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By R. Kok, N. B. Strydom, P. L. Jooste, W. H. Van Der Walt

Intermittent exposures to heat, and the retention of heat acclimatization by N. B. STRYDOM, M.Sc., Ph.D. (Illinois) (Fellow), R. KOK, M.Sc. (Potch.) (Visitor), P. L. jOOSTE, M.Sc. (Stell.) (Visitor), and W. H. VAN DER WALT, B.Sc. (Potch.) (Visitor) Twenty-one heat acclimatized subjects were assessed for the degree of acclimatization attained with respect to heart rate, rectal temperature, and sweat rate during a standard four-hour heat-stress test. Thereafter, they were put on light duties in cool environm ents for four weeks, except for four hours of exposure to heat every seventh day. Their state of heat acclimatization was again assessed two days after the final week's exposure. Although heart rates and body temperatures showed significant increases over the initial values, no differences were observed in sweat rates and, in general, the subjects were rated as still adequately acclimatized to heat.

Jan 7, 1975

By C. H. Johannes, N. B. Strydom, C. H. Van Graan, J. G. A. Van Heerden

Note: The practical application of microclimate cooling in an underground stope in a gold mine by C. H. JOHANNES, C. H. VAN GRAAN, N. B. STRYDOM and J. G. A. VAN HEERDEN INTRODUCTION Although much information was available on the use of pre-frozen jackets as micro climate coolers in underground situations!, 2, no information was available on their performance under practical conditions in stopes. The objectives of this study were. O.F .S. Branch Minutes of the General Meeting held in the upstairs lounge at the Harmony Country Club, Harmony G.M. Co. limited, on Wednesday 12th November, 1975 at 4.00 p.m. NIM reports Report no. 343 A mineralogical investigation of gold-bearing sulphidic ore from the Florence-Devonian Mine, Barberton.(20th May, 1968; re-issued Dec. 1975). Report no. 1384 . Flotation tests on samples of Canadian copper-zinc ores. (12th Nov., 1971; re-issued Nov. 1975). The results are given of laboratory Report no. 1488 Extraction of rutile from Highveld smelter slags. (28th Sep., 1972; re. issued Nov., 1975). Report no. 1499 The production of medium -carbon ferrochromi'um. (4th Dec., 1972; reissued Nov. 1975). Report no. 1521 The dissipation of electrical power in the burden of a submerged-arc furnace. (15th Feb., 1973; re-issued Nov. 1975). Report no. 1527 The physicochemical properties of slags associated with the smelting of nickel sulphide concentrates. (21st Feb., 1973; re-issued Nov. 1975). Report no. 1544 The recovery of salable ferrochromium from material discarded by Ferrometals Limited. (11th Jun., 1973; re-issued Nov. 1975). Report no. 1547 Physicochemical and thermodynamic properties of slags in the system MgO-AlOl.5SiO2. (23rd Aug., 1973; re-issued Nov. 1975). Report no. 1548 Physicochemical properties of slags in the system MgO-Al2O3-SiO2 and their application to the technology of ferro-alloy smelting. (13th Jul., 1973; re-issued Nov. 1975). Report no. 1553 Characterization of the flotation properties of fluorspar from smallscale batch and pilotplant tests. (27th Sep., 1973; re-issued Nov. 1975). Report no. 1555 The analysis, by atomic-absorption spectrophotometry, of matte-leach residues. (2nd Oct., 1973; re-issued Nov. 1975). Report no. 1590 The separation of osmium from ruthenium in hydrochloric acid solutions. (18th Jan., 1974; re-issued Oct. 1975.) Report no. 1606 The electrical-resistance characteristics of the charge in the electric reduction furnace. (1st Feb., 1974; re-issued Oct. 1975). Report no. 1622 The electrical conductivity of the charge in a ferrosilicon furnace. (2nd Apr., 1974; reissued Oct. 1975).

Jan 3, 1976

By F. D. Agrensa, J. Hadjigeorgiou, E. Storimans, S. J. Thorpe

Reinforcement and surface support are part of an integrated system that transfers and shares loaduntil the excavation surface is stabilized or until the ground support system fails. Steel mesh is the most popular primary surface support element in underground hard rock mines in Canada. Mesh straps are a secondary surface support that provide additional containment as they distribute the load between and across the reinforcement elements. This investigation addresses the role of steel properties, and in particular steel chemistry, in the long-term performance of mesh and mesh straps when exposed to an aggressive corrosive environment. It reports on comparative accelerated corrosion studies to compare the resistance to corrosion of different surface support elements. This has significant implications on the choice of surface support and the anticipated rehabilitation requirements.

Oct 9, 2024

By P. O. Akinseye, F. T. Cawood

Mineral royalties are one of the oldest forms of mining taxation, and were initially introduced to extract economic rents from mining. Over time, the royalty regime has become more complex as it was identified as an important policy instrument that can achieve more multi-faceted outcomes. Such a multi-tiered approach in the use of the royalty instrument is also the case with South Africa. With South Africa’s new mineral royalty regime now in place for ten years, it is perhaps time to assess its impact and effectiveness. To carry out this assessment, an econometric evaluative study was undertaken using four major commodities in South Africa, namely gold, platinum, iron ore, and coal. The study explored five different policy options for government to consider and tested them to determine the most favourable one that will realize the regime’s policy objectives. After the assessment, two major options stood out. Hence, this paper seeks to highlight which of the two options is the most favourable for consideration by policymakers. Based on that study, we find that the current structure is effective, but also recommend that the factors in the formula for refined minerals be ‘modified’ to reduce the capped profitability ratio from the current 60% to 30% and the maximum royalty rate for refined minerals from 5% to 3%. The minimum rate of 0.5% during times of depressed mineral prices and no or low profitability will not be affected.

Dec 1, 2021

By N. Hamlef

In this study, the effects of heat treatment on phase formation and surface morphology of the Cr-Pt coated system are investigated using X-ray diffraction and electron microscopy techniques. The CrPt andCr4Pt (Cr3Pt - A15 type) phases were formed after heat treatment of the coated samples. Heat treating at 1000°C renders a distinct island coating morphology that is non-continuous in nature. A diffusional model is proposed for this coated system with regards to the surface morphology formation after heat treatment.

Jan 1, 2014

By T. Uysal

The increasing demand for rare earth elements (REE) in highly strategic sectors such as hybrid electric vehicles, renewable energy, communication technologies, and the defense industry has made REE production methods important. In recent years, studies on REE have increased rapidly; however there are many studies on REE, there are not enough studies in the literature on the economics of the beneficiation process. RE ores are generally leached after beneficiation by gravity, magnetic and flotation methods. In this study, direct leaching, attrition scrubbing and leaching, and flotation and leaching methods are evaluated economically based on the data for the Mountain Pass (MP) facility. According to the sensitivity analysis performed as a function of capital cost (CAPEX), operating cost (OPEX), and rare earths oxides (REO) recovery, REO recovery has the biggest effect on the process economies. Although the flotation method entails additional investment and operating costs, transportation and operating costs are significantly reduced result of the higher grade and recovery. The flotation method is more profitable, with larger NPV and IRR values and a shorter payback period.

Jul 2, 2022

By G. M. Evans, S. Mitra, A. V. Nguyen

As an alternative to the conventional flotation method, there has been continual research in an effort to enhance base metal ores and combustibles recovery using ultrasonics. These studies however were largely limited to the pre-treatment of ores for the removal of surface contaminants while the effect of ultrasonics on the bubble and pulp-phase interactions remained somewhat unexplored. Noting this deficiency, this study aimed to investigate the mechanistic effect of an ultrasonic field in an impeller less flotation cell specifically focusing on the bubble-particle interaction dynamics. A lab-scale flotation cell (capacity 1 litre) was designed, involving a vertically oriented ultrasonic probe (20 kHz, rated at 1.2 kW) and operated in the output power range from 1 to 20% with continuous liquid recirculation. Particle suspension was achieved by the combined action of recirculation and ultrasonic pulses. Interactions of coarse size glass ballotini particles (D32 = 314 μm) with bubbles (< 1 mm diameter) in the presence of a surfactant were studied, using high-speed imaging. Application of an ultrasonic pulse in the aqueous medium resulted in the generation of numerous microbubbles which increased with increasing input power and duration of the ultrasonic pulse time. Such periodic pulses introduced at a high level of turbulence in the pulp phase facilitated adequate bubble-particle contacts. Microbubbles played a key role in forming particle clusters which were observed to be floatable even in the absence of any carrier bubbles. When carrier bubbles were introduced, some of these particle clusters attached to the bubble surface and conveniently floated. It was noted that a favourable state of bubble-particle interaction was achievable to produce stable bubble-particles aggregates by suitably controlling the input power and period of the applied ultrasonic pulse. Keywords: Flotation, bubble-particle interactions, collision, attachment, detachment, ultrasonic pulse

Jan 1, 2020

By P. de A. Barbosa, M. G. Bergerman, E. da Fonseca

Located in the state of Pará, Brazil, the Sossego copper and gold mine consists of a heterogeneous geological deposit. Its complexity derives from the hydrothermal alteration, the ore-forming event, which modified the host rocks, such as granite, and metamorphosed volcanic rocks into several mineral assemblages. Different mineral assemblages have led to differences in abrasiveness. A few Bond abrasion tests conducted during the mine feasibility study did not provide a robust abrasiveness database, thus the variation of physical properties for some mineralisation host rocks was not possible. Although several test methods may be used to determine ore abrasiveness, the Bond method is the one most commonly used in the mining industry. Despite being simple to carry out, this test method has certain limitations as to particle size and the amount of ore sample required, which often makes it difficult or even impossible to apply in the early stages of a project and in geometallurgical studies. The Laboratoire Central des Ponts et Chaussées (LCPC) test may provide an alternative, as it requires a smaller amount of fine-grained material. This study aimed to provide data on wear properties of various ore types from Sossego mine using the LCPC method. It included validation for 40 different ore samples using the Bond test as a benchmark. The results showed good correlation, indicating it may be possible to use the LCPC test as an alternative to the Bond abrasion test. A high abrasiveness index was found for acid metavolcanic rock, confirming the results observed in Sossego mill’s operating database, pointing to a mineralogical drive to amorphous quartz. Keywords: Abrasiveness, geometallurgy, copper ore, Bond abrasion test, LCPC

Jan 1, 2020

By M. J. U. T. Van Wijngaarden

SYNOPSIS The corrosion characteristics of a new steel, 14Cr, which is a modification of the well-known 3CR12, in aqueous sulphate solution were studied through polarization diagrams and a computer analysis based on the polarization¬resistance technique. It was found that the corrosion rate of 14Cr steel is independent of pH for pH values above 6, but, below a pH value of 4, the corrosion rate increases sharply with decreasing pH. In air-saturated solutions of neutral and mildly alkaline pH, the corrosion rate is approximately 60 µm per year. The 14Cr steel shows a twentyfold improvement in corrosion resistance over that of 3CR12 in sulphate solutions at pH 2,0. This is considered to be due to the beneficial effect of its higher chromium and nickel contents.

Jan 1, 1985

By G. Asbjörnsson, E. Hulthén, P. Papadopoulou, C. M. Evertsson

Crushing plant managers need to assess, manage, and communicate the environmental impact induced by their crushing plant operations as a step towards the sustainable development of the company. However, performing reliable environmental impact calculations of crushing plants can be challenging when the availability of operational and emission data is low, and when the company’s environmental expertise is not adapted and connected to plant operations (or does not currently exist). To address these challenges, this paper proposes a practical approach where the lifecycle assessment methodology (LCA) is combined with process simulations in a web-based tool. To describe what functionality such a tool should have to be incorporated into a company’s workflow, the system that surrounds a crushing plant is analysed. Further, a case study with a three-stage crushing plant is introduced to showcase how the simulated power draw results produced with the beta version of the tool can be compared to measured sensor data from the crushing plant for one operational day. The results indicate that the simulation tool can provide an adequate estimation of the specific energy for the different material fractions and give an overview of the environmental impact of the process caused by electricity and explosives consumption. Plant managers and operators can use this tool to calculate the environmental impacts of their plant and simulate how different operational strategies influence them. Keywords: LCA, environmental impact, coarse comminution, crushing plant

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

The May General Meeting of the Institute was held in Kelvin House, Johannesburg on 20th May, at 4.30 p.m. Mr V. C. Robinson (Vice-President) was in the Chair in the absence, overseas, of the President, Mr J. K. E. Douglas. There were also present 16 Fellows: Messrs J. A. Adamson, R. S. J. du Toit, J. A. Drummond, D. F. A. Grave, T. L. Gibbs, G. H. Grange, D. V. Howat, P. H. Kitto, Dr P. J. LIoyd, Messrs B. H. L. Leach, J. de V. Lambrechts, Dr J. T. McIntyre, Messrs C. S. MacPhail, P. W. van Rensburg, S. G. Taussig, W. S. Rapson. Six Members: Messrs E. L. Atkinson, R. Hemp, Dr J. Martinson, Messrs A. H. Munro, G. J. van Jaarsveld and J. H. Qwilliam. Two Associate Members: Messrs B. H. van Rensburg and H. Triiter. Four Visitors: Prof J. E. Kerrich, Dr G. K. Sluis-Cremer, Messrs D. Kisbey-Green and L. W. Isserow. For Secretariat: Mrs S. de Gersigny. Total present: 27. OBITUARY The Vice-President: "It is my sad duty to announce the death of Stephen Ring, a member who joined the Institute in ]961, and passed away on the 31st of December, 1969. I would ask you all to rise and observe a moment&apos;s silence. Thank you." MINUTES The Vice-President: "May we confirm the minutes of the Special General Meeting and Monthly General Meeting, held on 20th February, 1970, as published in the April issue of the Journal?" MEMBERSHIP The Vice-President: "I have much pleasure in announcing that the names of the undermentioned candidates, having been published in accordance with By-Law 5 2.2, Council has elected them to membership of the Institute in the following grades: Fellows: Denis Ian Field, Arthur Cecil Waiter Comyn, John Hall, Leon VercueiI. Members: Jan McLellan Vosloo, Jan van Velze. Graduates: Richard Darnley Beck, John Edward Andrews, Roderick Nowell Randell. Associates: Alexander Duncan Ross, Ian James Terrill. Students: Hendrik Jacobus Oostenwald Prins Smith, Graham Peter Gooding, Rudannes Raath Homan. "I welcome the newly, elected members to the Institute." GENERAL BUSINESS The Vice-President: "Are there any matters which you wish to raise under &apos;General&apos;? There being no matters to raise under &apos;General&apos;, we will proceed to the next item on the Agenda." PAPER FOR PRESENTATION The Vice-President: "It is my pleasant duty to call on Dr du Toit to deliver his paper, entitled, &apos;The functional relationship between dust hazard and the rate of collecting funds to pay compensation for pneumoconiosis&apos;." After the presentation of the paper (published in the March Journal) the Vice-President said: "This paper is a very important addition to the considerable volume of work applications on this subject of pneumoconiosis. The disease, in all its various forms, has received attention from many, many great men, both in the medical world, and engineers. The fact that there is this big volume of publications of literature on it still doesn&apos;t mean that we can get anywhere beyond the old, simple injunction, that the prevention of pneumoconiosis does not depend on compensation, levies or anything else. It simply depends on allaying dust as quickly as possible. "This paper, however, is another scientific landmark and I think, in a cold and dispassionate way, it sets out some important points in this whole subject of the relationship of the levy - the money of compensation to the dust which causes it. "I have, personally, very little to criticise in this paper but when I listened to Dr du Toit&apos;s final conclusions, I wondered whether the words, &apos;Within the data available&apos;, aren&apos;t the key to this whole situation. I agree that he has demonstrated a workable relationship between the current industries for levy and dustiness, but among the factors which he lists as being important, I know that there is one which is missing. This is extremely difficult to evaluate. It&apos;s a factor which has destroyed, on so many occasions, the work which has been done by so many genuine, intent, honest people working in this field, and this is this unknown factor, this hidden factor of political opportunism, which has so often played a very important part in pneumoconiosis compensation. "How many of us have seen the grubby, grasping fingers of power-mad demagogues, and I can name them for you - but I won&apos;t - and also the blatant vote-catching of certain politicians interfering in this field. How, at the end of all that, the poor scientist, the poor dedicated man in the Mines&apos; Department, who has to write the law of compensation, can operate, I do not know. "From this picture the ordinary layman recoils in horror. Among the casualties in this particular war, which has been fought over so many years, I am perfectly certain, are some of the criteria of certification, especially in &apos;56/,57, when that extraordinary condition, known as &apos;pulmonary disability&apos; was introduced. I am sure there were casualties then, in the criteria of certification. "Nevertheless, this paper is a worthy addition to the long list of scientific work done on this so-important

By E. Öğretici, S. Kahraman

The indirect estimation of intact rock properties is particularly useful for preliminary investigations in engineering projects. In this paper we examine the usability of electrical resistivity, a nondestructive measurement, for the prediction of physical and mechanical rock characteristics. Physico-mechanical tests (uniaxial compression, Brazilian tensile, density, and porosity tests) and electrical resistivity measurements were performed on specimens of 36 rock types. Before the resistivity tests, the specimens were completely saturated with saline solution. Evaluation of the test results showed that there are medium or strong correlations between resistivity and rock properties. There are also strong or stronger correlations between the two parameters for the rock classes. The regression equations developed were statistically tested, and their validity was confirmed. The results were also compared with previous studies. The conclusion is that electrical resistivity measurement can be used for reliably estimating physical and mechanical rock characteristics.

Aug 8, 2024

By N. Duda, P. Śliwiński, P. Stefaniak, B. Jachnik

Ventilation and air-conditioning are some of the most energy-consuming processes in deep underground mining. Additionally, the energy consumption of these processes systematically increases along with the expansion of the mine. Therefore, proper energy efficiency assessment and consumption forecasts of these systems are particularly important in modern mines for ongoing tracking and planning of the likely costs. In the article, a short-term prediction model for surface air–conditioning stations is described. This model takes into account dependencies that were identified, based on the data from the supervisory control and data acquisition (SCADA) systems. These dependencies between the response value and the external conditions are then incorporated into the model. This way, for example, the ambient temperature or the total number of specific days of the week (with sometimes significantly lower or higher than the weekly average energy consumption levels) are included. Taking into account these dependencies, and e.g. forecasted average monthly temperatures allow us to include the seasonality of energy consumption in the presented model. In the article, a sample energy efficiency analysis of the A/C system based on an example of the KGHM Polish Copper Polkowice-Sieroszowice mine is performed. The results of the solution proposed in the article are then evaluated, and compared to the currently functioning, more basic forecasting methods. However, given the general nature of the dependencies used in the model, similar solutions could be used in other case studies.

Sep 1, 2021

The February General Meeting of the Branch was held in the St. Helena Club at 8.00 p.m. on the 10th February, 1971. Mr G. Y. Nisbet (Chairman, O.F.S. Branch) was in the chair. There were also present: Seven Fellows: Messrs. N. A. Honnet, C. J. Isaac, J. M&apos; Meyer, I. Thomas (Committee Members), J. Lorenzen, S. L. S. Swart and D. Waterman. Six Members: Messrs. R. Campbell, D. J. Couperthwaite, R. Cross, A. H. Edwards, C. G. J. Vermeulen and G. J. C. Young. Two Graduates: Messrs. J. McLuskie and M. H. Smith. Six Associates: Messrs. J. Dean, W. F. de Lange, J. S. Freer, A. Hooper, A. Paschalides and L. Vorster. One Student: Mr D. J. Hammond and nine visitors, a total attendance of thirty-two. Minutes As the minutes of the General Meeting held on the 17th November, 1970 had not yet been published in the Journal, the Chairman moved that the adoption and discussion thereof be deferred to the next General Meeting. This motion was adopted unanimously. Office-bearers The Chairman informed the meeting that this branch had received the resignation of Mr J. N. Saunders. Following his resignation the Committee elected the following office-bearers: Chairman - Mr G. Y. Nisbet Vice Chairman - Mr J. M. Meyer The Chairman also announced that Messrs. J. M. Meyer and G. J. C. Young had been co-opted onto the Committee. General Members were advised that arrangements had been made for the Cookhouse Tunnel visit towards the end of March. Talk by J. Freer The Chairman called on Mr J. Freer to deliver his talk on "Uranium Extraction, Processing and Conversion for Fuel Element Manufacture". The presentation of this talk, illustrated by sketches, proved very interesting and entertaining and was received with applause from all present. Mr I. Thomas proposed a vote of thanks to Mr Freer on behalf of all members of the O.F.S. Branch. After thanking Mr Freer for his talk and all present for their attendance, the Chairman declared the meeting closed at 9.30 p.m.

By J. F. Morrison, C. H. Wyndham, N. B. Strydom

INTRODUCTION The shovelling of rock in stopes is still a basic and important operation in many gold mines in the removal of gold-bearing rock from the stopes. There is, however, little factual knowledge of the factors which influence the the rates of energy expenditure and work output, and of the way in which variations in these factors, individually or in combination, affect the mechanical efficiency of the mine workers. What for example is the influence of different rates of shovelling, shovel loads and distances of throw? How does stope width and dip of the stope affect the mechanical efficiency of men shovelling rock? Recently a simple physiological test was introduced into the gold mining industry for classifying Bantu recruits into those capable of hard, moderate and light work. If this test is used to select only those Bantu mine workers who are capable of hard work for the task of shovelling rock in stopes then the rate of energy expenditure which could be expected from these men is 1.5 litres/min for the entire period of the shift. With an adequate knowledge of the influence of the various factors which affect the rate of energy expenditure of men shovelling rock in stopes it would be possible to set work standards for Bantu mine workers in stopes. This should be done in terms of the rate of shovelling, the shovel load and the distance of throw for any combination of width of stope, dip of stope, condition of foot wall and grade of rock in such a way that the resultant energy expenditure would be the &apos;optimum&apos; that could be expected from the men but would be within their capacities for physical work of an endurance nature (that is, 1. 5 litres/min from the &apos;average&apos; Bantu mine worker). Work standards could thereby be determined for the different stopes of a mine on a sound and systematic basis. In order to supply the information required a study was carried out by the Human Sciences Laboratory in which the work output and energy expenditures (in terms of oxygen consumption in litres/min) were measured on six highly trained Bantu mine workers under the following conditions: (a) rates of shovelling of 3, 4, 5, 6, and 10 shovels per minute. (b) loads of from 9 to 18 lb on the shovel. (c) distances of throw from 8 to 20 ft. (d) stope width of 28 in., 42 in. and 72 in. (e) dip of stopes of 0°, 15° and 30°. (f) rough and smooth footwalls and various grades of rock size. This paper gives the main results of practical importance of this study. Method The experiments were designed and conducted in conjunction with the Work Study Department of one certain underground conditions such as variable stope widths, stope angle, etc., were made available in a mine Surface Training School and suitable subjects were selected from the large number of labourers being put through the training school. Subjects Bantu recruits who had returned to the mine for a new contract and who had previous underground experience on shovelling were considered to be suitable as subjects for the experiments. The particulars of the subjects are given in Table I. TABLE I PHYSICAL CHARACTERISTICS OF SUBJECTS Weight Height Surface area Max O2 capacity Subject (Kg) (cm) (sq meters) (Litre/minute) A 71.5 167.3 1.80 3.5 B 61.5 162.3 1.65 2.8 C 63.0 164.1 1.69 2.4 D 66.5 167.4 1.75 2.8 E 70.2 164.6 1.77 3.0 F 77.8 173.1 1.92 3.8 Training The method of shovelling, accepted by the Work Study Department, was demonstrated to the subjects who then practised the movements with empty shovels, under the supervision of an instructor. After the technique was mastered, the men started shovelling rock and were trained for at least four hours per day to work at the higher shovelling rates. Training was continued for three weeks to enable the subjects to achieve a reasonable degree of physical training and conditioning. Shovelling method In both the kneeling and standing positions the subjects faced the pile of rock, grasped the shovel in the accepted manner and pushed the blade of the shovel into the base of the pile of rock, sliding the blade between the rock and the concrete floor. In the standing position (72 in. wide stope) the back leg assisted in the movement by pushing the knee against the back of the hand holding the shovel handle. In the kneeling position the elbow was tucked into the side of the body so that the muscles of

Council and Standing Committees, 1978-1979 President: Dr M. G. Atmore. Vice-Presidents: D. A. Viljoen and Dr P. R. Jochens. Honorary Treasurer: J. K. E. Douglas. Immediate Past President: P. A. von Wielligh. Members of Council: J. D. Austin, A. N. Brown, H. E. James, Prof. R. P. King, Dr D. G. Krige, Prof. F. Q. P. Leiding, D. G. Malan, C. S. McPhail, J. C. Mostert, G. Y. Nisbet, H. G. M. Rose, W. T. Ruhmer, G. C. Thompson, R. A. von Maltitz. Chairman, Witbank-Middelburg Branch: T. S. Wilmot. Chairman, Orange Free State-Klerksdorp Branch: H. M. W. Eschenburg. Past Presidents Serving on Council: R. J. Adamson, H. Britten, J. K. E. Douglas, Prof. D. D. Howat, Dr J. P. Hugo, D. G. Maxwell, Prof. R. P. Plewman, Dr R. E. Robinson, Dr M. D. G. Salamon, P. W. J. van Rensburg. Standing Committee Chairmen: Membership, Dr P. R. Jochens ; Technical Programme - Metallurgy, Prof. R. P. King ; Technical Programme - Mining, H. G. M. Rose; Vacation School - Metallurgy, J. C. Mostert; Vacation School - Mining, D. G. Malan/J. D. Austin; Awards, P. A. von Wielligh; Excursions, D. A. Viljoen; Adjudication, P. A. von Wielligh; Constitution, Rules and Policy, P. A. von Wielligh; Monograph Series, Dr R. E. Robinson; Professional and Technician Train¬ing Committee, Dr M. D. G. Salamon; Career Guidance, D. G. Malan; Phoenix National Committee, Dr R. E. Robinson; 1982 World Congress, Dr M. G. Atmore; Witbank Coal Colloquium, Dr P. R. Jochens; Mines and Works, P. A. von Wielligh.

Jan 1, 1979

By C. Ntsele

Stirred milling technologies have firmly established themselves in concentrator circuits as energy-efficient alternatives to tumbling ball mills. High and continued increases in electricity costs, coupled with the ever-increasing power consumption by primary grinding circuits due to declining head grades of ore-bodies, provides a compelling case for these technologies. Additionally, the ability to successfully deploy stirred milling in coarse grinding applications extends the range of use in concentrators, thus increasing the opportunity matrix for energy optimization in a flowsheet. This paper therefore details methodologies and strategies that can be applied to evaluate the optimum stirred milling solution for different concentrator applications. These methods and strategies will focus specifically on the two major stirred mill machine types; namely, gravity-induced (VERTIMILL? grinding mill and Nippion-Eirich tower mill) and fluidized (SMD, Isamill?, Knelson-Deswik mill, etc. ). Finally, case studies from circuits across industry and laboratory tests will be used to illustrate the energy benefit from the use of stirred mills.

Jan 1, 2012

By H. G. M. Rose

Contribution to the above paper by H. G. M. Rose* (Fellow) INTRODUCTION Dr Lawrence is to be congratulated on his most interesting and instructive paper, particularly on his suggestion for a model to increase mining productivity through improved management performance. In view of an experiment initiated in one Union Corporation mine (Mine A) and later extended to a second mine (Mine B), it might be of interest to review the many human factors involved and the initial productivity results achieved.

Jan 7, 1974

By C. N. Eze, C. K. Ezeh, O. Nnabuife, N. M. Ugwoju, S. C. Enemuor, V. Okechukwu

In this study, the efficacy of Providencia vermicola KUBT-1 in the leaching and beneficiation of Agbaja iron ore was evaluated under varying conditions of temperature, ore particle size, and pH. Agbaja iron ore is a Nigerian low-grade ore containing about 43%–52% iron and a high amount of gangue materials, including phosphorus (1.4%–2.0%) and sulphur (0.12%). The study was organised in triplicate in shake flasks with 48 samples. One millilitre of washed cells of Providencia vermicola KUBT-1 suspended in normal saline at 0.5 McFarland standard (108 cells ml-1) was introduced into each flask containing 50 g of sterilised ore in 100 ml of bioleaching medium, and the samples incubated at room temperature for eight weeks. The levels of upgraded iron, mobilised sulphur, and phosphorus were determined by atomic absorption and ultraviolet spectrophotometric analyses, respectively. Results showed that a particle size of 0.8 mm was optimal for iron upgrading and sulphur mobilisation while 1.0 mm ore size was optimal for phosphorus mobilisation. Up to 89.60% of the iron was upgraded while phosphorus and sulphur were mobilised, leaving residual values of 0.223% and 0.02%, in the ore, respectively. The organism produced best beneficiation results at a pH of 2.5 and a temperature of 3ºC. Correlation analysis with the Pearson’s correlation model showed a positive correlation between iron upgrading and sulphur-phosphorus removal (r =1.000, and r =0.967), respectively. These results present Providencia vermicola KUBT-1 as a promising candidate for large scale leaching and beneficiation of Agbaja iron ore.

Dec 15, 2025