Abstract: Dibasic calcium hypochlorite scale present on the surfaces of process equipment, e.g., process vessels, used for the manufacture of neutral calcium hypochlorite is removed chemically by controllably adding chlorine to the process liquor under conditions of agitation while maintaining the pH of the process liquor at at least 7, e.g., from about 7 to about 10.5, thereby to solubilize the dibasic calcium hypochlorite scale without producing substantial amounts of elemental chlorine. In a preferred embodiment, the process liquor in the process equipment containing the dibasic calcium hypochlorite scale is forwarded to a further process vessel containing other less alkaline process liquor to which the chlorine is controllably added. The resulting hydrochloric acid-containing process liquor is recycled to the process equipment containing the dibasic scale and this procedure continued until the desired amount of dibasic calcium hypochlorite scale is solubilized.

Abstract: Dibasic calcium hypochlorite scale found on the surfaces of process equipment used for the manufacture of calcium hypochlorite is removed chemically by submerging the scale in water, thereby to form an aqueous alkaline solution, and controllably adding hydrochloric acid to the alkaline solution under conditions of agitation and while maintaining the pH of the solution at at least 7, thereby to solubilize the dibasic calcium hypochlorite scale without producing substantial amounts of elemental chlorine.

Abstract: Calcium hypochlorite particles and larger sodium chloride crystals are separated by passing an aqueous slurry containing such particles and crystals into a first classification zone comprising a two-stage substantially vertical elutriator-classifier. A first slurry in which the solid phase is predominantly calcium hypochlorite particles is removed from the upper stage of the first classification zone. A second slurry in which the solid phase is predominantly sodium chloride crystals is removed from the lower stage of the first classification zone and forwarded to a second classification zone comprising a two-stage substantially vertical elutriator-classifier. A slurry in which the solid phase is predominantly calcium hypochlorite particles is removed from the upper stage of the second classification zone and, in one embodiment, combined with overflow from the upper stage of the first classification zone.

Abstract: Calcium hypochlorite particles and larger separable sodium chloride crystals produced in a process for manufacturing calcium hypochlorite are effectively separated by use of a staged upward-flow elutriator-classifier. In particular, an aqueous slurry of the calcium hypochlorite particles and sodium chloride crystals are introduced into about the midpoint of the classifier and elutriated with fluid substantially saturated in calcium hypochlorite and sodium chloride. A first slurry in which the solid phase is predominantly calcium hypochlorite, e.g., at least 95 weight percent, is removed as overflow from the top of the classifier, and a second slurry in which the solid phase is predominantly sodium chloride is removed as underflow from the bottom of the classifier.In one embodiment, the first slurry is separated into a wet cake of calcium hypochlorite and bleach mother liquor, a portion of which liquor is used as elutriating fluid.