|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1994 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1993 : ¥1,600,000 (Direct Cost : ¥1,600,000)
To develop a noble granulation process in which the granules of various size having a moderate compressing strength are produced not by using any binding material but by modifying the surface properties of feed powder in high temperature fluidized bed, the morphological properties of granules such as their size distribution and shape and their recovery fraction were related with the experimental conditions by sieving analysis and SEM observation of the granules composed of various size fraction of alumina particles, which were formed in a spouting type fluidized bed at the temperature up to 700 K.The following results were obtained.
1) Spherical shaped granules were obtained for feed powders having the mean size under 1mum. For feed powders with the size over 2mum, the formation of granules was not observed.
2) The value of average diameter of granules was ranged from 70mum to 110mum, and increased with temperature rise. The value of recovery fraction of granules also increased with temp
3) The cumulative undersize fraction of granules was obeyed by a bimodal distribution which is expressed by two straight lines in log-normal probability diagram with a few exception. Any regular trend was not found in the relation between the geometric standard deviation of granules size, which was determined by assuming a single mode distribution, and the operational conditions such as gas velocity and temperature.
4) The granules obtained had the moderate strength such that they were not easily disintegrated during the course of sieving.
5) For relatively high temperature (above 600 K) , the effects of gas velocity on the average diameter and the recovery fraction of granules were not so remarkable as those of temperature. For room temperature, the value of both the average diameter and the recovery fraction of granules decreased with increasing gas velocity.
6) As for the operating time, the granulation was almost completed in a first few minute, and then the average value of granule diameter increased gradually with time. The value of recovery fraction of granules increased with time elapsed in the initial period of granulation, and then decreased with time via its maximum accompanied by the entrainment of relatively small granules. Less