SU833506A1 - Method of sodium chloride extraction - Google Patents

Description

The invention relates to the isolation of inorganic salts from solutions, in particular, to the isothermal crystallization of table salt, and can be used in the production of chicken fertilizers and table salt. A known method for separating sodium chloride by crystallizing it from a saturated solution in a circulating vacuum crystallizer with preheating the solution to a temperature of 1.5-3 ° C is higher than the temperature of the solution in crystallizer L. The disadvantage of the known method is the result of a crystalline product. The purpose of the invention is to increase the size of the crystals. This goal is achieved by separating sodium chloride by crystallizing it from a saturated solution in a circulating vacuum crystallizer with preheating the solution to a temperature 10–12 ° C above the temperature of the solution in a cristapl, to which steam is additionally supplied above the boiling point of the solution. The temperature difference between the heated solution and the solution in the crystallizer (10–12 ° C) ensures boiling up of the solution at the outlet of the jet pump feeding the solution to the crystallizer, and not in the separator of the crystallizer, as in the known method, which makes it possible to obtain larger product crystals. Example 1. A stock solution in an amount of 36 kg with a concentration of 26% NaCL and a temperature is supplied to a preheater, and then to a mold with controlled growth of crystals with a central circulation pipe. The temperature of solution E of the crystallizer is maintained at 55 ° C. The degree of evaporation of the solution is 25 ° C. 450 l / h circulating solution The results of experiments on the effect of preheating temperature on the particle size distribution of the obtained product are given in Table 1. Example 2. The initial solution in the amount of 36 kg with a concentration of 26% NaCL and a temperature of 20 ° C is fed to the residue. The temperature of the solution in the apparatus is maintained equal. The degree of evaporation of the solution is 25%. The flow rate of the circulating solution is 450 l / h. Overheating of the solution in the heating

the chamber is 12 C, and T. kip. solution.

Steam in the amount of 1.5 kg / h is fed to the inlet of the crystallizer circulation pipe.

 In tab. 2 shows the average size of NaCI crystals as a function of steam temperature.

Production of coarse-grained table salt allows to improve the technical and economic performance of centrifuges and filters, to obtain lower product moisture, and consequently, to reduce water consumption for washing the product and to increase the degree of extraction of the useful substance by 0.5%.

Table 1

Claims (2)

Claim 1. The method of separation of sodium chloride by crystallization of it from a saturated solution in a circulating vacuum crystallizer with pre-heating the solution, such that in order to increase the size of the crystals, the solution is heated to a temperature of 10 -12 ° C above the temperature of the solution in the mold. 2, the method of pop. 1, characterized in that the mold is additionally fed with steam at a temperature of ^3-15 ° C above the boiling point of the solution. ¹ Sources of information taken into account during the examination 55 1. Matusevich L.N. Crystallization from solutions in the chemical industry. Μ., '' Chemistry '' ¹ , 1968, p. 237 (prototype). ВНИИПИ Order 3906/17 Circulation 505 Subscription Branch of the PPP Patent, Uzhhorod, 4, Projectnaya st.