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By Y. Jeong, K. Kim

Excess water can lead to instability and even failure in tailings storage facilities (TSFs). Simply reducing the amount of water in TSFs could be the best way to ensure the safety of nearby communities. In this case study we investigated the effects of reducing the water content in tailings slurry at a copper-cobalt-zinc mine in Mexico. An environmentally friendly polymer was used as a drag reduction agent (DRA) to offset the increase in solids percentage. The potential effects of the increased solids concentration on the tailings transportation system were also assessed. A series of ‘what if’ studies was conducted to assess whether adding the polymer would allow the solids concentration to be increased without changing the pressure loss in the tailings pipeline. The studies entailed conducting pipe loop tests to investigate these changes under various solids/ polymer concentrations and then constructing a computational fluid dynamics (CFD) simulation model using the test results. The validated model was used to determine the optimal polymer percentages needed to maintain the same pressure loss under baseline (30% solids) conditions, and to assess the potential risks (clogging, increased erosion rates) to the pipelines. The potential water savings were found to be significant, varying from about 1.852 Mm3/a at 35% solids to 3.915 Mm3/a at 45% solids.

Dec 13, 2023

By T. Chikande

"Falls of ground pose costly hazards to personnel and equipment and thus measures should be taken to prevent them. This study endeavours to improve the support systems used in geotechnically poor ground at a Zimbabwean platinum mine by analysing the status quo and recommending an effective support system. Various techniques were used to determine the quality of ground conditions, predict the rock mass behaviour, and to identify the appropriate rockbolt type. An analysis of the current ground control methods and their limitations was also undertaken.The results showed that the current support system and mining practices in poor ground need to be modified to improve safety and productivity. Stoping overbreak is influenced by poor ground conditions and the explosives currently used. The use of emulsion is recommended to replace ANFO. Redesigning of pillars is also recommended in poor ground conditions. An evaluation of the current roofbolt system indicated an opportunity for improvement. With new insight on the performance of the shorter length roofbolts currently in use, a new support system was recommended taking into consideration cost-benefit analysis. Barring down using pinch bars in poor ground was seen as a risky and time-consuming exercise, hence the use of mechanical scalers is recommended to achieve zero harm and to meet production targets. Smoothwall blasting is recommended in poor ground to minimize excavation damage. Other recommendations include the use of hydrological surveys to determine groundwater levels and implement corrective measures. Both empirical and numerical modelling approaches need to be utilized in determining the optimum support. IntroductionThe presence of geological discontinuities such as faults and joints weakens the rock mass. Adequate support is critical in achieving zero harm in underground mines. This paper reviews the current support systems used in poor ground conditions at a Zimbabwean platinum mine. The area of research is located on the Great Dyke of Zimbabwe. The mine exploits platinum group elements (PGEs) and base metals. It is shallow, having a maximum depth of less than 300 m. The Great Dyke is the second largest reserve of PGEs, following the South African Bushveld Complex (Oberthur et al., 2012). It is a linear layered intrusion that extends for about 550 km with a maximum width of 11 km (Prendergast, 1989). The generalized section of the Great Dyke is almost like a trumpet, comprising layers that dip towards the centre. The reef exploited at the mine, the Mineralised Sulphide Zone (MSZ), is located in the pyroxenite layer, which is hosted in the ultramafic sequence. The MSZ is a uniform layer about 2– 3.5 m thick, dipping at around 10–14° from surface outcrop towards the axis of the basin, and located between bronzite and websterite horizons. The visible disseminated sulphide mineralization shows a typical and consistent vertical distribution of platinum group metal (PGM) and base metal values. The research was undertaken to review the current support systems used in geotechnically poor ground conditions in a bid to improve both safety and productivity."

Jan 1, 2016

By M. Z. Naghadehi, E. Emami, J. Sattarvand, R. Battulwar

In this paper, a methodology for a computerised recognition of joint sets on 3D point cloud models of rock masses is presented. The process starts with classifying joints on a 3D rock mass surface through training a deep network architecture and validated using manually labeled datasets. Then, individual joint surfaces are identified using the Density-Based Scan with Noise (DBSCAN) clustering algorithm. Subsequently, the orientations of the identified joint surfaces are computed by fitting least-square planes using the Random Sample Consensus (RANSAC). Finally, the joint planes are classified into different joint sets, and the dip direction and dip angle for each set are calculated. The performance of the proposed methodology has been evaluated using a case study. The results show that the presented procedure is fast, accurate, and robust.

Sep 1, 2021

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 B. Rezai, Z. Pourkarimi, M. Noaparast, S. Chehreh Chelgani

Nanobubbles (NBs) flotation separation can be an indicator for improving the efficiency of fine particles through the conventional process. Since flotation reagents such as frothers can reduce bubble size, they can potentially be used for the generation of NBs and develop a selective NB flotation separation. This study explored the flotation separation of fine phosphate particles from their associated minerals in the presence of NBs, which were generated by using a phosphate flotation reagent (Flo-YS: collector-frother). The results of flotation tests showed that in the presence of NBs, the flotation efficiency was significantly improved. However, in the presence of NBs, surface chemistry analyses (Fourier Transform Infrared Spectroscopy and High-Performance Liquid Chromatography) illustrated that the collector adsorption on the surface of phosphate particles decreased. A comparison between outcomes of various phosphate flotation conditions indicated that increasing the flotation efficiency in the presence of NBs may be due to the aggregation of fine particles by the generated NBs, and also selective adsorption of NBs (hydrophobisation) on the surface of particles. In other words, generating NBs by selective collectors may increase efficiency and decrease the collector consumption of a flotation process. Keywords: Phosphate, selective separation, fine particles, collector-frother, efficiency, mechanical flotation cell

Jan 1, 2020

By A. Esterhuizen

Since 2005 Two Rivers Platinum Mine has set out on an initiative to actively monitor and control ground conditions on a daily basis, by making use of borehole cameras and pro-actively amending the support and mining strategies based on day-to-day observations of the hangingwall conditions. Today the borehole camera observations form part of the Rock Engineering Department?s daily function, and the size and frequency of falls of ground and ensuing accident rates have been drastically reduced since implementation of the system. The Two Rivers Platinum fall-of-ground management system aims to support 100% of the possible fallout thickness, based on ongoing data gathering and interpretation, thereby ensuring safety and limiting support cost.

Jan 1, 2014

By S. Banisi, A. Ghasemi, E. Nematollahi

Discrete element method (DEM) has been used as a popular simulation method to verify designs by visualising how material will flow through complex equipment geometries. Although DEM simulation is a powerful design tool, finding a DEM model which includes real material properties (e.g., shape, cohesion and friction coefficients) is not computationally feasible. In order to obtain more realistic results, particle energy loss due to rolling friction has been highlighted by many researchers. To implement a reverse torque to account for rolling friction, various models have been proposed. On account of the complexity of the problem, there is no unique model for all applications (i.e. dynamic and pseudo-static regimes). In this paper, an in-house developed DEM software (KMPCDEM ©) was used to assess the robustness of three commonly used models by comparing the repose angle of iron ore pellets obtained through the draw down test in a laboratory setup and then the elastic–plastic spring dashpot model was modified based on considering the individual parameters instead of relative parameters of two contact entities. Results showed that the modified model could produce higher repose angle. The modified model was used to calibrate DEM simulation of repose angle of iron ore pellets in a laboratory setup of the draw down test. Comparison of the calibrated DEM simulation and laboratory results showed 2° differences between the predicted and measured angle of repose. This difference was attributed to considering the particle shape effects by assuming a spherical shape for particles. Keywords: DEM, rolling friction,particle shape, repose angle

Jan 1, 2020

By S. M. Spottiswoode, Linzer. L. M.

We report on further progress in improving seismic locations by using the so-called double-difference method (Spottiswoode and Milev, 1998 and Waldhauser et al., 1999). Double-differences are obtained either using picked arrival times or various measures of time differences obtained from waveform pairs. The double-difference method provides for much improved relative locations by reducing the effect of the errors in the wave velocity of ray paths between each event and each geophone. Further improvements are obtained by using known locations, such as blasts. One of the difficult problems that we have overcome is that of finding the best “weights” for the time corrections. Experience obtained in relative moment tensor inversions by Andersen (2001) suggests that use of median corrections is both more stable and more accurate, even while the locations of the individual events is based on weighted least-squares minimization. A hybrid location program with known reference events has been developed. Tests on a synthetic data set gave relative locations that were much less widely spread than the absolute locations. The use of known event coordinates (blasts) moved the relative locations back towards the real locations. These results are confirmed in preliminary analysis of data from a mine. The absolute locations are adjusted using blast events restricted to the line of tunnel development. Inter-event distances are distributed in a power-law fashion that suggests that the relative location accuracies are improved by a factor of three or more. Nous rendons compte des progrès faits dans l’amélioration des locations de séismes en utilisant la méthode appelée de double- différence (Spottiswoode and Milev, 1998 et Waldhauser et al., 1999). On obtient les double-différences soit en utilisant des temps d’arrivée choisis soit des mesures variées de différences de temps obtenues de doublets de forme d’onde. La méthode de double-différence fournit des locations relatives très améliorées en réduisant l’effet des erreurs dans la vitesse d’onde des trajectoires de rayon entre chaque évènement et chaque géophone. D’autres améliorations sont obtenues en utilisant des locations connues, telles que les coups de mine. Un des problèmes difficiles que nous avons surmontés est celui de trouver les meilleurs coefficients de pondération pour les corrections de temps. L’expérience obtenue dans des inversions de phases tensorielles relatives par Andersen (2001) suggère que l’utilisation de corrections médianes est à la fois plus stable et plus exacte, même lorsque la location des évènements individuels est basée sur minimisation pondérée de moindres carrés. Nous avons développé un programme hybride de location avec des évènements connus pour référence. Des tests sur des données artificielles ont donné des locations relatives qui étaient beaucoup moins étendues que les locations absolues. L’utilisation de coordonnées d’évènements connus (coups de mine) a ramené les locations relatives vers les locations réelles. L’analyse préliminaire des données d’une mine a confirmé ces résultats. Les locations absolues sont ajustées en utilisant des évènements de coup de mine restreints à la ligne du développement du tunnel. Les distances entre chaque évènement sont distribuées comme par loi exponentielle ce qui suggère que les degrés d’exactitude des locations relatives sont améliorés par un facteur de trois ou plus. Wir berichten über einen weiteren Fortschritt, die seismische Positionen unter Verwendung der zu sogenannten Doppel-Unterschied-Methode (Spottiswoode und Milev, 1998 und Waldhauser et al.,1999) zu verbessern. Doppel-Unterschiede werden entweder mit ausgewählten Ankunftszeiten oder verschiedenen Messungen von Zeitunterschieden erreicht, die von den Wellenformpaaren erhalten werden. Die Doppel-Unterschied-Methode liefert viel verbesserte relative Positionen unter Verringerung der Auswirkung von Fehlern in der Wellengeschwindigkeit von Strahlengängen zwischen jedem Fall und jedem Geophon. Weitere Verbesserungen werden erreicht, indem man bekannte Positionen, wie Sprengungen verwendet. Eines der schwierigen Probleme, die wir überwunden haben, ist jenes des Findens der besten "Gewichte" für die Zeitkorrekturen. Die Erfahrung, die in den relativen Momentspannerumkehrungen von Andersen (2001) gewonnen werden bietet den Schluß an, daß der Gebrauch von mittleren Korrekturen beständiger und genauer ist, sogar wenn die Positionen der einzelnen Fälle auf der bewerteten Reduzierung der Methode der kleinsten Quadrate basiert. Ein hybrides Positionsprogramm mit bekannten Bezugsfällen ist entwickelt worden. Tests auf einem synthetischen Dataset gaben relative Positionen, die viel weniger weit gestreut waren als die absoluten Positionen. Der Gebrauch von bekannten Fallkoordinaten (Sprengungen) schob die

Jan 1, 2003

By W. P. Channon, J. B. See

The reduction of fluxed and non-fluxed manganese, ores by ferromanganese silicide by W. P. CHANNON, B.Se. (Eng.), M.Sce. (Eng.) Wits. (Visitor) and J. B. SEE, B.Sce. Hons., Ph.D. (New South Wales), M.I.M., M.I.M.M. (Member) In South Africa, medium-carbonferromanganese is produced by the silicothermic reduction of slags containing MnO. Because of its importance in the production of refined ferromanganese, a study was made of the reaction between a premelted South African Mamatwan manganese ore and various ferromanganese silicide reducing alloys, with and without fluxing agents. Because the reaction is highly exothermic, temperature appeared to have little effect on the rates of manganese transfer to the metal and silicon transfer to the slag, and an apparent equilibrium was rapidly approached. Limits were determined for the favourable effects of fluxing additions, and manganese recoveries were found to decline as the ratio of CaO to MgO decreased as a result of the addition of basic flux. The recovery of manganese passed through a maximum, and subsequently decreased for variations in the ratio of alloy to ore. The results obtained, when used in conjunction with other physicochemical data related to this slag-metal system, suggest optimum slag compositions for the efficient manufacture of medium-carbon ferromanganese from Mamatwan ore.

Jan 3, 1977

By N. Mutemeri, T. -L. Field, M. Chuma

The categorization of artisanal and small-scale mining has a significant impact on perception and understanding of the sector, particularly from a livelihood perspective. Several developing countries classify different types of artisanal and small-scale mining based on legal status. Given the nature such activities, the tragedy of the commons theory has been applied to understand the inevitable environmental, economic, sociocultural, safety, and health negative externalities – which are products of informality and illegality. Consequently, formalization is a panacea to sustainability. This article aims to offer a conceptual organization and foundational knowledge for characterization of artisanal and small-scale mining. It seeks to identify existing literature on the subject to avoid replication and acknowledge other scholars. Moreover, the article aims to place the study within the context of existing literature, establishing relationships with other studies and why the research is necessary. This paper pinpoints gaps left from other studies in so far as the characterization of artisanal and small-scale mining is concerned. Thus, reviewing literature abetted in finding similarities and differences on how artisanal and small-scale mining is defined from a scholarly and legal basis. The paper ascertains major claims made by earlier research on this topic, such as environmental impacts, the lack of adequate regulatory framework, and presents querying and probing questions lacking from other studies.

Jul 10, 2024

By M. Rudolph, A. D. Renno, H. Wu

In this study, synthetic pure cassiterite and cassiterite doped with Fe were successfully produced by sintering. Their crystal structure and chemical compositions are characterised by optical microscopy, X-ray powder diffraction (XRD) as well as scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) based chemical composition analysis. The electrostatic behaviour of synthetic and natural cassiterite was studied by electrophoretic measurements. Their floatability was studied by microflotation with two types of anionic collectors. Results show that the cassiterite floatability with these collectors behaves differently and lead to two opposite results: Natural cassiterite (enriched with Fe) > undoped pure SnO2 by using sulfosuccinamate (Aerosol® 22) Undoped pure SnO2 > Fe3+ doped > natural cassiterite (enriched with Fe) by using styrene phosphonic acid (SPA). Keywords: Synthetic cassiterite, lattice impurities, flotation, zeta potential, Aerosol® 22, styrene phosphonic acid

Jan 1, 2020

By B. Kweto, W. Legodi, C. van Buuren, R. F. Sandenbergh

Biooxidation, and especially the BIOX® process, is a viable, economical and environmentally attractive process to liberate gold hosted in refractory sulfides by oxidatively leaching the sulfides as soluble sulfates. The moderate to high cyanide consumption during the subsequent cyanidiation of the washed biooxidation residue is probably caused by the retention on the solids of labile sulfur species formed during the multi-electron oxidation process of sulfide to sulfate. In this work the nature and mode of transport of the cyanicides in the products from the mesophile BIOX® process, as well as that of the combined mesophile and thermophile bioxidation process, were considered and strategies to reduce cyanide consumption evaluated. It was found that labile sulfur species were the major cyanide consumers in the mesophile biooxidation product, forming predominantly thiocyanate during cyanidation. The transfer of labile sulfur species was only marginally decreased by more intensive and thorough washing of the biooxidation products with warm and hot water, intense stirring and warm caustic leaching. A major reduction in cyanide consumption was however achieved by using a combined mesophile and thermophile biooxidation process. Keywords: Biooxidation, refractory sulfide gold ores, cyanide consumption

Jan 1, 2020

By M. Royker

Gold has been demonstrated as a possible catalyst for oxidation reactions. Some evidence for a possible promotion effect of platinum has also been recorded. The influence of platinum as promoter for Au/?-Al2O3 prepared via anionic ion-exchange for the oxidation of glycerol was investigated in a batch reactor at 60°C. It is inferred that the addition of platinum reduces the catalytic activity and the rate of deactivation, resulting in an overall higher final conversion of glycerol with increasing platinum loading. The addition of platinum to the catalyst favours the formation of the desired product, glyceric acid.

Jan 1, 2012

By D. K. Weatherley, T. P. Oladele, L. B. Bbosa

Comminution is a critical stage of mineral processing which aims to reduce the size of ore particles through breakage, consequently increasing the likelihood of liberation of valuable minerals. Several factors, such as pre-existing cracks, mineralogical composition and particle size, are known to affect ore breakage behaviour. While investigating the contributing role of each factor is essential to improve understanding of breakage, isolating individual factors by experiment is typically impractical. Numerical techniques such as the Bonded Particle Model-Discrete Element Method (BPM-DEM) have been developed as a means of studying closely controlled breakage conditions. This study evaluates this technique in modelling the effect of pre-existing cracks breakage behaviour for synthetic ore specimens during impact breakage in a short impact load cell (SILC). Synthetic ore was modelled as a collection of discrete entities connected by brittle-elastic beams. Model parameters were calibrated against macroscopic material properties of a conventional homogenous synthetic ore. The extent of pre-existing cracks within specimens was prescribed by varying discontinuities between the connecting entities. An approach with the insertion of seed points was used to model the mineralogy of the specimens. Results showed that pre-existing cracks resulted in a decrease in the fracture force as the crack density increased. Additionally, the irregularity of fracture patterns within rock specimens after impact became more apparent as the crack density increased. The findings were used to emphasise some of the attributable causes of the variation observed between ore hardness characterisation tests and in situ ore behaviour. Keywords: Element Method; Bonded Particle Model, synthetic rock sample; rock fracture, preexisting cracks

Jan 1, 2020

By K. Sasaki, Y. Oriia, Shigeto Kuroiwa, H. Miki, Yuji Aoki, T. Hirajima, G. P. W. Suyantara

The effect of a sulfite reagent on the floatability of chalcopyrite and enargite was investigated in this paper. The flotation tests using single and mixed minerals were performed under various concentrations of sulfite. The flotation tests using a single mineral showed that the sulfite reagent depressed the natural floatability of both minerals at pH 9. Surprisingly, enargite was floated after the addition of potassium amyl xanthate (PAX) following the sulfite treatment, and the floatability of chalcopyrite depressed under a similar condition. X-ray photoelectron spectroscopy analysis results showed that the sulfate species increased after the sulfite treatment on both minerals. However, the addition of PAX removed this sulfate species and rendered the enargite surface hydrophobic. This phenomenon was not observed on the chalcopyrite surface. FTIR analysis and PAX adsorption studies were performed to support this finding. The flotation of a mixed mineral was in agreement with the flotation of a single mineral, indicating a possibility for selective flotation of chalcopyrite and enargite using the proposed method. Keywords: Flotation, chalcopyrite, enargite, sulfite, potassium amyl xanthate

Jan 1, 2020

1. Book reviews Geostatistics for natural resources characterization, edited by G. Verly, M. David, A.G. Journel, and A. Marechal. Hingham (MA 02043, U.S.A.), D. Reidel Publishing Co., 1984. Pt I: 606 pp. Pt 11: 518 pp. U.S.$135,50 per set. Reviewer: D.G. Krige Magnesium, the international perspective, by Peter King. London, Financial Times Business Information Ltd, 1984. £120. 147 pp. Reviewer: D.G. Maxwell 2. Mintek reports Report M156 A kinetic study of the reactions of certain gaseous sulphur compounds with iron. Report MI57 Reaction mechanisms in the reduction of Winterveld chrome spinel with graphite and carbon. Report MI72 Computer programmes for the control and datamanipulation of a sequential X-rayfluorescence spectrometer. Report MI77 A proposed test for the determination of the grindabi/ity of fine materials. Report MI86 A survey of the erosion, corrosion, and abrasion of material-handling systems in the mining and mineralprocessing industry. 3. New journal Advanced materials & processes, issued monthly by American Society for Metals (Metals Park, Ohio 44073, U.S.A.). CIM conference The combined 24th Annual Conference of Metallurgists and the 15th Annual Hydrometallurgical Meeting will be held in Vancouver from 18th to 22nd August, 1985. Light metals The 8th International Light Metals Congress will take place from the 22nd to 26th June, 1987. These meetings, which take place traditionally every few years, are organized by the Austrian Metals Industry Association, the Austrian aluminium industry, and the University for Mining and Metallurgy in Leoben, in collaboration with the Aluminium-Zentrale Diisseldorf. President of AS&TS* Mr Arthur Woodington Reynolds (Sam) took office as President of The Associated Scientific and Technical Societies of South Africa on 28th November, 1984. Sam Reynolds was born in Boksburg on 27th December, 1930, and received his education at Christian Brothers College in Boksburg and at St John's College in Johannesburg. World mining Sweden, Finland, and Norway expect representatives of all mining countries in May-June 1987 to the 13th World Mining Congress in Stockholm. The Swedish Mining Association, the Finnish Association of Mining and Metallurgical Engineers, and The Association of Norwegian Mines will organize the Congress, together with the International Organizing Committee of the World Mining Congress. Sheet metal The German Group of the International Deep Drawing Research Group (IDDRG) will be organizing the 14th Biennial Congress of the IDDRG on 21st to 26th April, 1986, in Cologne and Munich. Safety in mines The 21st International Conference of Safety in Mines Research Institutes is to be held in Sydney from 20th to 25th October, 1985. ILAF A conferences The Instituto Latinoamericano del Fierro y el Acero (ILAFA) has scheduled the following congresses for 1985. Mechanical testing of materials The Deutsche Gesellschaft fiir Metallkunde, together with the Deutschen Verband fiir Materialpriifung and the Fachhochschule Osnabriick, is holding a course on the methods used for the mechanical testing of materials at Osnabriick from 9th to 11th September, 1985. Mine ventilation The Second U.S. Mine Ventilation Symposium will be presented from 23rd to 25th September, 1985, in Reno, Nevada, by the University of Nevada-Reno's Mackay School of Mines and Division of Continuing Education.

Jan 1, 1985

By L. S. Bicalho, W. J. Rodrigues, P. M. A. Rollo, P. R. G. Brandão, W. C. da Silva

Quadrilátero Ferrífero is an important mineral province located in Minas Gerais state, responsible for a substantial amount of iron production in Brazil. Among the concentration methods for iron ore practised by the mining companies in this region, the most important is the reverse cationic flotation. Dolomite iron formations, with the presence of hematite, quartz and dolomite, occur in several areas of mining and, with the deepening of the deposits, this type of ore, with low iron content and more complex mineralogy occurs frequently. Carbonaceous minerals, mainly dolomite, present a technological challenge for the concentration of iron ore by flotation. In the present study, the concentration of iron ore with 6% of dolomite content was evaluated. Bench flotation trials indicated that conventional iron ore flotation is not selective to float dolomite, thus compromising the iron content in the final concentrate. Alternative flotation routes were evaluated, and a selective condition was reached to float both quartz and dolomite using the combination of the cationic collector Flotigam 16424 with an anionic collector Flotinor 16551. It was demonstrated that the flotation of dolomite was improved with the combined use of both collectors in the cleaner stage, and by a previous quartz flotation in the rougher stage. Zeta potential analysis indicated specific adsorption as the adsorption mechanism between Flotinor 16551 and dolomite, confirming the high selectivity observed in the bench flotation tests. Keywords: Flotation, iron ore, dolomite

Jan 1, 2020

On 8th August, 1973, 57 members of the Institute visited Prieska Copper Mine at Copperton in the North Western Cape. After tea, the group was welcomed by the Management of the Mine, and Mr Grobler, the General Manager, gave an introductory talk. After they had been taken on a bus tour of the property, the members split up into groups and proceeded underground or to the concentrator. Of special interest to the mining members were the rock-handling methods in use at the mine. The stoping method that has been adopted is the continuous, long-hole sub-level open stoping system. The broken ore is moved with rubbertyred front-end loaders from the stope drawpoints to the ore passes. On the main tramming levels, the ore is collected by electric locomotives and discharged into the main shaft system at the bottom. At the shaft ore-pass system, a gyratory crusher that can accept rocks up to 1 m in diameter has been installed. The crushed product (minus 150 mm in diameter) will then be hoisted by a Koepe winder, which has a rated capacity of 900 tons per hour. The mine is also served by a declined roadway from surface, which facilitates the movement of heavy equipment. The most striking aspect is the productivity that can be achieved by the use of a trackless-mining system. For the production of 230 000 tons per month, it is estimated that 6 stopers and 7 developers will be required. The total labour force will be approximately 2500-2000 Bantu, 200 Coloured, and 300 Europeans. Training of maintenance and operating personnel is of the utmost importance, and it was interesting to note the extent to which non-White labour is being used in these occupations. Lunch was served at the single quarters, after which the group proceeded to the airfield for the return trip to Johannesburg. On behalf of the visitors, Professor de V. Lambrechts thanked Mr Grobler and his staff for the most interesting morning and for their hospitality,

Jan 10, 1973

By V. van der Merwe, C. W. Siyasiya

"A petrochemical company experiences premature thermal fatigue failure of the casting moulds used in catalyst production. The aim of the project was to find an alternative alloy that would outperform the current low-alloy cast steel used for the moulds. Based on their thermo-fatigue properties, 3CR12 ferritic stainless steel and H11 tool steel were chosen for testing and comparison with the currently used BS3100 B7 cast steel. Samples of each material were subjected to temperature cycling in a Gleeble 1500TM thermo-mechanical processing simulator, followed by surface analyses. The main parameters derived from the test work were the total true strain, the hot strength of the materials, and the number of cycles to failure. Additionally, the coefficient of thermal expansion for each material was measured using a Bähr dilatometer. H11 tool steel yielded the best performance by way of having the fewest surface cracks, the lowest total true strain per cycle, the most cycles to failure, the highest hot strength, and the lowest coefficient of thermal expansion.IntroductionThe Catalyst Manufacturing Plant (CMP) is a dusty environment with temperatures higher than ambient. Molten mill scale (magnetite, Fe3O4) is tapped from the electric arc furnace into the casting moulds at temperatures close to 1600°C. After 10 seconds the magnetite is quenched with a water spray for 50 seconds to a minimum temperature of 400°C. Sometimes there is residual water in the pans from the cooling fog process (water sprays) in the empty mould. In a typical plant, the factory produces 40–44 batches a day containing between 150–300 moulds, depending on the time required for the specific batch (Buchholz, 2014). The typical batch in the CMP usually weighs about 6 t. The thickness of the tap, speed of the casting belt, and tilting angle all affect the number of moulds per batch.One of the main problems faced during the molten mill scale casting is the premature failure of the casting moulds. Cracks initiate on the surface of the mould, which is in contact with the hot catalyst, and propagate into the interior of the mould. Cracks are generally concentrated in the middle area of the mould where the catalyst makes first contact with the mould, and which experiences the highest temperature fluctuations. This suggests that the cracks are caused by thermal fatigue during the casting process."

Jan 1, 2016

By X. Yang, G. D. Zhai

The prop is the most important part to ensure the proper functioning of hydraulic support. When the hydraulic support is impacted by the roof, the prop is prone to extrusion deformation, expansion, and even bursting. In order to study the stress on a doubly-telescopic hydraulic support prop under impact load, an impact simulation was carried out based on the drop weight method. First, the impact model of the hydraulic system of the prop was established in AMESim software and the dynamic response curves of the bottom and middle cylinder of the prop obtained. Then, according to the conservation of energy, the pressure formulaes in the hydraulic cylinder of the prop under impact load were derived and verified by the AMESim simulation results, and the maximum pressure on the inner surface of the hydraulic cylinder of the prop obtained. Lastly, the transient dynamic simulation of a hydraulic support prop was carried out in ANSYS Workbench software, and cloud diagrams of stress and deformation of the prop obtained using Workbench simulation. The AMESim simulation process describes the change in fluid pressure in the prop, and the pressure formulae can be used to estimate the internal pressure of the prop under impact load. The finite element analysis results show that the stress of the middle hydraulic cylinder is much greater than that on the bottom hydraulic cylinder under impact load, which can provide a reference for prop design.

Jul 2, 2022