Some Experiments on the Low-Temperature Removal of Carbonaceous Material from Clays

Experiments on a number of clays from different formations how that heating at 375 ~ for 16 hours removes 90 per cent. or more of the car-bonaceous material without removing combined water from the clay mineral. A close relationship sfound between percentage loss at 375~ and percentage carbon determined in the carbon-hydrogen furnace. The experiments described were carried out as part of a project to develop a procedure for determining the ignition loss of the clay mineral in clay, i.e., the IL value of the IL/MA ratio (Keeling, 1958, 1961). It was not intended to determine the proportion of carbonace-ous material as such although the method does in most instances give a good indication of this--but to isolate the ignition loss of carbonaceous material, and perhaps other constituents as well, from the ignition loss of the clay mineral. The method was suggested by observations that differential thermal and thermogravimetric curves of clays show little or no clay break-down below 400 ~ whereas much of the carbonaceous material is known to oxidize below this temperature. The first experiments were carried out on a North Staffordshire coal. Quantities of about 0.5 g (-72 mesh) were heated for 16 hours overnight in a furnace that was capable of maintaining controlled temperatures to within + 5~ from 300 ~ to 500 ~ Results are summarized in Table 1.