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The degradation of coal and the production of coal fines during handling and transport is a serious problem in processes that depend on closely sized large particles. To minimize the production of fines, a fundamental understanding of coal breakage is required, so, to clarify the complex nature of coal breakage, a series of experiments was conducted to determine the influence of the internal physical coal structures on compression breakage characteristics. The structures investigated are the cleat and layered structure of coal and the mineral inclusions. Samples of uniform size and shape were prepared from a large block of South African Waterberg coal. The samples were analyzed nondestructively using microfocus x-ray computed tomography then wrapped in cling film and mechanically compressed while the pressure applied was measured. The virtual three-dimensional volume tomograms of the initial sample and the progeny were compared and the changes qualitatively analyzed. Conclusions were drawn as to where the fatal cracks initialized and how the cracks propagated. Particle-size distributions were done to quantify the extent of breakage versus the breakage strength of the sample. It was found that, of all the internal structures, the inherent crack distribution has the biggest influence on breakage and breakage patterns of coal. [ABSTRACT FROM AUTHOR]

Pursuing a ‘natural-social scientific’ approach, I argue that constraints and opportunities provided by nature play a major role in South Africa's energy policy. Presently, the country's coal-dominated energy sector stands at a critical juncture. In order to overcome electricity shortages and provide a basis for economic growth, coal-fired power generation will have to expand. Regional cooperation on gas reserves and hydropower, a nuclear build-up programme at home and renewable energy constitute alternative strategies for South Africa to achieve energy security. I bring together natural conditions and social factors, reasoning that energy policy is largely determined by path-dependent developments. Path-dependent developments begin at critical junctures, where natural conditions and social factors jointly induce a course for the future that is extremely difficult to alter at a later point of time. Natural constraints and opportunities have received little attention in existing research but being aware of them helps us to better understand the present state of South Africa's energy sector and to assess the feasibility of envisaged strategies. [ABSTRACT FROM PUBLISHER]

A case study investigation was undertaken to explore the potential for introducing Cleaner Production (CP) to the South African coal mining and processing industry. A broad and integrated array of interventions was identified, highlighting the potential for CP to significantly reduce the environmental impacts of the case study collieries. Owing to the relative homogeneity of the South African coal mining industry, it is expected that CP may prove to be beneficial to the industry as a whole. However, it will only be able to fully embrace the approach once several economical, technological, and managerial barriers have been overcome. [ABSTRACT FROM AUTHOR]

The article examines the divergent views on the employment of women in underground mining by comparing labor practices in the coal mines of South Africa, where there were no women working underground in the mines, with those in the coal mines of India, where women were employed in large numbers after the second World War. After exploring the status of the mining industry in both countries in general and then on the social status of women in particular, the author obtained several reasons why women worked underground in Indian collieries, but not in those of South Africa in the first three decades of the twentieth century. These key reasons include technical requirements, economic pressures, cultural constraints, political campaigns and legal imperatives.

The use of retrospective occupational hygiene data for epidemiologic studies is useful in determining exposure-outcome relationships, but the potential for exposure misclassification is high. Although dust sampling in the South African coal industry has been a legal requirement for several decades, these historical data are not readily adequate for estimating past exposures. This study describes the respirable coal mine dust levels in three South African coal mines over time. Each of the participating mining operations had well-documented dust sampling information that was used to describe historical trends in dust exposure. Investigator-collected personal dust samples were taken using standardized techniques from the face, backbye (underground jobs not at the coal face), and surface from 50 miners at each mine, repeated over three sampling cycles. Job histories and exposure information was obtained from a sample of 684 current miners and 188 ex-miners. Linear models were developed to estimate the exposure levels associated with work in each mine, exposure zone, and over time using a combination of operator-collected historical data and investigator-collected samples. The estimated levels were then combined with work history information to calculate cumulative exposure metrics for the miner cohort. The mean historical and investigator-collected respirable dust levels were within international norms and South African standards. Silica content of the dust samples was also below the 5% regulatory action level. Mean respirable dust concentrations at the face, based on investigator-collected samples, were 0.9 mg/m 3 , 1.3 mg/m 3 , and 1.9 mg/m 3 at Mines 1, 2, and 3, respectively. The operator-collected samples showed considerable variability across exposure zones, mines, and time, with the annual means at the face ranging from 0.4 mg/m 3 to 2.9 mg/m 3 . Statistically significant findings were found between operator- and investigator-collected dust samples. Model-based arithmetic mean dust estimates at the face were 1.2 mg/m 3 , 2.0 mg/m 3 , and 0.9 mg/m 3 for Mines 1, 2, and 3, respectively. Using these levels, the mean cumulative exposure for the cohort was 56.8 mg-years/m 3 . Current miners had a mean cumulative exposure of 66.5 mg-years/m 3 , compared with ex-miners of 26.8 mg-years/m 3 . Improvements in dust management or the use of different sampling equipment could account for the significant differences seen between operator- and investigator-collected data. Regression modeling for estimating mean dust levels over time using combined historical and investigator-collected data seems a reasonable method and useful in constructing models to describe cumulative exposures in a cohort of current and ex-miners. [ABSTRACT FROM AUTHOR]

Analysis of Pillar Extraction Potential (A-PEP) is an intelligent tool that could be used as a preliminary output indicator when considering the secondary extraction of regional support pillars in the Witbank and Highveld coalfields of South Africa. Pillar extraction practices in South Africa have consumed a significant proportion of safety and fatality statistics in relation to its relative output (less than 5% of total South African coal production) and as a result research was undertaken in local pillar extraction operations and extended to similar operations in New South Wales, Australia to assess a way forward for pillar extraction in South Africa. The A-PEP tool is based on certain physical, risk and economic factors that combine to be indicative of operational success in terms of economic, health and safety attributes. In this paper it is successfully tested against two existing pillar extraction operations. [ABSTRACT FROM AUTHOR]

Focusing on two major coal-industry strikes, one in Alabama (1920-1921) and one in the Transvaal (1922), this article seeks to understand why the former was biracial and the latter only involved white employees. The contrast is interesting because of its wider significance within the US and South Africa, and because of resemblances between the two cases. In Alabama, blacks and whites undertook similar work and there were cultural commonalities as well as divides, but in the Transvaal the economic and social gulf was so great that, for practical purposes, there were two working classes. In Alabama, most black miners and most white miners were free and settled, and came from similar rural areas. In the Transvaal, whilst blacks were coerced and migrated between subsistence societies and the collieries, whites were free and settled, and mostly had proletarian backgrounds. In South Africa, the regular supply of 'cheap' black labour - upon which the economy depended - was maintained by institutions created or supported by the state. It is argued, finally, that whilst the possibility of interracialism was rooted in the outcome of the Civil War, the institutionalisation of a dual working class was a product of imperialist victory in the South African War. [ABSTRACT FROM AUTHOR]