BRIQUETTING OF COAL

Hokitika Guardian, 22 December 1931, Page 6

BRIQUETTING OF COAL

A USE FOR SLACK. . PROMISING EXPERIMENTS. .WELLINGTON, December 19. Efforts to utilise the whole product of the Dominion coal mines by turning the slack into briquettes have been made over a long period of years, with varying success. The* Waikato coal companies, who combined to establish a briquetting plant, made a definite forward move, but this does not dispose of the. problem for other classes of coal. Briquettes have been made, in past which have been quite .successful, but the amount of expensive material needed to bind the coal mixture put the process out of the question in a commercial sense. However, the associated coalowners of the Dominion (financially assisted the investigations of the Department of Scientific and Industrial Research, and a point has now been reached with briquetting experiments on bituir.'infnis coats which may be regarded as definitely promising success.

The process has passed the laboratory istage, for the preliminary work in the ’laboratory was sufficiently conclusive to warrant the establishment of a small plant capable of turning out briquettes for commercial use. It is known as a “pilot” plant, about onequarter the size which would be operated in commercial practice, but sufficiently large to give experience of practical value. This plant is at work in the State coal yard in Wellington, and can turn out three tons of briquettes daily.

AN OBJECT ACHIEVED

Various coal's and mixtures of coals are being used in experiments. The former Driquetting plants have fmlul because the proportion of pitch or bitumen needed to produce a. satislactory briquette for storage and handling was too large. This binding material costs «J 36 10s per ton, and the aim of the research workers was to produce results with the minimum quantity of bitumen or pitch in the coal mixture. The “pilot” plant has achieved the object in view. If it is necessary—as was the case in past experiments—to use' 10 .per cent of binder material, this added lbs per ton to the cost of the briquetting material, but the plant now at work lias cut the proportion of the expensive material down .to 6 per cent, and it is considered possible by studying the degree of screening of the coal, and the mixtures, to reduce the proportion of binder to 5 per cent, which woujjL mean a cost of 6s 6d per ton in addition to that of the slack coal which can be utilised'. ,

If the coal mines of the Dominion are provided with a cheap process ol briquetting, a profitable future ooe'is to them, as it wiU be. possible to find a market ’for the whole run of the coal produced. The great development of oil burning for steamers has considerably reduced the demand for slack coal, and with some mines this is almost a total loss. However, in the briquette form it will be capable of storage without deterioration, and can also be used by the largest coal consumer in the country, the Railway Department, which for locomotive' use at present is obliged to restrict orders to screened coal.