Control of the amount of alkali rebound during the calcination of heavy alkalis

Is back-alkalinization intended to control the moisture content of heavy alkali, thereby regulating the moisture content that enters the calcination process? To prevent caking in the furnace and blocking the feed inlet? I seem to remember having seen it before; I’m not sure if there are any other reasons. I hope fellow sailors can provide the correct answer.

The crystal size of the heavy alkali is between 50–150 μm. The residual liquid in the filter cake obtained from filtration causes the water content of the heavy alkali to be around 20%. This water exists in the form of a solution between the crystal particles of the heavy alkali, which gives it a tendency to form clumps. Practice has shown that when heavy lye contains a high amount of free water, above 9.5%, it will form balls and scabs; wet heavy lye mixed with an insufficient amount of soda ash, or when in contact with heated surfaces, is prone to adhering and forming scabs. To solve this problem. Before entering the calcination equipment, soda ash obtained from calcination is generally added to the heavy alkali (referred to as return alkali) in order to convert its free water into crystalline water (the moisture content in the mixed alkali is usually kept below 9%). Therefore, adding return alkali to maintain a loose state of the solid material is an effective measure to ensure the proper progress of the heavy alkali calcination process.

Could the brother upstairs tell me what level of moisture makes scarring most likely? From a production perspective, it seems there is no linear relationship between moisture content and the degree of scarring.