WEALTH IN WASTE.

Western Star, 3 February 1922, Page 3

WEALTH IN WASTE.

NEW; FUEL FROM SLACK. A process for converting coal slack —now practically a waste product of the mines—into a valuable smokeless fuel with gas and other derivatives, was recently demonstrated to representatives of the leading financial and daily London newspapers. ’Although coalite, tl/e fuel jin question, had previously been produced, various mechanical difficulties had prevented its manufacture on a commercial basis. These difficulties have been overcome, and after nine weeks of uninterrupted -working -of the secret process, the interests concerned decided to throw their works- open for inspection. The Low Temperature Carbonisation Co. has its works at Barnsley, hear Sheffield. Its main object has been to produce a smokeless fuel from coal slack, 'and in this, says the Financial News, it has succeeded). More than this, the fuel is claimed to; be superior to any other for domestic uses. In addition fio the coalite, there, is recovered from the low temperature retorts a quantity of coal tar rich in oil, which averages 18 gallons per ton of/ slack carbonised.

The special type of retort presents a marked contrast to the ordlinary high-temperature co-king retort, the surplus and wasted gases from one of which could be seen flaming out from a neighbouring works belong,ing to another company, whereas no 1 sign of smoke or'flame appeared from the low-temperature retorts. This- difference indicates the elimination of waste, and explains partly why coalite is so- different from ordinary coke. —Special Devices in Retorts.—

The material used in the process- is two • parts of ordinary coal slack,, a material of practically no commercial value, and one part of coking slack, costing only a few shillings a ton, After being mixed the slack is washed to removd soil, stone and other impurities, and only the good coal is passed to the hopperg above the retorts. It id in the retorts that the success 'of the whole process lies. Formerly, with low-temperdture retorts, great difficulty was experienced in discharging them, 1 since at the temperature used the fuel Ist at its greatest expansion. This difficulty has been overcome by an arrangement of two plates in the, middle -of the retort', held apart -during the carbonisation. , When the retort is to. be discharged, the plates are brought together, , thus releasing the coalite from the sides -of the retort, from which it falls into' a cooling chamber. Another feature is that this chamber is airtight, preventing the heated material from bursting: into flame through contact with -air. 'Cooling is effected by means of water coils surrounding the chamber. Once lighted up, by subsidiary means, the retorts are heated from the gas which they produce. Under the low-temperature process, a ton of' slack produces 14cwt. -of coalite, about equal in bulk to 28cwf. of coal, and 18'gallons of tar, which on distillation will give two or three gallons of benzol, eight or nine gallons of lubricating oil, and about a similar quantity of oil suitable for Diesel engines. 1 ;—'Possibilities of New Fuel.—

The writer in the Financial News concludes as follows:—The present plan at Barnsley is laidl out for 200 retorts, and completed in all parts for 100 retorts, of which 20 are ready, and have been in operation for upwards of nine weeks. The retorts are simple in construction, and otherwise the plant is generally ’similar to any gas-producing works, so that units could be placed! at pit' mouths' to utilise the slack of the mines. It is l interesting to note that in certain other countries low carbonisation is carried out for the sole purpose of recovering the tar, treating the residue “coke,” which here forms coalite, as a waste product. There is a ready market for far larger quantities of coalite than the company can yet produce, while the tar js in equally great demand, because 1 of its purity and l other speqial qualities. ' When it is' realised that of the 200,000,000 tons or so of coal consumed annually in the United Kingdom some 40,000,000 tons are utilised for domestic purposes, and! 75 per cent, of this is lost in smoke, the importance Of the process, if, as apipears, it is commercially practicable, cannot be over-estimated. It is estimated that were even 100,000,000 tons -carbonised by the low 1 temperature method Great Britain could export oil and motor spirit rather than import it, ‘ besjdes supplying all her domestic needs for coal.