Article January 9, 1902 Issue

How Briquettes are Made

New York Journal

WIDESPREAD curiosity exists as to the appearance and burning qualities of the new coal briquettes being made at Stockton, Cal. Samples of the product show a black object, round in form, having nine inches of circumference, with convex ends, which, though it comes from the coal pit and the petroleum well, leaves no trace on the cleanest hands. The convenience of the briquettes is apparent at first view, and those who have tested its burning qualities are unqualified in their praise.

A visit to the briquette factory of the Tesla Coal Company was made by a party of business men recently. It was found located on the Stockton water front, adjacent to the bunkers of the Tesla company, to which the cars of the Almeda and San Joaquin Railroad, owned by the fuel corporation, convey the fuel from the mines, thirty-six miles distant. The process of converting coal, asphaltum, and other ingredients into briquettes was seen to be simple in its very perfection. It is conducted under a patent owned by the Tesla Coal Company. The main object sought is the increase in the combustible value of the coal by chemical process so as to utilize the volatile gases, which although containing the largest amount of heat units, are permitted to escape in the burning of crude coal. This is a fact recognized by several European governments, which have introduced briquettes for fuel in their navies, requiring that they shall contain a greater number of heat units than the ordinary coal. Knowledge of the superior heating qualities of briquettes has also been acted upon in the Eastern States, where factories for their manufacture are well established; but it may be remarked in passing that the best of these are far inferior to the Tesla Coal Company's plant, as perfected by John Treadwell, the discoverer and developer of the Alaska gold and Tesla coal mines in economy of process and in satisfactory results.

Reduced to its simplest expression, the process of briquette manufacture consists in the pulverization of the coal, its mixture with the other ingredients, and their compression into compact shape adapted to easy handling and the securing of the best draught conditions. The reduction of the coal to powder form by means of crushers requires no description. It is then dried and heated to a high point, and only when this has been accomplished is the coal mixed with the other components of briquette fuel. Now comes the most interesting part of the process in the shape of the compression. This is obtained by passing the material by means of hoppers into the two great pressers. So nicely is the machinery adjusted that nothing is lost, whereas by the Eastern systems a large per cent of the material has to be returned to undergo again crushing, drying, heating, and mixture. By means of pistons working in opposite directions under the compulsion of large side wheels the fuel material is pressed into briquette form at a pressure of twenty-two thousand pounds. The briquettes are now perfect. They only require cooling, the throwing out of the few which do not come up to standard as to density or shape, and conveyance to the bunkers for shipment by car to market. This is done by machinery almost exclusively and does not call for description. The briquettes are facts when they leave the compressors. The daily capacity of these is five hundred tons, but undoubtedly their number will have to be increased as the public becomes acquainted with the advantages of the burning of briquettes. They are now in use in Stockon and Oakland, where it is found that a ton does the work of a ton and a quarter of the ordinary coast coals for domestic purposes, and increases the heat productions fifty per cent over steam coals.

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