1869.] 



Coed Washing. 



493 



is usually driven at the rate of about one hundred strokes per 

 minute, e is the sieve on which the coal rests, and after being 

 washed it passes away over the shoot f. A machine of this cha- 

 racter, with pistons of 3 

 feet diameter, and " bashes " ^i<^- 2- 



about 3 feet by 4 feet, will 

 require a supply of about 

 32 gallons of water per mi- 

 nute for each " bash," and 

 is capable of washing about 

 50 tons of coal per day per 

 "bash." A four "bash" 

 machine, capable of purify- 

 ing nearly 200 tons of coal 

 a-day, requires about a 12- 

 horse-power steam engine to 

 work it and the auxiliary 

 machinery. 



Having thus briefly explained the details of the washing 

 machine itself, we pass on to notice the entire process through 

 which the coal has to pass. The coal is brought direct from the 

 pits in trucks, and emptied into the hopper sunk below the level 

 of the ground, as shown in the left-hand corner of the engraving. 

 Thence, if the situation does not admit of putting a pair of crush- 

 ing roUers into the first reception pit, it is carried by a Jacob's 

 ladder, and thrown into a hopper, through which it passes to the 

 crushing mill, to be broken up into a suitable size for washing, by 

 which process also the attachment between the coal and its im- 

 purities is severed or loosened. After passing through the rollers 

 it is lifted up into another hopper, whence it falls into a number 

 of short shoots corresponding with the number of " bashes " in the 

 machine, and, a little above the point in the shoots where the coal 

 enters, water is admitted through a service pipe, by means of which 

 the coal is carried down on to the sieve, and the washing proceeds 

 in the manner already explained. 



According to one modification of this machine, which is in 

 extensive use at Saarbruck, in Germany, a number of "bashes," 

 instead of working separately, act together ; the washed coal from 

 one "bash" falhng over a small weir into the next, and so on 

 until it has passed through the entire series. Although, no doubt, 

 by this mode a much greater degree of purity is obtained in the 

 washed coal, the plan of using the " bashes " separately, as practised 

 in this country, is found to give results sufficiently satisfactory for 

 all practical 23urposes ; to continue the process further would, there- 

 fore, only be to incur additional expenditure without corresponding 

 results. 



