B. Genc

Spontaneous combustion risk in South African coalfields

The risk of spontaneous combustion is well known in the South African coal mining industry. All major coal producers in South Africa, such as Anglo Thermal Coal, BHP Billiton Energy Coal South Africa (Becsa), Exxaro, and Xstrata Coal or their predecessors have experienced spontaneous combustion incidents in their history. As stated by Phillips et al. (2011) there is always the risk of spontaneous combustion in underground mining (e.g. the Goedehoop fire in 2008), but spontaneous combustion can take place on both underground and surface coal mines. The current problem is in surface mines and nearly always in mines extracting previously worked seams i.e. where old bord and pillar workings are exposed. In the coming years it is very possible that the rate of spontaneous combustion will increase from its present low levels, due to factors such as higher ventilation pressures, an increased rate of mining, more working of previously mined seams, etc. It is also fairly certain that coal mining will face tougher environmental legislation limiting emissions in the near future. To ascertain the areas where spontaneous combustion risks are high, it is necessary to improve current laboratory procedures for testing and evaluating coal samples, combine the result with site and field data, and if necessary revise the laboratory rating system to better reflect South African conditions. The current laboratory tests are conducted in order to determine both the Wits-EHAC index and the crossing-point temperature, which are combined to obtain the propensities of the coal samples to undergo spontaneous combustion. This has resulted in a database of results to review and evaluate South African coal seams. Using this database, the high-risk areas in terms of spontaneous combustion can be identified. The tests, involving 119 samples, cover five consecutive years, between 2008 and 2012. The samples were from a wide variety of different coal seams and producing coalfields. All samples have been subjected to a series of laboratory tests, and the results analysed. A comprehensive database of these results is available, and is being continually updated as new test results are added.

A review of spontaneous combustion studies – South African context

Abstract One of the challenges in the coal mining industry is self-heating of coal as this can become a problem during mining operations, stockpiling and transportation. This study reviews the mechanism of self-heating, areas of spontaneous combustion, various factors influencing self-heating and different experimental studies to predict its occurrence. The technical control measures applied to minimise self-heating with special consideration to South African coals are also discussed. The distribution and association of unknown materials accelerating spontaneous combustion at different bands within the seam is yet to be studied. A site evaluation of the effects of these parameters is underway.

Measuring “optimisation” software utilisation in the South African mining industry

This paper discusses a new methodology to define and measure utilisation of mine planning software. An initial data set compiled in 2012 in an online database was updated in 2014 with additional and new information for software utilised in the South African mining industry. However, the online database only serves as a data repository and presentation platform. A methodology was required to analyse the data in the database to infer extent of utilisation of the software to enable better decision-making strategies by various stakeholders that include mining companies, software providers, consulting companies and educational institutions. The new methodology uses three variables, namely commodity, functionality and time stamp. In this paper, only one of the six mine planning software functionalities called the ‘Optimisation’ functionality is applied on five selected commodities, using the 2012 and 2014 time stamps. The work presented in this paper is part of a PhD research study in the School of Mining Engineering at the University of the Witwatersrand.

Challenges in the South African Platinum Sector

This paper considers the fundamentals affecting the South African platinum industry. It offers a brief overview of the current challenges faced by the platinum sector in general, and Anglo American Platinum in particular. It also examines the difficulties South African platinum producers face in planning their future capacity to deliver platinum to the market. Although no solutions are offered for the problems associated with the current wage negotiation, labour unrest and declining profit margins, the article nevertheless provides the reader with insights to the challenges facing the South African platinum sector. Several recommendations are offered.