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Professor R.F. Sandenbergh matriculated at Germiston Afrikaans High School, and then he obtained the degrees of B.Eng. (Chem.) in 1972, M.Eng. (Chem.) in 1975, and D.Eng. (Met.) in 1983-all from the University of Pretoria. Mr J.A.D. Britz matriculated in 1958 at the Roodepoort Hoerskool, and joined the mining industry in 1959 as a student mine official at the Rand Mines Training Centre. Mr J.A. Cruise matriculated at Durban High School and joined Union Corporation as a Learner Official in 1962. He was awarded a scholarship to read for B.Sc. and M.Sc. degrees in mining engineering at the University of the Witwatersrand

Jan 1, 1990

By T. Bohmer, L. Auret, N. Pillay, Z. Horn, P. Rambalee, A. Haasbroek

As part of a broader digital technology-enabled transformation programme, a major mining company is systematically implementing Advanced Process Control (APC) solutions and associated instrumentation throughout their operations. This paper highlights the approach and benefits of this holistic approach for a specific instrumentation installation, and APC installation at a South African coal processing plant. For the coal processing plant under consideration, a systematic approach was followed. Process sections/units are considered from upstream to downstream processing. APC solutions are designed for each process section and each process section is interrogated in terms of availability of sufficient process measurements to ensure stable, capable, and ultimately, optimised performance. Where insufficient process measurements are available, instrumentation upgrades are implemented. Finally, APC solutions are implemented, and evaluated in terms of productivity, safety, health, and environmental benefits. For the flotation section, an opportunity was identified to install froth sensors. The installed froth sensors provide measurements on froth velocity, bubble size, height, colour, and stability. The improved visibility that the froth sensors provided on the flotation process resulted in quick gains in terms of productivity: for example, instability in the feed to the flotation section could be quantified. This resulted in targeted process troubleshooting in an upstream thickener, and subsequent improvement of process stability, and reduced feed variance. The measurements from the froth sensors were further integrated in an APC solution. Proportional mass pull contributions per cell and per line can be inferred from the froth sensors, serving as controlled variables, while pulp level set points serve as the manipulated variables. On-off tests indicated that the advanced process control solution provided increases in yield and product quality.

Sep 1, 2021

The November General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 18th November, 1970, at 4.00 p.m. V. C. Robinson (President) was in the Chair. There were also present 30 Fellows, including J. K. E. Douglas, R. C. J. Goode, Dr J. P. Hugo, Prof J. de V. Lambrechts, D. G. Maxwell, Prof R. P. Plewman, Dr M. D. G. Salamon, P. W. J. van Rensburg, L. W. P. van den Bosch (Council Members), R. E. Burnton, S. Craib, D. de Villiers Oxford, J. C. Fritz, G. W. Gray, G. H. Henderson, S. D. Hill, C. H. Kruger, B. Leach, C. S. MacPhail, D. J. Molony, W. G. Fyne Mercier, R. A. Scott, M. v. R. Steyn, I. E. van Aswegan, A. D. Vos, J. M. Vosloo and N. Zolezzi. Four Members, including I. G. Evans, R. W. Shearer, W. Wilson. One Associate: P. M. C. Wilson. Four Students: H. G. Albertyn, J. T. Davies, P. G. Henderson and P. J. Pretorius. Fourteen Visitors, including S. R. Barker, F. H. Deist, Dr de Jager, L. F. Duvel, P. du P. Kruger, B. D. Maree, B. R. Meyer, R. Redmond, J. Rietief, A. W. S. Schumann, Mrs A. W. S. Schumann, T. S. Stoffberg, C. A. Visser and R. van der Wait. Secretary, D. C. Visser. Total present 55. The President: "Gentlemen, I would like to welcome all members of the Institute who are present, and visitors, and I would like specially to welcome any members of the Suid-Afrikaanse Akademie who are present this afternoon." OBITUARIES The President: "Before starting on the agenda the first item, of course, is unfortunately obituaries and it is my sad duty to announce the death of the following: I would like to start with a person who is not actually a member of the Institute but who, in his capacity as President of the Chamber of Mines, was Honorary President of this Institute three times and I refer, of course, to Mr Herman Calderwood Koch who passed away last Saturday. Then I would refer to Richard Beaumont Tasker, Life Fellow, who joined this Institute in 1932, and who died on the 22nd of October, 1970. Then, lastly, Mr Jean Francois du Plessis, a student, who joined the Institute on the 19th June, 1968, and passed away on the 11th of November, 1970, as the result of an accident. Mr du Plessis was to have received a Student Prize today for his paper entitled, Displacements and stresses in the vicinity of a horizontal long-wall'. We were all most upset to learn of his death last week, and we are now going to make arrangements to hand his prize to his widow on a suitable special occasion. As a mark of respect to the memory of the deceased, and in sympathy with the bereaved, I would ask you all to stand and observe a few moments' silence. Thank you." CONFIRMATION OF MINUTES The President: "May we confirm the minutes of the monthly general meeting which was held on 16th September, 1970, as published in the November Journal?" Agreed. MEMBERSHIP The President: "I have much pleasure in announcing that the names of the undermentioned candidates having been published in accordance with By-Law 5.2.2, Council has elected them to membership of the Institute in the following grades: Fellow: Ronald White Ballantine. Members: Jan Johannes Hertzog Viljoen, Agge Petrus Rutgerus van der Meer, Peter Anthony Reynolds, Ernest Esdaile Leyde Hans Lutz Klingmann, Ronald Archer.' Graduates: Trevor Stanley Schultz, Thomas Cochrane Meiklejohn, Leslie Harold Heyman, Dennis William Bosch, Sydney Stuart Absolom. Associates:Roderick James.Vermaak, Theodorus Daniel van Wyk, Michael Osmond Savignac Stedman, Leslie Owen Raymer, Bryan Arthur McKay, Leon Ellis Finlay Leask, Dudley Graham Lovedren Hall, John Arthur Gibbon, Richard Reginald de Villiers, Carel Frederik Boshoff. Students: Frederik Wilhelm Christian Coetzer, Phillippus Johannes de Wit, Jan van der Merwe Grimes, Davood Khareghani, Jan Wolvaardt Oberholzer, Johannes Lodewikus Pretorius Pieter Jacobus Strobos, Herbert Gerald Waldeck.' MEMBERS TRANSFERRED TO A HIGHER GRADE From Associate to Fellow: Howard Mitchell Wells. From Associate to Member: Ernest John Dominy. "I welcome the newly elected members to the Institute and congratulate the members who have been transferred to a higher grade." AWARDS The President: "It is with very great pleasure that I can announce that Council has agreed to make the following awards for papers presented to the Institute during the year ended July, 1970. Gold Medals to Prof Plewman and W. D. Ortlepp for their paper entitled 'The development and application of a digital computer method for the solution of strata control problems' written jointly with F. H. Deist (Visitor) and presented in September, 1969. A Silver Medal to Dr Finkelstein for his paper entitled 'The Influence of sulphydryl and cationic flotation reagents on cyanidation of native gold' written jointly with Dr K. G. Ashurst (Visitor), and presented in June 1969 at the Symposium on the Recovery of Pyrite. ' May I congratulate these gentlemen on the high honour they have won with their papers. As new medals are in the process of being designed the actual awards will be made at a later date to be announced to members.

By S. Bradshaw, A. Mabentsela

"Physical and numerical modelling methods were followed to identify mechanism(s) for tundish slag entrainment in a bare tundish and one with a flow control device (FCD).The physical and numerical models made use of water and paraffin to model steel and slag respectively. Observations from the physical model showed that the steel-slag interface remains immobile in both cases. Entrained paraffin formed droplets approximately 1 mm in diameter. Results from both models (numerical and physical) showed that in both cases (bare and FCD case), areas of high entrained slag concentration exist near the inlet region. The entrained slag concentration decreases towards the tundish endwalls.Flow patterns and velocities tangential to the steel-slag interface from the numerical model showed that slag entrainment in both the bare tundish and tundish with a FCD possibly takes place via two mechanisms. First, the slag moves across the steel-slag interface via mass transfer; secondly small velocities tangential to the interface at depths greater than 10 mm below the interface carry the already ‘entrained’ slag into the bulk steel phase. These tangential flow patterns are dominant in the inlet region, hence the high concentration of entrained slag in this region. IntroductionThe tundish serves as the last metallurgical vessel through which steel passes before solidifying in the moulds. It is in the tundish that the last traces of non-metallic inclusions should be removed, otherwise the inclusions carry over to the moulds and cause defects in the steel product. In the tundish, the slag is less dense than the melt and thus resides on the top of the melt. The slag provides a sink into which the non-metallic inclusions float to and dissolve. The slag also protects the melt from air and heat loss. However, when slag is entrained in the melt as a result of increased turbulence or shearing at the steel-slag interface, slag can become a source of nonmetallic inclusions.Numerous studies on flow patterns in the tundish have been carried out since the introduction of the tundish. These studies were aimed at improving the flow characteristics in the tundish (Chattopadhyay, Isac, and Guthri, 2010; Cloete, 2014; Jha, Dash, and Kumar, 2001; Jha, Rao, and Dewan, 2008;"

Jan 1, 2017

Mr R.D. Beck attended Felsted School in Essex (England) and the Royal School of Mines, University of London, where he ob¬tained the degree of B.Sc.(Eng.), A.R.S.M. in mineral technology in 1969. His other qualifications include Pr.Eng. (1976), C.Eng (1975), and M.I.M.M. (1975). He joined Gold Fields of South Africa in December 1969, and worked at Doornfontein Gold Mine, Greenside Colliery, West Driefontein Gold Mine, Zwartkloof Fluorspar, Gold Fields Laboratories, Gold Fields Head Office, Libanon Gold Mine, and Kloof Gold Mine before being appointed Plant Superintendent at East Driefontein Gold Mine in January 1973. In June 1976, he was transferred to Head Office as Group Metallurgist, followed, in November 1978, by his secondment to Black Mountain Mineral Development Company as Plant Superintendent, to take on-site responsibilities for staff training, plant commissioning, and start up. On his return to Head Office in July 1980 as Assistant Consulting Metallurgist, he was responsible for Black Mountain and new metallurgical projects. Then, in January 1984, he was appointed General Manager of the Zinc Corporation of South Africa Limited. He became a member of The South African Institute of Mining and Metallurgy in 1973.

Jan 1, 1985

By D. Minson, G. Lindner, S. Miskovic

Thickening is an essential process in the mining industry and currently one of the most costeffective technologies for recovering water from tailings streams. Improved performance of thickeners can lead to significant energy savings, and increased recovery of water close to the mill. Its performance is directly affected by the rheological properties of slurry at the raking zone. To further understand the dynamics of slurry inside thickeners, a multiphase particle-in-cell method (MP-PIC), is used to investigate its behaviour on a sliding channel. Parameters like particle-size distribution (PSD), rheological properties, and domain discretisation were benchmarked to study its influence on highly dense flows. The slurry concentration by weight of the samples ranged between 60 to 70% of solids by mass, under which conditions it is known to behave like a non-newtonian fluid. An experimental flume, 0.2 m wide and 2 m long, was used for validation under different angles and slurry composition. Visual analysis of the slurry height and shape, as well as velocity measurements, were compared with numerical data. The preliminary results show the ability of MP-PIC method to represent different types of highly dense flows, while still being computationally affordable and practical for industrial use. Keywords: High density thickener, CFD, MP-PIC, multiphase-flow

Jan 1, 2020

By G. M. Evans, S. Mitra, A. V. Nguyen

As an alternative to the conventional flotation method, there has been continual research in an effort to enhance base metal ores and combustibles recovery using ultrasonics. These studies however were largely limited to the pre-treatment of ores for the removal of surface contaminants while the effect of ultrasonics on the bubble and pulp-phase interactions remained somewhat unexplored. Noting this deficiency, this study aimed to investigate the mechanistic effect of an ultrasonic field in an impeller less flotation cell specifically focusing on the bubble-particle interaction dynamics. A lab-scale flotation cell (capacity 1 litre) was designed, involving a vertically oriented ultrasonic probe (20 kHz, rated at 1.2 kW) and operated in the output power range from 1 to 20% with continuous liquid recirculation. Particle suspension was achieved by the combined action of recirculation and ultrasonic pulses. Interactions of coarse size glass ballotini particles (D32 = 314 μm) with bubbles (< 1 mm diameter) in the presence of a surfactant were studied, using high-speed imaging. Application of an ultrasonic pulse in the aqueous medium resulted in the generation of numerous microbubbles which increased with increasing input power and duration of the ultrasonic pulse time. Such periodic pulses introduced at a high level of turbulence in the pulp phase facilitated adequate bubble-particle contacts. Microbubbles played a key role in forming particle clusters which were observed to be floatable even in the absence of any carrier bubbles. When carrier bubbles were introduced, some of these particle clusters attached to the bubble surface and conveniently floated. It was noted that a favourable state of bubble-particle interaction was achievable to produce stable bubble-particles aggregates by suitably controlling the input power and period of the applied ultrasonic pulse. Keywords: Flotation, bubble-particle interactions, collision, attachment, detachment, ultrasonic pulse

Jan 1, 2020

By F. P. Janse van Rensburg, P. J. Le Roux

"There are numerous factors that affect open stope stability and often result in falls of ground. These falls of ground can be attributed to factors such as beam failure due to a larger than normal roof area (hydraulic radius too large), adverse ground conditions, seismicity, the stress-strain environment, absence of support, and poor drill-and-blast practices. The effect of time on the stability of open stopes is sometimes underestimated and is relatively unknown, especially on Target Mine. Actual data was collected from open stopes at Target and analysed to show the effect of time on open stope stability. The benefits of this analysis will include improved understanding of time-dependent failure, which can assist in reducing dilution and the risk of sterilization of future mining blocks. IntroductionTarget Mine is situated adjacent to the town of Allanridge, some 20 km from Welkom in South Africa’s Free State Province, and is the most northerly mine in the Welkom Goldfields area (Figure 1). The mine consists of a single surface shaft system with a sub-shaft (Target 1C shaft) and a decline. Ownership was attained by Harmony Gold Mining Company Limited in May 2004 (Harmony Gold Mining Company Limited, 2010). Before discussing the selection of open stopes for the back-analyses, a brief explanation of open stoping as practiced at Target Mine will be given. The orebody is some 180 m in thickness and 270 m wide and comprises multiple reefs overlying one another. The 180 m thick reef package is termed the Eldorado Reefs, as shown in Figure 2. The Eldorado Reefs suboutcrop against the Dreyerskuil Reefs, as shown in Figure 3. The dip of the reef varies from as low as 10° in the west to 75° in the east.Compared with most Australian and Canadian open stoping mining operations, Target Mine is unique. In most Australian and Canadian mining operations the hangingwall and footwall of the open stopes comprise waste rock, and the orebody dips relatively steeply. Due to the depth of Target Mine, some 2300 m to 2500 m below surface, a destress slot (Figure 4) is mined to create an artificial, shallow mining environment whereby the field stress is managed and kept at values of around 60 MPa. The destress slot comprises a narrow tabular stope with an average width of 1.5 m, and is mined on the Dreyerskuil Reefs.At Target Mine the hangingwall, sidewalls, and footwall of the open stopes all comprise reef of different grades, except for the EA1, where the EB footwall is waste rock. If a stope, for example, is mined alongside an existing old stope, the western sidewall of this stope will consist of backfill. The general mining direction of open stopes is from the lowest position of the reef on the west, progressing up towards the east as shown in Figure 5."

Apr 1, 2019

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 R. Uwaoma, A. Goosen, R. Matjie, K. Mphahlele, J. Bunt

Coal properties that are associated with wear and damage of grinding equipment during pulverization prior to combustion were investigated. A South African Highveld feed coal and its beneficiated fractions were crushed to <1 >0.25 mm particles for the grindability tests. These particles were milled and screened into <75 μm and >75 μm fractions, which were analysed by different techniques to establish a correlation with the conventional Hardgrove Grindability Index (HGI). The <1.5 g.cm-3 float fraction, which contained 93 vol.% (mineral matter free) total -macerals,9% kaolinite, and had the lowest HGI (57) (hardest to grind) was pulverized for 15, 30, 60, and 120 minutes for particle size distribution analysis. This analysis indicated that the content of <75 μm particles increases with increased grinding time. The >1.9 g.cm-3 sink fraction, with the highest HGI (76), 44% kaolinite, and 20 vol.% total macerals, was ground easily to generate the highest proportion of <75 μm particles. Based on higher correlation coefficients (R2 = 0.77–0.91), the ash yield, mineral matter, petrographic composition, and fixed-carbon have significant effects on the HGI. Conversely, the inherent moisture and total sulphur (R2 = 0.48–0.62) have only minor effects on the HGI. Results from this investigation could be implemented in the preparation of a suitable pulverized fuel with little equipment wear, as well as utilizing mineralogical and petrographic compositions. Finally, the effect of microlithotypes and maceral types in South African feed coals on the HGI should be investigated in further pulverization and grindability studies.

Jul 5, 2023

By C. H. Wyndham, N. B. Strydom

INTRODUCTION Acclimatization of the labour force to heat is an integral aspect of gold mining in South Africa. A recent survey revealed that about 250,000 Bantu mine workers require to be acclimatized to heat each year. Until 1965 men were acclimatized by means of one of the Chamber of Mines methods (introduced by the Human Sciences Laboratory in 1953). This type of acclimatization was carried out underground where men shovelled rock in hot stopes under careful supervision. However, it has become increasingly difficult in the last few years for mines to provide underground the conditions of work and environmental heat required for adequate acclimatization to heat. In examining an alternative to acclimatization in underground hot stopes, the Human Sciences Laboratory carried out a trial in 1965 of acclimatization in an air-conditioned climatic room on the surface of a mine. The new procedures developed from this trial have been so successful that there are today 26 climatic rooms on different mines. These rooms have been built following a design proposed by Mr Hodgson of the National Mechanical Engineering Research Institute1. Approximately 85 per cent of the total number of men being acclimatized each year are put through the new procedures in these climatic rooms. This paper gives an account of the problems which arose and how they were solved, the inter-relationship between physical conditioning and climatic room acclimatization, the prodecures developed for elimination of labourers with low maximum oxygen intakes, and the advantages of climatic room acclimatization. CLIMATIC ROOMS The majority of the climatic rooms (twenty) have been built on the surface, but a number (six) of mines preferred to establish their acclimatization centres underground in order to decrease the initial costs involved in the construction of such facilities. These underground climatic rooms are usually located near shaft stations in redundant haulages and they can accommodate from 200 to 400 labourers, thus eliminating the need for multiple acclimatization shifts. Figs. 1-4 illustrate various aspects of a surface climatic room. PROBLEMS WHICH AROSE IN INTRODUCING CLIMATIC ROOM ACCLIMATISATION There were four main problems which arose in connection with the introduction of the new method. These were: (i) The type and rate of work to be used. (ii) The air conditions required to obtain optimum acclimatization. (iii) The duration of exposure to heat each day and the total number of days of acclimatization. (iv) The methods of cooling labourers with high body temperatures. Shovelling rock would have been the desirable type of physical work to employ, but the air-conditioned space required to accommodate large numbers of men and the difficulty in standardizing the work rate in shovelling led to the decision to employ instead the work procedure used by the Human Sciences Laboratory in acclimatizing men in the Laboratory. This is the lifting of the body weight against gravity when men step on and off a bench. It has the advantage that large numbers of men can work physically at the required rate in a relatively small space (120 men can be accommodated in an area of 70 ft by 21 ft) and the cost of construction and ventilation of the climatic rooms is thereby reduced. Also the work rate can be standardized by varying the height of the stepping benches in relation to the individuals&apos; body weights. The next problem was the air condition to be used in the climatic rooms. The Laboratory&apos;s research experience in acclimatization led it to choose an air temperature of 89°F (with the air almost saturated with water vapour) and an average velocity of air movement of 100 fpm. This air condition was combined with a work rate of 1,560 ft lb/min (oxygen consumption 1.0 litre/min) on day 1, and the work rate was increased gradually over the period of acclimatization to reach a work rate of 3,120 ft lb/min (oxygen consumption 1.6 litres/min) on day 9.

By E. Emami, J. Valencia, J. Sattarvand

The knowledge of the final location of a drillhole is critical in obtaining the expected blasting results. This paper proposes a new methodology to control the drilling accuracy in open-pit mines using aerial images and machine learning. Specifically, it investigates how support vector machines (SVM) and convolutional neural networks (CNN) are useful for automatically detecting blastholes over drone images captured in blasting patterns. Several datasets were obtained from different mines in Nevada (USA) and were used to train and test models. We then processed those images to create orthomosaic and digital elevation representations of the patterns. Thousands of patches were then extracted and augmented to develop SVM and CNN models. The results demonstrate that machine learning is useful for drillhole detection and, in this way, to control the drilling accuracy and use the explosive energy more efficiently.

Sep 1, 2021

By N. Hamlef

In this study, the effects of heat treatment on phase formation and surface morphology of the Cr-Pt coated system are investigated using X-ray diffraction and electron microscopy techniques. The CrPt andCr4Pt (Cr3Pt - A15 type) phases were formed after heat treatment of the coated samples. Heat treating at 1000°C renders a distinct island coating morphology that is non-continuous in nature. A diffusional model is proposed for this coated system with regards to the surface morphology formation after heat treatment.

Jan 1, 2014

By R. L. Setsepu, S. O. Bada, J. Abdulsalam

The utilization of biomass as a solid fuel for co-firing has received great attention from boiler manufacturers as a clean coal technology (CCT) option. This research aimed to produce biocoal pellets, as a clean energy fuel, using hydrochar from trees planted to rehabilitate acid mine drainage (AMD) water and fine coal discards. The hydrochar was synthesized by hydrothermal carbonization of Searsia lancea harvested from AMD-contaminated land at a temperature of 280°C and a residence time of 90 minutes. It was blended with discard coal (–1 mm) at ratios of 25% and 50% hydrochar to produce different forms of solid pelletized biocoal (BC). The physicochemical and mechanical properties of each of the biocoal pellet blends were determined. The 100% hydrochar had the highest calorific value of 29.99 MJ/kg, while the raw discard coal had a calorific value of 16.73 MJ/kg. The ash content decreased from 42% in the discard coal to 25% in the blend of 50% coal and 50% hydrochar biocoal pellets. Biocoal pellets comprising 25% hydrochar and 75% discard coal (BC25 HC/75 COAL) displayed the best mechanical properties (compressive strength 3.06 MPa) of all the fuels, but the physicochemical properties were inferior to the BC50 HC/50 COAL pellets. This research has demonstrated that hydrochar synthesized from a tree species planted for hydraulic control of AMD has the capability to act as a binder for improving the mechanical properties and energy characteristics of fine discard coal.

Dec 1, 2021

By N. Duda, P. Śliwiński, P. Stefaniak, B. Jachnik

Ventilation and air-conditioning are some of the most energy-consuming processes in deep underground mining. Additionally, the energy consumption of these processes systematically increases along with the expansion of the mine. Therefore, proper energy efficiency assessment and consumption forecasts of these systems are particularly important in modern mines for ongoing tracking and planning of the likely costs. In the article, a short-term prediction model for surface air–conditioning stations is described. This model takes into account dependencies that were identified, based on the data from the supervisory control and data acquisition (SCADA) systems. These dependencies between the response value and the external conditions are then incorporated into the model. This way, for example, the ambient temperature or the total number of specific days of the week (with sometimes significantly lower or higher than the weekly average energy consumption levels) are included. Taking into account these dependencies, and e.g. forecasted average monthly temperatures allow us to include the seasonality of energy consumption in the presented model. In the article, a sample energy efficiency analysis of the A/C system based on an example of the KGHM Polish Copper Polkowice-Sieroszowice mine is performed. The results of the solution proposed in the article are then evaluated, and compared to the currently functioning, more basic forecasting methods. However, given the general nature of the dependencies used in the model, similar solutions could be used in other case studies.

Sep 1, 2021

By F. Dutoy, M. B. Stella, C. F. Carrozza

Rare earth elements (REEs) are indispensable components in the manufacturing of high-tech devices, renewable energy technologies, and defence applications. As global demand for these elements continues to rise, there is a pressing need to optimize extraction processes for both efficiency and environmental sustainability. This study explores approaches to rare earth extraction using Ionquest® 801 and integrates a predictive modelling to enhance process understanding and optimization. We conducted a screening test varying pH process to evaluate the best extraction efficiency. Starting pregnant leach solution (PLS), solution was prepared in the lab with the following rare earth elements: La, Ce, Gd, Dy, and Υ, at 0.02 M for each element. The data obtained were used to develop empirical and mechanistic models to predict rare earth extraction yields and flowsheet. Further tests were performed by mixing specific concentrations of different extractant and/or phase modifier. Our experimental results demonstrated the effectiveness of the proposedextraction methods, highlighting improvements in both yield and selectivity. The developedmodels successfully captured the complex relationships between process parameters and extraction efficiency, providing valuable insights for process optimization.

Nov 6, 2024

By B. Genc

Safety in South African mines is a subject of significant interest, since many mining companies are experiencing production deficits due to safety-related stoppages. In this paper, safety data from the South African platinum mining sector is analysed for the period 2006 to 2010. The data was obtained from company annual reports as well as the Department of Mineral Resources, and analysis in the study is limited to injury and fatality data only. The overall safety performances of companies in the sector are compared, and opportunities for benchmarking and recognising potential sources of best practice amongst platinum miners are identified. Improving safety usually incurs a cost, and mining companies are particularly conscious of the importance of controlling costs. However, cost considerations often deal only with direct costs, and it has been shown that indirect costs are usually far more significant. Therefore, a greater safety spend will usually result in the creation of value for the mine since it will reduce the indirect costs associated with accidents. The results of some recent research in this area are presented. In this light, where available, the financial performances of mining companies in the sector, obtained from published annual results, are included in the benchmarking exercise to determine whether there is any correlation with safety performance.

Jan 1, 2012

By P. Ramsaywok, S Ndanduleni, G. Legodi

The objective of this paper is to share the optimisation journey of a pilot Reflux classifier (RC) circuit in the Exxaro GG1 plant, at Grootegeluk beneficiation complex in Lephalale, South Africa. The RC circuit was commissioned in 2016 to produce semi-soft coking coal at its fines circuit; however the stability of operation as well as the quality control of the coal product was not fully achieved. Various test campaigns and optimisation studies were conducted to understand and optimise the RC circuit at GG1. The studies revealed circuit design inefficiencies; provided an improved technical understanding of the current pilot circuit and the parameters required for the circuit to reach a stable operation. The operation was stabilised with its current inefficiencies to produce an average 12.5% ash semi-soft coking coal product for sustained periods, above the initial target of 10.3% ash. Keywords: Reflux classifier, coal

Jan 1, 2020

By K. Sasaki, S. Kuroiwa, H. Miki, Y. Aoki, T. Hirajima, Y. Orii, G. P. W. Suyantara

Selective flotation to separate copper minerals from, for example, Mo- and/or As-bearing minerals is a continuing problem because the selectivity of current systems is imperfect. Selective Cu-As flotation is currently difficult, and the most common Cu-Mo selective flotation method uses NaHS; this must be done in an enclosed system because, under acidic conditions, this method produces hydrogen sulfide. In this paper, some novel alternative flotation processes that use redox reactions are discussed; these methods have a much lower environmental impact. Oxidation and reduction reactions can be used to make copper minerals more hydrophilic and Mo-bearing minerals more hydrophobic. X-ray photoelectron spectroscopy (XPS) analyses indicated that the copper minerals became hydrophilic because hydrophilic iron precipitated and several hydroxides covered the copper minerals’ surfaces, whereas the molybdenum minerals remained hydrophobic because their sulfide surfaces were not covered. Flotation experiments on these minerals after redox treatments indicated that excellent separation of Cu-minerals from Mo-minerals can be achieved. Possible mechanisms for this separation were investigated using detailed surface analyses and thermodynamic calculations. The additives used to initiate the redox reactions are easy to handle and make these new flotation procedures better than current processes because the new methods do not emit effluent gas and because they are commercially viable. Keywords: Flotation; chalcopyrite; molybdenite; oxidation; reduction

Jan 1, 2020

By Z. Tshentu, M. Ngayek, P. Moleko-Boyce

This paper is focused on the development of iridium(IV)-specific quaternary diammonium cations containing electron-donating substituents in the benzyl group of methyl and electron-withdrawing substituents such as triflouromethyl and nitro groups. Quaternary diammonium cations used were tetra- 4-methylbenzyl-1,10-diammonium decane chloride (QuatDMDAMeBnz), tetrabenzyl-1,10- diammoniumdecane chloride (QuatDMDABnz), tetra-3-trifluoromethylbenzyl-1,10- diammoniumdecane chloride (QuatDMDACF3Bnz) and tetra-4-nitrobenzyl-1,10-diammoniumdecane chloride (QuatDMDANO2Bnz). Polyvinylbenzylchloride (PVBC) nanofibres were used as support material, and the functionalised nanofibres were used for separation of Ir(IV) from Rh(III). The sorbent materials were characterised by FTIR and elemental analysis. The efficiency of the quaternary diammonium cations was investigated in a column study under dynamic flow adsorption conditions. Column sorption of [IrCl6]2- and [RhCl5(H2O)]2- on nanofibres functionalised with diammonium cations showed [RhCl5(H2O)]2- was not adsorbed by the sorbent materials while [IrCl6]2- was loaded onto the column. The loading capacities of [IrCl6]2- on the quaternary diammonium sorbent materials increased in the order of F-QuatDMDAMeBnz (3.08 mg/g) < F-QuatDMDABnz (3.39 mg/g) < FQuatDMDACF3Bnz (5.46 mg/g) < F-QuatDMDANO2Bnz (7.10 mg/g). The loading capacity for Ir(IV) with quaternary diammonium cationic nanofibres increased with an increase in the electron-withdrawing nature of the substituent on the quaternising group. The charge delocalising ability of the 4-nitrobenzyl group resulted in the best interaction of the decamethylene diammonium cation with [IrCl6]2-. Keywords: Iridium(IV), rhodium(III), quaternary diammonium, polymer nanofibres, separation

Jan 1, 2020