228 COALFIELDS AND COLLIERIES OF AUSTRALIA. 



charging ports in the crown of each oven. The grade of the 

 rails laid along the top of a bank of ovens should be one per 

 cent., so as to assist in handling the charging canisters. The 

 firebricks are laid in loain or loam and clay, for if lime inortar 

 was heated and then played on with water, it would slack. 

 The doors of the ovens are raised and lowered by overhead 

 hand winches. 



The coal is obtained from the Mount Kiera colliery, and 

 after being tipped out is conveyed to the disintegrator shed by 

 a bucket elevator. The Carr's disintegrator is 3ft. Gin. in 

 diameter, and is capable of treating 200 tons in eight hours. 



No exact tests appear to have been made at the various 

 Australian coke works relative to the difference in 

 bulk and weight between the coal charged and the 

 coke produced. If a battery of ovens yields 65 per 

 cent, of coke, and by more careful work, either in 

 the construction of the ovens or in the supervision of 

 the process, this is increased one per cent., then there has been 

 an absolute saving of l-65th, or 1.53 per cent, of the total value 

 of the coke formerly produced, less the cost of loading, for all 

 the other expenses remain the same. There are no by product 

 ovens in Australia. It is doubtful, however, whether, under 

 local conditions, the amount of volatile hydrocarbons would 

 produce sufficient by-products to pay interest on the necessary 

 plant. Good coke, besides the fixed carbon and ash, will con- 

 tain a little volatile matter and water, consequently the actual 

 results of coke burning are not quite the same as that shown 

 by laboratory tests. 



The amount of ash in a coke may be increased above 

 that contained in the original coal, by the ash from 

 the coke burnt in the oven to give the necessary heat, by 

 handling coke in a dirty place, and from impure water used 

 for quenching. Some people claim that an increase of ash in 

 a coke, up to a certain limit, is an advantage, inasmuch as it 

 increases the hardness of the coke. But this only appears to 

 be true when the ash is a part of the structure, and not when it 

 is derived from outside sources ; the latter being further ob- 

 jected to since it is paid for as coke, and so far from giving oft 

 heat, requires not only heat, but fluxes to get rid of it, and 

 takes more handling. Commercial coke is the theoretical 

 yield less the loss in burning, and that of fine coke, or 

 "breeze." in handling: it is, however, increased by the ashes 

 and dirt gathered up. The loss in burning commercial coke 

 should not be more than 3 to 5 per cent, below the theoretical 

 amount.* 



*Catlett (C,) "Coking in Bee-Hive Ovens with Eeference to 

 Yield" (T. Am. Inst, Min. Eng., xxxiii., p 272, 1903). 



