An Automatic Coal Petrographical Analysis for Evaluating Coking Coals

Abstract

An automatic sy stem Jor evaluating the coking coals was develojled at Nippon Steel Corporation in 1974. In this system, the reflectance oj coal is measured automatically and rapidly and then converted to the coking parameters based on the coal petrographical point qf view. It takes only 30-100 min to make 2 X 10 4-1 X 10 5 measurements oj reflectance in a sample. From the measured reflectance distribution Jar the whole maceral and vitrillite alone, the coking index are comjmted. Many applications qf the automatic system Jar coal jletrograpJ~), have been developed with satisfactory results.

Analysis of coal blends by automated microscopy

“…A reduction in particle size increases the amount of material at the resinlcoal boundary. As the boundary region shows a gradation of brightness, this will lead to a spreading of the reflectance histogram to lower reflectances (Kojima & Sakurai, 1978). A more serious effect arises from the method used (Lee, 1985) to reject resin from the reflectance distribution.…”

“…Because manual petrographic examination is time consuming and therefore expensive, attempts have been made to automate the procedure. These range from automation of the apparatus used for manual petrography (Kojima & Sakurai, 1978;Davis & Vastola, 1977;McCartney et al, 1971) to the adaptation of computer-controlled image analyser systems (Harris, 1977;Luijckx & Roos, 1982;England et al, 1979;Lee & Mikka, 1982;Chao er al., 1982;Riepe & Steller, 1984).…”

Characterization of coals by automated optical image analysis 1. Vitrinite reflectance

“…This adds to the already widely recognized application of coal petrography to the selection of metallurgical coals: coke quality prediction methods have been developed in the U.S.S.R. (Ammosov et al, 1957), U.S.A. (Schapiro & Gray, 1960;Harrison, 1961;Benedict et al, 1968), F.R.G. (Mackowsky, 1977) and Japan (Kojima & Sakurai, 1980) and applied worldwide.…”

Image analyser measurements of coal reflectance

“…Two approaches have been taken to the automation of petrographic characterization of coal. The most common approach has been to automate the photometer based reflectance microscope used for manual coal petrography (Kojima & Sakurai, 1978;Davis, 1975;Davis & Vastola, 1977;McCartney & Ergun, 1969;McCartney et al, 1971;Kojima er al., 1974;Kojima, 1976). The use of image analysers has also been investigated at this laboratory (England et al, 1979) and elsewhere (Harris, 1977;Luijckx & Roos, 1982;Crelling, 1982).…”

“…A variation on the automated photometer point reflectance measurement procedure which provides a method of recognition for the vitrinite maceral has been reported by Kojima & Sakurai (1980) and Suzuki et al (1981). The technique is based on comparison of the reflectance at two closely spaced points, and acceptance as vitrinite those pairs of points which have approximately equal brightness.…”