GB654486A - Improvements in or relating to crystal growing means and method - Google Patents

Abstract

Apparatus for growing crystals of a chemical substance, such as lithium sulphate monohydrate and lithium selenate monohydrate, whose solubility decreases with increasing temperature of the solution, comprises a storage container 30, Fig. 2, in which the solution is maintained within a given range of temperature at a concentration below saturation, connected to a crystallization compartment 10 which is heated to above the saturation temperature of the solution in it, to cause growth of crystals 23. Preferably, the solution in the container <PICT:0654486/III/1> <PICT:0654486/III/2> 30 is at room temperature, say below 33 DEG C., the solution therein being saturated at 33 DEG C., and that in the crystallization compartment is heated to 50 DEG C., at which it is saturated. The seed crystals 23 are cemented to the holders 21 which are reciprocated in the solution, the latter being heated, under the control of thermostat 15, by a heater 11 which does not extend to the top of the solution. Seed plates of lithium sulphate monohydrate may be cut perpendicular to the polar or Y axis as at 55, Fig. 3, or parallel to the one of the four end or blunter sphenoid faces 57 as at 56, and the solution preferably contains 1/20 mol. of sulphuric acid to each litre of saturated aqueous solution. In a further arrangement of apparatus, Fig. 4 (not shown), a second crystallization compartment at a still higher temperature immediately follows the first.