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The October General Meeting of the Institute was held in Kelvin House, Johannesburg, on 15th October, 1969, at 4.30 p.m. Mr J. K. E. Douglas (President) was in the Chair. There were also present 17 Members, Messrs: M. Barcza, R. C. J. Goode, J. A. Nixon and V. C. Robinson (Council Members), M. L. Fitzgerald, D. F. H. Graves, C. G. Hinds, S. D. Hill, J. S. Hall, D. F. Malan, T. Meyer, W. pyne-Mercier, K. S. Rae, S. G. Taussig, L. W. P. van den Bosch, Dr A. Whillier, C. H. Wyndham. Four Associate Members: Messrs O. Davel, M. J. Martinson, M. P. J. Sandys, T. G. Harington. One Student: R. P. W. Henrard. Three Visitors: Messrs A. V. Pike, B. Schmitz, A. P. Raats. Secretaries: D. C. Visser and S. de. Gersigny. Total present: Twenty-eight. OBITUARY The President: "It is my said duty to announce the death of Pieter Ulrich Fischer, Member, who joined the Institute in 1961 and passed away on 24th June, 1969. As a mark of respect to the memory of the deceased and in sympathy with the bereaved I would ask you all to rise and observe a few moments' silence." MINUTES The President: "The minutes of the last meeting will only appear in next month's Journal and I would request that the confirmation of these minutes be held over." 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:" Members: Alexander Edward O'Meara, Anton Leopold Melvill, WilIiam Harold Wise, Eric John Dunstan, Frank Nel, Lubertus Hendrikus Jakob Poortier. Associate Members: Michael Irvine Britten, Selwyn Wilson Lange. James McCormack, Christiaan Lodewyk de Jongh, WilIiam Andrew Hustrulid, Reinhold Johannes Ortlepp, Felix Henry Lancaster. Graduates: Willem Adriaan Gericke, Hamish David Sneddon Miller, David lan Ossin, Robert Antony Layboume, Ewart John Shillaber, Colin Hewitt Wiggett. Affiliates: Bernard Andre Thomas, Waiter Arthur Wood, Andrew John George Paschalides, David John Perry, Alex Richardson, Gert Blekker Kotze. Student: Matthys Jacobus de Beer. MEMBERS TRANSFERRED TO A HIGHER GRADE From Associate Member to Member: David Alphonso Viljoen. From Student to Associate Member: Michael Charles Carruthers. "I welcome the newly elected members to the Institute and congratulate the members who have been transferred to a higher grade." PAPERS FOR PRESENTATION The President: "Professor Wyndham, may I call on you to deliver the paper entitled 'Factors affecting the mechanical efficiency of men shovelling rock in stopes', written jointly with J. F. Morrison, J. H. Viljoen, N. B. Strydom and A. Heyns." After the presentation of the paper the President said: "Gentlemen, I would like to thank Dr Wyndham and his colleagues for once again reporting through the medium of this Institute the results of the very important work they are carrying out at the Human Science Laboratories. It is most appropriate that this work which is leading to a better understanding of the capabilities and efficiency of the human body under the arduous conditions encountered underground should be reported to this forum. In this way our members, who are actively engaged in the job of mining, can firstly learn something of this research and secondly, can, with their practical knowledge of conditions underground, contribute to what has been learnt and possibly pose new problems for our scientists in the laboratories. The scientist should always have the opportunity of subjecting his research to the scrutiny of people engaged in practical operations. By the very nature of our gold mines we are unfortunately heavily dependent on a large labour force and while mechanization has been introduced wherever feasible, we are likely to continue to be heavily dependent on this labour. In accepting this fact we can be proud in this country of what has been achieved, not only in obtaining the best efficiency from labour but in ensuring that their working conditions are reasonable and that their health and well-being are adequately cared for. When one visits our gold mines, one cannot help being impressed with what is being done to ensure that we have a satisfied, happy and healthy labour force. The Human Sciences Laboratory with its scientific approach has assisted greatly in promoting a better understanding of the problems associated with labour under the conditions experienced on our mines. Thank you." Mr M. Martinson then contributed to the discussion. (This contribution will appear in a later issue of the Journal.) "Professor Wyndham, may I call on you to deliver the paper entitled 'Acclimatizing men to heat in climatic rooms on mines,' written jointly with Prof Strydom." After Dr Wyndham had presented the paper the President said: "Thank you Dr Wyndham for so ably describing the work associated with the acclimatization procedures on our gold mines. It has certainly been an eye-opener to those of us not familiar with this work and I believe it is very important that everyone and not only people in the gold mines should know about it. It is fortunate that all industries do not have the same arduous heat conditions experienced on our mines but other industries such as our chemical and metallurgical industries do have other problems relating to the adjustment of labour to the work situation. The scientific approach employed by the gold mines in tackling this problem is an example to these industries of what can be achieved by logical

By G. Drennan, A. Cameron

"South African mining operations depend on the skilled professionals produced through the tertiary education sector. In geoscience courses at the University of the Witwatersrand, which lead into the mining sector, there has been a significant increase in student intake over the past 15 years. This increase has been characterized by a radical shift in demography: in classes where white male students once formed the majority, black female students are now in the majority. This demographic shift appears closely linked to policies addressing issues of social justice and transformation in post-apartheid South Africa. We document this change and consider the role played by employment equity legislation (as in the Mining Charter) and corporate social investment strategies in the mining industry, notably through bursaries offered to black female students. We also look at the changing needs of the industry, where the critical need for managerial skills, not just technical knowledge, is highlighted through data from surveys of past students and industry managers. Our findings indicate the need for a curriculum adjustment to meet these changing requirements, as well as more rigorous selection criteria for bursars than simply gender, race, and appropriate matric results. IntroductionThe South African economy has historically been linked to mining and the exploitation of mineral resources. South African mining operations are dependent on the professional labour that is produced through the tertiary education sector, with critical thinking, teamwork, and the art of negotiation having been identified as the crucial skills required for this industry (Sideropoulos, 2014). Over the past three decades the South African system of education has gone through a period of dysfunction that it is struggling to rectify (Maphai, 2014). This has impacted on the levels of academic preparedness of students applying for places in higher education. Concurrently, government and university policies have widened access to higher education in response to the need to address issues of social injustice and transformation related to South Africa’s history of apartheid. As a result, the number of students admitted to universities has increased dramatically. In the School of Geosciences at the University of the Witwatersrand (Wits), the increase in student numbers has been accompanied by a significant change in demographics: classrooms which in the past were dominated by white males have given way to classrooms in which black females are often in the majority. This demographic shift is related to legislation such as the Mineral and Petroleum Resources Development Act and the Broadbased Socio-Economic Empowerment Charter, developed to reshape the socio-economic and equity frameworks of the country (Botha and Cronje, 2015). Requirements aimed at transformation in terms of management, skills development, and employment equity, together with corporate social investment (CSI) requirements, have resulted in bursaries being made available to attract students from designated groups, which in turn has increased the number of black students, and notably black female students, taking courses in geosciences. However, due to the economic downturn, instability in the mining industry has recently resulted in the downsizing of some mines, with international investors pulling out of South Africa. This instability resulted in devastating strikes across all sectors of the mining industry (Stewart, 2013) and in Marikana, an important platinum mining area, the strike culminated in a deadly shoot-out between miners and police. The resulting tensions spilled over into the gold mining sector, resulting in further strike action, shaft closures, and retrenchments. These challenges have implications not only for the mining industry in South Africa, but for the tertiary education providers whose graduates would have been absorbed into the mine-related workforce."

Jan 1, 2017

SACPE has asked the Journal to bring the following points to the notice of members who are about register with SACPE. When to Apply There is no set time to apply for registration. Engineers should apply when they believe that their training has met all the requirements of Policy Statement No. 1/3. Pitfalls Remember that it is the applicants' training that must be evaluated, and this requires the avoidance in the application of vague generalities such as 'My duties were design plant including its economic evaluation' or 'I was engaged in . . Requirements An example of what is required can perhaps best illustrate the point.

Jan 1, 1982

Each year the South African Institute of Mining and Metallurgy offers a prize (or prizes should the entries warrant it) of up to RlOO for the best paper or dissertation on a topic appropriate to the interests of the Institute. The competition is open to all Student Members of the Institute. A Student Member who is in fulltime study at a university may submit the dissertation or thesis he has to write in part fulfilment of his university degree, provided that it is presented in a manner and on a topic suitable for publication in the journal. Entries for 1976 should reach the Institute by 31st December, 1976.

Jan 10, 1976

The May General Meeting of the Institute was held in Kelvin House, Johannesburg, on 21st May, 1969, at 4.30 p.m. Mr J. K. E. Douglas (Vice-President) was in the Chair. There were also present twenty-two Members, including Messrs F. P. Bath, M. Bareza, A. R. C. Fowler, D. M. Jamieson, C. M. Mavrocordatos, D. G. Maxwell and J. A. Nixon (Council Members), Messrs T. Davidson, G. L. Diering, E. T. Dunstan, D. E. H. French, K. Hodgson, O. A. E. Jackson, A. F. Lee, A. Louw, D. L. Starkey, R. K. Wheeler and M. Youngworth. Four Associate Members including Messrs D. Blair Hook and G. R. Still. One Student Mr N. A. Barcza. Thirteen Visitors, including Messrs S. H. Ash, D. L. G. Bayne, E. Bayne, S. Bell, W. S. Garrett, L. S. Gibbs, R. C. Hamilton, M. Maguire, D. Rose and J. D. van Niekerk. Total Present: Fourty-one. OBITUARY The Vice-President: "It is my sad duty to announce the death of the following member of the Institute: Thomas Spence Haldane, Member, who joined the Institute in 1924 and passed away on 21st December, 1968. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, those present stood and observed silence for a few moments. MINUTES The Vice-President requested that confirmation of the minutes of the previous meeting be held over as they would only be appearing in the Journal of the following month. He also requested that confirmation of the minutes of the 75th Anniversary Meeting be held over. MEMBERSHIP The Vice-President: "I have much pleasure in announcing that the names of the under-mentioned candidates have been published in accordance with By-Law 5.2.2, and Council has elected them to membership of the Institute in the following grades: Members: Gideon Jacob Haumann, Peter John Cumming, Ian Stanley Dudman, Roderick Goldston Murchison. Associate Members: Francois Alwyn Beyers Fouche, Alan Marsh, Johannes Petrus van der Westhuysen, Waldo Edmund Stumpf, Ian Nicholas Ridley. Affiliates: Lutgerus Kolver Jooste, Roger Ainsley Ralph Kebble, Edward John Wainwright, Lewis William Davies. Graduate: Clive Graham Knobbs. MEMBER TRANSFERED TO A HIGHER GRADE From Student to Associate Member: Diethard OUo Eduard Fahrbach. I welcome the newly elected members to the Institute and congratulate the member who has been transferred to a higher grade." (Applause).

The May General Meeting of the Institute was held in Kelvin House, Johannesburg, on 21st May, 1969, at 4.30 p.m. Mr J. K. E. Douglas (Vice-President) was in the Chair. There were also present twenty-two Members, including Messrs F. P. Bath, M. Bareza, A. R. C. Fowler, D. M. Jamieson, C. M. Mavrocordatos, D. G. Maxwell and J. A. Nixon (Council Members), Messrs T. Davidson, G. L. Diering, E. T. Dunstan, D. E. H. French, K. Hodgson, O. A. E. Jackson, A. F. Lee, A. Louw, D. L. Starkey, R. K. Wheeler and M. Youngworth. Four Associate Members including Messrs D. Blair Hook and G. R. Still. One Student Mr N. A. Barcza. Thirteen Visitors, including Messrs S. H. Ash, D. L. G. Bayne, E. Bayne, S. Bell, W. S. Garrett, L. S. Gibbs, R. C. Hamilton, M. Maguire, D. Rose and J. D. van Niekerk. Total Present: Fourty-one. OBITUARY The Vice-President: "It is my sad duty to announce the death of the following member of the Institute: Thomas Spence Haldane, Member, who joined the Institute in 1924 and passed away on 21st December, 1968. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, those present stood and observed silence for a few moments. MINUTES The Vice-President requested that confirmation of the minutes of the previous meeting be held over as they would only be appearing in the Journal of the following month. He also requested that confirmation of the minutes of the 75th Anniversary Meeting be held over. MEMBERSHIP The Vice-President: "I have much pleasure in announcing that the names of the under-mentioned candidates have been published in accordance with By-Law 5.2.2, and Council has elected them to membership of the Institute in the following grades: Members: Gideon Jacob Haumann, Peter John Cumming, Ian Stanley Dudman, Roderick Goldston Murchison. Associate Members: Francois Alwyn Beyers Fouche, Alan Marsh, Johannes Petrus van der Westhuysen, Waldo Edmund Stumpf, Ian Nicholas Ridley. Affiliates: Lutgerus Kolver Jooste, Roger Ainsley Ralph Kebble, Edward John Wainwright, Lewis William Davies. Graduate: Clive Graham Knobbs. MEMBER TRANSFERED TO A HIGHER GRADE From Student to Associate Member: Diethard Otto Eduard Fahrbach. I welcome the newly elected members to the Institute and congratulate the member who has been transferred to a higher grade." (Applause).

By T. J. Otto, C. Musingwini

"The objective of any mining company is to sustainably maximize the net present value (NPV) throughout the life-of-mine (LOM). The expected NPV over the LOM is calculated based on a mine plan, yet the actual value realized by the mining company depends greatly on the level of intertemporal execution against the mine plan. Consequently, a major key performance indicator (KPI) that is often overlooked in open pit mining, due to a greater focus on temporal KPIs, is the degree of spatial compliance to the mine plan. Such focus sometimes leads to short-term actions being detrimental to long-term plans. In this paper we describe the development and implementation of a spatial mine-to-plan compliance reconciliation approach for an open pit mine. Application to a case study open pit iron ore mine in South Africa indicated a significant improvement in the spatial mine-to-plan compliance, from 69% to 94% over a three-year period from 2014 to 2016. These results indicate that implementation of the proposed spatial mine-to-plan compliance reconciliation approach can contribute positively to improving the level of spatial execution and assists in improving the alignment between short-term, medium-term, and LOM plans.IntroductionThe objective of any mining company is to maximize the net present value (NPV) throughout the life of mine (LOM). However, this objective needs to be fulfilled in a sustainable manner that considers the needs of various stakeholders, including employees, shareholders, and local communities where the mines operate. The expected NPV is calculated using a mine plan as a basis. Mine planning broadly involves identifying a strategy to exploit the mineral resource in a way that maximizes value at an acceptable level of risk throughout the LOM (Tholana and Neingo, 2016).The mine planning process is a well-recognized component in the mining value chain of an open pit mine. Figure 1 reflects the relative position of mine planning within a typical open-pit mining value chain from the mineral resource to the market"

Mar 1, 2019

By W. P. C. Duyvesteyn, J. R. Cutland, J. R. L. Russell

In 1970 it was decided to build a large new plant at the Chingola Division of N.C.C.M., Ltd., to treat concentrator tailings and leach residues with a low copper content by a leach-solvent extraction-electrowinning process. In order to assist in the establishment of the design parameters for the new plant, and to study the interaction of this plant with the existing leach-electrowinning plant, mathematical models, formulated as linear programs, have been developed and used extensively. The paper outlines the metallurgy of the plants and describes briefly the way in which the models have been formulated and used. The formulation involved the use of separable programming to form the products of some variables.

Jan 1, 2014

By Pieter de Waal

The beneficiation equipment under the control of plant metallurgists exploits the differences in the physical properties between valuable and waste mineral components. In many cases, laboratory results are too late for process control and can only serve the purpose of "post" reports, the calculation of a mass balance and the issue of a quality certificate. As a result, experienced operators regularly adjust separation equipment based on the colour and texture of the various product streams in the beneficiation plant. Metallurgists quickly learn to recognise the different minerals in their ore body. The stereo microscope has been a valuable tool used by operators to quantify known mineral species. For many years it was the only practical method available for the purpose of process control and even for quality contro1. The modem spectroscope is far superior to the human eye and can rapidly detect a change in mineral composition. New generation optical scanners and digital signal processors can provide useful signals, related to mineral composition that can readily be applied for the purpose of process control. Successful case studies, covering dry in-line and slurry applications as well as in-plant fast spot analysers are presented.

Jan 1, 2014

By L. Chanderman, C. E. Dohm

"Mineral Resource estimation (MRE) and classification are highly dependent on the confidence in the model of the orebody geometry, known as the geological model, within which the estimates are constrained. An understanding of the geology of a deposit is thus fundamental to the Mineral Resource evaluation process. The geological model is a function of the structural and depositional complexity of the geology captured by drilling information, which is limited in the early stages of a project. The information effect has a significant impact in terms of the interpretation of the geology as well as the estimation of grade continuity and the resultant risk associated with the Mineral Resource estimate and classification.Therefore, as new drilling information becomes available, it is necessary to update and refine the geological model to appropriately constrain the resource estimates. The grade information is also updated, including statistics and the spatial correlation characteristics. This refinement is based on geological interpretations derived from the drillhole information that becomes available throughout the life of the mine; orebody knowledge that comes from working experience of the deposit, as well as familiarity with the software package used for modelling, is also important.In updating, the potential to identify new resources in previously unknown areas may be realized. The opposite may also occur where previous interpretations of ore continuity are refuted. Both scenarios could result from a better understanding of the geology of the deposit and thus a more realistic MRE, which reduces geological risk. This paper describes how newly drilled advanced grade-control holes for a gold deposit in Mali were used to refine the 3D geological model for the deposit in an attempt to identify the potential for additional oxide ore using conventional geostatistical evaluation techniques."

Jan 1, 2017

By M. Izadi Yazdan-Abadi, S. H. Amiri, M. Ramezanizadeh, M. Bazmandeh

Iron ore concentrate is used as the fresh feed of pelletising plants. The green pellet properties depend on iron concentrate characteristics such as particle size distribution (PSD), specific surface area (Blaine value), iron grade, moisture content and grinding methods. The grinding methods affects particle size distribution and Blaine value. To find out the effects of grinding methods on pelletising process, green pellets were produced with concentrates that were reground by means of HPGR (high pressure grinding rolls) and ball mill. The Blaine values of ground concentrates in both types of milling were approximately 1400, 1600 and 1800 cm2/gr. The results of green pelletising tests on a pilot plant scale showed that at the same Blaine values, drop numbers of green pellets produced by ground concentrate inside HPGR were higher than the green pellets produced by ground concentrate inside a ball mill. Also, reground concentrates by means of HPGR, in comparison with ball mill, caused the production of green pellets, at higher wet and dry compression strengths. As a result, it was found that preparing the pelletising feed by means of HPGR led to more positive effects on the properties of green pellets. Keywords: Ball mill, HPGR, green pellet, drop number, wet and dry compression strengths

Jan 1, 2020

By J. N. van de Merwe

CONTRIBUTION BYH. WAGNER AND T.T. OZAN The paper by Dr J.N. van der Merwe makes an important contribution to the design of bord-and-pillar workings in the Vaal basin. It has been recognised for some time that the strength of coal seams in the Vaal basin is markedly lower than that of coal seams in other coal-mining districts in South Africa. However, there was insufficient data to quantify how much weaker the extensively jointed coal the Vaal basin is. A number of recent pillar collapses that occurred at Sigma colliery, the only remaining underground colliery in the Vaal basin, provided Dr Van der Merwe with an opportunity to make this assessment.

Jan 1, 1993

By M. Khodadazadeh, K. G. van den Boogaart, T. Leißner, L. Tusa, J. Gutzmer, R. Gloaguen, M. Kern

Ore sorting is a technology that is increasingly used to process primary raw materials. Timeconsuming and expensive empirical state-of-the-art test work is carried out to assess whether the use of ore sorting for the enrichment of a particular ore makes technical and economic sense. With the innovative simulation-based approach presented here, it is possible to direct the selection of a suitable sensor based on quantitative mineralogical and textural data, thus avoiding much of the empirical studies. Required data can be collected quickly and cost-effectively using available methods of automated mineralogy. The obtained parameters such as mineral grain size distribution, modal mineralogy, mineral area and mineral density distribution have been utilised in this study to simulate the prospects of success of ore sorting, applying different types of sensors. Empirical tests with commercially available sensor systems have been conducted to experimentally validate the predictions of the simulations. The estimation of the target mineral grade can be further optimised by the use of machine learning algorithms for the integration of automated mineralogy data and sensor data. The approach can easily be adapted to other types of raw materials and thus has great potential to become a key technology for the optimisation of processing experiments. Keywords: Automated mineralogy, hyperspectral imaging, machine learning, ore sorting

Jan 1, 2020

By J. van Zyl Visser

The advancement in Information Technology has resulted in a change in workflow practice in our Mineral Resource Management (MRM) offices on the mines and at our corporate office. This paper discusses the AngloGold approach in defining an IT strategy for MRM, a brief overview of systems usage and benefits. AngloGold has gone through a transformation phase and has positioned itself as a world-class, low cost producer. To support this objective, an initiative has been launched to provide the MRM division with an integrated MRM technical suite of systems with support of a Management Information System. Technical systems for a tabular orebody are not freely available and hence it took AngloGold almost seven years and a significant amount of capital to develop an integrated suite of technical systems. AngloGold MRM IT adopted the typical Zachman framework (value chain) approach in the analysis process and formulated the final deliverable in terms of AngloGold’s strategy. Major benefits have been realized through the ability to change planning scenarios in a short period of time and hence be able to increase reserves and NPV. The development of MRIS, which will become the flagship in AngloGold’s portfolio of systems is in phase two and this system will allow AngloGold to publish Resources and Reserves as per SAMREC and the JORC Code at will. The availability of information at all levels of the operations has made making decisions easier and hence some specialized reports such as the Basic Mining Equation were developed from the Corporate Data warehouse and from the MRM reporting database. Decision Support Systems(DSS) such as Business Objects and Oracle Express are now being used to assist in the process. The decision to use Business Objects to replace SAS reporting as the core reporting tool has resulted in the empowerment of the user and major cost saving as far as the use of consultants to set up standard reports.

Jan 1, 2003

By A. C. Lawrence, K. F. Mauer

Human factors in stope productivity -a field experiment by K. F. MAUER, M.A. (Visitor), and A. C. LAWRENCE, B.Econ., D.Com. (Member) An experiment in which three human variables were manipulated in eight stopes was conducted in a gold mine over a period of roughly six months. The three variables, which each had two levels, concerned the degree of movement from gangs, the quality of the Bantu production supervisors, and the extent to which gangs were composed of a single ethnic group (Malawians). Time was included as a variable with three levels in the analysis of the findings. On the average, stable gangs produced 12 per cent more than gangs with a high percentage of transfers, gangs with better production supervisors were more successful by nearly 9 per cent than those with poorer production supervisors, and homogeneous gangs were more productive than heterogeneous ones by as much as 15 per cent. In addition, it was found that a number of the variables exercised a joint influence on stope productivity and that the effects of the variables were accentuated by the len gth of time they had been in operation. V

Jan 10, 1973

By S. K. Murphy

A partial shaft pillar extraction project was embarked on at a mine in the West Wits mining region in South Africa. Prior to the extraction, a rock engineering assessment was conducted with the main objective being to establish which areas of the shaft pillar could be extracted without unduly affecting the stability of major infrastructure within the shaft pillar. Standard numerical modelling methods were used to conduct this assessment and several areas were identified for extraction. However, during the extraction process, it was found that the infrastructure was affected more than was originally predicted by linear elastic modelling. In addition to this, several large events resulted in far more large aftershocks than would normally be predicted. In order to gain an understanding of this phenomenon, seismic data was integrated with numerical modelling as follows: > The seismic data in the form of displacements was integrated in 3D space within the model to assess the effect of static stress changes associated with seismic activity > Data from large events was integrated onto specific structures, where displacements associated with large events were integrated onto the plane of structure in question. This paper describes the methodology and results obtained from each of the above processes and include insights into the mining process that were previously unfathomable using standard linear elastic numerical modelling. The way forward for this rock engineering assessment of partial shaft pillar extraction is also discussed.

Jan 1, 2012

By F. F. Roxborough, P. King, E. J. Pedroncelli

This paper describes tests on the performance of a continuous miner in cutting South African coal. Although coal cutting has been investigated extensively overseas, the results have not led to significant changes in machine design because these machines find little difficulty in cutting the softer overseas coals at a fast rate. In general, the results of the tests show that cutting efficiency improves markedly as the depth of cut per revolution of the drum increases, and that the best spacing of picks on the drum is twice the depth of cut. Pick shape is of secon¬dary importance in terms of cutting efficiency, only small differences having been found between the performances of conical- and chisel-shaped tools.

Jan 1, 1981

By Y. Zhou, G. Chisakuta, P. Bwando, G. Mitshabu

A newly started copper hydrometallurgical plant was confronted with a manganese oxidation issue in electrowinning. This oxidation, in the absence of the amount of iron required to stabilise the electrolyte oxidation-reduction potential, is known to produce oxidants (MnO2, MnO4) that can cause accelerated degradation of the organic phase components in solvent extraction and corrosion of lead anodes in electrowinning. The overpotential required to build up the protection layer on new anodes causes an increased electrolyte potential that creates oxidized species in the electrowinning tankhouse, and these species come back to solventextraction plant with the recycled spent electrolyte. This paper discusses the impacts of manganese oxidants on the health of a plant organic phase. It also outlines the actions taken using iron scraps and sulfur dioxide to mitigate the problem that happened due to the lack of ferrous iron sulfate available on site, as recommended for better control.

Jan 1, 2023

By F. L. D. Cloete

The following discussion relates to the paper by G. S. Hansford, C. D. Levy, and J. W. de Kock that appeared in the March 1976 issue of the Journal (vol. 76, no. 8, pp. 363-369) Competition for student members Each year the South African Institute of Mining and Metallurgy offers a prize (or prizes should the entries warrant it) of up to RI00 for the best paper or dissertation on a topic appropriate to the interests of the Institute. Engineering in South West Africa The SW A Engineering Profession Steering Committee was established on 4th April, 1977, its purpose being to formulate an Act covering the engineering profession in South West Africa.

Jan 1, 1978

By L. Petzold

The demand for stainless steel is ever-increasing. As an essential element in stainless steel-making process, so is the demand of chromite concentrate. At the same time, the industry proven technologies for beneficiation of chromite are limited. Chromite is only crushed, screened and jigged to produce a concentrate. However, for ultrafine and low-grade material, no satisfactory beneficiation methods for the enrichment of chromite fines exist in industrial operation. This poses a clear challenge for the industry, which Primetals Technologies has addressed with the development of a new beneficiation process. The aim of this process was to enrich low grade chromite tailings to a quality suitable for the smelting process. Required concentrate grades are different over the world, concentrate grades of Cr2O3=40% and lower are found at the Bushveld Complex, South Africa. The target for the present study was a Cr2O3-grade in the area of 49%. Three different chromite tailings with Cr2O3 grades between 16 % and 29 % were part of a study, executed by Primetals Technologies. All three tailing materials were characterised by Mineral Liberation Analysis (MLA). Based on the physical, chemical and mineralogical findings, process flowsheets were developed. The process flowsheets included grinding to ensure a full liberation of the chromite. The liberated material was classified at a cut size of 63 μm to a coarse and fine fraction. Gravity separation and flotation processes were tested with the coarse particle fraction. Due to the limitations of gravity separation with fine particles, only the flotation process is suitable and was tested with the fine fraction < 63 μm. A Design of Experiment (DoE) with six factors, each three levels, was conducted to identify optimal parameters for the fine chromite flotation. Two different collectors were tested: a phosphoric acid ester and a fatty acid type collector. In small scale test work a chromite concentration suitable for the smelting process was achieved. On this basis Primetals Technologies will develop a pilot-scale test program to research recirculation effects and upscale potential of the process. Keywords: Mineral processing, tailings beneficiation, flotation, density separation, process development, chromite

Jan 1, 2020