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By A. Ndibalema

Blasting is one of the primary functions in any mining operation. Despite the fact that it generally constitutes between 30% to 40% of the mining cost, blasting also affects the cost-effectiveness of down steam activities such as load and haul, safety, tyre life for haul trucks, crushing and milling. Over the past three decades, significant progress has been made in the development of new technology in an attempt to reduce costs and increase efficiencies and productivities of blasting activities. Mine to mill project concepts have paved the way for such developments. Other advancements have included sophisticated computer modelling technologies for blast design and performance analysis. There are many factors that affect the cost of blasting. These can be divided into two categories; controllable and uncontrollable. The latter includes costs related to depreciation, exchange rates and government legislation with the former category including contractor versus owner blasting costs, efficiency and productivity issues and product quality. Controllable factors have one common denominator which can determine their outcome; direct site management influence. Excavator digging rates and final floor conditions give a good measure of blasting performance, and alternatively cost effectiveness. This paper is aimed at benchmarking against a blast optimisation database, understanding the relationship between costs and identifying opportunities for improvement. Understanding the cost drivers allowed a typical cost model to be developed for the current mining operation at Geita and this was used to drive continuous improvement with emphasis on closing the information loop.

Jan 1, 2008

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.

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 publications 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. LAYOUT AND STYLE Orthodox sequence Title and author's name, with author's degrees, titles, position. Synopsis, including a brief statement of conclusions. Index, only if paper is long and involved. Introduction. 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 than 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. If there is any problem in producing formulae accurately by typewriter they should be inserted by handwriting in ink in the copy forwarded by authors. 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 Systeme International d'Unites (S.L) 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 kilogramms 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, n, 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 there. fore 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. . .' . . .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 organizations as well as to the Institute.

By A. J. S. Benade, N. B. Strydom, W. H. Van Der Walt

The performance of the improved microclimate suit by N. B. STRYDOM M.Sc., Ph.D. (Illinois) (Fellow), A. J. S. BENADE, B.Sc. (Potch.) (Visitor), and W. H. VAN DERWALT, M.Sc. (Potch.) (Visitor) An assessment has been made of a new improved microclimate jacket when worn by men working for four hours in a hot environment (wet-bulb temperature of 33,9°C and an air speed of 0,4 m/s) and at work rates of 35 Wand 70W. At the lower rate of work in heat, the use of microclimate suits maintained the rectal temperatures of the men at almost the same level as when they worked without that protection at normal room temperature (20°C). At the greater rate of work without protection, the men's rectal temperatures rose to 40°C within two to three hours, so that they could not complete four hours of work. When they wore microclimate suits, they easily completed four hours of work, and their rectal temperatures were lower than when they worked at the lower rate without protection.

Jan 8, 1975

By D. G. Hulbert, I. K. Craig, S. P. Moult

This paper describes the application of a throughput-optimization strategy to a run-of-mine (ROM) mining circuit that is controlled by a multivariable controller. The objective of the optimization strategy is to maximize the ROM throughput at a specific product size. Results from long-term tests, which indicated how 'steady-state' optimization can be achieved, were used for the throughput optimization. This strategy increased the ROM throughput by 11,4 per cent. A mathematical relationship relating residue to grind can be used to calculate the economic benefits of stabilizing control. It was estimated that the throughput optimizer could result in an increase in gold production worth Rl,4 million per annum when waste rock is treated, and that stabilizing control could increase the treatment plants annual revenue by R150 000. If the extra milling capacity brought about by the optimizer is interpreted as a capital cost saving of 10 per cent on the price of a new mil, then a capital cost saving of RI million could result.

Jan 1, 1992

By M. C. van Blerck

Since its introduction in 1956, the capital allowance has been increased and its scope widened. At present the allowance is 10% in respect of two categories of gold mine (post-1973 and other deep level mines) and 6% in respect of natural oil mines. The allowance is a significant incentive encouraging the development of new mines, to the benefit of both the fiscus and the South African economy as a whole. A strong case can be made for increasing the amount and the scope of the allowance. The Margo Report recommendation that the allowance should possibly be replaced with a system of direct grants is, in theory, neutral. However, practical difficulties exist with cash grants and there is concern with the implications elsewhere in the Margo Report that the capital allowance is excessive and that, as a consequence, such direct grants will represent an effective reduction in this incentive. I believe that the best course of action would be the retention (and enhancement) of the capital allowance and the expansion of its scope.

Jan 1, 1988

By J. Abdollahisharif

Optimal cut-off grade is one of the most critical parameters in open-pit mine design because it defines the ore and waste and thus determines the maximum net present value possible from the mining operation. Although the algorithm presented by Lane (Choosing the optimum cut-off grade. Colorado school of Mines Quarterly, vol. 59, no. 4, 1964. pp. 811-829) is the most common one in the literature, it does assume constant capacities of the mine, processing, and refinery. In this paper, Lane's original algorithm has been modified to consider variable processing capacities in order to determine the optimal cut-off grade in open-pit mines. The new algorithm proposed here is compared to both Lane's original algorithm and to a previous modification that incorporated rehabilitation costs into the cut-off grade estimation. The algorithm proposed here that permits variable processing capacities is shown to be superior for the determination of optimal cut-off grade to both these previous versions. In addition, a computer-based program was developed in Microsoft Office Excel© to calculate the optimal cut-off grade as proposed here.

Jan 1, 2012

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 1,400. Membership applications are accepted from suitably qualified persons and the requirements for entrance to the various grades of membership are summarised below. Members shall be 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 R4.00; Annual subscription R14.00 (town), R12.00 (country). Letters of designation: M.S.A.INST.M.M. Associate 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 R2.00; Annual subscription R12.00 (town), R10.00 (country). Letters of designation: A.M.S.INST.M.M. Affiliates 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 Affiliate, is at the time of his application, already a Student member, 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 Affiliates. Entrance fee R2.00; Annual subscription R12.00 (town), R10.00(country). Graduate Members 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 persmission of Council. Entrance fee R1.00; Annual subscription R7.00 (town), R6.00 (country). 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 the 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 (town), R3.00 (country). Other. The Council has the power to elect to the grade of Member or Associate 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 to the Secretary: South African Institute of Mining and Metallurgy, p.a. Box 1183, Johannesburg.

The first commercial Corex Plant in the world capable of producing liquid iron from a variety of low-grade coals was commissioned in 1990 by Iscor at its Pretoria Works. The Plant has an annual production capacity of 300 kt of liquid iron. Because the compulsory use of coke is eliminated, the new method offers an economic and revolutionary alternative to liquid-iron production. Coke used in traditional blastfurnaces is manufactured from high-grade coal of which the available sources in South Africa are limited.

Jan 1, 1991

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 1,400. Membership applications are accepted from suitably qualified persons and the requirements for entrance to the various grades of membership are summarised below. Members shall be 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 R4.00; Annual subscription R14.00 (town), R12.00 (country). Letters of designation: M.S.A.INST.M.M. Associate 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 R2.00; Annual subscription R12.00 (town), R10.00 (country). Letters of designation: A.M.S.INST.M.M. Affiliates 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 Affiliate, is at the time of his application, already a Student member, 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 Affiliates. Entrance fee R2.00; Annual subscription R12.00 (town), R10.00(country). Graduate Members 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 persmission of Council. Entrance fee Rl.00; Annual subscription R7.00 (town), R6.00 (country). 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 the 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 (town), R3.00 (country). Other. The Council has the power to elect to the grade of Member or Associate 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 to the Secretary: South African Institute of Mining and Metallurgy, P.D. Box 1183, Johannesburg.

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 1,400. Membership applications are accepted from suitably qualified persons and the requirements for entrance to the various grades of membership are summarised below. Members shall be 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 R4.00; Annual subscription R14.00 (town), R12.00 (country). Letters of designation: M.S.A.INST.M.M. Associate 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 R2.00; Annual subscription R12.00 (town), R10.00(country). Letters of designation: A.M.S.INST.M.M. Affiliates 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 Affiliate, is at the time of his application, already a Student member, 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 Affiliates. Entrance fee R2.00; Annual subscription R12.00 (town), R10.00(country). Graduate Members 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 R1.00; Annual subscription R7.00 (town), R6.00 (country). 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 (town), R3.00 (country). Other. The Council has the power to elect to the grade of Member or Associate 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 to the Secretary: South African Institute of Mining and Metallurgy, P.D. Box 1183, Johannesburg.

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 1,400. Membership applications are accepted from suitably qualified persons and the requirements for entrance to the various grades of membership are summarised below. Members shall be 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 R4.00; Annual subscription R14.00 (town), R12.00 (country). Letters of designation: M.S.A.lNST.M.M. Associate 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 R2.00; Annual subscription R12.00 (town), R10.00(country). Letters of designation: A.M.S.INST.M.M. Affiliates 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 Affiliate, is at the time of his application, already a Student member, 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 Affiliates. Entrance fee R2.00; Annual subscription R12.00 (town), R10.00(country). Graduate Members 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 persmission of Council. Entrance fee R1.00; Annual subscription R7.00 (town), R6.00 (country). 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 the 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 (town), R3.00 (country). Other. The Council has the power to elect to the grade of Member or Associate 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 to the Secretary: South African Institute of Mining and Metallurgy, P.O. Box 1183, Johannesburg.

By W. P. Channon, J. B. See

The reduction of fluxed and non-fluxed manganese, ores by ferromanganese silicide by W. P. CHANNON, B.Se. (Eng.), M.Sce. (Eng.) Wits. (Visitor) and J. B. SEE, B.Sce. Hons., Ph.D. (New South Wales), M.I.M., M.I.M.M. (Member) In South Africa, medium-carbonferromanganese is produced by the silicothermic reduction of slags containing MnO. Because of its importance in the production of refined ferromanganese, a study was made of the reaction between a premelted South African Mamatwan manganese ore and various ferromanganese silicide reducing alloys, with and without fluxing agents. Because the reaction is highly exothermic, temperature appeared to have little effect on the rates of manganese transfer to the metal and silicon transfer to the slag, and an apparent equilibrium was rapidly approached. Limits were determined for the favourable effects of fluxing additions, and manganese recoveries were found to decline as the ratio of CaO to MgO decreased as a result of the addition of basic flux. The recovery of manganese passed through a maximum, and subsequently decreased for variations in the ratio of alloy to ore. The results obtained, when used in conjunction with other physicochemical data related to this slag-metal system, suggest optimum slag compositions for the efficient manufacture of medium-carbon ferromanganese from Mamatwan ore.

Jan 3, 1977

By T. R. Twiddle

The sequential flotation of copper, lead, and zinc in that order is practised at the Broken Hill Concentrator of the Black Mountain Mineral Development Company (Pty) Limited. The minerals of economic importance are chalcopyrite, galena, and sphalerite, with associated silver. The targets for recovery and grade in the lead and zinc circuits were reached quite readily after start-up, but the copper circuit failed to meet the performance requirements with respect to both recovery' and grade. The original circuit for copper is described, together with the subsequent investigations and modifications that were required to produce acceptable metallurgical results. Circuits for semi-bulk and bulk flotation were tried, and the effect of the oxidation state of the pulp was investigated extensively and found to be all important. Tests were conducted on the depression of lead in the cleaning circuit by the use of sodium dichromate, and on heating with the addition of sulphurous acid. The latter technique was ultimately the more successful. The proportion of fresh to recycle water entering the circuit was shown to be important. The original reagent regime was altered and augmented. A more recent problem has been the contamination of the ore with cemented backfill. The changes that this new condition necessitated are described. Success has been measured by a continuous improvement in the economics of the copper recovery.

Jan 1, 1984

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

Jan 1, 1985

Contribution by W.D. Ortlepp? The authors are to be commended for publishing their interesting view of an aspect of deep-level mining technology that is becoming increasingly topical and vitally important. This is the second paper in the journal within four months to deal with the crucial needs of highly stressed tunnel construction, the other being the paper on the design and testing of rockburst support in the February 1994 issue. Both papers re-examine important innovative ideas that are more than a quarter of a century old, but that have not yet been implemented by the industry. It is to be hoped that they will now, taken together, serve as a new starting point for a definitive examination of what constitutes proper tunnel-support design. There can be no question that the need to develop a design approach that will solve the problems of tunnelling at depths of 4000 m or more has now become crucial. Contribution by A.M.J. Vervoort* Although the overall paper is very interesting and the future research (comparison between numerical simulations and underground measurements) will be very challenging, I would like to make some remarks regarding the set-up of the numerical model and the interpretation of the elastic results.

Jan 1, 1995

Guide Io Ihe Preparailon Of Papers For Publication In The Journal Of The South African Institute Of Mining And Metallurgy 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 the Council.

Jan 1, 1975

By C. A. Snyders

The research presented in this paper investigated the practical aspects of the recovery of platinum group metals (PGMs) from a dilute cyanide leach solution containing base metals, in a manner similar to that used for gold extraction in a typical CIP process, and focuses on both the adsorption and elution stages. The carrier-phase extraction of precious metals using activated carbon offers significant advantages over other processes in terms of simplicity, the high pre-concentration factor, rapid phase separation, and relatively low capital and operating costs. As a sorbent, activated carbon is still by far the most important material because of its large surface area, high adsorption capacity, porous structure, negligible environmental toxicity, low cost, and high purity standards. Adsorption tests were conducted on a pregnant alkaline leach solution (0.15 ppm Pt, 0.38 ppm Pd, 0.1 ppm Au) resulting from cyanide extraction performed in column leach tests. The initial adsorption rates of Pt, Pd, and Au were very fast and recoveries of these three metals were approximately 90 per cent after 2 hours, and 100 per cent for Pt, 97.4 per cent for Pd, and 99.9 per cent for Au after 72 hours. The parameters that influence the extraction of PGMs and Au were examined to assess their relative importance during the adsorption process in order to provide the basis for process optimization. The concentration of thiocyanate was not identified as significant factor for PGMs adsorption, while Ni concentration was the most significant extraction process parameter. Base metal cyanide complexes adsorb and compete with the PGM complexes for sites on activated carbon, and while copper adsorption can be minimized by adjusting the residence time, Ni adsorbs at approximately the same rate as the PGMs, influencing the loading capacity and adsorption kinetics of the PGMs. The feasibility of eluting platinum and palladium cyanide complexes from activated carbon using an analogue of the AARL process was investigated. Platinum and palladium elute from activated carbon almost to completion in 4 to 5 bed volumes at 80°C, while the elution of gold at this temperature is slow, with a significant amount of gold still to be eluted after 16 bed volumes. The equilibrium loading of gold is exothermic in nature (Fleming and Nicol, 1984) which will result in an increase in gold elution kinetics with an increase in temperature at similar pre-treatment conditions. A similar result was found for the elution of Pt and Pd. Cyanide pre-treatment was found to have a significant influence on PGM elution. Higher cyanide concentration in the pre-treatment step results in more efficient elution up to a point, and results suggest the possibility of an optimum cyanide concentration, beyond which elution efficiency starts decreasing due to increased ionic strength.

Jan 1, 2013

By A. Madowe

This paper discusses the mine planning process for Letseng diamond mine in the Kingdom of Lesotho, in conjunction with the various software packages used during the process. The major pillars of the long-term mine planning process at Letseng are pit optimization followed by pit design and scheduling. Letseng uses Gemcom Whittle and GEMS for pit optimization and design and Runge XPAC for scheduling. The output of the mine planning process results in the generation of published mineral reserves and provides input into the Letseng overall business plan. The process of defining the key inputs for the entire mine planning process is discussed, which covers: ? Pit optimization ? Slope design as an input ? Diamond price inputs ? Operating and capital cost inputs ? Haul road design ? Generation of pit shells ? Selection of an optimum pit shell and interim cutbacks using operational scenarios ? Sensitivity analysis on the selected optimum pit shell. ? Pit design ? Slope design criteria in the detailed design ? Split shell vs concentric pit design ? Practical mining widths to determine cutback design ? Ramp design ? Pit design process in the GEMS software package. ? Detailed scheduling ? Development of scheduling scenarios in the XPAC software package ? Planning through mining production bottlenecks. ? Company-level NPV model ? Comparing scenarios and input of the different schedule scenarios into the company NPV model. Keywords pit optimisation, mine planning, pit shell, recovery, dilution, revenue factor, pit design, split shell, sensitivity analysis, scheduling, production bottleneck, NPV, discounted cashflow.

Jul 1, 2013

By L. A. Cornish, R. Süss, M. Sephton, N. B. Maledi, J. H. Potgieter, L. Chown

The gas turbine industry is faced with a challenge to improve the performance of engines, while simultaneously adhering to stringent environmental legislation. One way of addressing the problem is by further increasing the recipient working temperatures. Unfortunately, the use of nickel based superalloys (NBSAs) in the gas turbine industry has reached its limitations. Although coatings can be used for small increases, and air cooling is also incorporated by design, attention is towards developing stronger metallurgical materials having higher melting points, with acceptable creep and corrosion resistance. A series of ternary and quaternary Platinum-based superalloys were developed. Platinum was selected because of its higher melting points compared to nickel, similar fcc structure and better corrosion properties. Mechanical characterisation studies of Platinum-based superalloys alloys, which included oxidation, creep and hardness, demonstrated reasonable results, outperforming an oxide dispersed strengthening (ODS) Fe-based superalloy (PM2000) and a nickel based superalloy (MAR-M200). During any materials development where high temperatures are concerned, high strength is the primary property of interest. However, during the development of gas turbines, component life and reliability, which are influenced by temperature, need to be taken into consideration, and therefore creep as well as corrosion (both temperature dependant properties), are important. These properties become significant with increasing temperatures. With increasing demand for higher temperatures, it is becoming increasingly important to include hot corrosion properties of the alloy during the material selection process. A short description on hot corrosion and its degradation mechanisms are given in this paper. Coatings are currently dominating as the best practical solution to address temperature increases. This paper looks at benefits and shortcomings of coatings over Pt-based superalloys as candidates for applications under extreme conditions. Key words: Hot corrosion, Pt-based superalloys, Ni-based superalloys, Coatings

Jan 1, 2006