The acidity becomes stronger during the concentration of the sodium carbonate mother liquor
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I have a question and would like to ask everyone for help. During the production of sodium thiosulfate pentahydrate, we observed a very strange phenomenon: initially, the pH of the mother liquor was around 9. As the concentration increased through triple-effect evaporation, the pH of the concentrated mother liquor continued to drop, until it reached around pH 6. The pH of the condensed water that evaporates is very high, around 10-12. Since carbon steel equipment was used, it deteriorated after a short time. In addition to sodium thiosulfate, the mother liquor also contains some sodium hydrosulfide. Is there any way to prevent his pH from dropping? What exactly are the components in the concentrated wastewater that carry away so much alkalinity?
This post was last edited by yyszyj on 2020-10-12 09:05. When sodium thiosulfate is heated in air, sulfur dioxide is produced, and the pH value inevitably decreases. When heated in air, sodium thiosulfate is oxidized and decomposed into sodium sulfate and sulfur dioxide; the chemical reaction equation is: 2Na₂S₂O₃ + 3O₂ = 2Na₂SO₄ + 2SO₂. When burned in an environment free from air, it produces sodium sulfate, sodium sulfide, and sulfur: 4Na₂S₂O₃ → heating → 3Na₂SO₄ + Na₂S + 4S
It mainly depends on what ingredients are used! What should the crystallization temperature be set at? Baume degree?
Specific gravity 52. Among the three effects, the first effect is around 105, the second effect is 80, and the third effect is about 60. After reaching the Baumé degree. It is then placed in a crystallization tank to cool and crystallize. My main question is why the pH keeps dropping during the concentration process.
Crystallization time? Crystallization temperature? How many effects for salt production?
Salt is extracted in three stages, but it is not in crystalline form at this point; it is then transferred to a crystallization tank where the crystallization process takes about 20 hours at a temperature of around 40 degrees.
Control the crystallization temperature, and generally, add some caustic soda to it