area of Rustenburg in the North West Province. The study population consisted of 195 available women working undergound at the mine. It is clear from the findings that mining companies are facing major challenges in their attempt to incorporate women in underground mining activities. Company policies regarding these issues must be firmly in place; however, the challenge lies in the translation of these policies into practice. In this regard, managers will have to play a leading role in the successful phasing in of women into the underground mining arena.

Jan 1, 2012

By N. A. Barcza

Pointing out that South Africa needs to utilize its wealth-creating activities, together with local and international investment, to further develop its industries, the address asserts that the mining and minerals industries, especially in the manufacture of beneficiated products, offer the greatest potential for South Africa to achieve its goal. As many mineral-beneficiation processes are based on pyrometallurgical routes, the address goes on to describe some historical - pyrometallurgical operations and to indicate probable developments in the future. These include growth in the fields of both precious and base metals. After discussing environmental and recycling matters, together with manpower requirements, the address concludes that the major growth in the mining and minerals industries will occur in the manufacture of steel, stainless steel, ferro-alloys (particularly ferrochromium), aluminium, and titania slag.

Jan 1, 1996

By E. T. Boome, A. C. Schmidt

P .E.R. T. and how P .E.R. T. techniques can be used in modern mine management by E. T. Boome and A. C. Schmidt Published in the Journal, December 1972 DISCUSSION A. E.W. FLETCHER A.c.S.A.* In making this contribution to the authors paper, I should first like to congratulate them on the clear and yet detailed way in which they have illustrated their subject. I should also like this contribution to be linked with Mr Hazell's paper "Mine Management by Objectives".

By J. C. David, G. Coetzer

The effect of varying aliphatic, olefinic, and aromatic groups in the N- and S-positions of dithiocarbamates was investigated in the selective and bulk flotation of a mixed copper-lead-zinc-iron ore. Selective and bulk flotation were found to be dependent on the type of functional group, as well as on the position of substitution.

Jan 1, 1989

By R. M. Morris, G. A. Matthesius, M. J. Desai

Slow pyrolysis experiments were caried out on samples of coal from north em Natal having a volatile mater content ranging between 10 and 25 per cent by mass and a constant particle-size distribution. The tests were conducted at atmospheric pressure in a helium atmosphere, and ata heating rate of 10 KImin and a final temperature of 1220 K. The pyrolysis products were taken as coke and volatile mater (tar and eight other species), and tMir respective yields were measured. The experimental results were used in the modification of an existing mathematical model and in the derivation of new corelations for some of the parameters of the model, so that the volatile products of a coal can be predicted from ultimate and proximate analyses of the coal. The pyrolysis tests showed good agreement between the model predictions and the experimental results.

Jan 1, 1987

By S. K. Kawatra

Feasibility studies of the on-stream analysis of lead in mineral slurries by S. K. KAWATRA. P. Eng. (Canada). Ph.D. (Australia). M.Sc. (India) (Visitor) Instruments for the measurement of lead in mineral slurries by the use of isotopes can be based on the absorption of Iow-energy gamma rays, backscattering of beta particles, or X-ray fluorescence. The merits of each method are discussed, and the reasons for the selection of the beta-backscattering technique are given. A system using this technique has been designed, constructed, and tested on samples of concentrates from an industrial concentrator.

Jan 8, 1976

By M. U. Özbay

A series of blasting experiments was carried out in an up-dip stope of a gold mine using short-perioddelay electric detonators. The main object of the investigation was to show the interactive effects of short-delay blasting. The delay range over which observations were made was restricted to between 10 and 200 ms. To quantify the blast results, data were collected on fragmentation, throw, position of muckpile, and ground vibration. For comparative purposes, blasting parameters for conventional pyrotechnic sequential firing were also measured. The paper describes the most relevant parts of the study and gives the experimental results. The interactive effects of short-delay blasting are analysed, and some aspects of the breaking mechanism are discussed.

Jan 1, 1985

By R Kersten

The note describes an exercise on the simulation of the frequency and size of seismic events on the basis of the frequency distribution of the events and their inter-arrival times (Le. the frequency distribution of the time elapsed between events). From the suite of available results, those of one simulation for a period of three months are included. The tentative conclusions drawn from the exercise indicate that the overall seismic activity in an area can be predicted for a time period, that structurally complex areas will have a higher incidence of seismic events than other areas, and that the position and time of an event cannot be predicted by the use of a wide-spread system such as that used at present.

Jan 1, 1985

By M. J. Sapko

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) recently conducted full-scale explosion experiments; these experiments evaluated the strength characteristics of various seal designs used for safely isolating worked-out areas in underground coal mines. Large-scale explosion tests were conducted within the multiple entry section of PRL's Lake Lynn Experimental Mine (LLEM) employing the only currently accepted test method endorsed by the Mine Safety and Health Administration (MSHA) for seal design in American mines. These explosion tests are labor-intensive, expensive to conduct, and can interfere with other critical underground safety and health research programs conducted by NIOSH. Therefore, the PRL has developed an alternative seal evaluation method, based on a hydrostatic pressure loading concept, that can facilitate the in-situ testing of seals in an operating mine. Two chambers within LLEM and one within the Safety Research Coal Mine (SRCM) were used for hydrostatic pressure loading various seal designs. The results from tests in these chambers compare favorably with those from the large-scale explosion tests in the multiple entries. Preliminary size-scaling relationships for predicting the strength of standard seal designs as a function of entry size is also presented. In addition to testing seal designs at the required 20 psi static pressure level, the new facilities also allow for the determination of the seal's ultimate failure pressure. This new approach shows promise as an alternative evaluation method for improving mine sealing technologies which, in turn, will enhance the safety of the underground personnel.

Jan 1, 2003