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By J. J. Cilliers, J-A. Lamamy, J. N. Rasera, K. Hadler

Production of oxygen on the moon can be achieved by reduction of lunar soil. One such reduction technology, hydrogen reduction, favours a high proportion of ilmenite in the feedstock. Ilmenite is present in lunar soil as a minor mineral phase, but it can be upgraded using electrostatic separation. This study presents the results of a preliminary investigation into the operating parameters and sensitivities of a free-fall electrostatic mineral separator for lunar applications. Samples of ballotini and ilmenite as well as simple binary mixtures of the two were tribocharged on copper and passed through a uniform electrostatic field. The field is varied to change the electrostatic force acting on the particles. The proportion of material reporting to the positive electrode collectors, negative electrode collectors or the central collector was measured to determine the separation performance. The data confirmed that the charge transferred from the tribocharger to each species is in agreement with the triboelectric series; ballotini was found to charge positively on copper and ilmenite negatively. Particle-particle contacts were dominant, however, resulting in a somewhat symmetrical particle distribution in the collectors. These findings indicate that the copper tribocharger design requires optimisation in order to substantially increase particle-wall contacts. Four binary mixtures with feed grades of ilmenite ranging from 5% to 20% were prepared and tested. This study found that a higher ilmenite head grade resulted in a higher concentrate grade (26.3% from a head grade of 20%) with low recovery (3.4%). In contrast, the lower feed grade resulted in a low concentrate grade but higher recovery. The mass yield of ilmenite was 1.4 times greater for the highest-grade feed than for the lowest. A subsequent study into the reprocessing of middling fraction found a nearly constant relationship between cumulative grade and recovery. This is the first investigation into the effect of feed grade on the concentrate grade and recovery for lunar mineral processing. Keywords: Lunar resources, beneficiation, electrostatic, SRU, ISRU

Jan 1, 2020

By X. Xiang, W. Xia, J. Yin

"TiCl4 slurry containing valuable metals is an unavoidable by-product of the titanium ore chlorination process. The recovery of these valuable metals, which include titanium, niobium, tantalum, and aluminum, is an urgent issue to tackle in the titanium industry. The results of this investigation show that the valuable metallic elements can be recovered from the slurry by evaporation in a sealed container and leaching with dilute hydrochloric acid. After evaporation at 200°C for 60 minutes, nearly 99% of the titanium was recovered in the form of TiCl4, which was formed by the reaction of the TiO2 in the slurry with AlCl3. After evaporation, metals like niobium, aluminum, and tantalum remained in the residue. By leaching with 2.1 mol/L HCl at a L/S ratio of 6:1 mL/g at 80°C for 60 minutes, the soluble metals, such as aluminum, iron, and copper were all removed from the residue, and the niobium and tantalum were further enriched in the leach residue. A concentrate containing 53.40 wt% Nb and 5.57 wt% Ta was obtained by washing the leach residue with dilute aqueous ammonia under stirring. A potential waste water purifying agent containing 263.75 g/L AlCl3 was produced by purifying the leaching solution with Al(OH)3 and modified polyacrylamide. IntrodutionTitanium tetrachloride (TiCl4) is an important intermediate in titanium metallurgy that is widely used in the production of titania and titanium sponge (Akhtar, Xiong, and Pratsinis, 1991). In conventional titanium metallurgical processes, high-titanium materials such as synthetic rutile and high-titanium slag are reacted with chlorine to produce TiCl4 in a fluidized-bed furnace. Accompanying elements, such as Al, Nb, and Fe also react with chlorine to form chlorides, which are mixed with gaseous TiCl4 (Anderson, 1917). In the condensation process, gaseous TiCl4 is refrigerated and high-boiling-point chlorides are precipitated in the liquid TiCl4 to form a slurry containing 50~60 wt% TiCl4 (Wang, Xiang, and Wang, 2012).Various methods have been proposed to recover TiCl4 from the slurry, including microwave heating and spray drying (Wang, Xiang, and Wang, 2012, Wang et al., 2010a). To date, the only way to recover the TiCl4 is to return the slurry to the fluidized-bed furnace. However, this causes fluctuations in the temperature in the furnace, resulting in incomplete reaction between titanium-rich materials and chlorine. Therefore, the slurry is often rinsed with water and neutralized by adding lime, which caused serious environmental pollution and wastes a valuable resource (Roy, Bhatt, and Rajagopal, 2003)."

May 1, 2019

By S. Adams, J. R. C. von Holdt, J. L. Broadhurst

Fugitive dust from mineral extraction and processing activities can significantly influence air quality, the environment, and the health and quality of life of workers and surrounding communities. Poor engagement and communication between experts and lay persons, disciplinary silos and polarised viewpoints have made it difficult to develop a holistic understanding of the complex health issues associated with environmental emissions of mine dusts, and consequently to design meaningful and integrated approaches to address such issues. The collaborative Global Challenges Research Fund (GCRF) Mine Dust and Health Network, hosted by Minerals to Metals at the University of Cape Town, serves as a collaborative think-tank to inform research directions within and across disciplines, government policy and regulations, health monitoring programmes at public clinics, industry best practice, community healthcare and impact prevention programmes. It focuses initially on the southern African region, but with the intention to expand to mining-intensive developing countries within the rest of Africa, South America and Asia. This paper outlines the approach and activities of this global transdisciplinary and intersectoral network and presents some of the key outputs and achievements to date. Keywords: Mine dust, Global Challenges Research Fund Mine Dust and Health Network

Jan 1, 2020

By R. B. Khumalo, M. S. Nyarela, R. C. Nemathithi

Palabora Mining Company is one of the largest low-grade copper mines globally. The mine uses block caving for the extraction of the orebody. This paper enumerates the drawpoint loading strategies for the overall head grade improvements, particularly for a block that is nearing depletion. A comprehensive literature review of various considerations relating to improving productivity in block caving is presented to contextualize the draw control in caving. From this study, an optimized draw control strategy is presented, which focuses on three parameters that include grade distribution, loading compliance, and tonnage splits per sector. An empirical method based on the relational study between various parameters is used to outline the key criteria to be used in the optimization of drawpoint loading in block caving.

Nov 30, 2022

1. Book reviews Nonparametric geostatistics, by S. Henley. London, Applied Science Publishers, 1981. xiv + 145 pp. Reviewer: Douglas M. Hawkins Mineral deposits and global tectonic settings, by A. H. G. Mitchell and M. S. Garison. London, Academic Press, Geology Series, 198!. Reviewer: J. Lurie The mining and mineral laws of South Africa, by B. L. S. Franklin and M. Kaplan. Durban, Butterworths, 1982. Cloth, 240 X 150 mm, Lxxcii + 853 pp. R197,50 + GST. Reviewer: M. J. Martinson Aluminium- Volume II, by M. H. Govett and J. Larsen. Sydney, Australian Mineral Economics (Pty) Ltd, 1982. Reviewer: D. G. Maxwell International technology for the nonferrous smelting industry, by Noyes Data Corporation. Reviewer: D. A. Viljoen 2. New publications Coaltransport- an analysis of technical and economic factors, by Dag Pike. London, Financial Times, 1982. £86 (D.K.), D.S. $175 (overseas including first class airmail postage). Small solute concentration differences determined by interferometry, by H.E.L.G. Schweigart. Pretoria, CERG-CSIR (P.O. Box 395, Pretoria), 1982. 3. Mintek reports Report M8A determination, using solid zirconia electrolytes, of the activities of chromium oxide in ferrochromium alloys and slags at 1650°C. Report M31Software for the design of multivariable control systems by use of the Inverse Nyquist Array. Report M37A literature survey of the metallurgical aspects of minerals in Witwatersrand gold ores.This survey reviews the information in the literature Report M 39 The use of masking agents in the determination, by hydride generation and atomicabsorption spectrophotometry, of arsenic, antimony, selenium, tellurium, and bismuth in the presence of noble metals. Report M40 The use of X -ray-fluorescence spectrometry in the determination of uranium, cobalt, and sulphur in materials from mine dumps. Report M44 A n on-line dilution system for spectrometry ustng an inductively coupled plasma source. Report M47 The separation of trace elements from iron, and the analysis of iron-rock ores for use as reference materials. Report M49 A programme in BASIC for the appending of computer files. Australian coal The editors of World Coal and World Mining have announced plans to sponsor the IVth International Coal Exploration Symposium. The symposium will be held in Sydney (Australia) from 15th to 19th May, 1983. Small mine economics The editors of World Mining and World Coal have announced plans to sponsor the Second International Symposium on Small Mine Economics and Expansion in Helsinki, Finland, from 12th to 16th June, 1983. The first symposium was held in Taxco, Mexico, in May 1981.

Jan 1, 1982

The November General Meeting of the Branch was held in the St. Helena Club at 8.00 p.m. on the 17th November, 1970. Mr J. N. Saunders (Chairman) was in the chair. There were also present six fellows, N. A. Honnet, C. J. Isaac, J. G. Kirchner, (Committee Members), J. M. Meyer, S. L. S. Swart and J. W. Wilson; seven members, D. V. Baum, M. de Lange, A. H. Edwards, G. J. G. Emere, E. R. Penny, G. P. Rundle, C. G. J. Vermeulen; six graduates, N. Mayer, H. Miller, E. J. Shillaber, P. J. H. Short, M. H. Smith, T. R. Stromsoe; five associates, M. Andriesse, A. E. Hooper, A. Paschalides, R. L. Solms, W. M. Todd; one student, J. C. Simms and 14 visitors. Apologies for absence were received from Messrs L. O. W. Leimer and G. Y. Nisbet. MINUTES OF THE ANNUAL GENERALMEETING The Minutes of the Annual General Meeting held on the 27th August, 1970, were taken as read. Their adoption, which was proposed by Mr N. A. Honnet and seconded by Mr J. G. Kirchner, was carried unanimously. MINUTES OF THE JULY GENERALMEETING The minutes of the General Meeting held on the 8th July, 1970, were taken as read. Their adoption, which was proposed by Mr C. J. Isaac and seconded by Mr J. G. Kirchner, was carried unanimously. GENERAL BUSINESS Members were advised that no more applications could be entertained for the visit to Western Holdings; they could, however, still apply to visit Welkom Mine and Harmony. TALK The Chairman invited Mr A. Paschalides to deliver his talk on 'Controlled blasting in stopes and new explosives developments'. The presentation proved to be of great interest to the meeting and lively discussion followed the talk. Mr N. A. Honnet proposed a vote of thanks to Mr Paschalides on behalf of all members of the O.F.S. Branch. CLOSURE The Chairman thanked Mr Paschalides for his talk and all present for their attendance, and as this was the last meeting for 1970 he wished all members a Merry Christmas and a Happy New Year. He declared the meeting closed at 9.30 p.m.

By L. Zhang, Y. Zhou, H. Wang, C. Mo

Fluorination of magnetite (Fe₃O₄) by NH₄HF₂ was investigated using simultaneous thermogravimetry and differential thermal analysis (TG-DTA), and observing the morphology and phase changes using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffractometry (XRD). The results indicate that fluorination with the involvement of oxygen begins at room temperature, peaks at 178.40C, and is completed at 2000C with the formation of only (NH₄)₃FeF₆. On heating, (NH₄)₃FeF₆ gradually releases NH₄F by the formation of NH₄FeF₄ at 2590C, then (NH₄)0.18FeF₃ at 3270C, and finally FeF₃ with minor FeF₂ at 4000C due to the partial reduction of Fe (III) to Fe (II). At 5500C, FeF₃ is oxidized to FeOF/Fe₂O₃.

Dec 13, 2022

NIM Reports Report No. 1563 Neutron activation analysis of samples from the Kimberley Reef Conglomerate. Report No. 1569 The use of DDTU as an analytical reagent for the noble metals. Special general meeting A Special General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 14th November, 1973. The President, Mr P. W. J. van Rensburg, opened the meeting at 9 a.m. and read the notice of the meeting, which was as follows: Colloquium and general meeting CONSTRUCTION OF SLIMES DAMS A General Meeting and Colloiquum on the above topic was held on November 14th and 15th, 1973, at Kelvin House, Johannesburg. Mr P. W. J. van Rensburg (President) was in the chair. The Colloquium was attended by 135 delegates and was opened by the President at 9.10 a.m. Orange Free State Branch PROCEEDINGS OF THE ANNUAL GENERAL MEETING The Annual General Meeting of the Branch was held in the Western Holdings Cant,een on Tuesday, 11th September, 1973, at 7.00 p.m. Book Review Westwood, W., and Cooper, B. S. Analytical methods in use in non-ferrous minin~ and metallur~ y: a selective review. London, Institute of Mining and Metallurgy, July 1973. 54 pp. £3.50.

Jan 12, 1973

By F. T. Cawood, C. C. Birc

The South African mineral resource royalty system, initiated in 2010, employs a hybrid ad valorem approach tied to profitability ratios. This rate is then applied to the total revenue from mineral sales. In this article we explore how the profitability ratio in the mineral resource royalty formulae interacts with the gold tax formula as applied to South African gold mines, devising a strategy for cut-off grade optimization. The study focuses on nine narrow, tabular-reef (Witwatersrand) gold mines. The approach involves a mixed-integer cut-off grade optimizer utilizing Excel Solver, incorporating relevant royalty and income tax formulae. Different mineral resource royalty cost scenarios were examined. Ignoring these costs in the break-even analysis lowers the cut-off grade but slightly boosts profits compared to considering expected costs. The developed optimizer model, recognizing the profitability aspect of the mineral resource royalty and income tax formulae, yielded a 6% lower cut-off grade than the base case. This is significant for increasing mine life. While the profit differences are marginal (0.2% compared to the break-even base case), substantial improvements were noted: a 6% increase in stope tons above cut-off grade, and a 4% rise in total revenue. Enhanced resource utilization (3% extra gold kilograms) reduces necessary development and overall costs, allowing for a reduction in the cut-off grade and ultimately, more profit.

Aug 8, 2024

By G. Chitiyo

Prediction of pothole characteristics is a challenging task, confronting production geologists at the platinum mines of the Bushveld Complex. The frequency, distribution, size, shape, severity and relationship (FDS3R) of potholes has a huge impact on mine planning and scheduling, and consequently cost. It is with this in mind that this study was initiated. Quantitative analysis of potholes indicates that pothole size (area covered) can be described by two partly overlapping lognormal distributions. These are referred to as Populations A (smaller) and B (larger). The range of observed pothole sizes conforms to a simple double exponential growth model based on Newton's Cooling Curve. A third size range of very large potholes (Population C) that could not be modelled properly within the proposed growth model is interpreted as to represent a very early phase of aggressive regional thermo-chemical erosion and potholing. In general, potholes are dominantly quasi circular with only a subordinate tendency of elongation. In the UG2, potholes with elongated forms are more prevalent in the size range between 20 and 500 m diameter. In the Merensky Reef elongated potholes are more common in the size range above 50 m in diameter. Although not distinctly visible, elongation of potholes in both the UG2 and the Merensky Reef show a net north/south orientation. Using shapes of pothole rims and floor areas, documented for the UG2 in the Waterval Shaft area, it is demonstrated that the northern, down-dip edges of potholes have steeper dips than the southern, up-dip edges. Spatial distribution studies using a uniform quadrant method suggest that in both the UG2 and the Merensky Reef, the potholes are randomly distributed, with a tendency towards clustering. Clustering appears to be more prevalent in the smaller Population A potholes. Bearing all findings in mind, it is found that the model of thermo-chemical erosion of the cumulus floor by new influxes of superheated magma best explains the observed data. Partial to complete melting of the cumulate floor occurred in three phases. The first represents the emplacement of hot magma. This magma, due to turbulent flow and high chemical and physical potential, aggressively attacks the existing floor (crystal mush on the magma/floor interface). Regional erosion is manifested by large, often coalescing potholes. During the second phase, when the magma emplacement process ceased and cooling in situ started, two distinct periods of pothole formation ensued. The first is related to rapid cooling along the relatively steep part of the Newton Cooling Curve, when Population B potholes nucleated randomly and grew rapidly with concurrent convective overturn and largely laminar flow condition. The second period of cooling occurred on the shallow-dipping part of the Newton Cooling Curve. Population A pothole growth became more subdued and nucleation appears to have been, at least locally, clustered. The final phase of this proposed 'super magma cycle' was introduced when chromitite crystallization and precipitation terminated pothole formation. This was followed sequentially by pyroxene and plagioclase crystallization to form the typical cyclic units of the Critical Zone. No suitable proxy could be found for the prediction of pothole density of potholes associated with the UG2 (likely due to limited spatial data coverage), and these are best predicted by extrapolation. The Merensky Reef slope index, in contrast, provides a proxy for pothole density, enabling prediction with reasonable confidence. This predictive model has been verified using underground information. The findings made during the course of this investigation have, when implemented, significant impact. Successful implementation will not only allow enhanced resource and reserve definition, but also better mine planning and scheduling.

Jan 1, 2008

By D. Paktunc, S. P. du Preez, J. P. Beukes, P. G. van Zyl, A. Jordaan

"The chromium (Cr) content of stainless steel originates from recycled scrap and/or ferrochrome (FeCr), which is produced mainly by the carbothermic reduction of chromite ore. The oxidative sintered pellet production process is one of the most widely applied FeCr processes. The supplier of this technology specifies that recycling of chromite-containing dust collected from the pellet sintering off-gas and fines screened out from the sintered pellets (collectively referred to as pre-oxidized chromite fines) should be limited to a maximum of 4 wt% of the total pellet composition. However, the results presented in this paper suggest that recycling of such fines up to a limit of 32 wt% of the total pellet composition may improve the compressive and abrasion strengths of the cured pellet. In addition, electron microprobe and quantitative X-ray diffraction (XRD) analyses demonstrate that chromite grains present in the pre-oxidized chromite fines consist, at least partially, of crystalline phases/compounds that will improve the metallurgical efficiency and specific electricity consumption (i.e. MWh/ton FeCr produced) of the smelting process. Introduction Stainless steel is a vital modern-day alloy that is well-known for its corrosion resistance, which is mainly due to the inclusion of chromium (Cr) (ICDA, 2013). Stainless steel is mostly produced from recycled scrap and ferrochrome (FeCr), a relatively crude alloy of Cr and iron (Fe). FeCr is predominantly produced by the carbothermic reduction of chromite, a mineral belonging to the spinel group characterized by the unit formula [(Mg,Fe2+)(Al,Cr,Fe3+)2O4] (Haggerty, 1991; Paktunc and Cabri, 1995; Tathavakar, Antony, and Jha, 2005). Although Cr can occur in 82 different minerals, chromite is the only source of new Cr units that can be exploited in commercial volumes (Motzer and Engineers, 2004). Approximately 95% of mined chromite is used in the production of various FeCr grades, of which high-carbon and charge grade FeCr are the most common (ICDA, 2013)."

Feb 1, 2019

By K. Shin

Determining the anisotropy of rocks has in the past been difficult and rarely attempted in engineering practice. Here we have developed a new practical methodology for measuring orthotropic anisotropy that requires only one hollow cylinder specimen to determine the anisotropy of a set, even when the directions of the anisotropic axes are unknown. Autrefois, la détermination de l’anisotropie des roches était difficile et elle a été rarement essayée dans la pratique de l’ingénierie. Voilà c’est nous qui avons mis au point une nouvelle méthodologie pratique pour mesurer le coefficient de conductibilité thermique de l’anisotropie qui exige un seul spécimen du cylindre creux afin de déterminer l’anisotropie d’une série, même si les directions des axes anisotropiques sont inconnues. Früher war die Bestimmung der Anisotropie von Gesteinen ein schwieriges Verfahren, das in der technologischen Praxis nur selten in Angriff genommen wurde. Wir haben hier eine neue praktische Methodik zur Messung der orthotropen Anisotropie entwickelt, bei der nur ein Hohlzylinder an Gesteinsproben benötigt wird, um die Anisotropie einer Reihe von Steinen zu bestimmen, selbst wenn die Richtungen der Anisotropieachsen unbekannt sind.

Jan 1, 2003

By A. Singh, R. D. Govender

The current method employed to quantify the efficiency of separation of ferromagnetic ores by wet low intensity magnetic drum separators (WLIMS) incorporates the use of a conventional benchscale Davis Tube (DT) operating at a magnetic field intensity that is equivalent to that of the drum’s surface. However, empirical research has indicated that the magnetic force, or force index, rather than the magnetic field intensity, is the critical factor in the operation of the magnetic separator (Murariu and Svoboda, 2002). Furthermore, the current aforementioned practice would yield incorrect information as the magnetic field gradients produced by a typical WLIMS unit differs considerably from that of a bench-scale DT. In light of this, research on magnetite focusing primarily on the scale-up of DT results to pilotscale WLIMS were undertaken. The investigation entailed a comparative study between that of a typical WLIMS circuit and a bench-scale DT. The purpose was to practically evaluate the performance of a WLIMS, bench-marked against the traditional laboratory-scale DT unit. Moreover, the secondary objective was to produce a magnetite concentrate graded at 69% Fe, 95% -45μm, as a suitable source of separation media for use in the Dense Medium Separation (DMS) industry. Fundamental findings of previous works provided a framework for the study, however, a realworld approach was explored. Preliminary testwork conducted at Mintek investigated the performance of a DT and a typical multi-stage laboratory-scale WLIMS circuit (operating at 1000 Gauss at the surface). The results attained indicated that a DT operating at high intensities is comparable to a single rougher WLIMS stage. Additionally, it was observed that the three stage laboratory-scale WLIMS circuit performed similarly to the DT operating at 1000 Gauss. Moreover, piloting testwork was undertaken, carried out in larger 380mm drums, and the results attained showed a strong correlation with laboratory-scale findings. Keywords: Davis Tube, wet low intensity magnetic separation, magnetite

Jan 1, 2020

By R. L. Attridge

Namibia's newest mining enterprise, the Navachab Gold Mine, was officially opened by President Sam Nujomo during June 1990. The mine is a joint venture between Erongo Mining & Exploration Company Limited, Metal Mining Corporation of Canada, and Rand Mines Windhoek (Pty) Ltd. Erongo has a 70 per cent interest in the mine, while Metal Mining and Rand Mines hold 20 per cent and 10 per cent respectively. Anglo American Corporation and its associates hold two-thirds of Erongo shares and CDM (Pty) Ltd one-third. The Mine is managed by Erongo Mining & Exploration Company. The property is located some 10 km southwest of the town of Karibib and 170 km west-northwest of the Namibian capital of Windhoek (Fig. 1), the name of the Mine being taken from the farm on which the gold deposits were discovered. Navachab is an opencast operation and was brought into production in December 1989 at a cost of around R84 milion-RS,2 million under budget. The plant is designed to treat 840 kt annually at an average gold grade of 2,6 g/t. This wil produce 1900 kg of gold per year, which at today's prices will earn Namibia more than R60 million in foreign exchange.

Jan 1, 1991

By N. C. J. Dempers, J. A. L. Parker, R. A. Wildenboer

More than half of global cobalt reserves are located in the Southern African Copperbelt, stretching over the northern tip of Zambia and southern area of the Democratic Republic of Congo. In these areas, cobalt is not typically produced as a primary product but as a byproduct of copper production. Ores from this region often contain uranium, which is readily leached under typical copper leach conditions and enters the process. Uranium does not pose a challenge to copper production, but it becomes a significant problem when it follows cobalt to the cobalt precipitation process and results in unacceptably high levels of U in the final Co product. This paper evaluates the existing process technologies that can be used to remove uranium from cobalt-bearing process streams, including phosphate precipitation and ion exchange. Advantages and disadvantages of the uranium removal processes are discussed, and important design considerations are highlighted.

Jan 1, 2023

By M. Louarrat, G. Enaime, A. Yaacoubi, A. Baçaoui, J. Blin

"The purpose of this study is to prepare a new activated carbon from olive stones for use in gold recovery by carbon-in-leach (CIL) and carbon-inpulp (CIP). The preparation method chosen was physical activation using steam. The effect of four process parameters: the residence time for carbonization, the activation temperature, the residence time for activation, and steam flow, were studied by the mean of response surface method (RSM) in order to optimize the yield, iodine index, and attrition characteristics. These two last responses were used as primary indicators of gold recovery capacity and mechanical strength. The results obtained show that optimal activated carbon can be prepared under the following conditions: a carbonization time of 157 minutes, activation at 921°C for 53 minutes, and a water vapour flow of 0.18 mL/min. This optimum carbon has an iodine value greater than 1100 mg/g and an attrition index in the order of 0.74%. These values reflect the quality of the precursor (olive stones) as a raw material for the development of an effective new activated carbon for the gold mining industry. IntroductionActivated carbon is an effective adsorbent widely used in industry due to its high surface area, well-developed reproducible microporous structure, and high degree of surface reactivity and adsorption capacity. World consumption of activated carbon is steadily increasing. It is primarily used in industrial wastewater and gas treatment and also for silver and gold recovery from cyanide solutions (Syna and Valix, 2003; Soleimani and Kaghazchi, 2008; Buah and Williams, 2010; Eddy et al., 2011). However, activated carbon is expensive and it needs to be regenerated after each adsorption cycle. In order to decrease the cost of manufacturing activated carbon, low-cost forest and agricultural wastes are considered promising new materials. In recent years considerable research has been reported on activated carbon from agricultural wastes, such as olive stones (Yavu et al., 2010), acorn shells (Sahin and Saka, 2013), peanut shells (Wu, Guo, and Fu, 2013), grape seeds (Jimenez-Cordero, 2014), coconut shells (Yalcin and Arol, 2002; Gratuito, 2008), palm shells (Sumathi, 2009), cherry stones (Jaramilloa, Gomez-Serrano, and A´lvareza, 2009), macadamia nut shells (Eddy, 2011), apricot stones (Soleimani and Kaghazchi, 2008), and bagass (Syna and Valix, 2003)."

Mar 1, 2019

By P. F. Dicks, N. J. Shackleton, E. H. W. Theron, V. Malysiak

Flotation is a complex physical chemical process in which flotation reagents play a vital role in valuable minerals recovery and concentrate grades. This study examines the performance of new generation AECI Mining Chemicals (previously named Senmin) collectors. They were developed to enhance the valuable minerals recovery and flotation selectivity by tailoring the collectors to target specific valuable mineral species present in an ore and thus create added value for concentrators treating PGM ores. The case study was conducted on a Platreef ore, where batch flotation tests were performed and the concentrates were mineralogically characterised for PGE and BMS using QEMSCAN. Further batch flotation testwork was conducted on Merensky and UG2 ores from various localities in South Africa to confirm the trends observed for Platreef ore. The results have shown that there is a strong correlation between PGE mineral type and AECI Mining Chemicals collector type - clearly demonstrating that one reagent type does not fit all flotation applications. Keywords: Batch flotation, QEMSCAN, collectors, PGE and BMS

Jan 1, 2020

By R. Singh, A. K. Dhawan, M. Dixit, H. Dev

ABSTRACT: The modulus of deformation of rock mass is an important engineering parameter required for the design of foundation of hydraulic structure and to study the interaction of rock mass and the structure at the foundation support. Different equipment and techniques are used to arrive at the design modulus value. Since any error in the estimation of modulus values results in multiplication of its effects in the analysis, it is necessary to know about the reliability of testing equipment and procedures. In the present study modulus values obtained by different in-situ equipment at different project sites have been compared. KURZFASSUNG: Der Verformungsmodul von der Felsenmasse ist technisch ein wichtiger Parameter, den man zur Konstuktion des Grunds fuer die Hydro – Tektonik, benoetigt um auch die gegenseitige Beeinflussung der Felsenmasse und der Tektonik am Traggrund zu betrachten. Verschiedene Geraete und Methoden werden angewandt, um den Ausfuehrungsmodul -Wert zu erreichen. Es ist erforderlich, die Zuverlaessigkeit der Pruefeinrichtung sowie des Verfahrens zu kennen, da irgend ein Fehler in der Abschaetzung von Modulwerten in der Analyse zu einer Vervielfachung ihrer Einwirkung fuehrt. In der vorligenden Arbeit werden die Modulwerte gewonnen aus unterschiedlichen Einrichtungen an Ort und Stelle and verschiedenen Projekt -Stellen mit einander verglichen. SOMMAIRE: Le module de deformation d’une roche est un parametre important pour la conception et realisation des ouvrages hydrauliques ainsi que pour etudier l’interaction de la roche et de la structure d’appuis de base. De divers equipments et techniques sont employes pour determiner la valeur de ce module de conception. Puisque l’effet d’une erreur d’evaluation du module devient multiplie dans l’analyse, il est necessaire de savoir la fiabilite des equipments et des methods qu’on ulilise. Dans cette etude, on a compare les valeurs des modules obtenues en employant les equipments in-situ aux sites differents de projets.

Jan 1, 2003

By D. B. Swanepoel

Hulamin Rolled Products (Ltd) developed a high Mn and Si containing alloy, EN 4017 as a scrap consuming alloy from the waste generated in producing their range of clad products for brazing of inter alia automotive heat exchangers. The multifaceted composition of this alloy (Al -1.2 wt% Si -1.1 wt% Mn -0.2 wt% Mg-0.26 wt% Cu) suggested that it might display some degree of strengthening via precipitate formation of the Mg2 Si-types. The aging isotherms constructed showed that EN 4017 with 0.19% Mg reached a lower peak strength (YS~210 MPa and UTS~260 MPa)compared to the EN 4017 material with 0.43% Mg (YS~270 MPa and UTS~325 MPa). The higher Mg variant of EN 4017 was comparable with the age-hardenable reference alloy EN 6061. Selected area electron diffraction (SAED) studies proved that the microstructure of age hardened EN 4017 contained a combination of ß', ß" and U2 phase after being aged at 175ºC for 65 h. The general microstructure contained precipitate free zones as well as grain boundary Si films, although these did not lead to significant embrittlement. The role of Mn dispersoids in the fracture mechanism of 4017 is also discussed. The article will compare the behaviour of EN 4017 with that EN6061. Keywords: Age-hardening, dispersoids, magnesium silicide, precipitate free zones

Jan 1, 2009

COUNCIL The following served on Council during the year under review: Office bearers: Messrs V. C. Robinson (President), Prof D. D. Howat and Dr J. P. Hugo (Vice-Presidents), J. K. E. Douglas (Immediate Past President) and D. G. Maxwell (Honorary Treasurer). Ordinary Members of Council: Dr M. G. Atmore, Dr J. M. Bereza, H. P. Carlisle, W. W. Malan, C. E. Mavrocordatos, Prof R. P. Plewman, Dr R. E. Robinson, Dr M. D. G. Salamon, P. W. J. van Rensburg, L. W. P. van den Bosch, P. A. von Wielligh. Branch Chairmen: J. Meintjes, J. M. Meyer (Acting), J. N. Saunders (Retired). Past Presidents serving on Council: R. J. Adamson, M. Barcza, H. Britten, R. C. J. Goode, P. Lambooy, Prof J. de V. Lambrechts, Dr J. T. Mclntyre, J. F. Reid, H. Simon. Ten Council meetings were held during the year with an average attendance of eighteen and the standing committees held forty-six meetings. FINANCE The annual accounts, which are attached to this report, show an excess of income over expenditure of R5 051 compared with an excess of expenditure over income last year of R4 608. This major reversal of fortunes is due in the first instance, of course, to the increased subscriptions. There were, however, other important contributors, particularly sales of the Proceedings of the Symposium on Open Pit Mining and profits on the operation of symposia and colloquia. It would appear from a study of the accounts that there has been a substantial drop in expenditure on secretarial fees. In actual fact, however, our total expenditure on secretarial fees was higher. A portion of this expenditure was charged against the administration of the Symposium on Open Pit Mining and, in addition, the charge against the Journal accounts for secretarial fees was increased. It will be recalled that in last year's annual report it was mentioned that subsequent to the new arrangement for publication of the Journal, the expected improvement in the finances of the Journal had been slow in materialising. After a total period of 18 months there was still no sign of improvement and it was accordingly decided to end the arrangement. As a result, the drain on the finances of the Institute was considerably lessened in the second half of the year. During the course of the year Council became concerned about the rapid depletion of our accumulated funds and gave careful and detailed attention to all aspects of the Institute's financial affairs. Particular attention was given to: 1. The fact that the Institute does not have a solid financial backing and must appeal for funds every time any special event such as a symposium is held. 2. The responsibilities of the Institute to the profession and the community, with particular reference to the desirability of establishing Institute bursaries and participating in other educational activities. 3. The rapidly rising cost of living. 4. The immediate financial position of the Institute. 5. The rapidly increasing cost of publishing the Journal due to the increasing number of papers available. In the meantime the immediate financial position of the Institute has improved but as this is due largely to non-recurring or irregular items of revenue, it should not be given undue weight. After careful consideration it was decided that an appeal should be made to industry for financial assistance, which would be used to cover the cost of symposia and other unusual expenditure and also, if possible, to build up the capital resources of the Institute so that there is a solid foundation for the future. Before appealing to industry, Council wished to be quite certain that there could be no criticism of the Institute for not having done our best in a personal capacity. Furthermore, Council examined many comparative statistics, including those circulated to members, which showed that, while expenditure per member has risen at an average annual rate of 7,5% over the last fifteen years, subscription revenue per member has risen at only 3,4% per annum. It was with this background that your Council decided to raise the subscriptions. Initial approaches have been made to the big mining groups and there has been a very generous response, although the details of how financial assistance will be provided have not yet been worked out. It seems likely that some form of affiliated company membership will be the most suitable method of achieving this. When these details have been fixed, it is the intention to extend the appeal to all corners of the mining industry as well as manufacturing and metallurgical industries. It is believed that these measures will ensure that the finances of the Institute are placed on a firm foundation on which the expanding activities can be planned. The MacArthur Forrest Memorial Fund shows an excess of income over expenditure of R73 and the total fund was, therefore, increased by this amount to R4 411. The balance sheet shows that the market value of quoted shares and debentures increased during the year fron R6 540 to R9 160. The market value is now almost exactly the same as the book value. Accumulated funds now amount to R23 010 compared with R17 959 a year ago.