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THE PROCESS OF BRIQUETTING.

Having given the details of the different methods and apparatus employed in the preparation of compressed fuel with the use of a bond, it may not be amiss to give in a single view a general idea of the arrangement and working of a briquette plant. This will be seen by reference to Plate XVII.

This process begins properly after the preparation by sorting, pulverizing, washing and drying, or otherwise cleaning the coal.

The fine coal is dumped into the pit nearest the drying furnace. It is raised by elevator buckets and emptied into a trough, through which it is carried by an endless screw to the center of the drying furnace. Falling upon the revolving table inside the chamber, the rakes move it continually toward the outside as the table turns, until finally it is discharged into the trough connecting with the agglomerator.

The pitch is pulverized, raised by an elevator, and carried forward by an endless band to a hopper, whence it falls into the same trough in which the dried coal has been discharged. The hopper contains the arrangement for regulating the amount of pitch to be added. The pitch and coal are then carried forward together by the endless screw to the mixing chamber, where the mixture is perfected by proper mechanical means and the degree of heat necessary for successful agglomeration secured by a steam jacket. The paste then falls upon the distributing table from which the moulds are filled, the moulding table revolves until the mould comes between the dies or stamps. The compression takes place, and the finished briquette, after a quarter revolution, falls upon an endless band, and is carried away for drying and storage or shipment.

In drying such briquettes it is advisable not to pile them more than three high while they are yet warm, as in such case sufficient heat is sometimes evolved to cause their ignition. After they have thoroughly cooled there is no further danger of such ignition.

COST OF BRIQUETTE PLANTS AND OF THE MANUFACTURE OF BRIQUETTES.

The prices quoted by the manufacturers of the various systems of presses and machinery differ widely. Preissig gives as the cost at factory of complete plants the following figures, which are approximately correct, some of them having been revised and present quotations used: