RU2088525C1 - Method for production of common salt - Google Patents

Abstract

FIELD: production of common salt having improved quality, said salt may be used both in chemical industry and in food industry. SUBSTANCE: origin brine comprising NaCl is initially heated to 60-80 C, the process takes place at pH 7.5-8.5 till concentration of NaCl in concentrate is 30-35 mass %. Then counterflow spraying is carried out at 480-650 C. EFFECT: increased yield of product and content of main substance in it; improved efficiency; simplified technology. 1 tbl

Description

 The invention relates to a method for the production of table salt of high quality, used both in the chemical industry and in the food industry.

A known method of producing sodium chloride, including heating the source brine to 82-92 ^o C, evaporation under vacuum, crystallization in a suspended layer and the withdrawal of the resulting mother liquor [1]
The disadvantages of this method include the complexity and energy intensity of the process. In addition, salt obtained by the above method is coarse and contains a large amount of impurities.

 To reduce dispersion and improve the quality of table salt, methods were proposed for treating the salt pulp with alternating current [2] with ultrasound [3] and other methods. But known methods are also energy-intensive and complex in hardware design.

The closest technical solution to the prototype is a method for producing table salt, which consists in drying a brine containing NaCl in a spray dryer with a straight-through motion from bottom to top of the coolant and the solution supplied through the nozzle with compressed air. Used direct-flow type spray dryers with coolant and brine feed through nozzles from below. Dried table salt is trapped in a cyclone dust collector [4]
The main disadvantages of the known technical solutions are
a relatively low content of the main substance in the target product;
clogging of equipment (dryers) with impurities and the main product, which leads to frequent shutdown of the dryer for cleaning and, accordingly, reduces the productivity and yield of the target product;
corrosion of equipment.

The aim of the invention is to remedy the above disadvantages, namely
increasing the yield of the target product and the content of the main substance in it;
increase in productivity;
reduction of equipment downtime;
technology simplification.

The goal is achieved in that the initial brine containing NaCl is preheated at 60 80 ^o C to the content of NaCl in concentrate 30 35 wt. and a pH of 7.5 to 8.5 and thereafter countercurrently sprayed at 480,650 ^° C.

Preheating up to 480 650 ^o C to pH 7.5 8.5 is necessary for subsequent more complete extraction of moisture, an increased concentration of the main substance in the target product will save energy pressures flue gases by increasing the concentration of the main substance in the brine fed to the spray after preheating is more uniform dehydration, without sintering and clumping of salts in the dryer. In addition, preheating changes the pH of the brine, which further reduces equipment corrosion. Moreover, finely divided table salt is obtained (dispersion less than 1 mm is 91 wt.) Practically without moisture content, which does not cake during long-term storage.

 As the initial brine, the brine of the Yar-Bishkadak field of the following practically constant composition was used, wt.

NaCl 23.52
Na ₂ SO ₄ 0,03
CaSO ₄ 0.27
MgSO ₄ 0.05
KCl 0.03
Water 76.11
the pH of the brine is 7.35 to 7.40, the density is 1.198 g / cm ³ .

 The process is as follows.

Crude brine from the brine station is fed into a heating tank, where the temperature is maintained at 60 82 ^o C for 0.5-1.0 hours to a concentration of NaCl 30 35 wt. Next, the concentrated brine is countercurrently fed to a spray dryer of the type СРЦ 3200 (4000), where the temperature is maintained at 480 650 ^o C, and the exhaust gases 120 180 ^o C.

This type of dryer and the supply of countercurrent brine provides a better product with a minimum amount of moisture. In the proposed method, the resulting table salt is finely dispersed, without moisture. The dispersion is 0.05 0.10 mm, at least 92% of the total amount, bulk density 0.30 - 0.35 g / cm ³ .

 Examples confirming the invention are presented in the table.

 Based on the data presented, it is seen that table salt obtained by the proposed method has high quality characteristics, namely, high selectivity (97.5 99.0 wt.), High content of the main substance in the target product NaCl and the fineness of the target product allow us to compare obtained table salt with indicators of the highest class of salt of Extra salt, where additional costs are used to obtain it - cleaning, grinding, and the proposed method allows to obtain high-quality salt without additional costs high quality ol after spray drying is already underway on the packaging. In addition, the dryer worked without stopping for 12 months.

Claims (1)

A method of producing sodium chloride from a brine containing NaCl in a spray dryer, characterized in that the initial brine is preheated to 60 82 ^o With the content of the main substance NaCl 30 35 wt. and a brine pH of 7.5 to 8.5 and then countercurrently sprayed at 480,650 ^{° C.} in a spray dryer.

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