초록 ▼

Separating Ca(NO3)2.4H2O from a nitrophosphate digestion liquor by crystallization, wherein Ca(NO3)2.4H2O seeding material with a particle size smaller than 100 m3)2.4H2O crystallized out is separated from the cooled liquor. The Ca(NO3 )2.4H2O is substantially crystallized out without excessive cool

Separating Ca(NO3)2.4H2O from a nitrophosphate digestion liquor by crystallization, wherein Ca(NO3)2.4H2O seeding material with a particle size smaller than 100 m3)2.4H2O crystallized out is separated from the cooled liquor. The Ca(NO3 )2.4H2O is substantially crystallized out without excessive cooling as very coarse and uniform particles which can be easily separated out.

대표청구항 ▼

A process for separating calcium nitrate tetrahydrate by crystallization during batchwise cooling from a digestion liquor obtained by digesting phosphate rock with nitric acid, which process comprises; initially cooling the digestion liquor using a cooling medium having a temperature higher than the

A process for separating calcium nitrate tetrahydrate by crystallization during batchwise cooling from a digestion liquor obtained by digesting phosphate rock with nitric acid, which process comprises; initially cooling the digestion liquor using a cooling medium having a temperature higher than the nucleation temperature of the digestion liquor and adding about 50,000 to 200,000 calcium nitrate tetrahydrate seeds per kg of the digestion liquor to be cooled to the digestion liquor, said seeds having a particle size less than 100 m0.1°C. and 2°C. below the saturation temperature of the digestion liquor whereby calcium nitrate tetrahydrate crystals grow from said seeds, the initial cooling continuing as long as the concentration of calcium nitrate tetrahydrate crystals in the digestion liquor is less than about 20%, thereafter, when the concentration of said crystals in the digestion liquor has increased to above about 20%, subsequently cooling the digestion liquor using a cooling medium having a temperature lower than the nucleation temperature of the digestion liquor; and separating out the calcium nitrate tetrahydrate crystallized out in this process from the thus-cooled digestion liquor.