SU833481A1 - Method of sodium thiosulfate production - Google Patents

Description

(54) METHOD FOR PRODUCING SODIUM SULPHATE

I

The invention relates to the chemical industry and can be used in the production of sodium thiosulfate.

A known method for the preparation of crystalline sodium thiosulfate, which consists in that the thiosulfate solutions are subjected to vacuum evaporation until the concentration of sodium thiosulfate Na 750-800 g / l Q

The closest to the proposed technical essence is the method of producing sodium thiosulfate. Thiosulfate solutions evaporated to a concentration of 730-760 g / l, defend and filtered from precipitated salts and water-insoluble residue. When cooled, NaiSeOs Tt5HiO 2 crystallizes from the mother liquor.

However, by a known method in the sediment falls a small amount of salts, their ratio to the soluble residue of 7.5 to 8.1; the significant presence of an insoluble residue determines the filtration process of the LII and the content of the mother liquor in it; significant losses of sodium thiosulfate with queen cell are observed due to the high moisture content of the precipitate.

The purpose of the invention is to reduce the loss of sodium thiosulfate with precipitate.

This goal is achieved by increasing the concentration of sodium thiosulfate solution evaporated at 100 ° C to 930-955 g / l, while the amount of muds falling out of solution increases 5.3 times (from 2.4-2.6 to 12.7 -13.82 kg).

Example 1. Take 1000 kg of sodium thiosulfate solution of composition: 34.5; NaaSOiiO, 9; 1.7 and evaporated to a concentration of 730 g / l. $. 2.4 kg of salts are precipitated. With an increase in the ion centration of the evaporated solution to 930 g / l, the amount of precipitated salts increases to 12.7 kg. The ratio of salts to the insoluble residue in the sediment is 7.5: 1 in the known and 42.3: 1 in the proposed methods.

Example 2. 100 kg of sodium thiosulfate solution of composition,%: 34.5; 0.9; NatSO 1.7 evaporated to 760 g / l, precipitates 2.6 kg of salts. When evaporated to 955 g / l, the amount of salts is 13.82 kg. The ratio of fallen soya to the insoluble pot increases from 8.1: 1 to 46.1: 1.

When separating the precipitated precipitate from the trisulfate solution due to a decrease in the moisture content of the precipitate, the loss of sodium thiosulfate is reduced by 49.9 kg / ton of sodium hydrated sodium thiosulfate.

The choice of the final concentration of sodium thiosulfate in the evaporated solution is determined by the ratio of the precipitated salts to the water-insoluble residue, which determines the filtration process and the content of the mother liquor in the sediment.

When evaporation below the specified limit, the ratio of the precipitated salts to the insoluble residue is small, above — a low-mobility pulp of crystals is obtained and its transportation is difficult.

The proposed method of purifying thiosulfate solutions from the salts contained in them by the method of deep evaporation shows that the annual effect of the introduction

its production for the conditions of one enterprise is determined at 132.4 thousand rubles. in year.

Claims (2)

1. USSR author's certificate number 244312, cl. From 01 to 17/66, 1968. 2. Technological regulations No. 10 of sodium thiosulfate production, 1976.