The problem as to how the refuse of coal shall be utilized has been solved in the manufacture from it of an agglomerated artificial fuel, which is coming more and more into general use on railways and steamboats, in the industries, and even in domestic heating.
The qualities that a good agglomerating machine should present are as follows:
1. Very great simplicity, inasmuch as it is called upon to operate in an atmosphere charged with coal dust, pitch, and steam; and, under such conditions, it is important that it may be easily got at for cleaning, and that the changing of its parts (which wear rapidly) may be effected without, so to speak, interrupting its running.
2. The compression must be powerful, and, that the product may be homogeneous, must operate progressively and not by shocks. It must especially act as much as possible upon the entire surface of the conglomerate, and this is something that most machines fail to do.
3. The removal from the mould must be effected easily, and not depend upon a play of pistons or springs, which soon become foul, and the operation of which is very irregular.
The operations embraced in the manufacture of this kind of fuel are as follows:
The refuse is sifted in order to separate the dust from the grains of coal. The dust is not submitted to a washing. The grains are classed into two sizes, after removing the nut size, which is sold separately. The grains of each size are washed separately. The washed grains are either drained or dried by a hydro-extractor in order to free them from the greater part of the water, the presence of this being an obstacle to their perfect agglomeration. The water, however, should not be entirely extracted because the combustibles being poor conductors of heat, a certain amount of dampness must be preserved to obtain an equal division of heat in the paste when the mixture is warmed.
After being dried the grains are mixed with the coal dust, and broken coal pitch is added in the proportion of eight to ten per cent. of the coal. The mixture is then thrown into a crushing machine, where it is reduced to powder and intimately mixed. It then passes into a pug-mill into which superheated steam is admitted, and by this means is converted into a plastic paste. This paste is then led into an agitator for the double purpose of freeing it from the steam that it contains, and of distributing it in the moulds of the compressing machine.
IMPROVED MACHINE FOR COMPRESSING REFUSE COAL INTO FUEL.
Bilan's machine, shown in the accompanying cut, is designed for manufacturing spherical conglomerates for domestic purposes. It consists of a cast iron frame supporting four vertical moulding wheels placed at right angles to each other and tangent to the line of the centers. These wheels carry on their periphery cavities that have the form of a quarter of a sphere. They thus form at the point of contact a complete sphere in which the material is inclosed. The paste is thrown by shovel, or emptied by buckets and chain, into the hopper fixed at the upper part of the frame. From here it is taken up by two helices, mounted on a vertical shaft traversing the hopper, and forced toward the point where the four moulding wheels meet. The driving pulley of the machine is keyed upon a horizontal shaft which is provided with two endless screws that actuate two gear-wheels, and these latter set in motion the four moulding wheels by means of beveled pinions. The four moulding wheels being accurately adjusted so that their cavities meet each other at every revolution, carry along the paste furnished them by the hopper, compress it powerfully on the four quarters, and, separating by a further revolution, allow the finished ball to drop out.
The external crown of the wheels carrying the moulds consists of four segments, which may be taken apart at will to be replaced by others when worn.
This Machine Produces About 40 Tons Per Day Of This Globular Artificial Fuel