Colored ammonium sulfate
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Sir, the ammonium sulfate produced by my factory turns red after passing through the hot air inlet and then the cold air inlet of the vibrating fluidized bed. When this red-colored fertilizer is placed in the hot air duct to be heated, it turns white; however, when it is taken to a cooler place, it turns back to orange-red-brown. May I ask what impurities are causing this phenomenon? (It’s not that the fertilizer is always red every time it’s produced; it’s just that it’s been particularly red these times. Actually, after being stored for a few days, the edges of the ammonium sulfate also turn red.) :(
If the product is red, there are roughly two possibilities: one is iron ions, and the other is SCN ions. I haven’t encountered a situation where discoloration occurs during the production process either; it would be possible to check the concentrations of iron ions and SCN in the ammonium sulfide mother liquor.
The desulfurization liquid enters the saturator; please check it
Is the ammonium sulfate produced by the poster’s facility the main product, or is it a by-product recovered from flue gas desulfurization?
May I humbly ask: Does the complex formed by “iron ions and SCN ions” exhibit the phenomenon described by the OP, where a red color appears and then disappears?
Ammonium sulfate, before desulfurization or after?
If it is ferricyanide complexation, the decomposition conditions are quite high. It seems to require 300 degrees; there is a possibility of complexation first followed by decomposition
If that is the case, and the ammonium sulfate is produced by purifying the gas generated by coke ovens, then check the temperature in the space above the coke oven; this situation is likely caused by phenol in the coke oven gas entering the ammonium sulfate.
If your ammonium sulfate is produced after desulfurization, it’s likely caused by the gas carrying along desulfurization liquid. Therefore, the key is to resolve the issue of liquid carryover during desulfurization