COAL, TAR AND, COKE

Evening Post, Volume XCVI, Issue 40, 15 August 1918, Page 4

COAL, TAR AND, COKE

A REVIEW OF THE INDUSTRY

At the conclusion of an address by Professor T. H. Easterfield before the Philosophical Society last night On "The Distillation of Coal, and the Eesulting By-products," the Chairman, Mr. S. Jenkinson, expressed the general opinion of the members by stating that the address had been one of the most interesting and illuminating that had been delivered to the society for a long time.

Coal heated out of contact with air, said the • Professor, broke up into coke, tar, water, and conl gas, the proportions varying greatly 'according to the class of coal and the process followed. A ton of coal would give off from 4000 to 17,000 cubic feet of gas. The latter amount was not obtained in New Zealand, but was reached in some European furnaces under special conditions. The coke varied from 50 per cent, to 85 per cent,, and about 5 per cent, of tar was realised. Coal v;as first treated as was wood destined for charcoal, that is, it was eimply piled up in heaps and covered with earth, Mid then allowed to buni until no flame was visible, the mass being red-hot tliroughout. Next came the' beehive oven, which produced excellent coke, but wasted the whole of the gas and tar. The Jameson oven Followed, which made it possible for the tar to be collected, though it was put to little use. The speaker, with the aid of diagrams, then explained thn gradual advances mads in the development of coke ovens to the modern processes wherein a | part_ of the gas given off during the heating was used for the continuance of the process. Even the best of the systems wsre open to considerable improvement. Coke-making under present conditions, given a market, was a highly profitable business, for the manufacturer obtained his coke and cleared the cost of production by the sale of by-products. Such a business was, however, only possible where a- great deal of coke was required for metallurgical purposes. Processes having for their end the production of ga.s rather than coke were then discussed, the speaker again pointing out the developments that had been made from the earlier and more wasteful systems till, theoretically at least, a modern installation was automatic in action. Further modifications in modern systems were necessary on account of the requirements as regards by-products, said the speaker, who then went on to outline the. ever widening field of usefulness of the- many by-products. Aniliho was not a dye, as many people thought; it wns a colourless fluid, but when acted upon by almost any chemical it had the property 1 of changing- to one of a. great variety <>f lines. The production of . disinfectants, based on carbolic acid, benzene, as distinct from benzine, tuolene, of vital importance in the manufacture of explo ; sives,- naptholene, and other „ product* was dealt with briefly and concisely.

In answer to a question as to why Now Zealand gas manufacturers made little or no lise of tfc many by-productf, Pro. lessor Easterfield stated'that the matter was one of demand. In England nfcout half, the pvonti \v«s mad'o from gas, 30 per cent, from coke, and 1 the remainder from other products. In New Zealand, however, practically the whole profit ll;as obtained from the sale of gas. -Although there was much talk about the amount of waste from the Dominion's gasworks, the demand was not enough to make the development of those by-products a profitable investment. Ammonia, for instance, could not be produced locally on account of the high, cost of the acid neces6aTy for its production.