| 摘要 |
<p>PROBLEM TO BE SOLVED: To maintain permeability in an ore bed in superior state and to stably produce a product having satisfactory quality with high efficiency by specifying the maximum grain size of return powder. SOLUTION: It is found that the deterioration in permeability, due to fluctuations in the grain size distribution of return powder, is attributable to pelletizing, that is, the reason why deterioration in permeability is brought about is that, when return powder having a wide range of grain size distribution are charged, resultant pellets after pelletizing have also a wide range of grain size distribution and, as a result, the percentage of voids in the ore bed is lowered. Accordingly, in order to solve this problem, the maximum grain size of return powder is controlled to <=6mm to arrange the grain size distribution of the pellets more uniformly. By this method, a time to the completion of sintering can be shortened and productivity can be improved.</p> |
