What is the purpose of adding sulfur in soda ash production?

Hanging sulfur refers to adding sodium sulfide to the carbonization tower. The purpose is to prevent tower wall corrosion from causing soda ash iron to rise. However, the concentration must be controlled and the liquid level at the top of the tower must not be too high. I hope carbonization technicians will participate more in this discussion.

1. In the ammonia absorption and carbonization system, the tower body, storage tank and pipelines are corroded by the solution, and the liquid contains divalent and trivalent Fe ions. In the alkali making tower, part of the trivalent Fe will precipitate out as Fe(OH)3 and mix in the sodium bicarbonate crystal, causing the soda ash to color and become "red alkali". The conventional method to prevent the production of red alkali is to add Na2S to the ammonia mother liquor in an amount of about 0.4--0.6Kg per ton of soda ash. Part of the sulfide ions produces ferrous sulfide, and part of it analyzes elemental sulfur. The strong film of ferrous sulfide formed on the surface of iron equipment and pipelines acts as a protective layer and can withstand the corrosion of equipment by ammonia salt water. Therefore, the heavy alkali and soda ash produced will not contain rust, ensuring the whiteness and iron content of soda ash. 2. Sometimes there are a large number of iron ions in ammonia salt water. When a large amount of sodium sulfide is added, "grey alkali" will appear. In order to prevent the production of "red alkali" and "gray alkali", the sulfur ion concentration must be controlled appropriately, and a large amount of air cannot leak into the carbon dioxide gas. When carbon temperature and pressure fluctuate greatly, attention must also be paid to the sulfur content.

1# xymny The purpose of hanging sulfur: Let Fe S form a thin and dense anti-corrosion film that blocks the medium and the device wall, slowing down the corrosion of ammonia absorption and carbonization equipment. Fe S anti-corrosion film is easily damaged, weakened or loses its anti-corrosion effect under the following conditions:: 1. The temperature is too high. 2. The CO2 content in the solution increases and the pH value decreases, causing the loss of S2- (escaping into H2S gas), thereby accelerating the dissolution of the Fe S film. 3. There is more O2 mixed into the gas or the inside of the equipment is deactivated, and the Fe S film is oxidized.

Well, that's a good reply, thank you all! !