Production process of sodium sulfate
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Why is two-stage crystallization and centrifugation required to produce solid sodium sulfate powder using a 13% sodium sulfate solution? First, cooling crystallization—centrifugation, then evaporation crystallization—centrifugation. Why does cooling crystallization—centrifugation yield sodium sulfate decahydrate, while evaporation crystallization—centrifugation yields anhydrous sodium sulfate?
Is it evaporation crystallization that causes the water molecules to be heated and lost?
The crystallization temperature is the main factor affecting crystal water. Temperature range: Crystalline state – 0–32.38°C: crystallizes as Na2SO4·10H2O; 32.38–241°C: crystallizes as Na2SO4 (rhombic); above 241°C: crystallizes as Na2SO4 (monoclinic)
Such a process takes energy conservation and reduced production costs into account. Direct heating and evaporation are used to obtain anhydrous sodium sulfate; in this method, all the water must be evaporated at once, which requires a large amount of water to be evaporated and thus prolongs the process. Through two crystallization steps, the first step yields crystals containing 10 molecules of water, which is simpler and requires less water to be evaporated. The unnecessary water can then be separated through centrifugation, which makes the process more energy-efficient
It is also possible that it is for the purpose of removing impurities~
How is cooling crystallization achieved in the first step for a 13% sodium sulfate solution? Should it be concentrated first and then cooled? Will this save energy? And won’t the sodium sulfate decahydrate that is produced be difficult to handle! Regarding your second question, the reply on the 3rd floor was excellent! For your evaporation crystallization followed by centrifugation, what method is used for the evaporation process? I’ve been learning about *this area recently; could the original poster provide more information?
Evaporative crystallization is a process for concentrating a solution, and it is not intended to evaporate the entire solution dry. For the evaporation process, multi-effect evaporation or the currently popular MVR mechanical evaporation can be chosen; the decision regarding which evaporation process to use depends on your utility conditions.
This post was last edited by sfy111 on 2017-11-29 at 15:19. The view is correct; we are professionals in the production of sodium sulfate. Where did the poster get the 13% sodium sulfate solution? It seems that using multi-effect evaporation to increase the concentration before cooling would save energy
Indeed, if evaporation is carried out directly, the soluble salts in the mother liquor remain in the product as impurities; crystallization or recrystallization may serve to purify it
Is the saturated solubility of sodium sulfate affected by metal ions and organic substances?
Yes, energy consumption is lower when concentration is achieved through multi-effect evaporation followed by recrystallization; however, it requires higher standards for corrosion protection of the equipment. Recently, our high-temperature resistant lining rubber sheets have performed well in several similar projects, and we look forward to the opportunity to work together.