In order to establish the manufacturing process of smokeless domestic fuel from Japanese fine coals of weakly caking property, their heat treatments at 400-475°C with a fluidized bed, followed by direct briquetting of hot chars formed, were fundamentally studied.
The reactor, made of refractory glass, was heated up by external electric heater at the selected temperature.
In each batch, 35g of fine coal was heat treated in the reactor and char obtained was fed to the mould and compressed with an oil press.
Results of the tests on several factors affecting on briquettability of char were as follows:
(a) When weakly caking coals of free swelling number ranging from 3 to 61/2 were used, they gave briquettes of high compression strength.
(b) The properties of briquettes were good, when the range of heat treatment temperature was between 425°C and 450°C, and also when the temperature of mould was maintained above 350°C.
(c) In general, reducing the oxygen content in the fluidizing was, the strength of briquettes increased.
But for higher rank coals used, when the oxygen content was reduced extremely, the blockage was observed in the reactor due to agglomeration of coal particles.
(d) The volatile matter of char was from 25% to 35% (d. a. f.).
