| 摘要 |
A continuous process for the production of calcium hypochlorite comprises admixing a slurry of lime containing insoluble impurities with a saturated calcium hypochlorite solution in a crystallizing zone. An impure slurry of coarse dibasic calcium hypochlorite crystals, small crystals of dibasic calcium hypochlorite, and fine insolubles comprised of unreacted lime particles and fine insolubles in a mother liquor is formed. The slurry is fed to the intermediate section of a separation zone. An aqueous sodium chloride elutriant is fed to the lower section of the separation zone to contact the slurry and to separate a slurry of fine insolubles and small crystals of dibasic calcium hypochlorite in elutriant from the dibasic calcium hypochlorite crystals. Small crystals of dibasic calcium hypochlorite are separated from the fine insolubles in the intermediate section of the separation zone. These small crystals can be recycled to the crystallizing zone or destroyed by chlorination. The slurry of fine insolubles is conveyed in the elutriant to the upper section of the separation zone. A slurry of purified coarse dibasic calcium hypochlorite crystals in elutriant is removed from the lower section of the separation zone, the rate of removal of the purified coarse crystals of dibasic calcium hypochlorite being controlled to maintain a rising velocity in the lower section of the separation zone of from about 0.5 to about 7 centimeters per minute. Purified coarse dibasic calcium hypochlorite crystals are separated from a dibasic calcium hypochlorite mother liquor, and admixed with an alkali metal hypochlorite solution to produce a mixed alkali slurry. The mixed alkali slurry is chlorinated to form a slurry of calcium hypochlorite dihydrate crystals in a saturated calcium hypochlorite solution. The slurry of calcium hypochorite dihydrate crystals is separated to provide a cake of calcium hypochlorite dihydrate crystals and a saturated calcium hypochlorite solution. The cake of calcium hypochlorite dihydrate crystals is dried to produce granular calcium hypochlorite. The saturated calcium hypochlorite solution is recycled to the crystallizing zone. |
