Search Documents

By H. S. Baloyi, J. J. Rust

Spiral concentrators are widely applied to beneficiate commodities such as Cr2O3, mineral sands, and ferrochrome. The application of spirals for heavy minerals has been limited to a feed top size of 1 mm. At particle sizes larger than this, friction retards heavy particles and the particles' primary velocity approaches zero, resulting in a solids build-up, therefore inhibiting further separation. Recently, a new Multotec SC25 spiral model was introduced to the industry, which aids in beneficiating particles of up to 3 mm, with successes having been demonstrated in ferrochrome slag and titanium-bearing minerals. This spiral also has potential in electronic waste applications. This paper examines the applicability of the SC25 spiral in coarse Cr2O3 recovery. This stems from the fact that junior chrome miners tend to discard particles larger than 1 mm as they neither have milling nor dense media circuits. Also, alluvial chrome miners discard +1 mm even though this size fraction contains recoverable and liberated Cr2O3. The SC25 spiral has shown better Cr2O3 separation efficiencies than the SC21 model and with higher SiO2 rejection at saleable grades, thus providing an additional revenue stream specifically for the coarser (+820 μm) size fractions. Keywords: Spiral concentrators, chromite recovery, specific gravity, SC25 spiral, coarse spiral

Jan 1, 2020

The Institute was founded in 1894 as the Chemical and Metallurgical Society of South Africa. In 1904 it was reconstituted as the Chemical Metallurgical and Mining Society of South Africa and in 1956 it became the South African Institute of Mining and Metallurgy. The objects of the Institute are to advance the science and practice of mining and metallurgy, to afford opportunities for the interchange and recording of knowledge of mining and metallurgy and to ensure high standards of professional conduct and competence. Membership benefits include monthly issues of the Journal of the Institute, monthly General Meetings at which papers are read, symposia, excursions to mining and industrial concerns and the use of club facilities at Kelvin House. Technical journals received on an exchange basis are available to members at the Johannesburg Public Library. The current membership of the Institute is over 1,600. Membership applications are accepted from suitably qualified persons and the requirements for entrance to the various grades of membership are summarised below. Fellows shall not be less than 30 years of age, shall be university graduates in pure or applied science or shall produce evidence to the satisfaction of the Council that they have successfully completed a co-ordinated course of study in pure or applied science of at least three years' duration at an approved university or institution deemed by the Council to be of equivalent status. Members shall have been employed in senior technical positions in important mining or metallurgical undertakings for at least five years or they shall have practised as mining or metallurgical consultants for at least five years. They shall be practising their profession at the time of application. Entrance fee RI0.00, Annual subscription RI7.00. Letters of designation: F.S.A.I.M.M. Members shall be not less than 25 years of age and shall be university graduates in pure or applied science, or shall have successfully completed co-ordinated courses of study in pure or applied science of at least three years' duration. They shall have been engaged in work of an approved technical character in the mining or metallurgical industries, of which not less than two years shall have been in positions of responsibility. A candidate shall be practising his profession at the time of his application. Entrance fee R8.00, Annual subscription RI5.00. Letters of designation: M.S.A.I.M.M. Associates shall be not less than twenty-five years of age, and shall have been engaged in positions of responsibility in, or associated with, the mining or metallurgical industries for periods of not less than three years. If, however, the candidate for admission to the higher grade of Associate, is at the time of his application, already a Student, he need satisfy the Council only that he is, at the time of his application, engaged in a position of responsibility in or associated with the mining or metallurgical industries. In all cases the applicants shall satisfy the Council that they are fit and proper persons to become Associates. Entrance fee R8.00, Annual subscription RI5.00. Graduates shall be not less than 21 years of age and shall be university graduates in pure or applied science, or have completed co-ordinated courses of study in pure or applied science of at least three years' duration at an approved university or institution. They shall not remain Graduate members after attaining the age of 30 years without the permission of Council. Entrance fee R2.00, Annual subscription R10.00. Students shall be persons not less than 18 years of age who are being educated or trained in a manner approved by the Council, to occupy a technical position in or associated with the mining or metallurgical industries and who, furthermore, shall not have attained the qualification required for a higher grade of membership. They may remain Students until they have obtained the necessary qualifications for transfer to a higher grade of membership, but not after the end of the Institute's financial year in which they attain the age of 28 (twenty-eight) years. They shall then transfer to a higher grade to retain membership of the Institute. The Council may relax the provisions of this clause in such cases as it considers appropriate. Entrance fee nil; Annual subscription R3.00. Other. The Council has the power to elect to the grade of Fellow or Member, candidates who may not fulfil all the requirements for entrance to these grades but whose status, professional achievements and practical experience in mining or metallurgy justify such election. Applications. Requests for membership application forms should be addressed on the attached form to the Secretary, South African Institute of Mining and Metallurgy, P.O. Box 61019, Marshalltown, Transvaal.

By R. F. Botha

I want to thank you for inviting me to deliver this, the closing address at the final plenary session of the 15th Congress of the Council of Mining and Metalurgical Institutions. Your Council has an impressive title, and justly so. Consider the expertise, the skill, the capacity, the achievement, that is gathered together here in this room this afternoon.

Jan 1, 1994

By H. M. Friede

Discussion of the above paper by A. SIFF The steely nature of the Iron Age objects mentioned in Dr Friede's paper point to two hypotheses. (1) The African iron workers were conversant with the art of direct steel manufacture. (2) They were less knowledgeable of the art of the production of carbonless iron. In this context I cannot but quote T. A. Wertime.

Jan 1, 1980

By H. Scott-Russell

Ladies and Gentlemen. It is my great pleasure on behalf of The South African Institute of Mining and Metallurgy and The Geological Society of South Africa to welcome you to the 15th CMMI Congress and to Southern Africa. It is a great honour to be hosting this event and we have been looking forward to it for a long time. I am sure the technical discussions and visits will be of great value, and I am confident you will return with pleasant memories of places and people in South Africa and neighbouring countries. The theme of this Congress, Resources and Technology', is appropriate for discussions on the ways and means of going forward in the minerals industry to create the employment and wealth so sorely needed in this region. The technical programme will give mineral industry professionals from different parts of the world the opportunity to share experience and expertise for the purpose of making operations more productive, safer and environmentally acceptable to the world at large. Delegates will be exposed to current technical developments by means of 133 papers prepared for the congress: 30 on geological subjects, 45 on mining, 29 on extractive metallurgy, and 29 in the field of metals technology.

Jan 1, 1994

By M. F. Dawson, S. B. Davis

SYNOPSIS This paper describes the size reduction of limestone smaller than 1 mm by attrition grinding, using quartz (1 to 3 mm) as the grinding medium in a laboratory rig. The ore and grinding medium were closely sized fractions, and the particle size of the grinding medium was at least three sizes larger than that of the ore. Batch tests showed that the size reduction of the feed followed two first-order rate processes: one for an apparently fast-breaking ore fraction, and a slower one for most of the ore (86 per cent). The production of fines (material smaller than 10 µm) followed a zero-order rate equation. Continuous runs showed that the process could be modelled as a perfectly mixed system provided that the discharge screen did not selectively retain coarser particles of ore. The ratio of medium to ore (both by mass and by volume) was found to have a significant effect, the most energy¬efficient grinding occurring at ratios between 1 and 2. The solids content of the slurry also had a significant effect, the greatest efficiency being obtained at 50 to 65 per cent solids (by mass). Within these energy-efficient ranges of medium-to-ore and solids content, the lower values resulted in maximum feed breakage and the higher values in maximum fines production. The most important factor in the breakage of feed was the difference in the particle size of the grinding medium and the ore; the amount of ore broken out of the feed size for a given energy input was found to increase linearly with the difference between the size of the grinding medium and that of the ore up to 2 mm. The production of fines increased similarly, but only up to a difference of about 1,2 mm, when it levelled off at about 5 kg/kW ? h. The mechanism proposed for attritioning is mainly the abrasion of 1 µm planes of limestone along the crystal axes, with some fracturing along existing lines of weakness. The energy consumption of nearly 200 kW ? h per ton of product smaller than 10 µm appears to be higher than that in other types of milling. It is concluded that the value of attrition milling lies in its selectivity; in this work, only the softer limestone and virtually none of the hard quartz grinding medium was comminuted.

Jan 1, 1989

By M. I. Brittan

Discussion Dr R. E. Robinson (Fellow): The author must be congratulated on a very meticulous and self-contained piece of work. It is indeed a pleasure to read a paper that is so clearly and systematically laid out, and where the conclusions and the testwork conducted have been so clearly described. The paper is complete in itself, which makes it very difficult for someone who is not intimately involved in the whole Torco project to make any comments on its content. However, two points that, strictly speaking, fall outside the scope of the paper are of considerable interest. The first relates to the particle size of the material treated. In the paper, the testwork is confined to one standard particle size (minus 60 plus 100 mesh). The essential feature of the paper is to indicate that the rate-controlling reaction in the whole segregation process is the rate of reaction of the ore particles with the reducing agent and the hydrogen chloride. One wonders, therefore, to what extent this relatively slow rate of reaction is affected by the particle size of the ore itself. One imagines that the reaction must take place by contact of the hydrogen chloride with the surface of the mineral particles, and it is reasonable to suspect that the rate of diffusion of the copper ions to the surface is a relatively slow process and is thus the limiting factor in this particular rate of reaction. It is possible, for example, that the improvement obtained, when the ore is subjected to reducing conditions before the chlorination, is due to a breakdown in the crystal structure of the original particle. This breakdown is brought about by the reduction and by the consequent increase in surface area available for reaction with hydrogen chloride. Can the author indicate whether any work has been done along these lines, and whether it has been established that the reaction depends on the surface area available? The second point relates to the application of this kinetic study to the actual operation of a Torco reactor. It was once planned to feed the sodium chloride, together with the reducing agent, into the top of the segregation chamber. In the paper, the author mentions that it has now been established that the segregation chamber behaves, to all intents and purposes, as a fluidized bed, and that there is, therefore, a rapid evolution of gas in the lower regions of the chamber, which, it is imagined, displaces the gas phase rapidly. Since the reaction between sodium chloride, water vapour, and the aluminium silicates in the ore is extremely rapid, one wonders how much of the hydrogen chloride produced is removed from the reaction zone before it has had time to react with the copper minerals. The extremely low consumption of sodium chloride (which is a vital feature of the Torco process) must depend on an extremely rapid circulation of the hydrogen chloride gas to all the ore particles in the segregation chamber. One wonders, therefore, if a system for the introduction of the sodium chloride into the bottom regions of the chamber might not result in even greater efficiency in the utilization of sodium chloride. ProC D. D. Howat (Fellow): All of us who have been concerned with the study of chemical reactions at high temperatures are keenly interested in kinetics and are well aware that this is not an easy study experimentally. Dr. Brittan is to be congratulated on the development of neat experimental methods and for his full discussion of the results obtained. Although the segregation process for the extraction of copper from oxide and silicate ores has been known for almost fifty years, the fundamental chemical and physical changes involved have been little understood and the fundamental data are very scanty. The work now in progress at A.A.R.L., together with that sponsored by the Anglo American Corporation in other research institutions throughout the world, is bound to produce new fundamental data and a much more complete understanding of this rather fascinating process. It is already apparent that some of the old and well-worn chemical reactions that were postulated to occur, just cannot take place in the way which was formerly accepted. Dr Brittan's work, carefully conducted and thoroughly analyzed as it has been, still leaves us with one great outstanding problem. The thermodynamic data and the possible reactions set out in Table I (page 281) of his paper leave us asking, in complete despair, how can copper be converted into a volatile chloride in the presence of HCl, CO and carbon at temperatures about 800°C? The thermodynamics all combine to show that copper should be reduced to metal as the first step in the process. This brings us right up against the second problem. If copper were reduced to the metal how would HCI convert it to the volatile chloride? On top of these problems is the unknown reason for the very high speed of reaction between CO, HCI and the ground copper ore. Still further into the region of the unknown is the reaction by which gaseous hydrochloric acid is produced in the actual process. Perhaps Dr Brittan is feeling grateful that he doesn't have to try to explain this reaction-at this stage of the research programme at least. The results very clearly show that both CO and HCl gas are essential for rapid production of the volatile copper chloride. Dr Brittan states that 18 minutes were required to attain 83 per cent extraction with HCl gas alone and this was reduced to 4 minutes when CO was

Jan 2, 1970

By R. Mumbi, M. Peart, E. Arinaitwe, B. Mbao, J. Zulu

Since 1925, xanthates have been widely used in sulfide flotation due to their low cost, ease of manufacture, and ability to float most value species. However, the industry's increasing need for safer and more selective alternatives, driven by low head grades, poor-quality, difficult-to-process ore with complex mineralogy, and stricter environmental regulations, has led to the development of Solvay's AERO® XR series of collectors. These custom-formulated products are based on greener chemistries and offer metallurgical benefits that are similar to or better than those of xanthates, without the safety concerns. Developed through Solvay's Flotation Matrix (FM) 100 approach, the XR series collectors are suitable for a wide range of applications, including the processing of Cu, Zn, and Cu-Ni, as well as the flotation of precious metals. This paper will highlight the differences between xanthates and XR series collectors, and present case studies of their successful commercial application at various global operations.

Jan 1, 2023

By F. Wang, P. Rosario, A. Vazirizadeh

Advances in data science, machine learning, and artificial intelligence are transforming mining and mineral processing, and making them more algorithm intensive. The paradigm is shifting from one of detection and control to one of prediction and optimisation. To build up reliable prediction and optimisation models these steps should be passed: collect, aggregate, cleanse, and process large amounts of complex, structured, and unstructured data as a first stage. Next, the right tools must be used to extract meaningful features from the operational data for the build-up of a prediction model. A grinding circuit is one of the challenging areas in terms of determining its overall efficiency and the prediction of product quality. In a processing plant, some of the KPIs are typically unmeasurable or infrequently measured for real-time application, e.g. ore grindability and grind size. However, these variables are required to calculate the grinding circuit efficiency and to model the operation performance. In this paper, advanced analytic tools have been used to extract one selected KPI (cyclone overall P80 or final grind size) and its relationship with measured variables for an industrial dataset. The results illustrate that the performance of the grinding circuit can be predicted for real-time monitoring by means of measured data. Keywords: Grinding circuit, data-driven, machine learning, process modelling, hybrid modelling

Jan 1, 2020

By A. C. Wingrove

The paper outlines the selection of a dewatered tailings backfill system for the Johannesburg Consolidated Investment Gold Division, and covers the following aspects: (i) 16 Shaft pilot testwork; (ii) engineering design problems relating to the Cooke 3 Shaft backfill operation; (iii) in-line mixing - applications with respect to the Randfontein Estates Gold Mine and Western Areas Gold Mine backfill operations; and (iv) pipeline friction losses.

Jan 1, 1988

By L. Prosch

"The word 'sustainability' has gotten such a work out lately that the whole concept is in danger of floating away on a sea of inoffensiveness" Michael Pollon. It is estimated that approximately 65% of the roughly 130 million carats of diamonds mined globally per annum originate in Africa and has an annual value of US$ 8.4 billion', Many of these mines are located in remote areas of the continent where the directly affected project community's income is often well below the poverty line. Often associated with these communities are occurrences of localized over exploitation of natural resources, environmental destruction and the abundance of social ills.

Jan 1, 2010

By T. S. Kagogo

The factors affecting haul truck tyre performance and the effectiveness of the management system at Rossing Uranium Mine were investigated with the aim of increasing tyre performance in terms of running hours until failure. The main objectives were to identify the types of tyre failure, their causes and cost implications, and evaluate the effectiveness of the management system. A site severity survey, weight study, and TKPH studies were conducted to determine the pit conditions, and an analysis of failed tyres carried out. The results showed that tyre performance at the mine has declined from 2009 to date, and the increase in lost value amounted to R5.7 million in 2012 alone. The main cause of tyre failure is loose rocks in the pit. The present management system in the load and haul department is not effective enough due to operational constraints it is facing.

Jan 1, 2014

By M. Mpofu, G. Stenzel, F. Magweregwede, B. Maphalala, T. Kgarume

Surface coal operations in which mining activities are conducted above old underground workings experience hot holes after drilling. In a coal mine, hot holes are defined as shot holes, which after being drilled have an in-hole ambient temperature of 40°C or above or show a temperature increase of 3°C or more during monitoring. Hot holes and other cavities, such as cracks, pose health and safety risks to workers, such as exposure to hot air and high concentrations of noxious gases released from these holes. In addition, workers may be exposed to premature detonation of explosives caused by in-hole temperature increases and chemical reactions. To this end, Coaltech Research Association commissioned a project to develop a Best Practice Guideline for the management of hot holes. This paper is a compilation of the activities conducted in the development of the Best Practice Guideline between 2021 and 2022. The activities included a review of standard operating procedures and hot-hole temperature-measuring and -monitoring devices, and the assessment of current hot-hole procedures at selected mines. The results indicated that management of hot holes requires a focus on pre-emptive risk assessment of mining blocks, identification of hot holes using the correct temperature-measuring devices, and continuous monitoring of hot holes from the time of drilling until just before blasting. Hot-hole management accessories, such as polyvinyl chloride sleeves, were found to be effective in insulating the hot-hole emulsion from the rock mass temperature, thus preventing the potential for premature detonation.

Sep 9, 2024

By B. M. Wainstein

An extension of lognormal theory and its application to risk analysis models for new mining ventures by B. M. WAINSTEIN*, B.Sc., M.B.A. (Witwatersrand) (Visitor) The lognormal distribution, which remains the most popular distribution model for ore values, is investigated. The T-distribution, an integral part of this theory, is dependent on the sample size, n, and the unknown population parameter, o2, which cannot be integrated out. Hence, o2constitutes a nuisance parameter. In this study, the robustness of the T-distribution to changes in o2 is examined. It is found that the T-distribution is robust for 0,1 <= o2 >= 2,5, a domain covering most practical applications of the lognormal theory. By the use of o2 = 0,7, multiplier factors, which facilitate the computation of the confidence limits, are derived for a comprehensive set of confidence levels.

Jan 4, 1975

By O. K. H. Sheff

Despite many years of a successful policy for our Journal, the Journal Committee is in the course of adopting a new approach with which to enter the present decade. The objectives are to improve the readability of the Journal, without forfeiting the quality achieved in the past, by adding an extra dimension through the inclusion of applied-engineering papers, i.e. technically oriented papers.

Jan 1, 1990

It is a great honour to officiate at the celebration of the centenary of the South African Institute of Mining and Metalurgy. Tonight&apos;s festivities bring back happy memories of my association with South Africa&apos;s mining industry during my tenure of office as Minister of Mineral and Energy Affairs. They also remind me of the illustrious personalities who have preceded me on this podium. The Pioneers They include Sir Percy Fitzpatrick, who spoke in 1909 on the eve of the Union, General Smuts, and, on many occasions during the 1920s and 1930, Jan H. Hofmeyr. The basic issues addressed by them continue to enjoy the Institute&apos;s attention today, namely the optimal and safe exploitation of our country&apos;s mineral resources and cost-effective extraction of minerals from their ores. Translated into the Institute&apos;s key objective it reads: To initiate and give effect to the means whereby the requirements for technology and scientific knowledge if the minerals and metals section if the South African economy is satisfied.

Jan 1, 1994

The following diagrams should replace the Figs. 4, 5, and 6 that appeared on pages 412 and 413 of the October 1986 issue. These relate to the paper entitled&apos; A new method for the rapid float-sink analysis of coal fines&apos; by J-P. Franzidis and M.C. Harris Womanpower In 1981 the Publicity Committee of the Federation of Societies of Professional Engineers (FSPE) decided that one way in which the engineering manpower pool could be increased would be by the introduction of womanpower to the profession. Since then, Std 9 and 10 girls have been invited to attend the engineering winterschools held annually at the various universities under the auspices of SAFUES. Coal-mining wastes The 2nd International Symposium on the Reclamation, Treatment and Utilization of Coal Mining Wastes will be held in Nottingham (England) from 7th to 11th September, 1987.

Jan 1, 1986

By S. K. De Kok

Over a period of three years, since samples first became available, laboratory and pilot plant experiments have been conducted to develop a method of treatment to recover copper and zinc in saleable grades of concentrates from the Prieska complex sulphide orebody. These experiments have been based on adaptations of principles investigated by research workers and applied to similar ore types throughout the world. The differential flotation process finally worked out involves a comparatively coarse grind, flotation of the copper at near-neutral pH with the use of a zinc-cyande sphalerite depressant, followed by flotation of the reactivated sphalerite. This procedure has had such success that the construction of a full-scale plant is proceeding with confidence that the small-scale operations will be duplicated or improved upon. It is to be expected that the large plant will follow the pattern of almost every flotation plant that has been built in that modifications to the circuitry and reagent systems will be made as experience is gained.

By H. M. Wells

The influence of economics on the design of mine shaft systems by H, M. WEI.LS, Pr. Eng., M.Se. (Fellow) The purpose of this paper is to review some of the more important economic criteria that must be taken into account when planning the number, type, size, and distribution of the shafts, or shaft systems, required to exploit a block of payable ore. The postulated philosophy governing the selection of design parameters is that of optimization of the financial return per rand of venture capital employed for the project as a whole. While this criterion may not necessarily satisfy the investment objective under all circumstances (as, for instance, where risk limitation is important), it does serve to place the relative economic advantages and disadvantages of specific design features, which may sometimes be in opposition, into correct perspective with respect to the overall economics of the project under the prevailing economic climate at the time of the investigation.

By H. A. Uys

The metallurgy of tin smelting In a submerged arc furnace By H. A. UYS, Ing. Metallurgy (Pretoria) (Visitor) The control of tin smelting demands a knowledge of slag characteristics and of the equilibrium reaction that governs the process. These factors are explained by reference to the tin-smelting operation at Iscor, Vanderbijlpark. In the primary cycle, it is important to obtain the highest possible FeO content in the slag. In the secondary cycle, a primary slag high in FeO gives a hardhead (iron-tin alloy) high in iron, which is essential if a high ratio of FeO to SnO is to be obtained in the secondary slag. This determines the economy of the smelting operation: the iron that is introduced into the system from the ore concentrate must go out in the secondary slag. Additions of lime are necessary in the secondary cycle but must be limited if the volume of slag is to be kept Iow.

Jan 1, 1977