| Summary: | 'Coke' may be described as the cellular residue from the carbonisation of a coking coal in commercial ovens or-retorts at a temperature of about 9000C; and a 'Coking coal' as a coal which will yield a commercial coke when it is carbonised. Some of the questions arising from these descriptions are:- What are the standards required of a commercial coke; what is the cause of coke-formation; what are the characteristics of coking coals and how may they-be judged; and how can the quality of coke be improved? It is not proposed to discuss these questions in detail but it is important to be aware of them in order to understand the way the coking industry has developed. These questions have been asked since coke has been used on a commercial scale and the answers to them have altered with circumstances as science and technology have changed. The qualities which render a coke most useful, or most readily saleable vary according to the use to which it is to be put. For all combustion processes, which account for most of the coke used, it would be expected that the intrinsic 'combustibility' would be important. The manner in which a ooke burns depends-so much however upon such factors asp for example, the size of the pieces and the rate of supply of air to the fuel-bed, that differences in intrinsic combustibility may be masked. From observation of the various factors upon whioh the usefulness of a coke for particular purposes depends, it is possible to indicate those qualities of a coke which render it most valuable, for all, or most, purposes (Continues...).
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