In the limestone slurry preparation system, the cyclone is used to separate the limestone with larger particles from the slurry and send it back to the ball mill for further grinding. That is, the cyclone underflow containing larger limestone particles returns to the feed end of the ball mill, and the overflow liquid containing finer limestone particles enters the limestone slurry tank.

In gypsum primary dewatering, the purpose of the cyclone is to thicken the gypsum slurry. The solids content of the cyclone inlet slurry is generally about 15%, the solids content of the underflow slurry can be more than 50%, while the solids content of the overflow slurry is less than 4%, and the concentration size of the separated slurry depends on the gypsum particle size distribution. The underflow liquid is sent to secondary dewatering equipment, such as vacuum belt filter for further dewatering.

The role of primary dewatering:

① Increase the concentration of slurry solids and reduce the volume of slurry processed by the secondary dewatering equipment. The high solids content of the slurry entering the secondary dewatering equipment will help improve the output rate of gypsum cake.

② Use part of the separated dilute slurry (filtrate water) to adjust the concentration of the absorption tower slurry, and at the same time regulate the system water balance stability. The dilute slurry after the primary dewatering can be used to prepare limestone slurry after being collected by the filtrate water tank.

③ Separate the unreacted fine-grained limestone in the slurry and reduce the content of limestone in the underflow slurry, which helps to improve the utilization rate of limestone and the quality of gypsum.

④ Discharge a certain amount of wastewater outside the system (through the wastewater treatment system) to control the concentration of heavy metals, CI-, etc. in the circulating slurry of the absorber tower and improve the quality of the slurry.