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By T. Bhambhani, J. Jankolovits

Sphalerite flotation using copper sulfate has been performed in the industry for decades and the mechanism of Cu activation is well established. Despite its ubiquity, many practical questions surrounding copper sulfate persist. It is not clear how iron selectivity is achieved in zinc circuits given the propensity of iron sulfides to be activated by copper. Also, the large variation in copper sulfate dosages across different plants and ore types cannot be explained. Lastly, Zn flotation with greatly reduced copper sulfate dosages attracts significant interest and has been demonstrated in certain laboratory settings, but no information is available on why those laboratory solutions have not been adopted in plant practice. Flotation studies are presented that demonstrate that Zn flotation with very low copper sulfate dosages is possible when using certain novel collectors that are not practised in the industry. However, these reagent schemes are impractical because of a heretofore unappreciated and critical role that copper sulfate plays in Fe rejection. With both very low and standard copper sulfate dosages, copper sulfate influences both Zn flotation and Fe rejection. The results highlight the multifaceted role of copper sulfate in zinc flotation and the need to holistically consider complex systems’ behaviour to understand flotation reagent mechanisms and optimise plant performance. Keywords: Sphalerite flotation, metal activation, copper sulfate, iron rejection

Jan 1, 2020

By D. N. Esfahani, K. Khazen, M. Mohammadi

Electrowinning is one of the nickel recovery processes from solutions obtained from the leaching of nickel sources. Every year significant amounts of nickel products are used in various industrial processes and daily life, such as catalysts or batteries, which are a valuable source of nickel for recovery. Nickel purity is also very important in the electrowinning process, because the amount of impurities in nickel such as sulphur, if greater than 100 ppm, make it unsuitable for use in catalysts and plating. Because sulfur is intrinsic to the sulphate electrowinning system, we needed to investigate parameters that can affect the quality and purity of nickel. In this regard, experiments were performed in static and circulating electrowinning processes. A monitoring and circulation system was designed and built to measure voltage, current and temperature as well as to circulate the solution in the system at a specified rate. It was then observed that nickel ion concentration, pH, using the circulation system and additives, were factors affecting the purity and quality of nickel, and in the best case the amount of sulphur in nickel was below 100 ppm. Keywords: Nickel, electrowinning, sulphur impurity

Jan 1, 2020

By Franz E. Pawlek

Synopsis This is a summary of investigations in the field of pressure leaching carried out at the Institute for Extractive Metallurgy of the Technical University of Berlin-West during the last seven years. The efficient dispersion of gas in a liquid and its dissolutions as well as the events at the phase boundary when leaching ZnS are reported. At the end two examples are given for the use of pressure leaching in the processing of smelter by-products. INTRODUCTION About 20 years ago, experiments were independently started in Canada and in Berlin on the subject of dissolving sulfidic ores without preliminary treatment by means of leaching under increased oxygen pressure. In Canada ammoniacal solutions were mainly employed, and F. A. Forward and his co-workers were successful in applying this process on a large industrial scale1, 2. This process is used in Fort Saskatchewan to produce about 15,000 tons of Ni per year. In Berlin, investigations were started on leaching with acid solutions3, 4. This process had also been used on a large industrial scale in the D.S.A., but the choice of unfavourable working conditions led to great difficulties, and to giving up this process for industrial use. Later on in Berlin work was carried out especially on the kinetics of pressure leaching 5, 6, 7, 8, 9 and its applications to the processing of smelter by-products, in particular of mattes and speisses10, 11, 12, 13, 14. The dissolution of ores and by-products can be subdivided into four steps: 1. the efficient dispersion of the gas, so that its dissolution occurs over as great a surface area as possible, since only the dissolved oxygen reacts with the solid, 2. the suspension of the solid, so that the entire surface can take part in the reaction, 3. the phase boundary reaction, 4. the removal of the reaction products. The first two steps belong to the field of process engineering and will be discussed from this point of view. The aim of these experiments15 was to find out first of all the limits of efficiency of self-sucking stirrers in solutions of low viscosity with regard to the mass transfer. In addition, the effect of ultrasonics in the same reaction system was studied. The experiments were carried out in a lucite container as shown in Fig. 1. Four baffles of 0.1 d width were in the stirring vessel. The height of these baffles was adjustable. For every experiment one litre of liquid was used. An infinitely variable direct current motor, which was fixed with a hollow shaft, served as the driving power for the stirrer.

By M. Rudolph, R. Tolosana-Delgado, G. van den Boogaart, M. Reuter, U. Peuker

This paper addresses the challenge to define a concept of entropy (state of order) for a textured particle system. Both the particle texture, the intergrowth respectively, and the particle size influence the order of a particle system. The smaller the particles become, the more particles form the solid system and the more permutations of the structure of the particle bed are possible. The texture within a particle is fixed, as long as it is not subjected to changes due to comminution, flocculation or agglomeration. The paper will present a definition of entropy, which is able to reflect qualitatively and quantitatively the intergrowth and the size (distribution) of the particles. Theoretical examples will show how different breakage mechanisms can be identified using the entropy definition. Furthermore, we will define the specifications for data sets to calculate the entropy of a particle system. Keywords: Milling, mineral liberation, intergrowth, statistical entropy, modelling

Jan 1, 2020

By E. Schoeman

Ion exchange resins were investigated for the effective recovery of platinum, palladium, and gold from a pregnant cyanide heap leach solution. Screening results indicated that strong-base anion exchange resins proved to be most effective in the recovery of these metal cyanides. Gold was selectively recovered with the use of Minix, while effective recovery of gold, platinum, and palladium over the base metals, copper, and iron, was achieved with Amberlite PWA-5. Successful elution of these metal cyanides was possible from both Minix and Amberlite PWA-5, using a 2M potassium thiocyanate solution at ambient temperature. Acidic thiourea was unable to elute platinum from either Minix or Amberlite PWA-5. Effective elution of palladium and gold were, however, achieved with use of acidic thiourea. Using these results, two conceptual flow diagrams for the recovery of these metals from cyanide solutions are proposed.

Jan 1, 2012

The following notes have been compiled to assist authors in the preparation of papers for presentation to the Institute and for publication in the Journal. All papers must meet the standards set by the Council of the Institute, and for this purpose all papers are referred to at least two referees appointed by Council. STANDARDS FOR ACCEPTANCE To merit consideration papers should conform to the high standards which have been established for publication over many years. Papers on research should contain matter that is new, interpretations that are novel or of new significance and conclusions that cast a fresh light on old ideas. Descriptive papers should not be a repetition of well-known practices or ideas but should incorporate developments which would be of real interest to technical men and of benefit to the mining and metallurgical Industry. In some cases a well prepared review paper can be of value, and will be considered for publication. All papers and particularly research papers, no matter how technical the subject, should be written with the average reader of the Journal in mind, to ensure wide interest. The amount of textbook material included in a contribution should be the minimum essential to the argument. The length of a paper is not the criterion of its worth and it should be as brief and concise as possible, consistent with the lucid presentation of the subject. Only in very exceptional circumstances should a paper exceed 15 pages of the Journal (15 000 words, if there are no tables or diagrams). Six to ten pages is more normal. NOTE: Papers in the Journal are printed in 10 point type, which is larger than the 8 point type used on this page. For special publication Council may decide on page sizes smaller than A4 used for this Journal. The text should be typewritten, double-spaced, on one side only on A4 size paper, leaving a left-hand margin of 4 cm, and should be submitted in duplicate to facilitate the work of the referees and editors. Orthodox sequence Title and author's name, with author's degrees, titles, position. Synopsis. Index, only if paper is long and involved. Introduction, including a brief statement of conclusion. Development of the main substance. Conclusions, in more detail. Acknowledgements. References. Title: This should be as brief as possible, yet give a good idea of the subject and character of the paper. Style: Writing should conform to certain prescribed standards. The Institute is guided in its requirements by: Collins, F. H., Authors & Printers' Dictionary-Oxford University Press. Hart, H. Rules for Compositors and Readers. Humphrey Milford (familiarly known as the Oxford Rules). Fowler, H. W. & F. G. The King's English-Oxford University Press. General: A few well selected diagrams and illustrations are often more pertinent that an amorphous mass of text. Over-statement and dogmatism are jarring and have no place in technical writing. Avoid the use of the first person, be objective and do not include irrelevant or extraneous matter. Avoid unnecessary use of capitals and hyphens, while punctuation should be used sparingly and be governed by the needs of sense and diction. Sentences should be short, uninvolved and unambiguous. Paragraphs should also be short and serve to separate basic ideas into compact groups. Quotation marks should be of the 'single' type for quotations and "double" for quoted matter within quotations. Interpretations in the text should be marked off by parentheses ( ), whereas brackets [ ] are employed to enclose explanatory matter in the text. Words to be printed in italics should be underlined singly. For small capitals they are to be underlined DOUBLY and for large capitals TREBLY. Abbreviations and symbols are laid down in British Standard 1991. Abbreviations are the same for the singular and plural, e.g. cm for centimetre and centimetres, kg for kilogram and kilograms. Percentages are written in the text as per cent; the symbol % is restricted to tables. A full stop after an abbreviation is only used if there is likely to be confusion of meaning. Metric System: The Systemé International d'Unites (S.I.) is to be used for expressing quantities. This is a coherent system of metric units derived from six basic units (metre, kilogramme, second, ampere, kelvin, and candela), from which are derived all other units, e.g. the unit of force is the newton (N) for kilogramme metre per second per second (kg m/s2). Always use the standard metric abbreviations. Commas must not be used for separating groups of digits. For ease of reading digits should be grouped in threes counting from the decimal point towards the left and the right. Illustrations: Drawings and diagrams are to be in black India ink and should be about 18 cm wide. When submitting graphical representations avoid a fine grid if possible. Curves should be in heavy line to stand out. Lettering too should be bold as a reduction in size is often involved in the printing process. (A single column is 8.5 cm wide.) Numbering of tables should be in Roman numerals: I, 11, etc. and figures in Arabic numerals: Fig. 1, Fig. 2, etc. (Always use the abbreviation for figure.) Photographs should be black and white glossy prints. As a guide to the printer the author should indicate by means of notes in the typescript where tables and figures, etc. are to appear in the text. Paragraphs: A decimal system of numbering paragraphs may be used when the paper is long and complicated and there is a need for frequent reference to other parts of the paper. Proof correction: Galley proofs are sent to authors for the correction of printers' errors and not for the purpose of making alterations and additions which may be expensive. Should an author make alterations which are considered excessive, he may be required to pay for them. Standard symbols as laid down in British Standard 1219C should be used. SYNOPSIS It is most important that the synopsis should provide a clear outline of the contents of the paper, the results obtained and the author's conclusions. It should be written concisely and in normal rather than abbreviated English and should not exceed 250 words. While the emphasis is on brevity this should not be laboured to the extent of leaving out important matter or impairing intelligibility. Summaries simplify the task of abstractors and therefore should present a balanced and complete picture. It is preferable to use standard rather than proprietary terms. FOOTNOTES AND REFERENCES Footnotes should be used only when they are indispensable. In the typescript they should appear immediately below the line to which they refer and not at the foot of the page. References should be indicated by super-script, thus. . .1 . . .2. Do not use the word Bibliography. When authors cite publications of other societies or technical and trade journals, titles should be abbreviated in accordance with the standards adopted by this Journal. GENERAL The Council will consider the publication of technical notes taking up to three pages (maximum 3 000 words). Written contributions are invited to the discussion of all papers published in the Journal. The editors, however, are empowered by the Council to edit all contributions. Once a paper or a note has been submitted to the Institute, that document becomes the property of the Institute, which then holds the copyright when it is published. The Institute as a body is, however, not responsible for the statements made or opinions expressed in any of its publications. Reproduction from the Journal is permitted provided there is full acknowledgement of the source. These points should be borne in mind by authors who may submit their work to other organisations as well as to the Institute.

By J. Jacobs

The three-product cyclone was originally developed in Russia and is now extensively used in China. The cyclone has recently entered the South African coal industry, and with the obvious advantages that this item of process equipment offers our ever-evolving industry it is safe to assume that it will add value to dense medium circuits in South Africa. Some of the possible applications include: ? Producing multiple products using a single dense medium circuit. These can typically be a primary product with calorific value of 27.50 MJ/kg and a secondary (middling) product with a calorific value of 22 MJ/kg ? High-density separation with a low circulating medium density. Anglo Thermal Coal and Exxaro have pioneered the use of these units at Umlalazi and New Clydesdale respectively. Extensive test work has been performed at Umlalazi to determine the efficiency of the unit and to determine how it compares with the conventional DSM (Dutch School of Mines) cyclone. Some people in the coal industry were initially sceptical and expected the performance of the three-product cyclone to be inferior to that of the conventional dense medium cyclone. The results of the test work have, however, shown that the efficiency of the unit is comparable to that of the cyclones currently employed. A valid concern expressed is the control over the cut-point density of the second stage separation, and work is on-going to find the optimal way to control the secondary separation density. Theoretically, the secondary separation density can be manipulated by changing the orifices of the unit, especially the spigot of the secondary stage. This remains to be proven, and a series of tests is currently being planned. Whatever the result of these tests may be, the three-product cyclone definitely has a place in the South African coal processing industry as it offers a low OPEX and CAPEX solution for producing multiple products from a single circuit, as well as the ability to operate at very high separation densities, while making use of low-density circulating medium. Keywords dense medium separation, DSM, three-product cyclone, coal processing.

Nov 1, 2013

By I. Ashmole

The dimension stone industry is not widely known or appreciated within the mainstream mining industry. This is in spite of the fact that the industry has grown at an average of over 7% per annum since 1980, and is estimated to now have a global turnover in excess of US$ 60 Billion per annum. Production technologies, particularly in the developed world where labour costs are high, have developed rapidly over the past two decades. Aligned with this, there has been a significant trend in adoption of a more professional mining approach in the exploration for and operation of dimension stone quarries. In fact, in the experience of the authors, mining a dimension stone deposit successfully if often more challenging from a mining engineering point of view than many conventional surface mines. This paper gives an overview of the industry and then proceeds to discuss best practice in exploration for dimension stone and to outline the latest technologies applied in mining of dimension stone. These technologies are varied and the specific combination of technologies applied in any given quarry is determined by both the physical properties of the material as well as the influence of geology which significantly impacts on the recovery of saleable material and hence the economics of the quarry.

Jan 1, 2008

Rock mass classification systems are extensively used in rock engineering design work, and mine design is no exception. Among the systems most widely used for mining-related design work are the NGI 0-system (Barton et al., 1974), the RMR system (Bieniawski, 1976), the MRMR system (Laubscher and Taylor, 1976) and, more recently, the GSI system (Hoek et al., 1998). Classifying the rock mass is widely seen as being the fieldwork required to characterize the rock mass and enable the application of empirical design methods associated with the different classification systems. This paper argues that it is fundamentally important to recognize the distinction between rock mass characterization and rock mass classification. These two processes should, in most cases, be separated from each other. Rock mass characterization should be used to determine the intrinsic properties of the rock mass independently of the application; i.e. independent from the infrastructure to be designed, the size, shape, and orientation of the excavation(s) or pillar(s), etc. Rock mass characterization should also be compatible with most classification systems and empirical design methods to be used. Rock mass characterization is the background fieldwork required to perform rock mass classification and/or engineering design work. Rock mass classification is the subsequent step to the characterization, and an integral part of the design process. Parameters that vary according to the design, such as the relative orientation of geological structures compared to the opening or the mine-induced stresses, should be calculated as part of the rock mass classification and design process, rather than during the rock mass characterization process. The failure to distinguish between rock mass characterization and rock mass classification can lead to major design errors and poor results.

Jan 1, 2012

By A. Della Rocca, P. Jonker, B. Henning

Successful prediction of the collection efficiency of cyclone separators is a necessary step in cyclone design and verification. Aside from standard empirical relations, CFD modelling is widely adopted to supplement the design of cyclone units in relation to the desired separation performance. Nevertheless, effective adoption of numerical modelling is sometimes prevented by large modelling errors, especially for small size particles which are more subject to turbulence effects than larger particle classes. In the past, this motivated the adoption of more refined turbulence modelling approaches, such as large-eddy simulations. These approaches provide greater insight into time dependent behaviour, while leading to larger computational cost with respect to more standard approaches. In this paper, an effective Eulerian-Lagrangian Reynolds-averaged Navier-Stokes (RANS) approach is investigated, which is able to predict the complete separation efficiency curve with satisfactory accuracy, without requiring prohibitively long computational times. An assessment of the proposed approach is carried out against experimental data from large laboratory scale cyclones, in the form of mean and fluctuating velocity profiles from LDA measurements (Hoekstra, 2000), as well as with respect to the experimental separation curve (Zhao, 2005). The final application to a full-scale industrial cyclone unit is then carried out with the aim of tuning the cyclone design to the separation efficiency curve as required by downstream processes. Keywords: Cyclones, separation, CFD, RANS, RSM, Lagrangian

Jan 1, 2020

By M. Ndabeni, J. H. van Vreden, M. Le Roux, Q. P. Campbell

It is not uncommon for gold slurry ponds or screen oversize dumps to contain several different types of carbon-rich contaminants. These contaminants act as robbers of dissolved gold which has a detrimental effect during the downstream carbon-in-leach (CIL) or carbon-in-pulp (CIP) processes. With a renewed interest in the reprocessing of contaminated gold waste ponds and dumps, preconcentration of the feed to either the CIL or CIP process becomes important to maximise profits from these resources. An added advantage in removing these resources, which were once thought of as being uneconomical, is the availability of land that can further be rehabilitated for community development projects. For gravity separation, an example of suitable technology is the Reflux Classifier (RC), which can be used for the separation of materials of different densities and can be used as a pre-concentration step. In this project, a laboratory-scale Reflux Classifier was used to pre-concentrate a gold-bearing sample obtained from a waste dump situated to the east of Johannesburg, South Africa. The material had an average gold grade of 1.9 g/ton and a carbon content of 10%. This material was first fed to a semi-batch Reflux Classifier that was used to fractionate it into several different density intervals by varying the fluidisation water feed rate, followed by continuous runs at fixed water flow rates. The results showed that a cumulative gold recovery of 60%, carbon recovery of 85%, and mass pull of 41% was possible for a fluidisation water feed rate of 15 L/min, while a rate of 20 L/min resulted in a gold recovery, carbon recovery and mass pull of 83%, 92% and 79% respectively, which translated into a concentrate gold grade above the set target of 3 g/ton. Continuous operation at 20 L/min yielded an underflow stream with 84% gold recovery at a grade of 5.4 g/ton. Keywords: Reflux Classification, gold recovery

Jan 1, 2020

By R. M. Mashishi, T. Malehase, O. J. Okonkwo

The concentrations of selected trace elements (As, Cd, Hg, and Pb in run-of-mine (ROM) coal, discard, and coal product were investigated to assess the efficiency of beneficiation in reducing trace element concentrations and ascertain any implications regarding environmental compliance to regulatory frameworks. Samples were collected from a colliery in Mpumalanga Province twice a month for a period of 24 months. The samples were ashed to approximately 0.21 mm, then digested in a mixture of 70% HNO3 and 40% HF and analysed using inductively coupled plasma-mass spectrometry (ICP-MS). Except for Pb, the mean concentration of all elements decreased from the ROM stage to the coal product stage. The order in which trace elements occurred from the highest to lowest throughout the production chain was Pb>As>Hg>Cd. With the exception of Cd, the mean trace element concentrations in the discard were above the total concentration threshold (TCT) set for landfill disposal. The As, Hg, and Cd concentrations in the product were well below the thresholds for all land uses. However, Pb concentrations in the product coal were above legal limits, which is of concern with regard to environmental compliance and the performance and marketability of the product.

Dec 13, 2023

By H. W. Read, L. G. D. Napier

Change is endemic in our society. Future change will be accelerated by an explosion in technology, communication, and political thought. To meet these challenges, rapid structural changes have been taking place in mining organizations both here and abroad. The management of shaft-sinking projects is a case in point. Shaft sinking is a seminal element in the sustained well-being of a deep level mining venture. Its accomplishment is fraught with risk, involves a high level of capital expenditure, and is a precursor to profitable mining investment. The purpose of this paper is to present a concise and practical picture of the concepts, methods, and techniques of professional project management as applied to shaft-sinking projects.

Jan 1, 1994

By J. A. C. Diering

The determination of stresses and displacements close to tabular excavations is of considerable importance in the planning of tunnels and of remnant and pillar layouts. This paper gives a description of a simple yet effective method for the achievement of improved values from an analogue or MINSIM type of analysis. Essentially, closures and rides (the movement of hanging-wall relative to footwall) in mined-out areas are assumed to vary in a piecewise linear fashion as opposed to a piecewise constant fashion. As the former fashion more closely resembles the true variation, it is possible for the stresses and displacements at points close to the excavations to be calculated with much better accuracy.

Jan 1, 1980

By C. J. Alberts

The perception exists in many organizations that, once an energy management system is employed, there need not be any further adjustments to such a system. This is not true, as the field of energy management is a dynamic field, and constant feedback and adjustments are needed to enhance the efficiency of a system to the point that substantial pay-back can be obtained. It is stressed that for any energy management system to be successful, careful planning should permeate through the organization, from the top level decision-makers to the workplace. This paper describes a dynamic technique by which energy management strategies can be evaluated by viewing the effects of the strategies on the organization as a whole.

Jan 1, 1997

By R. J. Davidson, W. D. Douglas, J. A. Tumilty

SYNOPSIS Two pilot plants operating on different types of carbon were used to generate steady-state adsorption data in the treatment of gold-plant solutions of high and low tenor. A pilot plant comprising three 4 m long columns and using 3 mm extruded activated carbon was used to treat pregnant solutions with a gold concentration of 5 to 8 g/t at pH 10 to 11,5. Column influent was pumped at a super¬ficial flow velocity of 0,5 m/min while the carbon was moved daily so as to effect gold loadings on the carbon of 5 to 10 k /t. With a carbon-bed depth of 12 m, an adsorption efficiency of 99,9 per cent was obtained in a bed depth of 9 m, which was subsequently reduced to 8 m when the depth of the carbon bed was reduced to 8 m. This improvement in efficiency was attributed to the reduced residence time of the carbon from 12 to 8 days. A corresponding decrease in adsorbed silica indicated that some silica fouling of the carbon had occurred. A second pilot plant, comprising a single column 6 m in length and using coconut-shell carbon of 1,0 to 2,4 mm, treated a solution with a gold concentration of 0,7 g/t at pH 8,0. Feed solution was pumped at a superficial flow velocity of 1,0 m/min while carbon was moved every 8 hours to give gold loadings of more than 5 kg/t. An adsorp¬tion efficiency of 99,5 per cent was indicated at steady state. Intermittent washing of the column with dilute hydrochloric acid was shown to have a beneficial effect on the gold adsorption and to reduce the pressure drop across the column. Intermittent washing with dilute sulphuric acid indicated that there had been some passivation of the car¬bon during the treatment of a solution with a gold concentration of only 0,2 g/t. Compared with other adsorption systems, the countercurrent moving bed appears to offer significant advantages in terms of metallurgical efficiency and capital investment. The inability normally associated with moving-bed systems to treat solutions containing suspended solids may be overcome to a degree by the use of relatively coarse extrud¬ed carbon.

Jan 1, 1985

By F. S. Hoseinian, D. Deglon, L. leal Filho, M. Safari, T. C. Souza Pinto

This paper investigates the effect of chemical and physical operational parameters on the reverse flotation of Timbopeba itabirite iron ore in a pilot-scale pneumatic flotation cell. Operational parameters include collector and depressant dosages, feed rate, superficial gas velocity and solids concentration. Results show that increasing collector dosage results in an increase in quartz recovery, particularly for the coarser quartz where recovery increases by nearly 30%. Increasing depressant dosage results in a decrease in both quartz recovery and hematite loss, for the coarser hematite particles. Increasing the feed rate has no effect on quartz recovery or hematite loss, suggesting that the pneumatic flotation cell is not residence time constrained. Increasing the superficial gas velocity results in an increase in quartz recovery to an optimum at a Jg of around 0.6 cm/s after which it decreases significantly, particularly for the coarser particles where recovery decreases by as much as 50%. Decreasing the solids concentration does not affect quartz recovery but results in significant decreases in hematite loss. Here, fine and coarse hematite loss decreases from around 25% to 12% and 10% to 2% respectively. Superficial gas velocity and solids concentration are operating parameters which have the largest effect on the flotation performance of the pneumatic flotation cell. Results suggest that this flotation cell should be operated at relatively low superficial gas velocities and solids concentrations. However, these are pilot-scale findings and would need to be tested at an industrial-scale where different operating conditions may be optimal. Keywords: Operational parameters, reverse froth flotation; entrainment; iron ore

Jan 1, 2020

By T. Wennberg

An elevated location of a paste thickener on a ridge close to the disposal area is considered at a Swedish iron ore mine. About 0.7 M tonnes of thickened tailings are planned to be layered as paste in the vicinity of the thickener over several years with pipeline lengths of up to 900 m after about 20 years. In order to clarify the pipeline pumping characteristics of the tailings product for volumetric solids concentration from 40 to 50%, experiments in loop systems with pipeline inner diameters from 0.063 to 0.152 m have been carried out with various types of pumps. The results and comparisons carried out here showed that the performance of centrifugal pumps cannot simply be related to the rheology, but factors related to pump design and build-up tendencies of material within the pump and other particle properties may be of equal importance. During the first years of operation only one thickener underflow pump is required. The reliability and performance for various pump configurations are planned to be investigated systematically in order to meet the most effective long-term solution for paste thickener operation, pipeline distribution and placement in the disposal area as the discharge point advances over the life of the project.

Jan 1, 2007

By Z. Ruetz

Portable X-ray fluorescence (pXRF) analysis has been widely adopted in the geochemical and environmental field as a cost-saving alternative to standard analyses. This paper outlines the efficacy of a method for indirectly quantifying organic copper content in solvent extraction circuits via stripping of the chelated metal with concentrated sulfuric acid in a single contact and subsequent pXRF aqueous analysis. pXRF analysis is common within the mining industry but presents unique challenges with liquid analysis, the most prevalent of which are briefly discussed. This method was developed specifically for mining operations with regional constraints and limited resources. Providing an in-field alternative to flame atomic absorption spectrophotometry and inductively coupled plasma optical emission spectroscopy, this entirely mobile XRF analysis method produces consistent and accurate results within minutes and at a fraction of the cost.

Jan 1, 2023

By H. A. D. Kirsten

Written contribution by L.J. Besaanst I am a Mechanical Engineering Technician (T3), and wish to further my education to at least NHD (T4) level. I read your paper in the Journal of The South African Institute of Mining and Metallurgy with great interest, and must compliment you on its brilliance. However, there are some questions I should like to ask, and certain points I should like to highlight. I should appreciate your comments. Written contribution by J.F. Curtis The comprehensive and finely detailed survey of, and proposals for, engineering education in South Africa reflects the author's wide experience in the needs for, and the provision of, such education. This paper wil make a major contribution to the enhancement of the profession of engineering and the improvement in quality of engineering activities in South Africa. Contribution by G.W. Annandalet I have studied your paper in some detail, and am of the opinion that it makes an important contribution to the topic of the development of technological manpower, which is currently being debated in South Africa at al levels. Debate on this topic has risen above the level of academic discussion; it has been discussed by the Economic Advisory Council of the President, and is being considered at Ministerial level. Author's reply to L.J. Besaans Thank you for your contribution and complimentary remarks. As you have pointed out, there are certainly many aspects that will have to be addressed in the resolution of the crisis in engineering education. I trust that the following comments satisfactorily answer the queries you have raised. Author's General Comments Since publication of the paper, attention has become focused on the provision of employment opportunities an aspect not dealt with specifically in the paper. The following comments serve to indicate some of the directions in which job opportunities will have to be developed in the numbers that will be required.

Jan 1, 1991