Search Documents

By D. Pienaar, C. O’Connor, B. McFadzean

Dithiophosphate (DTP) is classically used as a co-collector in sulphide mineral flotation, where xanthate-DTP mixtures have been shown to synergistically improve mineral flotation performance. Notwithstanding the improved recoveries observed, ethyl DTP does not appear to behave as a conventional collector, since it has been shown that it does not adsorb onto certain sulphide mineral surfaces. Recent investigations have nevertheless indicated that when ethyl DTP does not adsorb onto the sulphide mineral surface, the presence of a non-ionic frother can activate a synergistic increase in pulp phase mineral recovery, and bubble-particle attachment probability. A regular solution approach was used to determine the interactions between thiol collectors and non-ionic frothers at the air-water interface. Attractive interactions were observed between longer alkyl chain DTPs and frothers, whereas the activity of xanthates at the air-water interface were too weak to determine if an interaction was occurring. This is the first time that such interactions have been shown for the DTP-frother system and represents an important contribution to our understanding of the role of DTP reagents in the flotation process. Keywords: Collector-frother interaction, dithiophosphate, surfactant synergism

Jan 1, 2020

By T. Song, X. Wang, X. O. Xia, X. J. Luo, B. Chen

Interparticle breakage is the main crushing mode of an inertia cone crusher according to its working principle and feeding condition. In this paper the breakage behaviour of an inertia cone crusher is investigated, based on energy controlled compression combined with the vibration theory, rather than geometry controlled compression (form conditioned) which plays a major role in conventional eccentric cone crushers. The effect of feeding and operating conditions on breakage behaviour was described quantitatively from the perspective of energy consumption and product size distribution. The influence of feeding conditions, discharge size settings and vibration exciter speeds on the crushing process and product quality has been studied according to the results of laboratory crushing experiments. The results of the experiments show that the particle size of broken products becomes finer with the decrease of a discharge gap within the gap range selected by the experiment. The product size increases significantly when the gap approaches the upper limit of 6 mm. The variation of eccentric speed has a more prominent effect on reducing the product size compared with the change of discharge gap. The change in product size is not apparent when the eccentric speed rises to a certain level. The throughput of an inertia cone crusher is sensitive to the change of discharge gap, which increases linearly with the discharge gap and decreases with the eccentric speed. The change of feeding conditions has little influence on the crusher throughput. Keywords: Inertia cone crusher, interparticle breakage, energy consumption, product size distribution

Jan 1, 2020

By Y. Makola, M. Kilumba, S. Mwaba, P. Ilunga, F. Banze, B. Nel, P. Kyoni, N. Mautsa, R. Nkomba, G. Ilu

Kamoto Copper Company is a copper cobalt mining company established in Lualaba Province of Democratic Republic of Congo under a Joint Venture between Glencore PLC and Gecamines (the state-owned mining company). Operations consist of underground and open pit mines, a concentrator producing sulfide concentrate and oxide ores milled slurry, and a hydrometallurgy plant producing copper cathode and cobalt hydroxides from concentrate and ores. The production capacity is 300 k/a of copper cathode and 35 kt/a of cobalt hydroxide. Since Q4 2020, the Luilu hydrometallurgy plant has experienced operational instabilities due to increase in proportion of dolomite in the ore mined and fed to the plant. This was diagnosed by the significant increase in calcium grade in ore and acid consumption, continuous foaming, and overflow of tanks with subsequent adverse impact on equipment availability due to corrosion caused by acidic spills, structure integrity, and safety concerns around the acidic slurry spills. Production was adversely impact due above equipment availability and often throughput restriction to mitigate the foaming and overflows. A high gangue-acid-consuming ore management programme was developed with the aim of mitigating these impacts. The programme included: (i) use of defoamer agent in leach to stop foaming and overflow, (ii) design of a mechanical solution to leach foaming and overflow, and (iii) froth flotation for copper and cobalt minerals separation from dolomite. Only option (i) is presented in this paper. Through laboratory testwork, pilot-plant testing, plant trial, and full plant implementation, Kamoto Copper successfully implemented a defoamer agent (Kemfoam X9980) dosing at leach, resulting in significant reduction in foaming and overflow of leach reactors and countercurrent decantation thickeners. The optimum defoamer dose rate obtained was 20 mg/L. Since then, the Luilu recovered its operational stability, the corrosion of critical equipment ceased, and availability improved as the acidic leach slurry spills ceased. The constraint on throughput due to leach foaming was addressed and the frequency of sliming events in the thickeners was significantly reduced as the foaming on the supernatant surface ceased, with subsequent significant reduction in interfacial crud in solvent extraction.

Jan 1, 2023

By G-L. Wu, S-W. Wu

"The hot deformation behaviour of Nb-Ti microalloyed high-strength steel was investigated. Hot compression tests were conducted in the temperature range 900 to 1100°C under strain rates of 0.1, 1, and 5 s-1. Dynamic recrystallization (DRX) occurs as the main flow softening mechanism at high temperature and low strain rate. The hot deformation activation energy was calculated to be about 404 699 J/mol. The constitutive equation was developed to describe the relationship between peak stress, strain rate, and deformation temperature. The characteristics of DRX at different deformation conditions were extracted from the stressstrain curves using the work hardening parameter. The Cingara-McQueen equation was developed to predict the flow curves up to the peak strain. The processing maps were obtained on the basis of a dynamic materials model. The results predict an instability region in the temperature range 1010 to 1100°C when the strain rate exceeds 0.78 s-1. IntroductionThe 700 MPa grade HSLA steel is widely used in engineering machinery, automotive beams, carriages, and axle tubes, etc. (Pan et al., 2017 ). Generally, such grades contain a moderately high amount of Mn (approx. 1.4% and above), and microalloying elements like Nb, Ti, V, and Mo to impart the desired strength and toughness through solid-solution strengthening, precipitation hardening, and grain refinement dislocation strengthening (Chen and Yu, 2012; Opiela, 2014). However, the production costs can be greatly reduced by replacing part of the Nb, V, or Mo with inexpensive Ti and adopting the compact strip production CSP process (Opiela, 2014; Chen et al., 2015). Furthermore, the microalloying technology coupled with new-generation thermomechanical control processing (NG-TMCP) has proved efficient for achieving the proper balance between strength, toughness, ductility, and formability by means of a suitable combination of chemical composition and thermomechanical treatment parameters (Shukla et al., 2012; Wu, Zhou, and Liu, 2017).In hot forming processes, the complex microstructural evolutions are often induced by multiplicative hot deformation mechanisms, such as work hardening (WH), dynamic recovery (DRV), and dynamic recrystallization (DRX) (Zhang et al., 2014; Liang et al., 2015). Dynamic softening behaviour during hot processing has generated considerable interest because component properties are influenced significantly by its corresponding microstructural evolution (Wu et al., 2010). During deformation in the DRX process, deformed grains are replaced with substructures and newly formed fine and uniformly distributed grains. This occurs only when a critical strain for the onset of DRX is reached, and at the same time, the minimum rate of energy dissipating is reached (Ferdowsi et al., 2014). DRV occurs at a high strain rate and low temperature, reducing the stored energy greatly and making DRX difficult (Liang et al., 2015). The microstructural changes during DRX are sensitive to the processing parameters, such as strain rate, deformation temperature, and strain (Zhang et al., 2014; Ferdowsi et al., 2014). Therefore, in order to optimize the hot processing parameters, it is important to understand the behaviour of hot deformation visà- vis control of microstructural evolution."

May 1, 2019

By F. T. Cawood, M. N. M. Cudjoe

The ability to conduct real-time material tracking in mines has been a long-standing challenge. Technological innovations such as radio frequency identification technology (RFID) have over the years contributed to the effective tracking of material flow and reporting of metal content. This paper outlines the laboratory procedures and results from testing the suitability of microdot technology as a viable technique for real-time material tracking in mining. The paper clarifies the reasons for conducting the test and presents the material safety data sheet (MSDS) from a South African and Canadian perspective. Microdots from three aerosol systems were immersed in water, heated to 100°C, and crushed into coarse and fine material. These tests were used to ascertain if the technology could withstand mining conditions. A strength, weakness, opportunity, and threat (SWOT) analysis was used to evaluate and compare microdot technology with RFID. It was shown that microdot technology has some potential to track ore parcels because data integrity was retained after exposure to post-blast mining conditions. However, more improvement is required to digitally detect microdots before the technology can be implemented at scale in the mining industry.

Apr 2, 2022

By G. Akdogan, T. P. Kekana, Q. G. Reynolds

The DC arc plasma gasifier concept is currently under development at Mintek for testing the feasibility of producing syngas from waste coal fines and dry steam. The technology is intended for the valorisation of low-grade discard coals into market-quality syngas, which may then be used for largescale electrical power generation to address current grid supply challenges in South Africa. Other potential applications include feedstock for petro-chemical plants, fuel for transportation vehicles, domestic and industrial heating, and others. The proposed concept of a DC arc plasma gasifier was developed based on a plasma torch, metallurgical-based and entrained flow coal gasifiers. The principles of design and operation of the proposed gasifier are based on the concept of the Westinghouse Plasma Corporation (WPC) gasifier where the torches are substituted by graphite electrodes from which electric arc plasmas are generated. The DC section of the gasifier will be designed considering Mintek’s experience in the sealing of the furnace as carried out in the Mintek Thermal Magnesium Process. As part of the building blocks of a full conceptual design, the feasibility of the DC arc plasma gasifier was investigated through testing and modelling of its critical elements as proof of concept. The main activities of this work included pilot scale evaluation of the arc behaviour in the presence of dry steam, modelling of the temperature distribution within the reactor and explosibility studies on three different coal dust samples. Keywords: DC arc plasma gasifier, explosibility index, lower explosion limit, minimum ignition energy

Jan 1, 2020

By Y. Fan, D. H. Zhang, J. Y. Xu

The hydrogeological conditions in the Chambishi mine area in Zambia. were investigated. Chambishi is a very wet mine and groundwater discharge costs are high. The research goal was to identify methods to reduce the discharge costs without greatly affecting the mining process. Hydrogeological data was obtained from measurements in drill-holes and from drill cores. The differences in structural deformation in different areas determine whether a layer of rock is an aquifer. In the mine region, the Lower Roan Group ore shale and quartz-sandstone unconformably lie on the basal schist and granite aquifuge. The Upper Roan Group dolomite is continuously distributed over a large area around the orebody. This dolomite is the main target of groundwater control efforts, and its water yield is also influenced by the deformation intensity. Based on the observations, backfilling was gradually adopted to appropriately safeguard the integrity of the aquifuge above the orebody. The overlapping relationship between the aquifer and aquifuge has been utilized to increase mine drainage efficiency. This measure has not only greatly reduced the costs of mine drainage, but also improced protection of the groundwater environment. The old drill-holes that were not sealed after exploration drilling were grouted. Further, possible water-conducting fracture zones were investigated. Cover drilling towards the suspected zone was conducted to prevent the high-pressure groundwater from shallower aquifers from entering stopes in deep areas of the mine.

Jun 10, 2024

By M. Shaw, H. R. Heydenrych, A. E. Lewis, E. Glass, J. Chivavava

The removal of calcium from the retentates of reverse osmosis (RO) treated minewater is desirable since it allows the recovery of both additional potable water (through RO) and higher-purity salts (in downstream processing). This, in turn, reduces the need for costly and unsustainable evaporation ponds and enhances the economics and operability of potential zero-liquid discharge downstream processes, e.g. evaporative-, cooling- and eutectic freeze-crystallisation. For this study, a multi-component retentate high in sodium content was considered, typical of those emanating from minewater reclamation plants in Mpumalanga, South Africa. Four technologies were evaluated to remove calcium: gypsum precipitation by addition of lime; calcium carbonate precipitation by addition of soda-ash; heating crystallisation of calcium sulphate anhydrite; and cooling crystallisation of gypsum. Full processes were developed and simulated using electrolyte thermodynamics. Using the results of these simulations, capital- and operating costs, as well as revenues were calculated and used in economic comparisons of the processes. Sensitivities to key purchasing and selling prices were also investigated to understand the impact of changes in these variables. For the case of a low magnesium-to-sodium ratio in the feed, gypsum precipitation through lime addition was found to have the lowest operating and total annualised costs; but, if revenue could be derived from the sale of sodium sulphate, calcium carbonate precipitation through soda-ash addition was favoured. Keywords: Calcium removal, gypsum precipitation, calcium carbonate precipitation, heating crystallsation, cooling crystallisation, economic comparison

Jan 1, 2020

By S. Purushotham, Y. R. Murthy, M. Narasimha, S. K. Tripathy, M. Kumar

Spiral concentrators are gravity-based separators widely used to beneficiate coal, heavy minerals and beach sand. It consists of a helicoid trough that spirals downward in the helical configuration around an axial column. The particle segregation takes place based on size and density under the influence of gravity as the particles spiral down within the thin water layer. In the last century, most design modifications of this equipment were based on trial and error based lab-scale experimentations and empirical approach. The use of Computational Fluid Dynamics (CFD) has gained interest in the past two decades to understand the underlying flow physics in the spiral concentrators. In this paper, we used CFD to model the fluid flow and investigate the particle segregation inside a conventional LD9 spiral concentrator. Firstly, the Volume of Fluid model was used to resolve the liquid-air interface. The liquid depth and flow field predictions for varying flowrates were validated against the experimental literature data. One-way coupled VOF-LPT model was then used to describe the particle dynamics in the spiral flow field assuming dilute particulate flow. Moderate dense particulate flow (20 vol.%) was then modelled using the Algebraic Slip Mixture (ASM) model. Four particle-phases representing particles of different sizes of dual-density were simulated, and the component particle segregation was analysed. Keywords: Spiral concentrator, two-phase flow, multiphase, discrete phase model, ASM model

Jan 1, 2020

By L. Kühnel, H. Lieberwirth

Confined bed comminution in High Pressure Grinding Rollers (HPGR) and Vertical Roller Mills (VRM) is gaining substantial attention in many applications. Previously used mainly for milling coal or construction materials, HPGR and VRM have started to complement or even replace tumbling mills in ore beneficiation. Materials like coal or clinker are relatively homogenous, however, in comparison to metal ores and wall rocks. This characteristic poses a new challenge to the confined bed comminution but also an opportunity. Fuerstenau and Abouzeid have investigated the selectivity in comminution of a mixture of particles of different strength in a particle bed. The median particle size and particle size distribution (PSD) of the two constituents used were kept constant. Only the proportion of the two constituents was modified. The competence of a material is, however, also a function of particle size. Smaller particles tend to be more competent than larger ones of the same material. If selective comminution is applied on ores, this size influence has to be understood. The paper presents research results on this topic based on experimental investigations with model materials as well as with natural particles, which were stressed in a piston-die press. It appeared that the comminution result depends substantially on the material characteristics and the composition of the mixture. Conclusions will be drawn for the application in future applications of selective comminution in mineral processing. Keywords: Confined bed comminution, HPGR, VRM, piston die press, particle size

Jan 1, 2020

By E. Saari, B. Musuku, K. Jansson

The quality of the concentrator plant process water is crucial for high performing mineral flotation circuits. Significant metal recovery and concentrate grade losses have been noticed particularly in more closed water loops. The recovery and quality losses have started to emerge mainly with decreased freshwater usage and because of changes in tailings management towards tailings thickening, paste, or dry stacking. These changes result in shorter, closed water loops with a rapid build-up of harmful components with negative impact on the beneficiation process. Consequently, water quality has a direct link to decreased product value and sales returns. Complete cleaning or water blending might not be the right way to achieve high recovery and high-quality products. Instead, the key is to understand what kind of water qualities are needed for the flotation of specific minerals. In this study harmful substances in various plant water streams were removed and/or modified by pilot-scale dissolved air flotation. Batch-scale mineral flotation tests with the untreated and treated water were then performed by using fresh ore samples and the plant’s own laboratory flotation procedure. The results indicate that because of dissolved air flotation, the mineral flotation recoveries were enhanced by 1‒3.3%. Keywords: Mineral recovery, metal recovery, mineral quality, process water, concentrator, beneficiation, mineral processing, flotation, process water treatment

Jan 1, 2020

By D. D. Marsden

The paper briefly outlines the history of the successful development of vegetating techniques for mine-residue deposits. It seeks to place on record the major roles played by M.J. Mrost, who initiated and systematically developed the concept, and W.H. Cook, who continued the trials and successfully directed a stupendous large-scale project. The vegetating techniques currently practised are outlined, and it is concluded that vegetating is still the only surface-stabilizing technique of any significance that is employed throughout the world.

Jan 1, 1987

This paper describes the operating practice and design features of an intensive-cyanidation plant at the East Gold Plant of Vaal Reefs Exploration and Mining Company Limited (V.R.E.M.). After the development oh cyanidation route for the treatment of gold-plant gravity concentrates by the Anglo American Research laboratories (A.A.R.L.), a full scale plant was commissioned at Western Holdings (Welkom Division) Gold Mine in March 1977, and the V.R.E.M. plant was commissioned in August 1981. Although the gravity-concentration route does not now enjoy the prominence of former times, in an existing conventional plant the intensive-cyanidation route can successfully replace mercury amalgamation.

Jan 1, 1984

By H. White

The applicability of ground penetrating radar (GPR) in numerous qualitative applications has been demonstrated over the past five years in the South African mining industry. These applications include the delineation of faults and dykes, fracture mapping, delineation of shear zones, mapping of depth of weathering, and the delineation of contact between different rock types. The qualitative nature of the data collected using existing commercial GPR systems, often relying on expert interpretation, has however mitigated against the full scale routine application of GPR in the mining industry. The recent development of the RockRadar system by ISS International has, to a large extent, overcome these problems. The result is that quantitative rock-mass studies can now be performed with the RockRadar system.

Jan 1, 1996

By K. Sinding

This paper discusses reasons for mining company mergers that have become the fashion, the role of the ?Juniors? and asks what the motives might really be. It examines changes in company concentration over the last 20 years in key mineral segments. Data at different stages of a project are examined to attempt to elucidate the role of the ?Juniors?. Areas for further research are suggested.

Jan 1, 2009

Council and Standing Committees - 1982/83 President: Prof. A. N. Brown Vice Presidents: Prof. R. P. King and J. D. Austin Honorary Treasurer: Prof. D. G. Krige Immediate Past President: G. Y. Nisbet Members of Council: B. C. Alberts, R. H. English, P. T. Fewell, C. E. Fivaz, J. S. Freer, Prof. G. G. Garrett, J. J. Geldenhuys, Dr A. K. Haines, P. N. Harris, H. E. James, Dr B. K. Loveday, Dr J. Lurie, D. G. Malan, G. Pienaar, B. E. Protheroe, Dr 0. K. H. Steffen, G. C. Thompson, Dr H. Wagner, Dr P. T. Wedepohl. Chairman, Witbank/Middelburg Branch: H. C. van Zyl.

Jan 1, 1983

By J. P. Kirsch

This paper sets out to clearly identify all elements that make up an effective furnace feed system. These are outlined and the more common types of technology are listed. These technologies all play an important role in the final delivery of all feed materials to the furnace.

Jan 1, 2008

By K. I. Afewu, L. C. Woollacott

The design of in-pulp adsorption vessels in the gold industry has, for the most part, been seen as a problem involving the suspension of fine particles o ore in a slurry. The need for the vessel to be designed as a mass-transfer contactor has received insufficient attention. The current series of papers addresses this need The previous paper considered the question of the scale dependence of the film transfer coefficient. This paper examines the mixing considerations that are relevant. A review of the literature and an examination of a limited set of data provide some insight into the mixing conditions needed for the dispersion of the particles of adsorbent. The mixing requirements for the suspension of the ore particles are also considered, and conclusions are drawn in regard to the design of mechanically agitated vessels for gold in-pulp adsorption circuits.

Jan 1, 1995

1. Book review • World mineral statistics 1974 to 1978. Production: Exports: Imports. London, H.M.S.O., Institute of Geological Sciences, 1980. (Reviewer: R. P. King) This edition is the third in a regular series prepared by the Institute of Geological Sciences. It is a useful compilation of statistics on the production, export, and import of fifty-eight different mineral commodities. Each mineral is listed by country, and a table is provided for the annual production, the annual imports, and the annual exports for each commodity included. However, some commodities are treated in considerably more detail; for example, aluminium and bauxite have tables under the following headings: Production of Bauxite, Production of Alumina, Production of Primary Aluminium, Exports of Bauxite, Alumina and Aluminium, Imports of Bauxite, Alumina and Aluminium. The information presented is the latest official information available from primary sources; the compilers have not relied on data from secondary compilations. This publication will be of considerable assistance to all who are concerned with the trading of mineral commodities and their production.

Jan 1, 1981

By R. R. Mankowski

The work described in this paper is an attempt to increase present-day knowledge of fatigue in mine hoisting cables, particularly the internal energy loss arising from interwire/strand friction in a cable undergoing periodic non-planar transverse vibration. Such frictional energy loss is known to be one of the major influences limiting useful working life of hoisting cables in use today, and is responsible for the large capital outlay required to maintain the high safety factors prescribed by the mining industry. The experimental method employed identifies two mechanical characteristics of cables that are independent of amplitude and frequency, and are primarily attributed to the type of cable construction. Interest is focused the time rate of change of curvature as the major parameter influencing the internal damping mechanism. Empirical results confirm that amplitude and mode number play an important role in quantifying the internal losses, and also reveal that a critical radius of curvature exists below which damage due to vibration fatigue rises exponentialy to potentially high levels.

Jan 1, 1988