Coal Industry (patents) Limited

Michael David Gray

Geoffrey M Kimber

David Ernest Shipley

A low-impurity coke suitable for the production of electrodes for aluminium manufacture is prepared by extracting coal volatile matter content greater than about 28% by weight on a dry ash free basis with a highly aromatic hydrocarbon extractant of which the middle 90% boils in the range 250.degree. to 350.degree. C at a temperature of about 380.degree. to 450.degree. C, in the liquid phase, insoluble matter is separated off and the extract is heated to remove distillable oil and coked wherein the residence time of coal in the extraction step is controlled and the weight ratio of extractant to coal during extraction is maintained greater than 3:1 to maintain a substantially constant specific resistivity of the filter cake.

Manufacture of coke

A process for the production of coke which process comprises extracting coal at an elevated temperature with a suitable solvent, filtering undissolved material from the extract, concentrating the extract and thereafter coking the concentrated extract while recovering the solvent for re-circulation characterised in that prior to digestion of the coal the solvent is subjected to coking under conditions comparable with the conditions under which the coal solution is subjected to coking until coking of all the cokable components in the solvent is substantially complete.

Improvements in and relating to the production of coke

The invention relates to a process for the production of coke having a low mineral matter content which process comprises digesting coal in a high boiling aromatic oil solvent at a temperature within the range of 350.degree.C. to 480.degree.C. separating insoluble matter from the coal digest to give a coal extract and coking the coal extract characterized in that the coal prior to digestion has a volatile matter content within the range of 13% to 28% by weight.

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Cheltenham, United Kingdom

Michael David Gray