Abstract
Crystallizing conditions of gross gypsum crystal were discussed statistically, and were concluded as following :
1) Three temperatures of decomposing the phosphate with 50° Be' H2SO4 were analysed as “highly significant” between 86° and 120° or 180°C.
2) Three ground phosphate, 80-150, 150-250, and 250-mesh of Tyler sieve, were discussed and was “significant” 80-150 mesh.
3) Conditions producible hemihydrate gypsum (H2SO4 of 40 % or 30 % was used) were adapted and the hemi-hydrate were recrystallized to dihyrate 1. merely washing with water. 2. with water and temperature, 3. with 1 % Sodium tertarate solution, 4. same as 3. but with temperature, 5. same as 3. but after neutralized. Recrystallizing conditions were analysed as “highly significant” between 1. and 3.
