Improvements in and relating to the production of crystals

摘要

In the crystallization of naphthalene, the mother liquor from which crystals have already been recovered is admixed with the solution from which crystals are to be recovered, prior to crystallizing, in an amount sufficient to ensure that after crystallization the mixture of crystals and mother liquor remains in a mobile condition. Sufficient mother liquor may be added, for example, that the crystallized product contains more than 40 per cent of drainable mother liquor by volume. 100 Volumes of hot naphthalene-containing oil pre-cooled in a cooler 2 is mixed with 40 volumes of cold mother liquor from a reservoir 3 by means of pumps 6, 8 and delivered to a pipe line 11. Instead of mixing the solutions in stages, a single pump may be used. The mixture may be further cooled by providing the pipe 11 with a water jacket. Crystallization is completed in an agitator 14 and the mobile mixture resulting, dried in a centrifugal drier 16, after screening if desired through a screen 15. Excess mother liquor from the screen and drier are returned to the reservoir 3.ALSO:In the crystallization of substances which yield a relatively solid mixture of crystals and mother liquor from a solution, the mother liquor from which crystals have already been recovered is admixed with the solution from which crystals are to be recovered, prior to crystallizing in an amount sufficient to ensure that after crystallization the mixture of crystals and mother liquor remains in a mobile condition. Sufficient mother liquor may be added, for example, that the crystallized product contains more than 40 per cent of drainable mother liquor by volume. 100 volumes of hot naphthalene-containing oil pre-cooled in a cooler 2 is mixed with 40 volumes of cold mother liquor from a reservoir 3 by means of pumps 6, 8 and delivered to a pipe line 11. Instead of mixing the solutions in stages, a single pump may be used. The mixture may be further cooled by providing the pipe 11 with a water jacket. Crystallization is completed in an agitator 14 and the mobile mixture resulting, dried in a centrifugal drier 16, after screening if desired through a screen 15. Excess mother liquor from the screen and drier are returned to the reservoir 3.