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By S. Kauchali

"Underground coal gasification (UCG) is recognized as an efficient mining technique capable of chemically converting the coal from deep coal seams into synthesis gas. Depending on the main constituents of the synthesis gas, chemicals, electricity, or heat can be produced at the surface. This paper provides a high-level graphical method to assist practitioners in developing preliminary gasification processes and experimental programmes prior to detailed designs or field trials. The graphical method identifies theoretical limits of operation for sensible gasification within a thermally balanced region, based primarily on the basic coal chemistry. The analyses of the theoretical outputs are compared to actual field trials from sites in the USA and Australia, with very favourable results. A South African coal is studied to determine the possible synthesis gas outputs achievable using various UCG techniques: controlled retractable injection point (CRIP) and linked vertical wells (LVW). For CRIP techniques, an important result suggests that pyrolysis, and subsequent char production, are important intermediate phenomena allowing for increased thermal efficiencies of UCG. The conclusion is that South African coals need to be studied for pyrolysis-char behaviour as part of any future UCG programme. The results also suggest that UCG with CRIP would be a preferred technology choice for Bosjesspruit coal where pyrolysis dynamics are important. Lastly, the use of CO2 as oxidant in the gasification process is shown to produce syngas with significant higher heating value. Introduction and literature surveyCoal is a commonly utilized fossil fuel, providing over 40% of global electricity demand and about 90% of South Africa’s primary energy needs. However, less than 20% of the known world resources are suitable for possible extraction using conventional surface and underground mining techniques (Andrianopolous,, Korre, and Durucan, 2015). Underground coal gasification (UCG) has the potential to recover the energy stored in coal in an environmentally responsible manner by exploiting seams that are deemed unmineable by traditional methods. The UCG process, if successfully developed, can increase coal reserves substantially. For example, in the Limpopo region of South Africa alone, the estimated potential for UCG gas, based on existing geological records, is over 400 trillion cubic feet (TCF) natural gas equivalent – this is about a hundred times more gas than the existing 4-TCF Pande-Temane natural gas field reserve in Mozambique (de Pontes, Mocumbi, and Sangweni, 2014)."

Oct 1, 2018

By K. Wu, L. Li, D. W. Zhou, J. W. Yu

The presence of a fractured water-conducting zone (FWCZ) is of significant importance for the safety of underground mining under water bodies. When a coal mining area is covered with a thick layer of alluvial soil, the height, width, and distribution pattern of the FWCZ in the area shows unique features. The internal mechanism by which thick alluvial soil affects the FWCZ is still unknown. Using the Huainan coal mining area (HCMA) in China as a case study, we investigated the impact of thick alluvial soil on the height, width, and distribution pattern of the FWCZ through numerical simulation using the distinct element method, theoretical derivation, and data validation. The results indicate that a thick layer of alluvial soil inhibits the FWCZ height and increases the FWCZ lateral width. When the soil-to-rock ratio is greater than a certain value (the numerical result in this study is 15:18), the FWCZ height and width are affected by the thick alluvium significantly, and the thick alluvial soil alters the shape of the FWCZ from tall and thin to short and wide. The load exerted by the alluvial soil transfers downward to influence the FWCZ; however, this process is obstructed by the hard strata in the bedrock. Therefore, the vertical and lateral change trends show a similar step pattern. Our results can provide a basis for accurate calculation of the FWCZ height in mining areas with thick alluvial soil, to mitigate mine water hazards and increase the safety of underground mining in coal mines covered with a thick alluvium layer. Moreover, reducing the FWCZ height can help extend the upper extraction limit in coal mines covered with a thick alluvium layer, which reduces the thickness of the impermeable coal pillar and increases coal production.

Jan 1, 2016

Numbering of the Journal Because computer and library authorities prefer journal subscriptions to be based on the calendar year, and because the present numbering system of the Journal of the South African Institute of Mining and Metallurgy does not conform with the calendar year, it has been decided to change the numbering system of the Journal.

Jan 1, 1979

By Jean-Claude Paye

In February 1996 the OECD's Environment Policy Committee will commemorate its 25th anniversary with a fifth meeting at Ministerial level. Environment ministers will be taking stock of the progress made by OECD countries in protecting and managing the environment in that quarter-century, and sharing views on likely challenges and co-operative responses. Ministers can point to many important accomplishments. Scientific understanding and technological tools for establishing and monitoring risks to human health and the environment have improved dramatically since the early 1970s. All OECD countries now have in place comprehensive environmental legislation, supported by specialized institutions for policy design, implementation and enforcement. The results of these efforts are increasingly evident in the form of cleaner air and water, and improved protection of natural areas, notwithstanding the many complex problems that remain.

Jan 1, 1996

By J P. van Dyk

The dramatic strengthening of the rand against the dollar as well as a decline in quantity and quality of locally available concentrates have had a dramatic impact on Zincor?s operations during the previous two years. Zincor has responded with the implementation of a number of technical improvements to the process to decrease cost and increase revenue and plant flexibility. Among the initiatives is the pre-leaching and pelletising of the zinc concentrate, de-bottlenecking and process improvements in the leach and purification circuits, the introduction of cathode washing and automated cathode stacking in the cell house and the installation of a new furnace to produce pre-alloyed jumbos. This paper will describe these initiatives and others that Zincor have recently taken to stay competitive in changing global base metals market.

Jan 1, 2005

By J. N. Van der Merwe

"Platinum is a highly valuable resource, its safe and economic extraction is paramount. The success of platinum mining by the bord and pillar method depends heavily on a comprehensive and dependable pillar design method. Pillars need to be large enough to safely support the load and small enough to avoid loss of resources. A critical evaluation of current pillar design systems used in narrow-reef platinum mining was undertaken using practical experience from a large feasibility-stage platinum exploration project, supplemented by observations from several platinum mines in Zimbabwe. An extensive literature survey was undertaken in order to determine the current status of design systems. Through this approach, the shortcomings of current pillar design systems are highlighted. Areas are proposed for further research to obtain a better understanding on how additional factors influence pillar system stability. The exploration work highlighted how rock mass classification methods can be utilized in determining the overall strength of pillars. Current pillar design systems for narrow-reef platinum mining consider width-to-heightratio (usually with different exponents for width and height) and the strength of the pillar material. However, there are many more important factors that are not considered and which have a bearing on pillar system stability. An in-depth study of these parameters with a view to establish effective narrow- reef platinum mining pillar design systems needs to be undertaken. IntroductionPillars have been used as a means of support since the early days of mining. Pillarsupported mining methods such as bord and pillar require a reliable design system for them to be successful. This paper presents an evaluation of the current hard-rock mining pillar design systems as applied to a practical large-scale narrow-reef platinum mining feasibility study. It is vital to have a dependable pillar design system for economic and sustainable mining. Using an extensive database collected from the project, the pillar strength formulae were tested and several discrepancies noted. This necessitates the establishment of more reliable pillar design systems. In narrow-reef platinum mining, large compressive stresses accompanied by geological and geotechnical factors contribute to pillar instability. A well-formulated pillar design system is required that accounts for such factors so as to minimize pillar failures."

Jan 1, 2017

This symposium, being held at The President Hotel, Johannesburg on 9th-11th September, 1969, is being jointly sponsored by The South African Institute of Mining and Metallurgy, The South African Corrosion Council and the Southern Africa Stainless Steel Development Association, and supported by the C.S.I.R. The three days of technical sessions, at which 350 delegates are expected, will include introductory films on the properties and uses of stainless steels, papers on corrosion problems and prevention, design and economics, welding and applications in industries of particular importance to South Africa. The programme includes four overseas guest speakers who are acknowledged leaders in their respective fields. Detailed programmes together with application forms for registration will be published shortly. Enquiries to P.G. Box 8954, Johannesburg.

By J. E. Friant, R. P. H. Willis, J. Maaren

Considerable effort is currently directed towards the development of non-explosive mining methods with the potential to allow continuous mining in narrow reef conditions. Besides improving productivity, continuous mining results in concentrated mining which has a significant impact on reducing infrastructure costs. CSIR: Miningtek recognized the potential of mini-disc cutters in a long or short wall application for selective hard rock mining in 1999. EEA was chartered to build a 780 mm diameter by 800 mm deep drum cutter head. While EEA designed and built the head, CSIR designed and built the drive mechanism and chassis for the trial machine. After assembly and shop testing at CSIR’s facility, the machine was shipped to a platinum mine for trials. This paper traces the development of mini-disc cutters and their application in South Africa.

Sep 1, 2001

The value of incentive payments in the mining industry by K. SMITH, A.R.S.M., B.Sc. (London) (Member) This paper reviews the history of incentive payments in the mining industry, and gives some indication of the magnitude of improvement that has been achieved by this means in the past. The objective is to promote a more general belief in the efficacy of these methods, and thus to encourage their wider and more effective application by mining engineers in general, and by the rising generation in particular. It is concluded, from a consideration of current productivity levels in the gold-mining industry (still South Africa's leading revenue earner), that further substantial improvement can be achieved by a better understanding of the time-tested principles of incentive payments.

Jan 5, 1974

By R. W. O. Kersten

It was decided that Anglovaal should conduct a course on technical computing to help middle and upper mine management (40 years and older) to use computers. Background This decision was taken against the background of perception that various people have of computers and computer-related processes. People of the older generation Book review Rock mechanics for underground mining, by RH.G. Brady and E. T. Brown. London, George AlIen & Unwin, 1985. 527 pp. Reviewer: S. Budavari Mine safety awards The mining challenge of our time is the maintenance of the very highest safety standards, says a Chamber of Mines Executive. Haulage in surface mines An international symposium on 'Of-highway Haulage in Surface Mines' is to be held in Edmonton, Canada, from 15th to 17th May, 1989.

Jan 1, 1988

By D. vas As, Constance M. Vleggaar, P. D. Toens

A facility at the National Nuclear Research Centre, Pelindaba, for the calibration of gamma survey meters used in uranium-prospecting operations by P. D. TOENS, D.Sc. (Fellow), D. van ASt, M.Sc. (Visitor), and CONSTANCE M. VLEGGAAR, B.Se. (Visitor) Ground radiometric surveys in uranium prospecting have in the past suffered from two serious shortcomings. Owing to varying instrument sensitivity and the often arbitrary height at which readings are taken, it has been impossible to compare results obtained in different surveys and, moreover, to relate such readings to actual U30s concentrations. A set of calibration sources designed to overcome these problems has recently been constructed on the site of the National Nuclear Research Centre, Pelindaba. A discussion of the standards applied and the instrument calibration procedure is presented.

The 90th Annual General Meeting of The South African Institute of Mining and Metallurgy was held at Kelvin House, Johannesburg, on 19th August, 1987. Dr H. Wagner (President) was in the Chair and declared the meeting open at 16h00. Obituaries The President read out the names of the departed Members as follows: N.M. Airey, F.J. Kisbey-Green, Dr R.A. Pelletier, C.B. Anderson, A.R. Cator, J. van Heerden, P.J. Burman, C.C. Crosson, M. Livingstone¬Blevins, S.T. Firman, V.E. Kisbey-Green, and A.L. Corna. All stood and observed a moment of silence as a mark of respect. Minutes The minutes of the 89th Meeting of the SAIMM, which was held on 20th of August, 1986, were confirmed.

Jan 1, 1987

The 99th Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Gold Room, Transvaal Automobile Club, 60 5th Street, Lower Houghton, Johannesburg on Wednesday, 14th August, 1996. Obituaries The President announced the death, during the year, of the following members: Life Fellows H.L. Munro, H.S. Simpson, P.L. Ward Fellows I.M. Hossy, A.E. O'Meara Retired Fellows E.A. Arvidson, R.F. Bourne, F. Hawke, W. Lloyd, J.M. Meyer Members J. Allen, P.A. Boardman, L.M. Jacobs, G.F. Marx, G.D. Perry, R.W. Spraggs Retired Member M. Milner Associate I. Pieterse. In memory of the deceased and in sympathy with the bereaved, all rose and observed a moment of silence.

Jan 1, 1996

By K. R. Vost

"In situ" measurements of the surface heat transfer coefficient in underground airways by K. R. VeST,* B.Se. (Glas.), M.Se. (N.S.W.) (Visitor) Few "in situ" measurements have been made of the surface heat transfer coefficient in mine airways despite the importance of this coefficient in determining the heat flow into the ventilating air. In this paper, the values obtained at various air velocities and the comparisons of these values with theoretical values are given. Examples are also given ofthe errors which would result if rock surface temperatures were obtained by extrapolation from temperatures further into the rock without taking into account the time delay which occurs before a given change in air temperature reaches the points from which extrapolation is carried out.

By P. Gonzalez

Minera La Parreña, S.A. de C.V., Milpillas operation is an underground mine designed to process 8 352 tons of ore per day for the recovery of copper through crushing, heap leaching, solvent extraction and electrowinning facilities. In order to optimize copper recovery during leaching, the ore is crushed to 13 mm and subjected to primary sampling every 15 minutes for metallurgical accounting. At the same particle size, primary sample goes to secondary sampling and then, the secondary sample is crushed to 2 mm before tertiary sampling. The tertiary sample is sent to laboratory where a final sample is obtained and pulverized to 106 microns for copper assay. This paper shows a review of sampling strategy focused on minimizing or eliminating sampling errors and an experiment designed to determine copper head grade profile as well as the best sampling frequency.

Jan 1, 2009

By Z. Botha

Sheryl Sandberg, the COO of Facebook, published a book titled 'Lean In', where she invites women to sit at the table. In summary, to 'sit at the table' entails not only embracing opportunity, but to actively seek out opportunities in leadership positions. Sandberg points out that, unfortunately, apart from institutional obstacles, a woman's own perceived limitations have a negative impact on her leadership ambitions. To create an environment where diversity will flourish, where everyone has a seat at the table and everyone has a voice, safety must be established first. To establish safety within a diverse team, there is power in relationships and connections. This study will first and foremost review theories in literature as to why diversity and inclusion are so important and the value that diversity brings to our industry. The study also recommends a few focus areas for improving diversity and inclusion in the industry.

Sep 1, 2022

By D. Ackerman, S. Cole, G. Langefeld, I. Parker

The removal of gravel from the seabed using a hydraulic mining tool is a complex multi-phase problem that cannot be analysed using traditional continuum based simulation techniques. One potential approach is to simulate the behaviours of the solid phase via the discrete element method and the liquid phase via finite volume based computational fluid dynamics. The interaction between the phases is accounted for by Eulerian coupling. The feasibility of using the combined computational fluid dynamics-discrete element method to simulate gravel entrainment from an idealized seabed is evaluated. The simulation results are validated using experimental data. It is concluded that while the current approach appears feasible, further work needs to be done to improve the accuracy of the simulation and to evaluate the approach?s ability to model more complex behaviours.

Jan 1, 2007

Historical Background. South Africa's industrial history began with the discovery of gold and diamonds during the last century, and the mining industry was the first chief component of our technological development. During the past six decades, quantum leaps were made in other fields, too, when other industries and research bodies such as Escom, NDC, Iscor, Sasol, Foskor, Alusaf, Mintek, cs I R, SA B S, and A E C were established. These meaningful additions have two outstanding characteristics. Firstly, they were linked mainly to primary activities such as energy and minerals and, secondly, their establishment was to a large extent due to the driving force of individuals such as Van der Bijl, Van Eck, Rossouw, Schonland, and Roux, rather than to impersonal government policy. Encouraging signs of the evolution of such policy has emerged during the past few years.

Jan 1, 1989

By L. A. Jagger

The world?s second largest producer of platinum, Impala Platinum Ltd, approved two new twin shaft projects at the end of September 2004, Nos. 16 and 20 Shafts. Both shaft projects are stand-alone entities and are being sunk from surface. Previously Impala had embarked on a strategy of extending the life of its third generation shafts by means declines. No. 16 Shaft is the first of a new fourth generation shaft complex, while No. 20 Shaft is the last of the third generation type shafts in the so-called shallow to intermediate mining zone. This paper details the basic designs of each project and covers the initial implementation. Although both projects are twin shaft systems, the access methods from the shafts to the reef horizon differ. Initiatives implemented to speed up the projects are also briefly covered.

Jan 1, 2006

By A. J. Buchan

The wear of steel pipelines used for the transportation of backfill slurries is frequently regarded as an erosion problem only. An investigation was undertaken of the likely contribution to the total 'wear rate' made by corrosion. Use was made of a pipe flow loop with catholically protected specimens and corrosion inhibitors. Laboratory electrochemical tests utilizing a rotating-cylinder electrode were also conducted. The slurries used were classified tailings from two mines at a relative density of 1,7. The velocities were between 2 and 4,9 m/s. Substantial decreases in the wear rate of up to 80 per cent for one slurry and up to 67 per cent for the other were obtained with the use of corrosion control, showing that corrosion and, more importantly, interaction between erosion and corrosion, contribute a significant portion of the overall wear in steel pipelines

Jan 1, 1994