Abstract
The Thermo-Plasticity of vitrains of five Japanese caking coals and four foreign caking coals have been examined from the ordinary A. S. T. M. test and some other fluidity measurements with the Gieseler plastmeter.
The temperatures showing initial softening, fusion, maximum fluidity and solidification increases with rank of coal.
The fluidity of Japanese coals is higher than that of foreign coals at about same rank. And the coal at about 86 percent carbon content has a maximum fluidity.
This shows that the greater the content of tar and/or liquid-forming constituents in coals is.
Around the initial softening point, the fluidity of coals hardly changes and shows an almost constant value for a long residence time at constant temperature.
Around the fusion point, the fluidity of Miike coal (84.5%C) and Yubari coal (86.2%C) exceptionally increases with residence time up to about 150 minutes and then becomes almost constant up to 250 minutes. Flow curves for these coals at constant temperatures below the fusion points, obtained by measuring fluidities over a range of shear stress, indicate that these coals behave substantially as a plastic fluid.
Above the fusion point, the fluidity of coals increases steeply at first, shows a maximum, and then decreases with increase of residence time at constant temperature.
The time getting to the maximum fluidity increases with rank of coal at a constant temperature and decreases with increase of carbonizing temperature.
