| 摘要 |
PROBLEM TO BE SOLVED: To obtain a coal blend which can give coke reduced in a bulk density without lowering strength by blending caking coal with noncaking or low-caking coal having a specified grain size. SOLUTION: The grain size of the noncaking or low-caking coal should be 3 mm or smaller (100%). It is desirable that a carbon powder having a softening or melting temperature higher than the coking temperature be added to a coal blend comprising caking coal and noncaking or low-caking coal. It is exemplified by a high-softening or melting-temperature carbon powder such as oil coke, powdery coke or anthracite. The pores of coke are formed in such a way that the gas produced from coal when it is in a softened or molten state at about 380 deg.C is entrapped in it when the melt is solidified. As the viscosity of the soften or molten layer is increasing, the rate of discharge of the produced gas is retarded, the volume of entrapped gas increases, and the porosity increases. Because the excessively large pore diameter causes a lowered coke strength, it is desirable that the pore size is 10-100μm. By making the particles of the inert component as a solid layer finer, the viscosity of the softened or molten layer of coal can be increased.
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