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By H. E. James

During the past ten years there has been an upsurge of interest in the development of selective ion exchange resins and solvents, and of ion-exchange and solvent extraction equipment tailored to the special requirements of mineral-processing circuits. It is therefore not surprising that the recent Symposium on Ion Exchange and Solvent Extraction in Mineral Processing, held at the National Institute for Metallurgy (NIM) on 7th and 8th February, 1980, was a resounding success. This Symposium, organized jointly by NIM. Ion exchange and solvent extraction The Symposium on Ion Exchange and Solvent Extraction in Mineral Processing, which was organized jointly by the National Institute for Metallurgy, the South African Institution of Chemical Engineers, and the South African Institute of Mining and Metallurgy, was held in Randburg on 7th and 8th February, 1980. Analytical chemistry The Fifth International Conference on Analytical Chemistry, organized by the Chemical Society, is to be held at Lancaster University, England, from 20th to 26th July, 1980. Coal mining The First International Symposium on Thick and Steep Seam Coal Mining will be held in London from 18th to 21st May, 1980. Mineral processing The XIV International Mineral Processing Congress will be held in Toronto from 10th to 16th October, 1982. The theme of the congress will be 'Worldwide industrial application of mineral processing technology'. Sessions will be held on the following:

Jan 1, 1980

A Special General Meeting, followed by the February General Meeting of the Institute, was held in Kelvin House, Johannesburg, on 18th February, 1970, at 4.30 p.m. Mr J. K. E. Douglas (President) was in the Chair. There were also present 24 Members: Messrs A. R. C. Fowler, R. C. J. Goode, Prof D. D. Howat, Messrs D. G. Maxwell, J. A. Nixon, P. W. J. van Rensburg (Council Members), C. A. Border, J. C. Fritz, E. K. Gibson, P. L. Grimbeek, S. D. Hill, D. A. Immelman, P. J. Uoyd, M. Mrost, C. S. Macphail, D. G. Malan, W. D. Ortlepp, R. S. Pearson, A. J. H. Pole, Dr W. S. Rapson, L. W. P. van den Bosch, R. A. von Maltitz and Dr A. Whillier. Eight Associate Members: Dr M. I. Brittan, Messrs J. Brett, I. E. Clarke, C. L. de Jongh, W. B. Evans, D. Loubser, R. C. More O'Ferrall and G. R. Still. One Graduate: Mr T. J. Kotze. One Student: Mr J. A. Cruise. Nine Visitors: including Dr N. G. W. Cook, Messrs M. D. Labuschagne, A. Nicoll, S. Sadowski, Dr A. M. Starfield and Dr H. Wagner. Secretary: Mr D. C. Visser. Total present: 45. SPECIAL GENERAL MEETING The President: "You will have received notices of the Special General Meeting and I declare it duly constituted. In keeping with the trend of overseas and local institutes, your Council recommends that we should change our membership classification as indicated in the notes of the meeting. The new grades are proposed to replace those presently in the Constitution and By-Laws. In terms of Clause 4.8 of the Constitution a special general meeting must be held for the purpose of considering and, if approved, adopting with or without amendments, the revision of the undermentioned clauses of the Constitution, which Council now recommends should read as follows. Clause 2.2 'Corporate Members shall comprise the grades of Honorary Life Fellow, Fellow and Member', these being the equivalent of Honorary Life Member, Member and Associate Member. Clause 2.6. 'Non-Corporate Member shall comprise the grade of Honorary Fellow, Graduate, Associate and Student.' Are there any questions in regard to this proposal? If not would someone propose that these clauses be amended and adopted?" Proposer: Mr A. J. Nixon. Seconder: Prof D. D. Howat. The motion was then adopted. The President: "It is recommended that Clause 2.15 should read, 'A Corporate of the Member of the Institute shall be entitled to use the following authorised letters designating the grade of Membership in Honorary Life Fellow and Fellow, F.S.A.I.M.M. and Member, M.S.A.I.M.M.' Previously we used the letters M.S.A.Inst.M.M. and your Council considered that we should adopt the simpler lettering. Could I ask someone to propose that this amendment be adopted?" Proposer: Mr R. C. J. Goode.

By K. Gharibi, A. Dehghani, S. Farrokhpay, M. Aghajanloo, M. Ostadrahimi

The effect of flotation operational parameters on froth stability and froth recovery was studied. Froth stability was measured using a special column. To determine the froth recovery, the froth height change model and froth height exponential model were used. It was found that since the interactions between the pulp and froth zones affect the time of froth formation, the exponential model is more suitable than the froth height change method for determining the froth recovery. The results showed that superficial air velocity and collector dosage have, respectively, the highest and lowest effect on the froth recovery, while froth recovery decreases sharply with increasing froth height.

Jan 1, 2021

"The management of outlier grades in positively skewed gold distributions is a contentious issue. Incorporating outliers in standard ordinary kriging (OK) estimation procedures in a way that honours the data without smearing extreme grades into surrounding areas has been problematic. Cutting or capping of outliers to mitigate their influence in estimation techniques is common practice, while methods that manipulate the OK system of equations fail to honour the data. We propose a method of post-processing of kriging weights that provides realistic OK estimates and mitigates smearing without manipulating kriging equations or changing the original grades. The method requires that the data is not clustered, is approximately equally spaced, and is of the same support. Positively skewed data is ordered on attribute grade and nonlinearly transformed to a Gaussian histogram of categorical bins whose frequency is based on their likelihood of occurrence and location in the sample distributions. Factors that restrict kriging weights are calculated by dividing the percentage frequency of data in each bin by the percentage frequency of data in the bin with the highest frequency. Restriction factors applied to the kriging weights in the OK estimation restrict the range of influence in proportion to their probability of occurrence in the distribution. Smear reduction post-processing is easy to implement and addresses issues arising from negative kriging weights while considering the spatial location of samples, the sample grades, and their probability of occurrence. The method mitigates both smoothing and conditional bias.IntroductionOutliers are sample observations that deviate considerably from the standard or expected (Hawkins, 1980). These deviations can be high or low in grade depending on the distribution. The presence of outliers in a mine sampling campaign could provoke mixed reactions. Mining engineers might view high-grade outliers as a promise of achieving higher grades, while the geostatisticians view outliers as affecting the accuracy and precision of the overall estimate, among other issues. Having identified outliers, the geostatistician must decide how to account for their presence and treat them so that true underlying estimates are not distorted. Advanced knowledge of the deposit allows the geostatistician to identify and treat outliers acceptably, especially where samples are limited in number and the true grade distribution is uncertain. If ignored, or treated incorrectly, outliers are likely to lead to smearing of extreme grades into the surrounding estimates, thereby steering regions towards potential under- or over-estimation."

Apr 1, 2019

By A. Lane

The socio economic risks of mining in South Africa have been emerging for some time now, and have been brought into sharp relief by recent events in the platinum sector. The slow pace of social upliftment in the country has lead to widespread social unrest with consequent calls for different forms of resource nationalism. Fundamentally, the key stakeholders are not fully aligned, and are not engaging productively. This poses significant above-the-ground risk to mining companies. Measuring social impact, deploying inclusive solutions and engaging effectively with stakeholders are three ways in which mining companies can mitigate this risk.

Jan 1, 2012

By N. A. Sithole, S. A. C. Hockaday, P. J. A. Bezuidenhout

The Northern Cape Province in South Africa has high levels of annual direct normal solar irradiance and reserves of zinc (Zn) ores. The question arises as to the benefits of integrating renewable solar energy into the beneficiation routes of these reserves. The paper evaluates a novel flowsheet for the production and beneficiation of Zn in this region, maximising localised solar energy as a source for both electricity and process heat. Solar variability is discussed and the cost and benefits of thermal storage in the flowsheets are evaluated by its influence on the levelised costs of electricity and process energy over the project life-time at a possible implementation site. The results of the developed scoping model showed that solar photovoltaic integration to provide electricity for electrowinning without battery storage can lead to more than 10% cost saving on electricity over the lifetime of the project. Additional savings potential was identified when battery storage was included to enable the solar PV system to supply electricity during peak tariff periods. The solar thermal case showed the most promise with savings of 70% on heating costs for casting, while solar PV electricity without storage resulted in a 16% cost saving on heating for casting over the lifetime of the project. Solar PV electricity generation resulted in the avoidance of more than 20% of CO2 emissions from grid electricity use. Solar thermal heating can avoid up to 80% of the CO2 emissions associated with grid electricity use for remelting of Zn cathodes for casting. The CO2 emissions are indirect and not subject to South African carbon tax. Keywords: Solar process energy, zinc beneficiation, flowsheet evaluation

Jan 1, 2020

ADVANCES IN EXTRACTION METALLURGY AND REFINING A symposium organised by the Institution of Mining and Metallurgy will be held in London from 4th to 6th October, 1971. Particulars can be obtained from: The Secretary, Institution of Mining and Metallurgy, 44 Portland Place, London WIN 4BR, ENGLAND. ICAMC -71 - HUNGARY The Third International Conference on Automatic Control of Mines and Collieries will be held at Balantsfured, Hungary from 27th to 30th September, 1971. Further particulars can be obtained from: ICAMC - 71, Budapest 3, P.O. Box 115, HUNGARY. AUSTRALIAN INSTITUTE OF MINING AND METALLURGY Illawarra Branch A symposium on "Blast Furnace Injection" is to be held at Wollongong University College from 15th to 17th February, 1972. About 20 papers on various aspects of blast furnace injection will be presented, including two on nonferrous furnaces. Further particulars may be obtained from: N. Standish, Chairman, Symposium Committee, Wollongong University, Australia 2600.

By H. C. Van Der Merwe

In the 21st century, dynamic, accurate digital 3-D geological models are essential to the pursuit of safe, efficient and profitable mining. This is particularly true for the deep-level underground mines in South Africa. The Sirovision® solution is a collaboration project between the Australian CSIRO (Commonwealth Scientific and Industrial Research Organisation), Datamine Software Ltd. and AngloGold Ashanti Ltd (AGA). The purpose of the project is to provide a fully integrated digital rock face imaging, geological mapping and modelling system for the AGA gold mining operations. The CSIRO-developed Sirovision® Stereo Camera Rig (SCR) consists of two digital cameras, alighting system, a laser guidance system and image processing software. The imaging system works on the principles of photogrammetry, i.e. overlaying of two 2-D images with a central focus point, with mathematical algorithms extracting 3-D information from the 2-D image pair. The output from matching several image pairs is a computer-generated, full 3-D, virtual copy of the mining excavation. The image resolution and relief ares of sufficient quality to distinguish different rock types and structural contacts. Functionality within Datamine Studio3 is used to add geological intelligence to the 3-D images provided by Sirovision®. The geologist identifies and ?draws? lines representing geological features directly onto the image. By utilizing the inherent ?topography? of the 3-D image, the software is able to convert the lines into 3-D surfaces, ready for use in the 3-D geological model. Subsequent to promising underground test results from AGA?s Sunrise Dam Gold Mine (SDGM) in Australia and other mining operations worldwide, it was decided to test the Sirovision® system in the South African deep-level gold mines. The first underground tests at Moab Khotsong Mine began in January 2009. The objectives of these tests entailed the capturing of 3-D images of selected development ends, mapping of geological features onto the 3-D images and integration of the mapping data with the 3-D geological model. Some downsides have cropped up during the feasibility testing, related to practicality of the SCR for acquisition of 3-Dimagery in the deep-level underground operating environment. These constraints will have to be addressed prior to operational implementation. Facing such difficulties is not unusual when attempting to implement new technology in such a challenging working environment and testwork is still in progress at the mine in order to prove the concept of using this technology in a Witwatersrand underground gold mine. The great advantage of the Sirovision® solution is that it offers the geologist the opportunity to work remotely on a 3-D virtual copy of a mining excavation, without the heat, humidity, hazards and time constraints associated with physical mapping in an underground workplace.

Jan 1, 2009

International Solvent Extraction Conference 1971 ISEC '71, which will be held in The Hague, The Netherlands, from 18th to 23rd April, 1971, is being sponsored by the Society of Chemical Industry in association with the Koninklijk Instituut van Ingenieurs, the Institution of Chemical Engineers and the Koninklijke Nederlandse Chemische Vereniging. The Working Party on Distillation, Absorption and Extraction of the European Federation of Chemical Engineering is participating in the Conference, which is the 101st event of the Federation. The scope of the Conference covers the entire science and technology of liquid-liquid extraction as applied in all branches of industry. Thus sessions will cover both chemical and chemical engineering aspects of the subject as applied to both inorganic and organic solutes. The conference aims to bring together academic and industrial workers in the field from all parts of the world. The programme includes over 100 papers by authors in 26 countries. Full details of the papers, together with registration forms, are contained in a detailed programme, copies of which are now available from: ISEC '71, 14 Belgrave Square, London, S.W.1, U.K. Department of Mining and Mineral Technology of the Royal School of Mines Postgraduate Courses Technical and economic challenges facing the minerals industry, together with progressive change in methods and equipment, increasingly necessitate re-training of experienced professional engineers who aim for top places. In order to meet this need, this Department has for some years run one year M.Sc. courses. Engineers, often sponsored by their employers, have a choice of three courses which are respectively devoted to mining, applied rock mechanics or mineral process design. The course in Mining is divided into five subjects, which are treated from the business management point of view. It is intended to provide middle management with a knowledge of those techniques that are required by the mining engineering function in the preparation of modern projects. The course in Mineral Process Design provides a systematic use of mineral sciences, engineering and economics for ore testing and process design, so as best to balance the technical and financial requirements for specific mineral resources. The course in Engineering Rock Mechanics is designed to provide a specialized training in the engineering applications of rock mechanics for engineers and geologists, so that they are equipped to treat a wide variety of problems in mining and civil engineering. Prerequisite qualifications are a good first degree in a related subject, plus industrial experience: The rewards include an M.Sc. of the University of London and the Diploma of the Imperial College (DIC). The limited number of places available (12 in each group) makes early application advisable. Full details are available from the Registrar, Imperial College, London, S.W.7.

By R Kersten

The note describes an exercise on the simulation of the frequency and size of seismic events on the basis of the frequency distribution of the events and their inter-arrival times (Le. the frequency distribution of the time elapsed between events). From the suite of available results, those of one simulation for a period of three months are included. The tentative conclusions drawn from the exercise indicate that the overall seismic activity in an area can be predicted for a time period, that structurally complex areas will have a higher incidence of seismic events than other areas, and that the position and time of an event cannot be predicted by the use of a wide-spread system such as that used at present.

Jan 1, 1985

By P. K. Hofmeyr

Traditional fire assay dates back over 3000 years and has changed very little over that time. The only improvement is to replace the gravimetric finish with dissolution of the Precious Metal bead followed by AA or ICP analysis of the solution. The newly developed FIP A (Fast In-line Fire Assay) method allows full automation of the fire assay process from sample preparation to spark analysis of the Pb button. This results in fully quantitative analyses for Pt, Pd, Rh, Ru, lr, Au and Ag in typically less than an hour after a sample is entered into the system. Detection limits are theoretically Pt 0.08 ppm, Pd 0.002 ppm, Rh 0.002 ppm, Au 0.08 ppm and Ag 0.002 ppm but in practice the lower measurable limits are about double these figures. Few opportunities have been available to present data obtained using the FIFA system as all FIFA laboratories have been in the domain of a Pt mining company which prefers to keep all Pt analytical matters confidential. However, IMP has recently participated in the round robin exercise to establish recommended values for a new series of Merensky Reef and UO-2 Layer reference materials produced by African Mineral Standards. The precision of the results was excellent being on average Pt 2.05%, Pd 1.25%, Rh 4.08% and Ru 4.94% being expressed as Relative Standard Deviation. The excellent precision is a reflection of the efficient collection of POEs in the Pb buttons and the homogeneity of the Pb buttons. However, the accuracy was not as good. The poorer accuracy is interpreted as the calibration of the spectrometer not being as good as desired due to the difficulty in acquiring a suitable range of standards with reliable recommended values for the PGEs. The most recent spectrometer was calibrated with the greatest care and produced slightly better results for Pt, Pd and Rh and slightly worse for Ru.

Jan 1, 2014

By V. A. Myazin, M. V. Korneykova, A. V. Svetlov, V. G. Minenko, D. V. Makarov, A. L. Samusev

The paper discusses the treatment problem of mine (waste) water for enterprises of the Russian Arctic. The wide range of relevant pollutants, financial resources, the availability of land for the construction of a treatment plant, waste generated during the treatment process are some of the factors controlling current and future process design solutions. All mining operations have adopted water treatment and water quality monitoring solutions, however there is no single approach to the problem and each industry participant operates within the scope of its available resources. The range of existing and emerging methods is extensive — from using constructed wetlands for the deposition of mineral nitrogen compounds in settling ponds, reagent deposition and chemical coagulation in exhausted mine workings, and filtering dams on the surface to retrofitting existing mine drainage treatment plants with the adoption of the electrochemical coagulation process. Methods of wastewater treatment from heavy metals, oil products, and nitrogen compounds are demonstrated in the example of two industrial facilities in the Murmansk region. It was found that the use of electrochemical coagulation provides effective treatment of mine water from NO3, NO2, Ni, Fetotal and petroleum hydrocarbons (the degree of purification from 50.5-99.7%), the use of phytotreatment system provides wastewater treatment from ammonium ions and nitrite ions by 53-84%, nitrate ions - by 22%. Keywords: Industrial water treatment, treatment flowcharts, settling ponds, constructed wetlands, reagent sedimentation, chemical coagulation, electrochemical coagulation

Jan 1, 2020

By R. D. Alorro, B. Tadesse, E. Aghaei

Cinnabar (HgS) and native mercury (Hg) are the most common naturally occurring forms of mercury found in most gold ores subsequently released into the environment during processing. Mercury and its compounds are extremely toxic and recognised as serious health and environmental hazards. This research investigates the possibility of mercury (Hg) removal from waste solutions from gold processing using iron-aluminium (Fe-Al) bimetallic particles. The synthesis of Fe-Al bimetallic particles using zero-valent aluminium and ferric chloride as precursors were performed following the optimisation of influencing factors. The presence of both metals in the prepared bimetals was confirmed by XRD analysis. The experiments for mercury removal by bimetals were designed using the central composite design and Minitab software based on two variables including contact time and adsorbent dosage. The best result of Hg(II) removal (>90%) was achieved using 4 g/L bimetals and contact time of 75 min. However, the statistical analysis of results indicated that these parameters have only a minor contribution to the removal of Hg(II) by Fe-Al bimetals. Higher bimetal dosage and contact time resulted in a higher Fe dissolution from the Al surface which can be attributed to the presence of nitrate (# $) ions in the solution. However, adding 0.1 M NaCl to the Hg solution had a positive impact on Hg removal by improving the conductivity and electron transfer within the solution. The Fe-Al bimetallic particles are promising substances for further testing of Hg removal from gold processing waste solutions with different conditions and constituents. Keywords: Mercury removal, gold processing, Fe-Al bimetals, optimisation

Jan 1, 2020

By A. Tekin

In almost all branches of industry, machinery and equipment in operation cause vibration. Some sources of vibration affect only the operator’s hands, fingers, and arms, while others have adverse effects on the entire -body. Various types and numbers of machines are utilized in the mining sector, and operators with them are exposed to mechanical vibrations caused by the mining machinery they use. A field study was conducted to evaluate the vibration risks to the operators using mining machines in open pit mines. Vibration levels and whole-body vibration (WBV) measurements using various types brands, and models of construction equipment were evaluated in three different mines in the west of Turkey and compared to the the criteria specified in the EU 2002/44/EC directive and ISO 2631-1 (1997) standards. The results showed that operators using mining machinery for 8 hours were exposed to WBV levels below the EU limit (1.15 m/s2), while 44% of these operators were exposed to levels above the EU action limit (0.5 m/s2). Measurement data collected from the working environment and the recommended improvements that need to be made to reduce WBV exposures are presented.

May 2, 2022

By A. Pareek, V. S. Masampally, V. Runkana

Mineral processing plants, in general, consist of comminution and separation circuits. Rougher flotation is considered as the heart of the separation circuit with concentrate grade and mineral recovery being the key productivity and quality parameters that affect the downstream operations and profitability. Online prediction of these parameters can help improve process performance in real-time. Past efforts to predict flotation cell performance have focused on building physics-based or machinelearning (ML) based models. Although physics-based models are popular in process design applications, ML models are more appropriate for online monitoring, control and optimisation due to their lower computational requirements. Deep learning (DL) is gaining prominence nowadays for application in industrial operations where a large amount of data is available. We have developed a DL model based on long short-term memory (LSTM) neural networks to forecast the two key performance indicators (KPIs), namely, mineral recovery and concentrate grade in a mineral processing plant. Rougher feed characteristics such as mineral grade and particle size distribution, upstream measurable disturbances such as throughput of the comminution circuit and pulp density, and control variables such as aeration rate, pH, and collector addition rate are considered as explanatory variables to train the model. The model was tested with data from an industrial mineral processing plant. For real-time dynamic predictions, the trained model appropriately accounts for mismatch in measurement frequency of real-time process data and off-line laboratory analysis data. Such a time series model can be used as a state observer in model predictive control techniques for optimal control of unit operations in a mineral processing plant. Keywords: Mineral processing, flotation, time-series, dynamic modelling, deep learning

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 L. Naude, J. Cloete, S. Engelbrecht

The results of an investigation evaluating whether an industrial plant, currently operating using sodium isobutyl xanthate (SIBX) as primary collector for sulphide minerals (mainly chalocopyrite), could adapt to operate using an alternate primary thiol collector without compromising plant and metallurgical performance. Initial laboratory scale flotation tests identified commercial dithiophosphate (DTP)-based and thionocarbamate (TC)-based collectors, that when blended, showed potential to replace the incumbent SIBX primary PGM collector. Industrial plant trail results show that there was no deterioration in recovery of 4E PGMs, even at a lower concentrate grade when operating the plant on the identified (DTP + TC)-based collector blend compared to SIBX. The effect on Cr2O3 content in the final concentrate was also found to be negligible. The (DTP + DTC)-based collector blend also showed promise in terms of plant adaptability in accommodating a new primary specialty collector blend. These observations highlighted the potential of replacing xanthate primary collectors with alternate thiol collector blends for PGM flotation. Keywords: PGM, xanthate replacement, specialty collector, sodium iso-butyl xanthate (SIBX), dithiophosphates (DTP), dithiocarbamates (DTC)

Jan 1, 2020

FEBRUARY GENERAL MEETING The January General Meeting of the Institute was held in Kelvin House, Johannesburg on 21st January, 1970, at 4.30 p.m. Mr V. C. Robinson (Vice-President) was in the Chair. There were also present eighteen Members, Messrs M. Barcza, A. R. C. Fowler, R. C. J. Goode, Prof J. de V. Lambrechts, Messrs T. C. A. Meyer, J. A. Nixon, V. C. Robinson and P. W. J. van Rensburg (Council Members), C. A. Border, D. F. H. Grave, S. D. Hill, A. F. Lee, W. L. le Roux, C. S. Macphail, D. L Starkey, S. G. Taussig, W. T. L Wayman and Dr A. Whillier. Three Associate Members, Dr M. I. Brittan, Messrs R. Hemp and M. J. Martinson. One Student, Mr R. P. W. Henrard. Two Visitors, Dr N. G. W. Cook and Mr J. B. Smith. Secretary, Mr D. C. Visser. Total present: Twenty-six. 1. OBITUARY The Vice-President: "It is my sad duty to announce the death of the following members of the Institute: Reginald Gordon McConnell, Member, who joined the Institute on 24th April, 1946 and passed away on 26th September, 1969. James Henry Moore, Member, who joined the Institute on 28th February, 1951 and passed away on 2nd January, 1970. As a mark of respect to the memory of the deceased and in sympathy with the bereaved I would ask those present to stand and observe a few moments silence." 2. MINUTES The Vice-President: "May we confirm the Minutes of the General Meetings held on 15th October and 19th November, 1969, as published in the December, 1969 issue of the Journal?" 3. MEMBERSHIP The Vice-President: "I have pleasure in announcing that the names of the under-mentioned 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: Member: Woodford Anson Gilbert. Associate Members: Michael John Harvey Tonking, Schalk Willem Vorster, Edward Alfred Cole, Johannes Godlieb Bosch. Graduate: Leonard Raymond Kilpatrick. Affiliates: Clive Frere Knight Pouiton, David Philip Ayliff, Kenneth Gillings, Edward Gilbert East. Students: Stirling Graham Low, Petrus Stephanus van der Merwe, Louis Johannes Fourie, Clive Maxwell Winterstein. MEMBERS TRANSFERRED TO A HIGHER GRADE From Associate Member to Member: Albert Arthur Hazell, Neville Martin Hayne. "I welcome the newly elected members to the Institute and congratulate the members who had been transferred to a higher grade. 4. GENERAL BUSINESS The Vice-President: "I wish to announce that except for the student prizes awarded at the November meeting, Council has decided to make no awards for 1969. Are there any further matters to raise under the heading of General? If not, we will proceed to the next item on the agenda which is the presentation of tonight&apos;s paper. 5. PAPER FOR PRESENTATION The Vice-President: "Professor Starfield may I call on you to deliver the paper entitled "A rapid method of calculating temperature increases along mine airways". After the presentation of the paper, the Vice-President said: The Vice-President: "Thank you very much, Professor Starfield. Gentlemen, I think that many of you here, who have to do with the design of mines in an age where costs and difficulties generally, are increasing at a rate which we find almost impossible to keep up with, I would agree with you that we are fortunate to have a band of people like Professor Starfield, and others who are dedicated to producing the tools, and methods which we need to sort out these problems. I am sure that you would agree with me, that the old rule-of-thumb methods are finished forever, that we can never go back to the methods which served us in the past, when we were close to the surface and had not met the conditions which we are meeting now, and which we are going to meet in an increasing degree in the future. It is to people like Professor Starfield, with these clear, completely logically described new methods, that we look for the solution of our problems in the future. I think the whole problem of layout of any mine, is one where you can reliably prognosticate what you are likely to find in a variety of circumstances to meet the wide range of things which must happen when you consider the costs in these modern operations. Thank you very much, Professor Starfield, for coming and giving us this paper. Thank you for making plain to me how these mathematical models of yours are used. I am sure that what you have said will be a very valuable addition to the archives of this Institution. Thank you very much, indeed, and Gentlemen, will you please show your appreciation in the normal way." (Applause). Professor J. de V. Lambrechts, Mr R. Hemp and Dr A. Whillier then contributed to the discussion. (These contributions will appear in a later issue of the Journal.) PAPERS OPEN FOR DISCUSSION The Vice-President: "Listed on the agenda are papers open for discussion. I would suggest that anyone wishing to contribute to these papers submit their contributions to the Secretary in writing." CONCLUSION The Vice-President: "I wish to thank members and visitors for their attendance, and now declare the meeting closed." The meeting closed at 5.30 p.m

By T. Bui, T. Wallmach, S. B. Blancher, A. Back, M. Pierre, V. Delarue, A. Kanzari

This study investigates nickel laterite porosity and its impact on geometallurgical modelling. We performed a detailed mineralogical study on a set of Ni-laterite samples originating from New Caledonia. Samples were analysed after heavy liquid separation by automated SEM (QEMSCAN®). Laboratory and QEMSCAN® modelling results do not correlate well. Ideal physical mineral properties such as mineral densities used in QEMSCAN® modelling do not match the actual physical densities of minerals. The presence of empty or water-filled pores can represent important amounts in minerals and change the overall density of a particle. An adequate modelling of real density separation of minerals and particles should consider the water-filled pores. The first step towards a better simulation was to integrate pores larger than 10 μm in diameter filled with water (density of 1 g/cm3) in the QEMSCAN® database. The results approached, but did not match the physical laboratory results. The second step was to identify nanometer to micrometer sized pores, which could not be identified by QEMSCAN®. It was possible to identify nanometric pores in enstatite, Fe-oxides, serpentine, talc and quartz, and radial aggregates of fibrous Fe-oxyhydroxides with high resolution SEM (HR-SEM). The quantification of those micro-sized pores was performed on 2D HR-SEM images using image-processing techniques developed in Python to calculate the nanometer to micrometer scale pores in each mineral. Despite the limitation of converting 2D imaging into 3D objects, in our case pore sizes and porosities, we were able to calculate a mean value of porosity for each mineral. The integration of this porosity in the calculation of particle densities yielded a good match between the QEMSCAN® model and the laboratory experiment results. Despite the complexity of a strongly weathered material, such as Ni-laterites, a good knowledge of the ore makes it possible to build reliable processing models. Keywords: Mineralogy, geometallurgy, nickel laterites, SEM, QEMSCAN®, porosity, density

Jan 1, 2020

By R. L. Machunda, A. M. Rugaika, D. D. Mdachi

Sedimentary and igneous rocks are the two primary sources of phosphate that are mined and beneficiated to fertilizer. During the beneficiation process, phosphate is lost into the tailings. We investigated phosphate concentrations in tailings dumps at Minjingu mine, Tanzania using energy-dispersive X-ray fluorescence spectrometry to quantify the chemical compositions. The phosphate content in the tailings varied from 12.91% phosphorus pentoxide (P2O5) in Tailings 2 to 19.61% in Tailings Dump 1. The naturally occurring phosphate concentration in rocks ranges from 3% to 35%, and phosphate tailings from various locations with P2O5 concentrations as low as 6.46-12.65% have been beneficiated to commercial fertilizer. Our investigation revealed that phosphate concentrations in Minjingu tailings may be sufficient to be recovered for commercial applications. Suitable recovery methods are discussed, and we recommend that beneficiation should be performed to minimize the loss of phosphate into tailings. Further research is needed to identify the optimal beneficiation methodology.

Aug 8, 2024