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By H. H. McGregor

SYNOPSIS Changes in the national productivity (gross national product per head of the population) have been assessed in order to derive a target figure for the required annual increase. The conclusion reached IS compared with the targets of the economic development programme of the Republic. Productivity and management structure in the gold mining industry is then analyzed together with investment in plant, machinery and equipment for rock handling purposes. The conclusion is drawn that productivity improvement does not appear to have accorded with the massive expenditures in plant and equipment, and in augmented management. The productivity of the manufacturing and construction sectors of the economy has been examined. The principal difficulty is that the main avenue of approach is the value of product divided by the total labour force. This introduces inflationary questions, and the use of a suitable deflator becomes of prime importance. Severa1 different methods of assessing the productivity improvement in the industrial sector have been used with what is regarded as a comparatively high degree of compatibility. Improvements in productivity in the manufacturing industry up to 1966 appear, from the information available, to have substantially exceeded comparable figures for the mining industry. There is however evidence that thereafter productivity of the manufacturing industry has not maintained this satisfactory rate of increase. If the economy is to achieve the planned rate of expansion, there is no doubt that greater attention to this aspect will be required in the future than has been accorded to it in the past.

By M. Rudolph, E. Schach

Tecflote is a new group of nitrile-based collectors for sulfide flotation. Water insolubility results in some interesting implications for the actual mechanism. It is not yet understood if Tecflote is directly adsorbed on the mineral surface as emulsion droplets or if it is only active at the air-water interface, affecting the interfacial rheology or electrostatic- and Van der Waals interactions, which have a direct impact on the bubble-particle contact. Different investigations including contact angle measurements, AFM studies and micro-flotation experiments are conducted to obtain a better understanding of the actual mechanism of Tecflote. Due to the reagent’s insoluble character, the Langmuir-Blodgett technique is used to investigate its behaviour in the air-water interface and to deposit defined layers of Tecflote on mineral substrates for the above-mentioned studies. An interferometric set up is used to investigate the influence of Tecflote on the film thinning between an air bubble and a mineral substrate. In addition, possible synergistic effects for the combination of Tecflote and conventional frothers (e.g. MIBC) are studied. Keywords: Sulfide flotation, insoluble collector

Jan 1, 2020

By C. E. Dohm

The paper serves to show the importance of both a geological model and geostatistical model that support one another in mineral resource evaluation. It highlights the advantage of reference models for the geometry, the geological, statistical and geostatistical models of various orebody types and introduces a method for quantifying the combined uncertainty in these models. The example presented reveals how the above levels of information can be applied to add value to a resource evaluation process. It is a generic example in that it is the technique of combining uncertainty in the geological model (boundaries) as well as the grade model to assess the overall risk in the estimation of the resource. Data from the coal industry is used to illustrate the techniques. The geological uncertainty is considered via categorical simulations and these are combined with simulations of the variables (grades, thickness,) being estimated in the resource. The simulation techniques used are based on the application of GSLIB software1and a general discussion of the two simulation processes is included. In conclusion the paper demonstrates how the results of two types of conditional sequential simulation can be combined to produce confidence limits that take both uncertainties into consideration. This technique does not replace the resource estimation; it serves as an additional tool to quantify confidence in the resource evaluation model. The topics considered in this contribution are in terms of continuous improvement of mineral resource evaluation.

Jan 1, 2003

By B. Nemutudi, X. Zhang, B. McFadzean, P. E. Ngoepe, P. P. Mkhonto, S. Pikinini

The comparison study on adsorption of potassium normal butyl xanthate (PNBX) and sodium (nbutyl) dithiocarbamate (SNBDTC) on sperrylite mineral forms a basis in understanding the floatability improvement and paves a way for the design of collectors that may impact on a wide range of arsenide minerals. This study used a computational density functional theory (DFT) and experimental microcalorimetry approach to determine the adsorption energies of PNBX and SNBDTC collectors onto a sperrylite mineral surface. From a computational aspect, we considered the most stable surface plane of (100) surface, which had been found to give the lowest surface energy, compared to the other surface planes. It was observed that the PNBX and SNBDTC preferred to bridge on the As and Pt atoms through the S atoms. These findings showed that the collector adsorbed on the surface through both Pt and As atoms and indicated that the As atoms were significantly active in the adsorptions. We found that the adsorption energies were in the order: SNBDTC (–278.38 kJ/mol) > PNBX (–270.92 kJ/mol), indicating that the dithiocarbamate had stronger exothermic adsorption than the xanthate. From the microcalorimetry test it was also found that the SNBDTC was more exothermic than the PNBX and the adsorption energies were: SNBDTC (–473.50 kJ/mol) > PNBX (–331.13 kJ/mol). These results showed that the nitrogen atom in the SNBDTC collector had a great influence on the adsorption strength of the collector on the mineral surface. This is due to the electron deposition behaviour of nitrogen atoms compared to the electron withdrawing character of oxygen and as such the SNBDTC showed better collecting ability than the PNBX. These results paved the way for the design of collectors for sperrylite and other arsenide minerals and suggested that nitrogen in a collector may significantly improve the ability of the collector for improved recovery. Keywords: Computational modelling, microcalorimetry, SNBDTC and PNBX collectors, adsorption energies

Jan 1, 2020

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

By F. M. Russell

Scheduling the extraction and rates of production for an underground mining operation is a common task carried out during the life of a mine, from the initial feasibility study through to the final production phase. The scheduling process can be complex when several requirements have to be satisfied, for example, match mill capacity and maximize net present value while constrained by mining sequence and availability of resources. Many mines have computer programs relevant to their operation but because they are site-specific they need considerable reprogramming to be adapted to other operations. Other methods currently in use also suffer drawbacks: manual spreadsheets are laborious, computerized spreadsheets cannot handle sufficient constraints, and operations research techniques require a complex mathematical model to be set up. The use of network analysis techniques has been proposed previously but the unavailability, until recently, of easily used computer programs has not allowed this approach to be developed. There are now many programs which can be used; however, the particular program which has been adapted to mine scheduling is Metier's 'Artemis-PC' running on IBM-XT or compatible machine. The use of network analysis offers many advantages, including the use of a logical mining sequence; activities can be as detailed as required; related activities can be readily incorporated, and costs can be easily extracted. A heuristic approach is necessary to optimize the schedule, but the ease and speed of program execution enables this to be readily achieved, while leaving the mining engineer in full control. The paper discusses the problems encountered in mine scheduling and current solutions. It then details the use of network analysis techniques and the application of the Artemis-PC program to solve mine scheduling problems.

Jan 1, 1987

By H. Zhong, S. Wang, Q. Lin

To improve the flotation performance of chalcopyrite collector, 2-(tert-butoxy)ethyl xanthate (TBEX) and its derivative O-(2-(tert-butoxy)ethyl)-N-ethyl-thionocarbamate (TBEETC) were designed and prepared by the introduction of a 2-(tert-butoxy) ethyl group into xanthate and thionocarbamate. TBEX and TBEETC were both prepared via the one-pot method with superior efficiency, which has significant commercial implications. The micro-flotation tests demonstrated that compared with sodium isobutyl xanthate (SIBX) and O-isopropyl-N-ethyl-thionocarbamate (Z-200), TBEX and TBEETC both possessed better collecting ability and selectivity for chalcopyrite. DFT calculations and XPS were utilised to investigate the flotation mechanism involving TBEX or TBEETC and chalcopyrite. The results demonstrate that although 2-(tert-butoxy) ethyl group does not interact with minerals directly, its introduction reduces the energy of HOMO, so that they can better accept electrons instead of donating electrons which leads to better interaction with copper atoms rather than iron atoms. Keywords: Chalcopyrite, flotation, thionocarbamate, xanthate, synthesis

Jan 1, 2020

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 А. V. Aksenov, S. G. Rybkin, А. Y. Senchenko

Recovered activated carbon fines result from processing of ore and concentrates via cyanide leaching and sorption of valuable metals on carbon at gold-mining plants. This intermediate product is characterised by the particles sized smaller than 0.6 mm and gold grade up to 300-500 g/t. Processing of carbon fines with recovery of valuable metals is not available at many plants due to the lack of optimal technology. The paper describes the testwork and development of an efficient technology to process carbon fines with the recovery of valuable metals into the target gold alloy. This innovative technology involves pelletising of fine activated carbon particles using an organic binder, drying and further firing of pellets in a grate fired furnace at 800-900 °С. The produced ash is subject to sintering with sodium nitrate and hydroxide at 600-700°С. The sintered ash is then leached in water. The insoluble residue containing gold and silver is removed by filtration, dried and smelted to produce gold alloy. Water solution containing sulphur and arsenic is subject to detoxification. Processing of recovered carbon fines according to the developed technology implies the use of standard full-scale equipment. The offered method to treat gold-bearing carbon fines was patented by the Eurasian Patent Office. Key words: Fine activated carbon particles, valuable metals, pelletizing, firing, ash, sintering, leaching, smelting

Jan 1, 2020

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 M. S. Shishvan, J. R. van Duijvenbode, L. M. Cloete, M. W. N. Buxton

Geochemical and mineralogical datasets from Tropicana Gold Mine, Australia, have been used to define ore fingerprints. VNIR/SWIR spectral data were represented by four normalised wavelength regions and were clustered to form spectral classes. Sequentially, these spectral class proportions within a block and collocated XRF data were clustered to form material types (fingerprints). The material types were related to an Equotip-BWi correlation. These correlations can be used to extrapolate a hardness signature and generate a BWi proxy for different blocks. The combined fingerprints and BWi proxy can assist as a tool for enhancing the prediction of comminution behaviour. They can explain specific domain-related hardness variations. For example, one material type could be separated into a softer (~15-18 kWh/t), and harder (>20 kWh/t) material blend. This was accomplished using the commonly overlooked VNIR region at 605 nm. This outcome has significance for blending strategies.

Sep 1, 2021

By S. Northey, N. Haque, S. Stoddart, W. Bruckard

Development of new technologies and procedures for managing mineral residues and wastes may benefit from a clear understanding of existing tailing management practices. There is a considerable variability in tailing management techniques used in the Australian copper and gold operations, with associated differences and flow-on effects for the mine site water balance. A database was created, capturing a total of 41 copper and gold processing operations in Australia. The database provides information on tailing generation rates, tailing properties (solids contents and particle size distributions) and tailing storage facility (TSF) types and configurations (e.g. total TSF surface area and wetted surface area). Significant variability was found for the above-mentioned parameters. The solid tailing generation rates ranged from 0.5-37 Mt per annum in 2015. Furthermore, both the solids contents and particle size ranges of the tailing were highly site-specific, and largely dependent on the processing flowsheets. Solids contents of tailings ranged from 45-74% by weight whilst P80 sizes of the concentrator (flotation) feed varied from 75-185 μm. The estimated pumping distance was up to 15 km. The presented data can potentially be used to better tailing management strategies by estimating the potential recoverable water and recycling it, thereby thus reducing tailing footprints. Keywords: Tailing management, tailing storage facility, water balance, mine site, flowsheeting

Jan 1, 2020

By А. Klemyatov, T. Vologdina, U. Gordeeva, S. Zbinets, А. Kalugin, N. Rozhdestvenskiy

The plants integrated in the PhosAgro group of companies perform processes from scientific research to the project, from ore mining to shipment of fertilisers and feed additives to consumers. An extensive process chain maintains smooth interaction at all stages from research to production. As an example, the paper shows the revamp of two beneficiation plants (ANOF-2 and ANOF-3), requiring a comprehensive approach to task solving. The intention of the revamp was to increase the total yield of apatite and nepheline concentrate, taking into account the gradual decline in the quality of ore being processed and ensuring the yield stability of final products during re-equipment of the plants. At ANOF-3, the crushing and grinding cycle was modernised, the production of nepheline concentrate was implemented, and the capacity of apatite flotation, dehydration, and drying was increased. At ANOF-2 a new process chain was implemented for the production of apatite concentrate in workshops previously used for the production of nepheline concentrate. The main building was withdrawn from operation, where ore grinding, apatite flotation and apatite concentrate thickening had been carried out. The total increase in apatite concentrate yield at two beneficiation plants was 1.3 times. A further increase in concentrate production is planned. Keywords: Apatite, nepheline, fertilisers, beneficiation, flotation, column flotation machines, revamp, fine screening

Jan 1, 2020

By V. A. Leão, V. S. Coimbra, V. A. A. Oliveira, R. F. M. de Souza, G. M. de Lima

A willemite concentrate consisting mainly of willemite (55.3%) and dolomite (15.6%) was reduced in a tube furnace with charcoal as reductant. The effects of temperature and varying reductant additions on zinc extraction were studied. A zinc recovery of 86% was achieved with 20% reductant in the charge at 1100°C. During reduction, the calcium oxide generated through calcination of the dolomite promoted decomposition of the willemite, thus lowering the temperature at which reduction took place. The presence of CaO improved the zinc recovery at all temperatures studied. The best zinc recovery (93%) was obtained in the presence of 5% CaO, 20% charcoal reductant, and at a temperature of 1100°C. The results show that the willemite concentrate studied has great potential to be used as a raw material for the Waelz process.

Nov 6, 2023

ERRATA-AUTHOR'S REPLY IN SEPTEMBER, 1970, JOURNAL: PAGE 52 I. Left half of the page, 4th paragraph, fifth line from the bottom: for 22 / 5 1/2 %, read 22 / 5 1/2 %. 2. Right half of the page, fifth paragraph from the bottom, third line from the bottom: for N(l - p), read N(1 - p)x. 3. Right half of the page, fourth paragraph from the bottom, second line: for: at time t after time zero, read: at time x after time zero. NOTICE TO ALL STUDENT MEMBERS OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY The Institute offers each year for competition among Student Members of the Institute a prize, or prizes, should entries so warrant it, of up to the value of R100 to be awarded to the Student Member or Members who submit the best paper or dissertation on a topic appropriate to the interests of the Institute. In the case of Student Members who are in full time study at a university the dissertation or thesis which they may have to write in part fulfilment of their university curriculum may be accepted provided it is presented in a manner and on a topic suitable for publication in the Journal. The closing date for the receipt of papers shall be 31st December each year.

By R. G. Jurd

This paper considers the introduction of large-scale longwall mining into South African coal mining, instead of the conventional mechanized bord-and-plllar mining that is widely practised at present. The two methods are compared, and longwall mining is found to have the advantage in several respects in some seams. The most cogent reasons for the introduction of the longwall method In some seams are associated with safety strata control and increased labour costs.

Jan 1, 1978

By B. Z. Weiss, N. R. Comins, F. Blum

Some aspects of the mechanical behaviour of chromium-containing dual-phase 3CR12 steel were investigated as a function of the temperature and strain rate. The yield stress was found to depend on both the temperature and the strain rate, with no substantial differences between the longitudinal and the transverse directions. The strain-rate sensitivity decreased with increasing temperature. The yield stress could be presented as a function of a temperature-strain-rate parameter. Impact test results showed substantial differences between the energy absorption of the transverse and longitudinal specimens above the ductile-brittle transition temperature. Changes in energy absorption with temperature were gradual for specimens in both orientations, and the transition from ductile to brittle behaviour occurred between 373 and 173 K. Strain rates ahead of the tip of notches with different geometries were calculated and measured experimentally.

Jan 1, 1990

By A. Becker, R. Tait, S. L. George, A. Carlisle

Surface treatments like laser shock peening (LSP) induce residual stresses penetrating up to 1 mm deep, surpassing traditional methods, thus significantly increasing the potential impact on materials prevalent in the automotive and aerospace sectors. Through extensive fatigue testing and fractography investigations, it was determined that LSP resulted in a fatigue life increase of over five times for aluminium alloy AA7075-T6 and titanium Ti-6Al-4V. Increased fatigue life was also noted in AISI316 stainless steel, which showed increases in fatigue life of 1.7x. While fatigue life in all cases improved, the efficacy of LSP was shown to be material dependent.

Jul 23, 2025

This paper illustrates the application of numerical modeling methods, in conjunction with limit-equilibrium techniques, to the location of critical slip surfaces in slope-stability problems. Initially, the Spencer slice-based method of analysis is introduced, together with a dynamic-programming algorithm for slip-surface location. This limit-equilibrium method is assessed critically through the use of an illustrative problem. The technique is then extended to locate the critical slip surface for a similar slope, but with more complex constitutive and yield relationships for the material comprising the slope. To this end, the use of the stress field generated from a finite-difference program, together with a dynamic-programming search routine, is presented as an advanced technique of slope-stability analysis for engineers.

Jan 1, 1993

By V. N. Medvedev, A. M. Bryukhanov

Stationary mine air control equipment enables monitoring of CH4 concentration only in sensor locations. CMC-4 individual indicator built into a caplight has been developed in Ukraine, extending CH4 monitoring to manned job sites. Major technical characteristics of the indicator are demonstrated. It features two operation thresholds: 1st threshold 1.0 to 2.0% vol. 2nd threshold 1.5 to 2.5% vol. Basic absolute accuracy ± 0.2% Caplight battery is a common power supply for the lamp and CH4 indicator, providing at least 10 hours of the system non-stop operation. Average pre-failure life is at least 10,000 hrs. It features: an explosion proof design and intrinsically safe test circuit; a small-sized sensor as an integral part of the caplight; a hybrid microcircuit to facilitate functioning of methane monitoring unit. The CMC-4 indicator weight is the weight of the caplight itself and equals 2.4 kg. A two-threshold design makes possible to distinguish between methane sources: slow accumulation due to diffusion or sudden rushes due to a gas-dynamic event. CMC-4 indicators in addition to stationary equipment minimize the risk of CH4 explosion underground determined as a product of accident intensity by calculated time interval.

Jan 1, 2003