| 摘要 |
<p>1,153,231. Sodium tripolyphosphates. FMC CORP. 22 June, 1967 [23 June, 1966(2)], No. 28771/67. Heading C1A. Sodium tripolyphosphates which differ in size and density having a size of substantially -20 + 100 mesh and bulk density between 0À95 and 1À3 g/cc. are prepared by feeding aqueous sodium orthophosphate having an Na/P molar ratio of 1À63 to 1À7 into afluidized bed comprising discrete particles of sodium tripolyphosphate at a temperature of 220-400‹ C. A portion of the particles are removed and separated into a coarse and a fine fraction. The coarse fraction is crushed, and optionally mixed with a portion of the fine fraction, to produce a mixture of average size smaller than that of the bed. This crushed mixture is recycled to the bed. The remaining fine fraction may be recovered as product Form II sodium tripolyphosphate or may be transferred to a second fluidized bed and maintained at 425-550‹ C. Sodium tripolyphosphate particles are removed from this second bed having a higher Form I content than the particles introduced. The crushed particles, in the first stage, are advantageously subjected to high-speed mechanical attrition before being recycled to the first bed.</p> |
