| 摘要 |
1278466 Boron trioxide UGINE KUHLMANN 16 Oct 1969 [17 Oct 1968] 50974/691 Heading C1A Substantially anhydrous granular boric oxide is prepared by dehydration of granular orthoboric acid in a process in which the acid is placed above a gas diffusion device through which hot air is passed at such a rate as to establish a fluidized bed with at least 150% and preferably 200% of the volume of the material at rest, the air having a temperature of 200-250‹ C. at the end of the process. Preferably air at 150‹ to 160‹ C. is used initially to effect a partial dehydration to B 2 O 3 .H 2 O or B 2 O 3 .0À5H 2 O and then further dehydration to substantially anhydrous B 2 O 3 is achieved with air at 200‹ to 250‹ C.
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