A Treatise on Earthly and Other Minerals and Mining (Paperback)

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. 1892 Excerpt: ...is not aimed at or desired for this reason. The lignite, as did the wood of which it is composed, contains a certain amount of resinous matter, and the secret of the pressing of the lignite into briquettes, and its cohesion in that form, is this very resin which is contained in the raw material. The pressure upon the surface of the lignite when in the press is enormous, and develops considerable heat, so much so that the hand can hardly support that of a newly-made briquette. Supposing, for instance, that absolutely dry lignite were sent into the press, the result would be that the heat developed would be so intense as to carbonise the resin in the lignite, and consequently the briquette would have no resistance but would crumble of itself to pieces. In order to obviate this, and to obtain a hard compact briquette, it has been proved by numerous experiments that the lignite, as it enters the press, must contain 18 per cent, of water, and that this amount is sufficient to prevent the carbonisation of the natural resin, and allows the development of just sufficient heat to permit of the resin becoming sticky, and this, combined with the force of the blow, forms a solid briquette with a polished surface, which does not soil the hands and which is not easily broken. A constant stream of water is kept in circulation around the press so as to keep it as cool as possible. The briquettes, as they leave the press, are steaming and the blow given to the succeeding briquette is utilized to impel those which have preceded it, so that the briquettes are guided in a continuous stream along a channel direct from the press to the storehouses, where they are piled in blocks to cool, or they may be loaded direct into railway waggons. Referring now to the general section of a...