Study of coal

Press, 2 August 1979, Page 17

Study of coal

A new method of lowtemperature ash analysis of coals will soon be used by research workers in the geology department of Canterbury University to help in future exploration and exploitation of West Coast coalfields and their subsequent industrial and commercial use. Three doctoral students are examining the older coals of the Greymouth area and the younger more widespread Brunner deposits in the Greymouth, Reefton and Mille r t o n-Stockton areas. Their studies involve both coal petrography and geochemical analysis and break new ground in New Zealand coal research. The work is supported in part by a grant of $17,000 from the Energy Research and Development Committee. The emphasis in these studies is on fundamental considerations: what were the original conditions under which the coal materials and associated sedimentary rock were laid down millions of years ago and what is the com-

position of the coal and the inorganic materials it contains? The answers will not only help With future coal exploration, but will give a guide to the properties of the coals within the fields for progressive exploitation and the suit ability of particular coals to various industrial and commercial applications. A knowledge of the concentration of sulphur and phosphorous in coal is, for instance, of close interest to the metallurgical industry. Coal petrography is the study of polished blocks and ultra-thin sections of coal with a polarising microscope. This analysis provides information on the original coal-forming materials and the degree of maturity attained by the coals in response to the high temperatures and pressures encountered in burial to various depths. The geocxmical analysis of the inorganic constituents present allows a predicton to be made of the optimum use of the

different coals. Coal ash is produced at low temperature without burning by intense radio frequency radiation. This permits oxidation at temperatures as low as 100 degrees without destroying the original mineral compounds. Both petrographic and low temperature ash analysis of coals are in their infancy in New Zealand. The New Zealand Geological Survey in the North Island and a geologist at the University of Auckland are also initiating similar studies of other coal deposits. These studies have been more widespread overseas, although low-temperature ashing is relatively new. To make use of overseas knowledge and expertise, the University of Canterbury group is obtaining partial assistance from coal specialists at the University of Wollongong, in Australia, where one of the doctoral students is enrolled, even though the project is partly supervised at Canterbury.