Process for refining crude salt

Abstract

The invention discloses a process for refining crude salt. A salt-leaching step comprises the following steps: sending crude salt to a salt leaching device, a ball mill, a primary salt slurry barrel, a thickener and a primary centrifuge in sequence; then sending salt slurry separated from the primary centrifuge to a secondary salt slurry barrel, a classificator and an immediate washing barrel for washing and thickening; then using condensate water to wash the salt slurry after entering the secondary centrifuge so as to remove bittern, thereby obtaining qualified leached salt; a crude bittern treatment step comprises the following steps: mixing leaching crude bittern in the salt leaching step in a crude bittern pool, and subsequently sending to a calcium-magnesium reactor so as to remove Ca<2+> and Mg<2+>; then entering a clarifying tank for clarifying; after increasing the temperature of the clarified clear liquor by a bittern heater, sending portion of clarified clear liquor to a refining bittern barrel for vacuum salt manufacturing with portion of clarified clear liquor for salt leaching use; and a vacuum salt manufacturing step comprises the following steps: sending refined salt water in the refining bittern barrel to a multi-effect evaporator for evaporating; finally discharging separated solid salt to the salt slurry barrel, the salt slurry thickener and the vacuum centrifuge, thereby obtaining leached salt. The method reduces the crude salt loss and lowers the content of SO4<2-> in the leached salt.

Description

technical field [0001] The invention relates to a process for refining crude salt. Background technique [0002] There are two main manufacturing methods of soda ash: ammonia soda method and combined soda method. Among them, the combined alkali method uses solid salt as raw material, and the mother liquor system is recycled in a closed circuit. In this process, insoluble and soluble impurities in the solid salt enter the system, which will inevitably affect the quality of the final product. Therefore, it is necessary to use solid salt as raw material. Raw salt is refined. [0003] The quality of washing salt is assessed by the content of impurities in the salt and the particle size of the salt. The content of impurities in the salt is assessed by Ca2+, Mg2+, and SO42-; the particle size of the salt is also an important quality indicator. The traditional salt washing process only takes the Ca2+, Mg2+ and trace SO42- impurities in the raw salt as the main purpose and the was...

AI Technical Summary

Problems solved by technology

The traditional salt washing process only takes the Ca2+, Mg2+ and trace SO42- impurities in the raw salt as the main purpose and the washing salt particle size as the main purpose, which can reduce AII turbidity, but cannot remove SO42-; in fact, SO42- is extremely harmful, and it will Accumulation in the mother liquor system will finally affect the quality of soda ash and industrial ammonium chloride

[0004] The existing salt washing process is usually two washing processes, and the washing brine is recycled by the lime-soda ash process of twice clarification in a step-by-step method. The need for ammonium chloride production; the brine treatment part is relatively high in investment and the clarification effect is not good; if this process is to achieve high-quality washing salt, the amount of discharge is large and the loss of salt is large

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