Method freezing separating mirabilite by brine solution

Abstract

The invention discloses a method of cold separating mirabilite in salt water solution, which comprises the following steps: (1) adjusting pH value of armed salt cake solution as alkalify; (2) proceeding pre-cool in the precooling system; (3) mixing with low-temperature low-nitrate water of incorporating salt cake with lower temperature through demirabilite treatment; controlling temperature at -10-0 deg.c; proceeding solid-liquid separation in salt cake settler; getting ten water sodium sulfate crystal and low nitrate water; (4) lowering temperature of part low nitrate water through freezing heat exchanger; recycling as low temperature nitrate water of step (3); discharging the other part of low nitrate water as byproduct.

Description

Technical field [0001] The invention relates to a method for separating Glauber's salt from an aqueous solution of Glauber's salt, which is used for the treatment of an aqueous solution of Glauber's salt in chlor-alkali, soda ash, salt making and other industries. Background technique [0002] In the membrane denitrification technology of chlor-alkali and other fields, the brine solution containing high sodium sulfate concentration is called high awn brine. There are currently the following treatment methods: [0003] One is to use the discharge method to achieve the purpose of eliminating sulfate. Although sulfate can be removed, the concentrated solution also contains sodium chloride. If the concentrated solution is directly discharged without treatment, sodium chloride will also be discharged. Will pollute the environment and increase operating costs. [0004] The second is to use the conventional freezing method, the principle is to use NaCl and Na 2 SO 4 The difference in th...

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Problems solved by technology

When the pre-cooled Gaomang brine enters the refrigeration heat exchange system and the temperature is further lowered, because sodium sulfate decahydrate precipitates after forming crystals, it is extremely easy to block the refrigeration heat exchanger and pipelines. This process is applied when the sulfate concentration is less than 30g / L solution can also maintain a long period of operation, when the concentration of sulfate radicals exceeds this value, due to the large amount of precipitation, the blockage of the equipment will be aggravated, the production cycle will be shortened, and the cleaning of the tank or the heat exchanger will be frequent. , or even serious clogging, which makes the production operation extremely unstable and wastes a lot of energy. Therefore, it is difficult to achieve the ideal operation effect for Gaomans brine to use the conventional freezing method to separate salt and nitrate

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