Recovery Work After Pit Fires; A Description of the Principal Methods Pursued Especially in Fiery Mines and of the Various Appliances Employed, Such as Respiratory- And Rescue-Apparatus, Dams, Etc - Softcover

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1901. Excerpt: ... VII. SPONTANEOUS IGNITION OF COAL IN BULK. According to Ainsworth, the principal causes of spontaneous ignition in coal are: friction, chemical action and pressure. The tendency of coal to become hot is due to absorption of solar heat and atmospheric oxygen. The carbon of coal being a bad conductor of heat, it therefore retains the greater part of the heat absorbed. In the case of damp coal, heat is developed in larger quantity than when dry, and the moisture is converted into vapour, this sweating being increased by the moisture. It may therefore be taken for granted that in large damp heaps of coal a great volume of heat can be developed under these favourable conditions, particularly in the bottom of the mass. Small coal is more active in this respect than large blocks, the heat being unable to escape as quickly as it is developed, owing to the absence of air circulation, and it therefore accumulates, the temperature increasing in proportion to the depth of the mass. Pressure is another cause of spontaneous combustion; for though in itself it does not produce any great amount of heat, it favours its development and accumulation. The most important cause of all, however, is chemical reaction. The heat thus developed seizes upon the elements for which it has the greatest affinity, iron pyrites being decomposed into iron and sulphur, and the latter oxidised. Naturally the first product of spontaneous ignition is steam, the other volatile gases being liberated according to their volatility and density. The latter quality increases and volatility diminishes the nearer we get to the bottom of the mass, until hot coal, giving off black smoke consisting of carbon, carbon dioxide and other gases, is reached. The liberation of gas goes on until nothing but coke ...

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