Please put some lolly in the poor families’ hat’ Parody on a Christmas chant This is the appropriate time to express the hope that all readers have a joyous festive season and to convey my best wishes for the forthcoming year. But it is also the time to pick out some items that relate to features of the industry in 2007. Very pleasingly, there have been a lot of papers on the mining aspect, many of which relate to mine planning, decision making and the selection of mining methods. It is fitting that in this end-of-year issue there are several papers on this topic including the application of ‘fuzzy logic’ to assist in decision making.
Of course the most important considerations in vital decision making are guidelines based on experience, expertise and familiarity with the theoretical aspects of rock mechanics. But it could be of value to be involved in the statistical approach so that in time a database can be built up to reduce the ‘fuzziness’ in the mathematical approach. One of the dominant topics in mining is the focus on mine safety and the concerns that have been expressed at many levels at the fatalities that have hit both gold and platinum mining operations in the last few months. Fatalities in mining are in the same category as road fatalities in that there is only one way to reach a zero target and that is to ban all humans on roads and in mining underground. I hesitate to join the band of armchair experts who pontificate on these tragic events and pronounce on the steps that have to be taken to expose and punish those deemed to be responsible.
But I must confess that I am surprised at the ‘fuzzy’ logic of the Chamber of Mines in joining hands with the National Union of Mineworkers on an across-theboard strike to protest against the recent accidents. All those involved in industry and government have expressed their distress and determination to allocate highest priority to safety aspects. A work stoppage would achieve nothing. What would be far more effective is not a polarization between management and workers but an affirmation of a determination to collaborate in attacking a frustratingly difficult problem. What a wonderful inspiration it would have been for the COM, NUM and the mining companies to join hands in an alternative approach. Rather than incur the losses of a one-day shutdown, they could allocate an equivalent amount of money to a fund to compensate the families and dependants of those killed or disabled. Another paper in this December issue that attracted my attention is that on the cleaner production (CP) assessment of the fine-coal waste material arising from most mines.
Coal was certainly a major topic during 2007, not so much in terms of papers in this Journal but in hitting the headlines in the media and in public opinion. This was the result of the frantic drive on the part of Escom to increase power production to meet the ever increasing demand. In reaching all-time records in exports, local consumption and prices, coal mining has emerged not as the Cinderella of the mining industry compared with gold and platinum but as a respected member of the billionaire club in terms of economic importance. Regretfully there were not only highlights but also lowlights, in the media focus on the degradation of farming areas and the environmental impact on water resources from the ubiquitous acid mine drainage (AMD).
The paper describes work at the University of Cape Town sponsored by the Water Research Commission, in identifying ways of avoiding the production of utilizing the fine-coal wastes, which seem to be inevitable in South African coal mines. It is claimed that there is a production of over 10 million tons a year of such material, and the energy value of these fines is of the same order as the run-of-mine coal (24 megajoules/kg). The assessment protocol focuses on an evaluation of various options to avoid dumping of these fines, for example by coarser grinding, or using the fines for the production of power or alternative fuels such as briquettes for low cost domestic use. Conversion to methane or liquid fuels is also considered as alternative ways of using these waste materials. Feasibility studies based on net present value calculations are then used to select the best clean production technology to be adopted.
However, like so many environmental assessment protocols and reports, there is little experimental evidence, and often this leads to rather superficial conclusions. For example, in this paper, no mention is made of the sulphur content of the fines which I believe is generally higher than in the coarse coal fractions and the fines are discarded to meet specifications. The sulphur is the crucial factor in the production of AMD, which has caused so much comment. Separation of coal and the sulphides such as in pyrite or organic sulphides in the coal, although not impossible, is not a matter of a simple flotation process, as implied in the CP assessment report. From several previous Journal Comments, readers will know that I rate the AMD problem as one of the ‘majors’ in what should be a national research initiative, particularly if coupled with the potential for utilizing the energy value of these coal fines in this time of power shortages. It seems that the DME feel likewise, and it was pleasing to learn that they have sponsored a chair of Clean Coal Technology in the Department of Chemical Engineering at the University of the Witwatersrand. So let us look forward to many research papers appearing in our Journal on coal from this group. R.E. Robinson December 2007
- Written by R.E. Robinson
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