CHAIRMAN'S ADDRESS - Coke Oven Managers Association

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A REVIEW OF C.O.M.A. ACTIVITIES, 1939-1945 - CLARKE 215.the Northern Section of the <strong>Association</strong> and the Institute of Fuel inNewcastle in May 1940, was followed by an interesting discussion. Someof the points raised are summarised in the paragraphs which follow.Mr. S. Tweedy observed that Durham coals had been carbonised by theConsett Iron Company for many years in both old and new ovens (wideand narrow chambers) under a variety of conditions, but no problems dueto swelling pressure had ever been experienced, although Dr. Mott hadpointed out that some Durham coals had been classed as “dangerous” or“likely to be dangerous” by the standard Koppers swelling test. Althoughpractical carbonising experience indicated that Durham coals are harmless,the results of the small-scale Koppers test had occasionally had an adverseeffect upon the sale of these coals, because some purchasers relied on theindications given by the Koppers apparatus. Dr. Mott had now providedevidence from his researches that Durham coals are not dangerous whencarbonised. Mr. Tweedy asked Dr. Mott if he had any informationconcerning certain coals used in Germany which exhibited a harmfultemporary expansion. Reports indicated that carbonisation of these coalshad resulted in damage to the oven walls or buckstays, but as the coke hadcontracted sufficiently, no difficulty had been experienced in pushing theovens. Mr. Tweedy said he considered that the maximum pressuredeveloped under constant volume might possibly give an indication of suchcoals, and asked Dr. Mott to comment on this suggestion. Mr. Tweedyasked if the samples of coal used in the investigations had been oven-driedprior to making the tests, and if so, for what length of time, as it was wellknownthat this process can give rise to oxidation, which would invalidatethe results.Mr. P.C. Pope said the conclusion he drew from Dr. Mott’s paper wasthat whilst the work was of great service, it was more useful in a negativerather than a positive direction. The various swelling tests of Koppers,Nedelmann and Baum-Heuser gave certain indications, but it wasquestionable whether they gave sufficiently reliable information uponwhich a Company could base a contract for the building of coke ovens. Thetests did not appear to be sufficiently accurate for that purpose, and withborderline coals the position was particularly difficult. There wasinsufficient indication concerning the safety of using various coals in ovensof different widths, rates of heating and carbonisation temperatures. It was,therefore, hoped that Dr. Mott would continue his work and devise a
216. THE COKE OVEN MANAGERS’ YEAR-BOOKmethod which would provide more practical and reliable results undervarious operating conditions. Mr. Pope asked Dr. Mott if the coals receivedfor testing from Germany and the U.S.A. had been received in sealed tinsin an inert atmosphere to avoid oxidation which might otherwise occur.Dr. F. Booley asked Dr. Mott how the bulk density of the coal at thesole level of an oven had been determined.Mr. G.H. Harrison enquired if the Koppers apparatus had been designedwith any relation to oven practice, particularly in respect of the freesurface, which amounts to 4 sq.ft. per ton of coal in a modem oven, but foran old-style oven would be 6 sq.ft. per ton. He considered that unless theapparatus was related to free surface, then useful results could not beexpected. Mr. Harrison also asked Dr. Mott if he had any experience withthe Koppers apparatus using sponge-producing coals, as he (Mr. Harrison)considered that these would probably give rise to a high expansion result inthat equipment.Dr. G.E. Foxwell submitted a lengthy written contribution to the paper.He noted that some coals had, in the past, been classified as dangerousalthough they had not actually damaged coke oven walls, and he stressedthe need for a reliable method for assessment of the conditions under whichany given coal would become dangerous. Dr. Foxwell reported that whenhe used the standard Koppers apparatus on a regular basis he was usuallyable to decide with some certainty whether a coal was, or was not, likely tobe dangerous, but there were many borderline coals for which the test didnot give a clear indication of their “possibly dangerous” behaviour oncarbonisation. From the viewpoint of the contractor building coke ovens,such coals would have to be regarded as dangerous. Dr. Foxwell wrote thatthe impression arising from reading the paper was that in order to avoid theerroneous labelling of certain coals, Dr. Mott had set out to whitewash asmany as possible of coals classified by the Koppers test as “possiblydangerous”. He had succeeded by modifying the test, but the questionswhich arose were whether the modifications which had been introducednow gave an accurate assessment of the coals, or whether the original testwas more accurate, or whether either test could be accepted. Commentingon the modifications which Dr. Mott had made to the standard procedurefor conducting a Koppers swelling test, Dr. Foxwell noted that the materialbelow 20-mesh I.M.M. sieve was being removed from the crushed sample
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CHAIRMAN'S ADDRESS - Coke Oven Managers Association

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