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By M. Karimi

Artificial neural networks (ANNs) have found their applications in the modelling of unit operations of mineral processing plants. In this research, laboratory-scale tests were conducted, using a three-inch diameter Mozley hydrocyclone. Main parameters included pressure drop at inlet, solid per cent, vortex and apex diameter were adjusted. The corrected cut size (d50c) and the flow rates of underflow and overflow were determined. Multi layers perceptron (MLP) feed forward network architectures were designed to predict the responses. The results showed a good correlation between experimental and network output, for corrected cut size and flow rates. Keywords: hydrocyclone, artificial neural network, corrected cut size, flow rates.

Jan 1, 2010

By D. François-Bongarçon

When it comes to sampling theory, a bad sampler is a bad sampler, no matter what, and a sampler is either bad or good. It also is of critical economic importance to tell and understand the difference, especially in a metallurgical plant. In this paper, the grand principles of Sampling Theory are first recalled, then the most popular types of sample cutters for plants are critically reviewed. It is concluded that the industry has a lot of progresses to make in that direction, although improvements usually pay for themselves very quickly.

Jan 1, 2002

By T. J. Otto, G. C. Lindeque

Productivity is improved by increasing the ratio of output to input. In an operating open-pit mine, improving the productivity of heavy mining equipment (HME) enables the unit cost of production to be reduced. To optimize HME productivity, the Kolomela open-pit iron ore mine transitioned to an enhanced short-term mine planning (STMP) process that supports the application of a manufacturing-type operating model. At the core of the enhanced STMP process is a focus on integration across the open-pit mining value chain. The interdependencies between mining activities are highlighted and emphasized, thus ensuring that mining activities are synchronized. The improvements related to HME productivity were monitored from 2019 to 2020. The utilization of mining area in the Leeuwfontein pit improved from 71% to 90%, and the blasting frequency reduced by 14% while the average blast size increased by 17%. The distance travelled during shovel relocations between mining phases reduced by 16%, and the lost time associated with drills relocating reduced by 53%. These productivity improvements resulted in an 11% increase in the loading rate of the main waste shovel at Kolomela from 0.9 Mt/month in 2019 to 1.0 Mt/month in 2020. The enhanced STMP process can be adapted to other open-pit mining operations.

Nov 1, 2021

By B. W. J. van Rensburg, M. J. Schmidt

Bulk materials handling systems are extensively used in the mining and minerals industry, where a fairly high incidence of structural failure is experienced, notwithstanding design compliance with appropriate standards. A number of case studies are explored to demonstrate how insufficient controls or protection systems have contributed to structural failures on mobile bulk handling equipment. The importance of design integration across engineering disciplines is highlighted. The revision of ISO 5049-1 (1994) is proposed to provide specific rules and guidelines pertaining to machine protection systems. It is further recommended that the structural design engineer of the original equipment manufacturer(OEM) fulfils a more prominent role during the final acceptance and handover of mobile bulk handling equipment, with specific reference to protection systems.

Jan 1, 2015

By E. Marè, D. R. Groot, R. Engelbrecht, T. Coetsee

Hydrogen peroxide is often used as an oxidising agent in experimental waste electronic equipment (WEE) leaching work. However, the high cost of peroxide is a negative factor in its consideration in further process development. A few studies have reported on the efficient application of peroxide addition schedules to ensure optimum reagent consumption. Large quantities of unleached substrate material contained in WEE feed material result in a large dead volume of material in the leaching reactor. This factor necessitates fast reaction rates to enable the use of a high feed material throughput reactor to enhance overall project viability via hydrometallurgical processing. In this study the effects of hydrogen peroxide addition schedules on base metal leaching efficiency and solution temperatures were tested at laboratory scale. The results showed that overall peroxide consumption can be optimised to lower levels by matching peroxide additions to the particular feed material’s leaching behaviour. A simplified integrated model for peroxide decomposition is used to explain its effect on solution temperatures and leaching rates. Keywords: Peroxide consumption, waste electronic equipment, copper leaching, integrated model

Jan 1, 2020

By N. K. Singo, J. D. Kramers

The reprocessing of tailings resources to extract gold on an industrial scale has become common practice. While these projects are common in the Witwatersrand basin, similar low-technology processes are not operational in smaller goldfields. This study explores the possibility of reclaiming the tailings dump of the Louis Moore Mine in the Giyani Greenstone Belt, investigates potential hazards to communities in the vicinity, and identifies mitigation strategies. Auger samples were taken from the Louis Moore tailings at depths of up to 5 m. Aqua regia leach analyses show Au concentrations of up to 1 g/t. Inferred estimations based on ordinary kriging (OK) and inverse distance weighted (IDW) methods put the residual Au resource in the Louis Moore tailings dump at 0.20 t. Reworking the tailings is viable, although a potential environmental risk exists in the form of elevated arsenic concentrations. Further exploration is required to determine the mineralogical associations of Au and As. Tailings reworking would assist in raising funds for mine rehabilitation. The secondary tailings could potentially be repurposed, which would provide employment and facilitate community development, as well as deliver environmental benefits.

Jul 1, 2021

By D. G. Krige

The problem of a realistic investment analysis for a new mining venture that sells its products on the international metal markets IS studied against the background factors, firstly, of different inflation rates between the countries hosting the mines and those. hosting the metal markets; and, secondly, of the changing pattern of currency exchange rates between such countries. The purchasing-power parity theory is used to establish a pattern of relationship between these two factors, and to develop a more logical approach to the long-term forecasting of metal prices in the currency of the country in which the mine is situated.

Jan 1, 1979

By R. T. Tshikhudo

Nanotechnology can provide solutions to many of the world?s socio-economic challenges. The application of nanomaterials for water treatment and analysis, point-of-care diagnostics and targeted drug delivery systems or devices could improve the quality of life for people in developing countries. Gold colloids have a long history (dating back to the 4th century AD) and are particularly well known for their aesthetic appeal and their therapeutic properties. Since Faraday published a report on the synthesis and properties of colloidal gold in 1857, a reasonable insight into the nature of gold sols (nucleation, growth and kinetics of coagulation) has been developed. Considerable attention has been drawn during the past few decades to the development and optimization of methods for the preparation of gold nanoparticles. In nanoscience and nanotechnology today, gold nanomaterials appear to be the most widely used material by both academics and industrialists. This is due to the extraordinary properties of gold nanoparticles (e.g. optical, catalytic, and magnetic?they are also known to act as strong Raman enhancers and may also amplify fluorescence under certain circumstances). Mintek, through Project AuTEK and the DST/Mintek Nanotechnology Innovation Centre (NIC), has been at the forefront of the development of new industrial uses for gold. Mintek?s gold nanotechnology programme focuses on the development of gold-based nanostructured materials and their applications in health, water and other related areas. While few projects use gold nanoparticles for water treatment and analysis, Mintek?s gold nanoparticles are widely used in the health sector. For example, gold nanoparticles are engineered and produced in large quantities as systems for targeted drug delivery. They are also used as tools for advanced rapid diagnostic tests. Both optical and electrochemical rapid diagnostic methods are developed for the human and animal health sectors for point-of-care testing. This paper gives a brief introduction and overview of gold nanotechnology, and desrcibes the development of some of Mintek?s gold nanoparticle targeted drug delivery systems and lateral flow point of care prototype devices.

Jan 1, 2009

By M. Nyoka

Historically bauxite-based refractories have been used in applications where andalusite-based refractories could work. Bauxite-based refractories were chosen over andalusite-based refractories mainly because of the availability of low-cost Chinese bauxite and also because many furnaces were designed by international companies that cannot easily access high-quality products. Currently, the availability of low-cost bauxite is under threat as a result of high export duties and tariffs as well as restrictions on the amount of material that China allows to be exported. South Africa is a major producer of andalusite, and this guarantees stability with respect to both availability and price. Refractories based on andalusite have an added economic advantage over bauxite-based refractories in that unlike bauxite, which requires high-temperature calcination before use, andalusite is used in its raw state. This paper constitutes a literature study of the merits, both technical and economic, of using refractories based on andalusite compared to bauxite-based refractories. Keywords bauxite, andalusite, refractory, furnaces, calcination.

Aug 1, 2013

By D. Schreuder

Conditions in the South African market relating to atmospheric emission control has changed dramatically over the last 10 years. Companies have become more responsible, environmentally aware, and have to comply to more stringent environmental limits set by legislation. This paper describes briefly the current best available atmospheric pollution abatement technologies relating to particulates, acid gases, NOx, acid mists, aerosols, mercury, dioxins and furans. Mention is also made as to the best practices for product work-up and waste product disposal.

Jan 1, 2006

By C. Legote

"This paper investigates the conditions leading to the indefinite termination of production in four critical primary panels at an underground coal mining operation, the observed shortcomings in the mining approach, and the proposed strategy to mine through the affected panels. Initial assessment of the abandoned panel conditions indicated time-dependent strata failure,(i.e. bolted roof failure overrunning intersections), which occurred from mere minutes to up to four weeks post-production, with and without prior warning of failure. This prompted the constant re-supporting of back areas, which raised safety and productivity concerns. Investigation of the initial mining conditions revealed that the failures were due to a critical combination of factors, the chief of which was isolated horizontal stress. Other factors that were initially overlooked by the mine (i.e. influence of hydraulic stress, misinterpretation of borehole data), resulted in the conditions being described as abnormal. Remedial actions were determined, and in so doing, a new strategic approach was formulated to thoroughly address all failure concerns. The four panels were explicitly planned to serve as the main intake and return airways for the recently commissioned secondary ventilation shaft, as well as providing access to millions of tons in proven coal reserves. It is thus imperative to mine the panels. A feasibility study showed that the proposed strategy set for implementation would be financially viable. Paper written as project work carried out in partial fulfilment for BEng(Mining Engineering) degree"

Jan 1, 2015

By C. J. Liebenberg

This paper focuses on the application of ion exchange technology for the recovery of copper from a leach solution originating from a heap bioleach in which base metals are leached from a low-grade ore that bears platinum group metals. Screening tests indicated that Dow XUS43605 has high selectivity for copper over the other metals in the solution, namely nickel, iron, cobalt, zinc, manganese, and aluminium. Batch adsorption kinetic experiments showed that copper adsorption equilibrium is attained at a fast rate. The kinetics of adsorption increased as the temperature was increased from 25°C to 60°C due to the decrease in solution viscosity and the subsequent improved intra-particle mass diffusion. Single-component Langmuir and Freundlich isotherm models were fitted to the batch copper adsorption equilibrium data, and a maximum copper capacity of 26 g/l was observed for Dow XUS43605. The effects of flow rate, temperature, pH, and initial metal concentration on the dynamic recovery of copper were investigated in fixed-bed columns, and it was determined that temperature and flow rate had the most significant impacts on the loading of copper on the resin at copper breakthrough. A 36% increase in copper loading at breakthrough was observed when the temperature was increased from 25°C to 60°C. Finally, it was determined that a split elution is possible by using different concentrations of H2S04 to first elute co-loaded nickel from the resin, followed by the elution of copper.

Jan 1, 2013

By M. G. Wimberger

The Merensky Reef zone, as developed on Impala Platinum?s Rustenburg Operations, displays a gradational mineralized zone, with grades decreasing from the Merensky Pegmatoid Unit into the footwall and hanging wall. A system of identifying a manageable method of defining the mining cut is introduced, termed the grade profile attenuation cut-off grade. Although horizontal grade selectivity is not applied in the mining of the Merensky Reef zone, low extraction of the orebody, due to manageable and non-manageable factors, can contribute to a reduction in revenue, even losses, due to fixed cost contributions in the mining and beneficiation of the ore. A model is proposed that integrates all variables affecting the revenue of the mining operation, including the grade profile attenuation cut-off grade, the extraction factors, commodity prices and exchange rates, utilizing numerical simulation techniques in a PC-based environment. A breakeven extraction factor for a specific cut-off grade is delivered for a range of market conditions. The breakeven extraction factor is a useful guide when designing mining layouts in structurally complex and low metal content areas. Incorporating distribution functions for individual commodity prices and exchange rates into the model provides mineral resource managers with a risk profile for individual mining areas. Shaft areas have varying grade profiles and each area should have individual models run, to prevent generalizations being made about acceptable risk levels on mining areas.

Jan 1, 2004

By R. Hansson

Zincite and spinel phases are present in the complex slag systems encountered in zinc/lead sintering and zinc smelting processes. These phases form extensive solid solutions and are stable over a wide range of compositions, temperatures and oxygen partial pressures. Accurate information on the stability of these phases is required in order to develop thermodynamic models of these slag systems. Phase equilibria in the Fe-Zn-O system have been experimentally studied for a range of conditions, between 900 and 1580°C and oxygen partial pressures (pO2) between air and metallic iron saturation, using equilibration and quenching techniques. The compositions of the phases were measured using Electron Probe X-ray Microanalysis (EPMA). The ferrous and ferric bulk iron concentrations were determined using a specially developed wet-chemical analysis procedure based on the use of ammonium metavanadate. XRD was used to confirm phase identification. A procedure was developed to overcome the problems associated with evaporation of zinc at lowpO2s and to ensure the achievement of equilibria. An isothermal section of the system FeO-Fe2O3-ZnO at high ZnO concentrations at 1200°C was constructed. The maximum solubilities of iron and zinc in zincite and spinel phases in equilibrium were determined at pO2=1*10-6atm at 1200and 1300°C. The morphology of the zincite crystals sharply changes in air between 1200 and 1300°C from rounded to plate-like. This is shown to be associated with significant increase in total iron concentration, the additional iron being principally in the form of ferric iron. Calculations performed by Fact Sage with a thermodynamically optimized database have been compared with the experimental results. Keywords: Phase Equilibria, Fe-Zn-O, Quenching, Wet-Chemistry, EPMA, XRD, ISP.

Jan 1, 2004

By G. Akdogan, M. Tadie, A. Tapfuma

The Southern African region contains abundant gold tailing heaps that are an environmental concern due to dust pollution and chemical contamination of nearby water bodies. Nevertheless, these heaps contain gold with potential to be extracted for financial gain. In this study, the feasibility of extraction of gold from a Witwatersrand gold tailings using glycine was investigated using a two-level full factorial design. Effects of variables such as glycine concentration at levels of 0.5–1.5 M with a solid–liquid ratio of 50–200 g/L were investigated. Although the solid–liquid ratio used in this study was below the industrial norm, it provides a starting point for investigating the applicability of this technology. To enhance the gold extraction, potassium permanganate pretreatment and copper ion addition were adopted. The results revealed that 91.4% gold extraction was achieved after 24 h pre-treatment of the tailings using 2 g/L potassium permanganate followed by subsequent leaching using 1.5 M glycine at pH 12, with 50 g/L solid–liquid ratio and 2 g/L copper ions. Statistically, the solid–liquid ratio and potassium permanganate pre-treatment of the tailings were found to be significant at 95% confidence interval, whilst interactions of copper ions and glycine concentration were significant factors. The work demonstrates that potassium permanganate pre-treatment prior to glycine leaching of low-grade secondary gold resources, such as tailings, can be beneficial. Furthermore, the methodology developed in this work provides an opportunity for further investigation of the recovery of gold hosted in complex mineralogical matrices.

Apr 14, 2024

By G. Akdogan, S. M. Bradshaw, A. P. Van Wyk, T. Punt

Recycling has become an important part of the lithium-ion battery (LIB) life cycle due to the growing demand for energy storage in applications like electric vehicles and renewable energy. Recycling spent LIBs provides a secondary source for strategically scarce metals, like lithium and cobalt, helping to reduce the environmental impact of LIBs. Organic acids have been proven to be effective lixiviants with the benefit of reduced environmental impacts, amongst which citric acid has shown to exhibit similar extraction performance when compared to mineral acids. Leaching LCO and NMC batteries with 1.5M citric acid and 2 vol.% H2O2 at 95°C, 20 g/L for 20 minutes achieved 93% Al, 90% Co, 96% Li, 94% Mn and 94% Ni dissolution. The strong chelating property of citric acid affects the separation of the metals, providing unique extraction opportunities. The first extraction uses 12 vol.% D2EHPA at a pH of 2.5 and O/A ratio of 2 to separate 96.4% Mn and 100% Al from the PLS in two counter-current stages. Stripping the loaded organic with 1.25M citric acid at an A/O ratio of 3 allows for up to 91% stripping of the manganese in a single stage. The second extraction then separates 96.5% Li from the PLS in three counter-current stages using 20 vol.% D2EHPA at a pH 5.5 and O/A ratio of 5. The raffinate remaining after the second separation contains 48.4 wt.% Co and 50.3 wt.% Ni. Keywords: Hydrometallurgy, lithium-ion batteries, metal recycling, citric acid, solvent extraction

Jan 1, 2020

By C. Sarkar

Increased competition in today’s global economy has put mineral industry under excessive pressure to effectively manage production assets to generate business wealth. Capital intensive industry (CII) organizations are seeking ways to manage skill resources, internal processes, and organizational networks with a view to reduce the cost of ownership of assets and increase efficiency of operations and service. The emerging concept of Enterprise Asset Management(EAM) is a collection of business processes that allow CII with right focus on return on investment on assets, to make right decisions on planning, acquisition, maintenance, operation, rehabilitation, and disposal of assets. Information technology (IT) can drive significant returns if the infrastructure covers seamlessly all business processes and all systems, like geographic information system, maintenance management, investment management, laboratory information management, and supervisory control and data acquisition system. The simple approach to IT in the past with disconnected silos of technology, information, and business processes cannot deliver the expected benefits under the modern business environment. Identification of business and application component is a prerequisite for the development of an asset management system that links effectively disciplined processes having characteristics of agility, speed, and integration. This paper discusses various issues and outlines the steps for developing an asset management roadmap in an organizsation. It also presents major business and application components of the system. Keywords: Enterprise asset management, Business architecture, Business component, Application component, Asset ownership, Asset operations, Information technology, Capital Intensive industry

Jan 1, 2003

"Chairman: Mr. K. F. LaneRapporteur: Mr C. T. ShawPapers:Design of crushing plant flow sheets by simulation by T. GurunThe impact of transportation networks upon the potential supply of base and precious metals from Sonora, Mexico by P. de V. Harris and D. E. EurestyProfitability sensitivity analysis of a mining venture by C. A. Beasley and E. P. PfleiderTechnological innovation and its potential effect on the opening of new gold mines in South Africa by N. C. JoughinMr Turgay Gurun, in presenting his paper, indicated that this simulator was no purely theoretical exercise, but that the model had been used in the design of crushing plants of capacities ranging from 3 000 tons per day to 66 000 tons per day, and that recently the design of a plant of capacity of 99 000 tons per day had been studied.The crushing plant simulator was an independent portion of a much more comprehensive simulator for the design of a. complete recovery plant. It would be possible to use each section of this simulator on its own, and simulators would be designed to cover flotation concentrates, cash flow analyses of the entire project, and so on.Each simulator would be backed by a comprehensive data bank. For example, the crushing plant simulator was backed by such a data bank which included the performance and cost data from five manufacturers for an average of 30 items of process and materials handling equipment each. This meant that data preparation involved generally less work than would be required for a manual calculation. On average, data preparation for one run took 30 minutes and three minutes of computer time on an IBM 360/40 completed the run. The model could be valuable as a design tool in that it allowed the designers an opportunity to make a thorough examination of many alternative designs. It was also of value to plant operators as it could be used to predict the consequences of operating decisions.This paper generated much interest and there were numerous questions and contributions, so many, in fact, that the discussion had to be cut short.It was pointed out by Mr K. F. Lane that crushing plants represented a very large capital investment. A plant designed for 40 000 tons per day at 98 per cent efficiency might well in practice be run at 50 000 tons per day at, say, 83 per cent efficiency. He asked how, therefore, their design could be investigated without building economic criteria into the model? The author conceded that this was a tender point. He would have liked to have given facilities for more variability of the metallurgical information. He pointed out, however, that while there was no overdesign for conservatism built into his system, some overdesign was inevitable as the performance characteristics given by the manufacturers were generally conservative. Also, in his system, if lower recovery was allowed for, the system would nut through more tonnage."

Jan 1, 2014

Published experimental data on thermodynamic behaviour of cobalt-containing slags have been reviewed and used in validating a recently developed thermodynamic model. The results from the exercise show that the model provides a reasonably good description of behaviour of cobalt in multi-component slag systems. The models for cobalt containing slags, matte and oxide solid solution phases were incorporated into CSIRO?s multi-phase equilibrium (MPE) package, which was used to calculate the equilibrium distribution of cobalt between matte and slag phases under various conditions. The results agreed well with the experimental data. Furthermore, the good agreement between the calculation and the plant data indicates that the operating conditions of industrial smelting and converting processes are close to equilibrium. Two diagrams showing the effects of slag chemistry and SO2and O2partial pressures on the distribution of cobalt between phases were generated for conditions similar to smelting and converting processes. These diagrams provide some useful guidelines for developing new strategies to improve cobalt recovery.

Jan 1, 2004

By L. Holappa

Ferroalloy production is an energy-intensive industrial sector with significant CO2 emissions. In this paper the current situation in ferroalloy processes is discussed from the standpoint of global environmental issues, trends and development. Progress and data of ferroalloys production are frequently compared with the steel industry, which is a closely related sector and the main user of ferroalloys. Emission factors of processes and electricity production are examined as well as possibilities and future scenarios of how to diminish CO2 emissions. As a part of this study a questionnaire was submitted to experts in the field of ferroalloys worldwide to survey opinions on the ferroalloy industry today and in the near future (2020). Eighteen questions concerning raw materials, energy, environmental aspects, by-products and economic aspects were responded to by seventeen experts, the answers were analysed and conclusions were drawn. Keywords Ferroalloys, energy, CO2 emissions, electricity, sustainability, questionnaire.

Jan 1, 2010