SU47678A1 - The method of separation of a mixture of sulphate, nitrate and chloride salts of alkali metals - Google Patents

Description

Separation of the mixture of water-soluble salts by crystallization, especially with the high solubility of the various components of the mixture, is a considerable difficulty and requires a long repeated operation.

The process can be simplified and accelerated with the use of froth flotation, which gives a considerably faster separation of the salt mixture into its constituent components.

When using this method, it is necessary to crush the mixture of salts, their saturated solution, a certain amount of flotation reagents for foaming, activating and depressing individual salts at different stages of separation, as well as a system of photoagarats used in ore mining (enrichment).

Fatty acids, naphthenic acids, petroleum sulfonic acids and some other products similar to these can be used as foam flotation agents.

With the complete composition of the mixture of sulphate, nitric acid and alkali metal chloride salts, the separation process is carried out according to the following scheme. A mixture of ground salts is agitated with a small amount of frothy flotation reagent (about 100 g / t) with the addition of mineral acid to

acidic (Ph-3-4) and floated. Sulfate salts are removed from the mixture with a concentrate (concentrate), since the latter have a particularly high floatability in an acidic medium, while nitric acid and chloride salts in an acidic medium are not completely floated. As a result of this operation, a concentrate is obtained with a high content and extraction of sulfate salts and a residue (tails) containing nitric acid and chloride salts.

The residue freed from sulfate salts is divided into sodium and potassium salts. Their separation is based on the property of solutions of sodium salts to strongly depress potassium salts. When the content in the solution from which the foam separation process takes place, 5% n above the sodium salt, the floatability of the potassium salts is completely excluded.

To separate the potassium salts from the sodium salts, after the separation of the sulphate salts, a certain amount of alkali is added to the residue to a neutral or somewhat alkaline reaction (Ph-7-10), a quantity of frothy flotation reagent (200-500 g / t) and again floated. With the foam, sodium salts are removed from the mixture to the concentrate, while potash remains in the residue (tailings). The process of separation of sodium salts from

potash is very perfect. With proper management of the process, the transfer of potassium salts to the concentrate is expressed in tenths of a percent, as appropriate, and in sodium tailings.

The separation of chloride salts from nitrate is based on the following property. Chloride salts have the ability to be very strongly activated by a small amount of salts of heavy metals, especially lead nitrate, while at the same time greatly reducing the floatability of nitrate salts in the presence of chloride.

To separate sodium chloride from nitrate, the mixture obtained is treated with 200-500 g / ta of lead nitrate (with some adjustment of the foaming reagent) and subjected to a froth flotation process. Sodium chloride is extracted into the concentrate with foam, and the rest (tails) is nitric acid. The separation gives good results and the degree of contamination of one salt to another is low.

To separate potassium chloride from nitrate, it is necessary to lower (less than 57 °) the content of sodium salts in the mother liquor, which can be achieved after separating the rest of the potassium salts from the mother liquors by filtration and already separating them from the solutions, t. e. with the addition of lead nitrate and with removal of potassium chloride with foam into the concentrate.

In the absence of one or more components in a salt mixture, their separation scheme is reduced accordingly.

Experimental data showed that the separation efficiency according to the found principle is quite high. When any mixture of these salts is separated according to the flotation method, the content of the separated salt in the concentrate is not lower than 95 ° / o by purity, with extraction from 95 ° o to 99 - / ("in other cases (for example, NaCI) the separation reaches full separation of the mixture.

The method will be used in the industrial exploitation of natural salt deposits, where, of course, the full amount of all of these salts will not be as well. only a mixture of two, three.

The subject matter of the invention.

A method of separating a mixture of sulphates, nitrates and alkali metal chloride salts, characterized in that said mixture of salts is floated in the presence of free mineral acid, alkalis are added to the residue to neutral or slightly alkaline reaction and floated to separate potassium salts from sodium salts, after whereby the fractions obtained are floated in the presence of heavy metal salts to separate the chlorides from the nitrates.