| 摘要 |
The invention relates to a process for preparing a pure, crystalline sodium sulphate by working up natural minerals which contain, besides thenardite and/or mirabilite, additionally glauberite, calcium sulphate and water-insoluble naturally occurring materials in the form of magnesium aluminium silicates. A process is proposed which, with as small as possible a plant expense, makes possible a pure crystalline sodium sulphate from naturally occurring minerals having a sodium sulphate content below 50 %, characterised in that the raw natural minerals are mixed with water, that this slurry is cooled until the dissolved sodium sulphate crystallises out in the form of Glauber's salt, that the Glauber's salt is separated from the mother liquor and is again dissolved in water, that the aqueous solution is admixed with a flocculation aid and that the sodium sulphate is, after separating the undissolved solids from this solution, recovered by crystallisation according to a conventional process. <IMAGE>
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