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By M. Kumral, S. Hmoud

Optimising the configuration of infill drill holes is an important step during mineral exploration campaigns. However, this optimisation process encompassing all possible drilling configurations within a mineral deposit is highly combinatorial and hard to solve in a reasonable time. This paper proposes using spatial clustering algorithms to divide the orebody into contiguous zones and target the best zones with infill drilling in order to reduce the size of this optimisation problem. Several clustering algorithms are assessed in a spatial context on hypothetical datasets. This evaluation shows that the hierarchical density-based spatial clustering application with noise (HDBSCAN) algorithm can be used in combination with the uniform manifold approximation and projection (UMAP) dimensionality reduction algorithm to identify contiguous zones in the orebody.

Sep 1, 2021

By L. L. Godirilwe, and A. Shibayama, G. Danha, K. Haga, Y. Takasaki

Selective extraction through leaching of an amorphous slag obtained from a base metal smelter plant in Botswana is investigated in this paper, where the main objective is to optimise the experimental variables that would result in the maximum selective extraction of the three base metals (Ni, Cu and Co) from the slag waste. Mineralogical tests showed that the sample is composed mainly of fayalite (Fe2SiO4), with a total entrapped metal sulphides content of about 1.0 wt.% occurring as fine occlusions in the fayalite phase. In our experimental program, we compare the effectiveness of two common leaching techniques. In the first method, we use sulphuric acid to carry out atmospheric beaker leaching tests, and in the second method we use high pressure oxidative leaching. The effects of acid concentration, oxidant addition/oxygen partial pressure and pulp density on metal dissolution rate are examined. The optimal Ni, Cu, Co extractions of 80.5%, 81.9 and 98% respectively were obtained under high pressure oxidative leaching conditions (150 oC, 0.6 M H2SO4, 0.5 MPa O2), with substantially low dissolved Fe of 9.6%, the majority of which was removed as jarosite in the residue. Atmospheric beaker leaching yielded poor extractions of Ni below 40% when sulphuric acid combined with hydrogen peroxide (1.0 M and 0.6 M respectively, 65 oC) were used for leaching, while Fe, Cu and Co dissolutions were each about 80%. Therefore, using high pressure oxidative leaching provides a possibility to effectively extract Ni, Cu and Co while producing an environmentally benign residue, thus alleviating the current adverse environmental issues associated with the abandoned smelter slag. Keywords: Slag, amorphous, fayalite, atmospheric beaker leaching, high-pressure oxidative leaching, extraction

Jan 1, 2020

By I. V. Filippova, Y. Foucaud, M. Badawi, O. Barrès, L. O. Filippov, S. Lebègue

Sodium silicate (Na2SiO3) is one of the most common reagents used in the froth flotation process, in which it is an efficient dispersant as well as a powerful gangue minerals depressant. Due to its high affinity with a lot of minerals, mostly silicates, it adsorbs on their surfaces and prevents the adsorption of the collectors, maintaining them hydrophilic. Hence, Na2SiO3 is widely used in the flotation separation of rare earth minerals, zinc minerals, iron minerals, scheelite, fluorite, apatite, and many other minerals. For decades, authors have demonstrated higher efficiency of Na2SiO3 when it is used in combination with sodium carbonate (Na2CO3), a common pH regulator. Among many well-known depressants, this system presented the best efficiency for many ores, including the Tabuaço scheelitebearing skarn studied herein. However, the mechanisms resulting in these strong positive synergistic effects are not well understood at the moment. Hence, the response surface methodology (RSM) was applied to this ore, considered as a case study, to optimize the depressing conditions and to study deeply the flotation behavior of this system. Strong synergistic effects between the two reagents were exhibited by the RSM, mostly affecting the scheelite, fluorite, and calcium-bearing silicates recoveries. This was attributed to surface carbonation of the minerals by Na2CO3, subsequently leading to a better depression by Na2SiO3. Overall, a 1:1 ratio between the two reagents displayed the best results in terms of WO3 grade and recovery. To gain understanding in the molecular mechanisms responsible for the aforementioned synergistic effects, FTIR studies were combined with state-of-the-art molecular modelling (Ab Initio Molecular Dynamics at 300 K) on fluorite, an archetype of calcium minerals. Keywords: Synergistic effects, scheelite, depressants, FTIR, DFT calculations

Jan 1, 2020

By S. Fuchida, Y. O. Zubair, C. Tokoro

Mining of As-bearing minerals had resulted in the release of arsenic species predominantly As(III), which is known to be more toxic, and undue exposure to it is detrimental to human organ systems. Many materials have been examined for As(III) removal, but it is still challenging to advance sustainable materials for effective removal of As(III). In this paper, a more eco-friendly and superparamagnetic Fe0-Fe3O4 composite was synthesised and evaluated for heterogeneous catalytic oxidation and removal of As(III) with peroxymonosulfate (PMS, KHSO5). The kinetic removal studies showed that removal of As(III) was probably through a chemical process and the Elovich model best represented the experimental data. The removal capacity for As(III) on Fe0-Fe3O4 with PMS (1.76 mmol/g) is superior to that without PMS (0.83 mmol/g). Combined results from XPS and ESR showed that As(III) was fully transformed to As(V) through catalytic oxidation by Fe0-Fe3O4/PMS and afterwards enhanced its removal. The removal mechanism of arsenic was ascribed to the formation of outer-sphere (electrostatic attraction) and inner-sphere complexes. The adsorbent can be separated easily from water due to its excellent magnetisation (64.5 emu/g) and also has good reusability potential as more than 85% of the initial concentration of As(III) was immobilised after five consecutive cycles. Keywords: Arsenite, Fe0-Fe3O4 composite, catalytic oxidation, removal mechanism

Jan 1, 2020

By B. P. Watson, D. Hoffmann, D. P. Roberts

Potholes on the Merensky and UG2 reefs in the Bushveld Complex occur as near-circular to elliptical depressions or slumps on the reef horizon, normally presenting as severe disruptions which prevent economic extraction. Within the pothole, the reef and other strata may either be attenuated, absent, or highly deformed, this being the result of the overlying hangingwall strata having slumped down. The hypotheses for pothole formation involve several mechanisms, including downward erosion, upward fluid movement, or synmagmatic deformation. When potholes are exposed in mine workings, significant fracturing is often observed. This fracturing is particularly evident in anorthosite rock types. Stress measurements were conducted in a pothole on the Merensky Reef to determine if the fracturing was due to high stress conditions. The paper describes the measurement results and numerical modelling that was done to determine the influence of depth and mining on the stress condition at the site. The results show that high stresses do exist in at least some potholes, and that current formation theories do not adequately explain the measured stresses. In support of understanding the high local stress associated with the pothole, the study explored several rock engineering modelling processes to validate the conditions of the study site and enclosing excavations. A better understanding of the stress conditions in potholes with additional data could lead to more appropriate support design and avoidance of potential rockbursts in these structures.

Jan 1, 2021

By J. C. Barry, J. H. van Laar, P. L. Crouse, H. Bissett, I. J. van der Walt

"Plasma-assisted spheroidisation of metal powders offers several technical advantages with respect to both the ease of materials handling and powder-metallurgical item manufacturing. Advantages include improved flowability, increased powder packing density, elimination of internal component cavities and fractures, changes in morphology resulting in decreased friction between particles and contamination during pneumatic transport and enhanced particle purity. In this empirical study, spherical iron particles were produced using a microwave plasma operating at atmospheric pressure and characterized using optical microscopy and SEM techniques. Iron powders were fed into the system at fixed operating conditions, resulting in particles with spherical structures. The theoretical estimate of the time required for melting to occur is 1.6 ms, an order of magnitude smaller than the actual residence time. IntroductionParticle design and functionalization has become an increasingly popular aspect of materials synthesis and powder-metallurgical item manufacturing. One such technique involves the spheroidisation and densification of feed materials, typically in the form of chemical powders with wide particle size distributions. The major benefits of powder spheroidisation include improved powder flowability, increased powder packing density and powder purity, reductions in internal voids and defects, as well as the ability to manipulate the particles surface morphologies (Boulos, 2004). Thermal plasma processing has the potential for scale-up and for producing industrial quantities of spheroidised powder.Thermal plasma technologies offer a wide spectrum of material synthesis and treatment options, amongst others the synthesis and spheroidisation of nano-sized ceramic and metal particles (Kumar and Selvarajan, 2006). The spheroidisation process occurs within the plasma discharge via in-flight heating and melting of the powder feed material, given high enough plasma temperatures (Fridman, 2008, p. 495). Surface tension in the molten droplets results in spherical, or nearly, spherical, powder particles being formed upon exiting the plasma discharge where the droplet undergoes rapid cooling and freezes. Quite often, the bulk density of these spherical particles is higher than that of the starting material (Boulos, Fauchais and Pfender, 2013, p. 42). The different plasma spheroidisation techniques reported include radio frequency (RF) induction thermal plasmas (Jiang and Boulos, 2006; Karoly and Szepvolgyi, 2005; Yuming, Junjie and Yanwei, 2013), nontransferred direct current (DC) thermal plasmas (Chaturvedi et al., 2014; Kumar and Selvarajan, 2008; Suresh, Selvarajan and Vijay., 2008) and microwave-assisted plasma processing methods (Chen, Gleiman and Phillips, 2001; Vanamu et al., 2004; Weigle et al., 2004)"

Jan 1, 2016

By R. G. Diale, H. R. Chauke, T. M. Ledwaba, P. E. Ngoepe

FeCo alloys play an important role in soft magnetic materials with a wide range of technological applications due to their high saturation magnetization and Curie temperature. However, these alloys have low ductility at room temperature. The ductility can be improved by the ternary addition of elements such as V. A density functional theory supercell approach was used to generate B2 Fe50Co50-xVx (0 ≤ x ≤ 50) structures and the properties were evaluated at different atomic percentage compositions to determine the ductility at room temperature. The structures were fully optimized to obtain better equilibrium ground-state properties such as lattice parameters and thermodynamic properties for both binary and ternary systems. The stability of Fe50Co50- xVx was evaluated from the heats of formation, elastic properties, and phonon dispersion curves. Furthermore, magnetic strength was evaluated from magnetic moments. It was found that all structures are thermodynamically stable due to the negative heats of formation. The calculated Pugh’s ratio and Poisson’s ratio confirm that alloying with V effectively improved the ductility. It was also found that Fe50Co50-xVx showed a positive shear modulus for the entire concentration range investigated, in agreement with phonon dispersion curves. The ternary addition of V to the FeCo system resulted in reduced magnetic strength due to a decrease in magnetic moments. These findings reveal that B2 FeCo-V alloys can be used as components and actuators for the automotive industry.

Jun 10, 2024

By P. C. Pistorius, M. P. Maphutha, J. D. Steenkamp

Advanced high-strength steels (AHSS) are sophisticated materials being developed by the steel industry to mitigate challenges related to the performance of motor vehicles. To meet the requirements of AHSS, the ferromanganese alloys (FeMn) utilized in the production of the steel are required to contain acceptable levels of unwanted impurities, i.e. P, S, N, H, and C. The focus of the current study was to investigate dephosphorization of ferromanganese to produce a low-P alloy that could be effectively utilized in the production of AHSS. The study involved conducting laboratory-scale testwork to study the efficiency of CaO-based slag systems to dephosphorize FeMn alloys. The addition of Na2O, CaF2, and BaO to MnO-CaO-SiO2 slag was considered. The test work was carried out in a 25 kW induction furnace at temperatures of 1350°C, 1400°C, and 1450°C. The P partition coefficient (Lp) remained small at <1, which is an indication that dephosphorization had not been achieved. The baseline slag, comprising 40%CaO-40%SiO2-20%MnO, reported higher Lp values. Addition of Na2O and CaF2 did not show any further benefit. Substituting half of the CaO by BaO, resulted in similar Lp values to those of the baseline slag under conditions of 1350°C and 1450°C at 30 minutes. In summary, based on the Lp values obtained, the conditions investigated with the CaO-based slags appeared to have been unfavourable for dephosphorization of FeMn alloys, as most of this impurity element remained in the alloy.

Sep 1, 2021

By A. Modi, C. Li, R. Kabwit, W. Y. Xinchao, R. Joshi

The KIMIN copper project can treat 1.7 million dry t/a copper-cobalt ore. It has three mills in operation, two using conventional milling in water and the third in raffinate. We introduce the project process circuit and the capital and operating costs of using the raffinate process compared with conventional milling in water. There is a capital saving of approximately 11.5% for major equipment by removing the pre-leach thickener. In addition, it also achieves an annual operating cost saving of USD 2.1 million due to an increase in 49% of acidic raffinate recycled and reduction in lime consumption. The features of CITIC’s new duplex stainless-steel ball mill ,as the key equipment of the system, are also introduced

Jan 1, 2023

By F. W. Petersen

The Conference Minerals & Materials &apos;96 was held in Somerset West, South Africa, from 31st July to 2nd August, 1996. It was organized by the Universities of Stellenbosch and Cape Town, the Cape Technikon, and the Western Cape Branch of The South African institute of Mining and Metallurgy (SAIMM). The three-day Conference was attended by 180 delegates, representing countries such as Australia, South Africa, United Kingdom, Finland, Sweden, Germany, Poland, Zambia, and Zimbabwe. The programme and associated exhibition were well organized, and each of the delegates received two volumes of proceedings containing the 77 papers presented at the Conference.

Jan 1, 1996

By C. J. Pretorius

More than 30 percent of the global demand for zircon (ZrSi04) is supplied by South Africa. A significant amount of the zircon is exported, and beneficiated products are then imported for industrial applications locally. Beneficiating the zircon locally could have a positive impact on the local market, since zircon is only one of many such cases. Ammonium acid fluoride serves as an alternative anhydrous fluorinating agent for zircon in the synthesis of several metal fluoridesl.2. It provides an effective dry fluorinating method and is easier to handle than hydrogen fluoride or fluorine gas. Zircon exposed to extreme plasma temperatures dissociates and becomes more reactive. The reaction of the plasma-dissociated zircon (Zr02?SiO2) with the ammonium acid fluoride (NH4F?XHF, where x= 1 to 5) forms two main intermediate compounds (NH4)3ZrFr(s) and (NH4) 2SiF6(s), the latter decomposing to form volatile products at relatively low temperatures, providing easy separation of the silicon and zirconium compounds. The ammonium zirconate compound decomposes to form zirconium tetrafluoride (ZrF4), which can be further manufactured into zirconium metal, to name but one product. Data on the kinetics of the reaction of ammonium acid fluoride with zircon and plasma-dissociated zircon, combined with the thermo-dynamic parameters of the reaction, is essential for the development of an industrial process for the production of a precursor for the manufacturing of zirconium metal, namely anhydrous ZrF4. Both the reaction kinetics and reaction parameters will be included in this study, as well as some proof that the reaction proceeds to ZrF4 on a small batch scale. If the exact reaction parameters can be pinned down, a wide spectrum of anhydrous metal fluorides can be synthesized through this fluorination route.

Jan 1, 2012

By G. A. Bezuidenhout, S. Bradshaw, W. Malan

"Currently, the matted-based collection process is most widely used for platinum group metal (PGM) recovery. However, because PGM-containing concentrates are becoming more enriched with UG2 (Upper Group 2) low-grade concentrates, this is expected to be integrated or replaced with an alloy collection process.The reduction LG (low-grade) concentrates with silicon carbide (SiC) was investigated. The purpose of the study was to ascertain the feasibility of using SiC as reductant with regard to metal fall, PGM grade in the alloy, slag composition, and overall PGM recovery, and if possible, the integration of such a process in the current matte-based collection process. Rowland and Easterns LG concentrate samples from Lonmin were analysed by Xray diffraction (XRD), X-ray fluorescence (XRF), and inductively coupled plasma mass spectrometry (ICP-MS). It was found that SiO2 and MgO are the most abundant oxides and Pd is the most abundant of the PGMs. Sulphide-bearing minerals such as chalcopyrite were detected in low concentrations (below 1%), and Cr2O3 concentrations are between 2-4%. SiC reduction of Rowland and Easterns concentrate were conducted at 1600°C with reductant to concentrate ratios ranging from 2.5 to 3.5 kg SiC per 100 kg concentrate.The reduction experiments revealed that PGM recoveries from Rowland concentrate were poor. SEM images showed entrained metal prills in the slag phase. The slag viscosity at the end of the melt was calculated by using FactSage, and the results indicated that the viscosity was higher than 4 poise, which is above that of Easterns slag. PGM recoveries for Easterns concentrate were significantly better. More than 85% of the Ir and Pd and almost 60% of the Pt were recovered in a test with a reductant to concentrate ratio of 3.5 kg SiC per 100 kg Easterns concentrate. At this reductant to concentrate ratio, Fe recovery was also the highest, at 66%. SEM imaging of a slag sample revealed few or no metal prills entrained. The FeO content in the initial concentrate charge was then increased by adding Peirce-Smith converter slag in order to decrease the slag viscosity and further increase PGM recovery. A test was conducted with the addition of 10 kg converter slag per 100 kg Easterns concentrate. The reductant to concentrate ratio was kept at 3.5 kg SiC per 100 kg Easterns concentrate. The Ir and Pd recoveries were more than 95%, while Pt recovery was almost 70%. Fe recovery increased to 76%. On the basis of these results an optimum feed ratio between Easterns and Rowland concentrates and Peirce-Smith converter slag were calculated. FactSage predicted that the concentrate charge should consist of 70-80% Easterns concentrate with 20-30 kg converter slag per 100 kg LG concentrate. SiC reduction of this optimum LG concentrate charge is expected to recover more than 90% of all PGMs. Cr and Si concentrations in the alloy will be below 1% in total.The effectiveness of SiC as reductant was also compared to carbon reduction. Carbon reduction of an optimum concentrate charge at the same reductant to concentrate ratio resulted in a marginally higher metal fall than SiC reduction. However, gas emissions and energy requirements are higher for carbon reduction.The study has shown that base metals and PGMs can be recovered in an iron alloy by SiC reduction of LG concentrate with converter slag additions. Integration of such a process into the matte-based collection process could be considered as a future alternative for smelting UG2 LG concentrates."

Jan 1, 2014

By A. Singh, K. Bisaka, G. Marape, T. Mokgomola

This paper investigated the pre-concentration amenability of sovite (carbonatite) ore to enhance the grade of rare earth elements (REE) bearing minerals by rejecting calcite, and to improve total rare earth elements (TREE) recovery using gravity and magnetic separation. A high proportion of calcite affects downstream processes like leaching due to high acid consumption. Multiple flowsheets combining gravity and magnetic separation were employed to target > 60% TREEs recovery to the final concentrate and > 60% calcite rejection to the tailings. Head analysis of the feed showed the sample’s main constituents as Fe (15.61%), Ca (16.04%), SiO2 (7.13%), and lastly TREEs (1.12%). Mineralogy liberation data at 2mm top size indicated poor liberation of TREEs, with the majority of minerals displaying < 30% mass greater than 80% liberated. Grain size distribution data showed that the majority of REE minerals are fine grained and report to the < 20 μm size class. Calcite liberation mineralogy showed < 60% mass greater than 80% liberation.A combination of a single-stage shaking table with a wet high intensity magnetic separator at a magnetic intensity of 7520 G was found to be the optimum flowsheet. For a shaking table feed with P80 of 150 μm followed by tails regrind to P80 of 45 μm as feed to wet high intensity magnetic separator, the overall mass balance results showed that 60.5% TREEs are recovered to the concentrate while 63.0% calcite is rejected to the tails. However, due to the fine-grained nature of This paper investigated the pre-concentration amenability of sovite (carbonatite) ore to enhance the grade of rare earth elements (REE) bearing minerals by rejecting calcite, and to improve total rare earth elements (TREE) recovery using gravity and magnetic separation. A high proportion of calcite affects downstream processes like leaching due to high acid consumption. Multiple flowsheets combining gravity and magnetic separation were employed to target > 60% TREEs recovery to the final concentrate and > 60% calcite rejection to the tailings. Head analysis of the feed showed the sample’s main constituents as Fe (15.61%), Ca (16.04%), SiO2 (7.13%), and lastly TREEs (1.12%). Mineralogy liberation data at 2mm top size indicated poor liberation of TREEs, with the majority of minerals displaying < 30% mass greater than 80% liberated. Grain size distribution data showed that the majority of REE minerals are fine grained and report to the < 20 μm size class. Calcite liberation mineralogy showed < 60% mass greater than 80% liberation.A combination of a single-stage shaking table with a wet high intensity magnetic separator at a magnetic intensity of 7520 G was found to be the optimum flowsheet. For a shaking table feed with P80 of 150 μm followed by tails regrind to P80 of 45 μm as feed to wet high intensity magnetic separator, the overall mass balance results showed that 60.5% TREEs are recovered to the concentrate while 63.0% calcite is rejected to the tails. However, due to the fine-grained nature of TREEs, no flowsheet improved their grade.

Nov 6, 2024

Dr Hanekom I would like to thank Dr Hanekom for a very valuable -contribution; it summarizes careful statistical test work which was an omission from the original paper. Minor manipulative details, the application of a finer measuring graticule and the reproducibility of the procedure are described and the author accepts with gratitude this ready-made answer to the first and second points of Dr Finkelstein&apos;s comments. Mr Williamson The author is indebted to Mr Williamson for historical background to early experiments with captive bubbles and it is conceded that the original paper described another avenue to an old flotation goal. The field of application is restricted and we would not work with all the material illustrated by Klassen and Mokrousov.1 The particles in Figure 74(a) are far too large and irregular; material in Figures (b) through (d) could be employed for semi-quantitative work in spite of obvious disadvantages; Figure 74(f) represents ideal conditions. We have studied this mineral-collector association in the size range given and results were satisfactory. For larger pick-up values than that illustrated an induction period of more than 0.01 second was required (actually 90 seconds for a maximum bubble load at pH 7.2 with 25 g/t oleic acid!). REFERENCE 1. KLASSEN,V. I. ANDMOKROUSOV,V. A., &apos;An Introduction to the Theory of Flotation,&apos; Butterworths, London, 128, Figure 74, (1963). Mr Slander and Mr Kooij Researchworkers in a practical mineral development laboratory may well ask what contribution yet another micro-technique can make to the problems of large scale ore flotation. The obvious answer is that there can be little or no direct translation of results obtained with a static system comprising air bubble and pure mineral concentrate to a dynamic multicomponent operation. However, for the rapid study of one mineral or variable some small scale apparatus must be employed. In the Anglo American Research Laboratory, the described semi-quantitative pick-up technique has filled a niche and requirement. For ourselves, the system represents a definite advance over the contact angle approach in that samples of minerals conventionally prepared in laboratory or plant may be used, which is a desired step nearer flotation. We bracket this pick-up apparatus with the Hallimond tube1,2 and evidence is now to hand that pick-up curves may often be related to flotation recoveries obtained from this tube with pure mineral samples and from the Fuerstenau glass cell3 with the total ore at low pulp densities. We would not wish to push the comparison of pick-up results past this stage for there is much published development work relating the Hallimond and Fuerstenau equipment to flotation on a larger scale. At the Anglo American Research Laboratory for example, a test in a Fuerstenau cell is often the final integrated step in laboratory investigations into the TORCO process. As these contributors rightly point out, pick-up tests can offer nothing towards the determination of optimum reagent dosage for large scale flotation. This is the function of bench-type flotation cells with up to 2 kg batches of ore. At this level, collector performance and consumption and physical properties of the froth are more comparable with large scale operation. The pick-up cell, Hallimond tube and Fuerstenau cell are essentially equipment from which the effect of control parameters can be derived. For the assessment of collector behaviour, the pick-up approach is rapid and economic and we offer here a pick-up contribution towards the flotation of Witwatersrand uraninite with anionic sulphonate collectors (Fig. 1). A large crystal of the local mineral was not available for contact angle measurements and owing to its low concentration in Witwatersrand gold-bearing reef, a small sample was laboriously obtained by tabling, superpanning and heavy medium separation. The pick-up values of a sized portion were determined by the described procedure in the presence of nine petroleum sulphonate collectors. Responses fell into two categories; "normal" curves (dotted lines) and a group of collectors which were very active at low concentration but showed depression of pick-up at the higher levels. The similarity in form of curves for collectors 1 and 3 was apparent and reagent 3 was found to be simply a diluent of 1. Otherwise, collector performance could not be related to either sulphonate content or molecular weight of the active constituent. However, reagent 2 gave the best performance in a bench flotation cell with regard to overall uranium distribution but, as predicted, reagent 1 yielded the best grades. Later pick-up tests with a similar class of collector have suggested that depression at high reagent concentrations may be due to "bubble armouring" whereby an hydrophilic air-liquid interface is produced which rejects mineral attachment. Prolonged investigations with the same mineral sample have not been required except for the study of uraninite which lasted for more than a year. Variation in pick-up response could not be detected over this period during which the mineral was stored under distilled water. The only visible change was a small efflorescence of lead sulphate, readily removed and decanted off after stirring with a glass rod in the sample tube. In its main role as a "trouble-shooter", the pick-up method is applied to fresh mineral samples taken from a flotation plant and soon discarded or from a current run in the ore-dressing laboratory. After production of a concentrate, a solvent cycle, as described in the original paper, may be required to remove heavy organics or other contaminants as when a sample has been taken from circuits containing detergents, grease or return flotation solutions. This solvent cycle will not remove chemisorbed collectors and we prefer not to work with minerals from flotation tailings or with pick-up cell discards. It has been thought preferable to answer the contributors&apos; other apprehensions with regard to sample preparation, activators, depressants and the physical properties of reagents in another paper on offer to this Journal. It covers pick-up investigations relating to the flotation of nickeliferous pyrrhotite at two Anglo American Corporation Mines, which approach seemed the correct orientation for a reply to another contributor to this paper.

By M. Dworzanowski

The difference in the magnetic properties of minerals is the basis for magnetic separation. All minerals can be generally classified as ferromagnetic (strongly magnetic), paramagnetic (weakly magnetic) or diamagnetic (non-magnetic). Magnetic separation can be conducted dry or wet. The majority of the applications of wet magnetic separation in the mining industry are based on the wet drum magnetic separator. The wet drum magnetic separator has been in use for over 50 years and its design is based on a rotating drum installed inside a tank. Inside the drum are stationary, permanent magnets arranged in an arc to provide the magnetic field. These magnets can be of the ceramic ferrite type providing a low intensity magnetic field or of the rare earth type providing a high intensity magnetic field.

Jan 1, 2010

By S. A. Lorentz, Y. Xu, C. Theron

The failure of tailings storage facilities (TSFs) results in the discharge of significant quantities of hazardous waste material into the natural environment. Research studies relating to slope instability have identified physical mechanisms such as rainfall-induced erosion, liquefaction, and shear failure as the main triggers. The generation of transient pressure waves and the mobilization of pre-event water in the unsaturated zone have been found to trigger shallow landslides in natural hillslopes. In this paper we review these physical mechanisms, known as groundwater ridging (GWR) and the Lisse effect (LE), from other studies. Previous researchers have explained both these phenomena through field and laboratory observations, numerical modelling, as well as conceptual discussions. These case studies demonstrate the impact of rainfall characteristics on the generation of transient pressure waves that rapidly increase the phreatic surface and change pore water suction. Reference is also made to the influence and behaviour of physical porous medium characteristics on the establishment of a continuous water phase that facilitates the transmission of an induced pressure head. However, previous studies fail to recognize the possibility that the pressure increase in pre-event water through pore air propagation could cause slope instability in tailings dams. The authors suggest that the physical properties and hydraulic behaviour of unsaturated porous tailings media make it susceptible to GWR and the LE, resulting in the creation of a potential failure plane.

Feb 2, 2022

1. New books Australian Institute of International Affairs. Uranium - energy source of the future? Canberra, thelnstitute (Box E181, P.O., Canberra, A.C.T. 2600, Australia), 1979. 202 pp. A$4,95 (postage 50c). Euroeconomics. The steel industry in Western Europe.. industrial and financial indicators. Paris, Eurofinance (9 Avenue Hoche, 75008 Paris, France), 1979. 167 pp. FF4,500 (Available in English and French.) M. B. Piggott. Load-bearing composite materials. Oxford, Pergamon Press, 1979. $15,00. J. H. E. Olaf. Automation and remote monitoring and control in mines. Essen (West Germany), Verlag Gliickauf GmbH, 1979. 200 pp. DM36. (In English.) J. P. Jenkins and E. T. Brown (eds). KWIC index of rock mechanics literature. Oxford, Pergamon, 1979. 742 pp. £60. R. J. Wakeman (ed.). Progress in filtration and separation 1. Amsterdam, Elsevier, 1979. 346 pp. Dfl.llO,OO. 2. New journal As from 1980, Coal Calendar is being published as a separate monthly periodical. 3. Proceedings L. E. St Pierre and G. R. Brown (eds). Future sources of organic raw materials. Oxford, Pergamon, 1979. 612 pp. £22,50. P. Haasen, V. Gerold, and G. Kostorz (eds). Strength of metals and alloys. Oxford, Pergamon, 1979. 3 vols., 1800 pp. $200. K. J. Miller and R. F. Smith (eds). Mechanical behaviour of materials. Oxford, Pergamon, 1979. 3 vols., 1800 pp. U.S.$200. 4. Tax relief? The Publishers&apos; Association of Great Britain recently issued a circular to a number of professional bodies drawing their attention to a court decision in favour of tax allowances on the purchase of textbooks. In January Electroheat The International Union for Electroheat, which com. prises a score of highly industrialized countries, every four years organizes a congress at which experts discuss the technicalities and economics of the latest applications of electroheat in industry and other sectors. Corrigenda: March issue The following amendments should be made to Table II of the paper &apos;Commodity analysis:

Jan 1, 1980

By J. P. Gous, M. Tangstad, J. D. Steenkamp

In April of 2013 a 48 MVA submerged arc furnace producing silicomanganese was excavated in South Africa. One of the areas excavated systematically was the furnace taphole. The aim was to obtain a refractory wear profile of the tap-hole area, together with affected hearth and sidewall refractory. Subsequently, thermodynamic modelling was applied to quantify the potential for chemical reaction between refractory and slag and refractory and metal in the tap-hole area.

Jan 1, 2014

By X. Chen, F. An, H. Chen, Z. Wang

The bottom drainage roadway plays a crucial role in preventing coal and gas outbursts by using underground gas drainage methods. Therefore, it is essential to select the ideal position of the bottom drainage roadway. In this paper use a combination of geological data and numerical simulation to study the ideal position of the bottom drainage roadway, we taking the gas drainage of the first workface of No. 3 coal seam in the Yuxi coal mine in China as an example. The geological study showed a limestone marker layer at an average vertical distance of 14 m from the first mining face. Using this marker layer, the bottom drainage roadway could be excavated without the risk of accidentally exposing the coal seam, and less crosscutting borehole drilling from the bottom drainage roadway would be required. Based on the needs of gas control, the layout of the bottom drainage roadway was selected as an external stagger type. Combined with the numerical simulation results, when located 20 m outside of the mining workface ‘footprint’ on the horizontal projection, the bottom drainage roadway was a sufficient distance from the stress concentration area during mining of workface 1301, which facilitated roadway maintenance. Furthermore, the length of the crosscutting boreholes is also relatively short, which reduces the amount and cost of drilling. The results of this study are expected to provide a reference for the selection of an ideal position of the bottom drainage roadway in field engineering.

May 2, 2022

By T. Uysal

Various morphological parameters that affect the flotation recovery of sphalerite were modelled and optimized using the response surface method (RSM). The effects of roughness value, shape factor, and collector concentration were investigated using the central composite full design method. The results were evaluated by analysis of variance. The optimum roughening time was found to be 25minutes, the optimum roughness value was 2.9071 μm, and the optimum collector concentrationwas 0.001 M. Using these values, a flotation recovery of 98.01% was obtained. Similarly, in shapefactor studies, the optimum grinding time was 15 seconds, the optimum roundness value 0.7421, and the optimum collector concentration 0.0009 M, which resulted in a flotation recovery of 94.30%. The average error between the optimization results and the experimental results was estimated to be less than 6%, and the R2 values were greater than 90%. The study shows that RSM can be effectively applied in finding the economic optimum condition for obtaining maximum flotation recovery with minimum reagent consumption.

Sep 6, 2023