GB605694A - A process for the recovery of potassium salts from solutions - Google Patents

Abstract

To obtain potassium salts from dilute solutions such as p sea-water, a soluble salt of dipicrylamine, such as the calcium, sodium, lithium or magnesium salt is added to precipitate the insoluble potassium salt. The latter is separated and treated with an acid, such as nitric, hydrochloric, sulphuric or acetic acid or with carbon dioxide under pressure, to form the corresponding potassium salt and free dipicrylamine, which is then converted, for instance, into the calcium salt by treatment with a solution of lime. The mother - liquor from which the potassium has been precipitated is treated with an acid such as nitric acid to set free the dipicrylamine from remaining dissolved salt. In the treatment of the potassium dipicrylaminate with nitric acid the acid concentration may be below 20 per cent below 30 DEG C. or 40-50 per cent at above 80 DEG C., the intermediate ranges being unsatisfactory. Hydrochloric acid may be used at 36 per cent and sulphuric acid at 79 per cent strength at 20 DEG C., but hydrochloric acid of 10 per cent may be used at higher temperatures. Quantitative examples are given.ALSO:To obtain potassium salts from dilute solutions such as sea water, a soluble salt of dipicrylamine, such as the calcium, p sodium, lithium or magnesium salt, is added to precipitate the insoluble potassium salt. The latter is separated and treated with an acid, such as nitric, hydrochloric, sulphuric or acetic acid or with carbon dioxide under pressure, to form the corresponding potassium salt and free dipicrylamine, which is then converted, for instance, into the calcium salt by treatment with a solution of lime. The mother-liquor from which the potassium has been precipitated is treated with an acid such as nitric acid to set free the dipicrylamine from remaining dissolved salt. This precipitation is preferably effected by adding the acid in portions at intervals of time such as 10 minutes in order to obtain crystals which are readily separated by filtration. In the treatment of the potassium dipicrylaminate with nitric acid, the acid concentration may be below 20 per cent below 30 DEG C. or 40-50 per cent at above 80 DEG C., the intermediate ranges being unsatisfactory. Hydrochloric acid may be used at 36 per cent and sulphuric acid at 79 per cent strength at 20 DEG C., but hydrochloric acid of 10 per cent may be used at higher temperatures. Quantitative examples are given.