Process for the production of solid magnesium sulphate monohydrate

摘要

PICT:0450987/III/1 Magnesium sulphate monohydrate is obtained by heating a concentrated magnesium sulphate solution, preferably by stages, to a temperature situated on the descending branch of the solubility curve, but at which the separation of solid salts does not take place, and then cooling the solution, preferably by stages, by spontaneous evaporation, to temperatures situated on the ascending branch of the solubility curve and which still lie within the range of formation of the monohydrate. As shown in the Figure, a saturated solution of magnesium sulphate at 75 DEG C. is forced by a pump 2 through the heaters 3, 4 and 5 in succession in which it is heated by stages, to 90 DEG , 105 DEG and 125 DEG C. respectively. The solution then flows in succession through the evaporators 6, 7 and 8 in which it is cooled by stages to 110 DEG , 95 DEG and 75 DEG C. respectively. The evaporators 6 and 7 may be injection evaporators and the evaporator 8 be provided with stirring mechanism. From vessel 8 the solution passes to a separator 9 for removal of deposited salt and the mother liquor is then recirculated through the heaters, evaporators, and separator together with fresh solution from tank 1. The hot vapours from evaporators 7 and 6 are used respectively for heating the heaters 3 and 4, the heater 5 being heated by live steam. The Specification as open to inspection under Sect. 91, comprises also the following subject-matter: the application of the process to the recovery of ferrous sulphate, manganese sulphate, sodium carbonate, or ferric chloride in the form of salts having a low content of water of crystallization. This subject-matter does not appear in the Specification as accepted.