To improve the quality of raw salt, the processes of crushing and washing can be adopted to obtain crushed and washed salt (hereinafter referred to as CWS, crushed and washed salt) with uniform particles and high purity. The CWS, after undergoing the drying process, meets the standards for edible salt.
As the main machines and equipment are crusher and washer, the crushed and washed salt plant is called a mechanical salt refinery.
After removing large impurities through the hopper and vibrating feeder, the raw salt is conveyed by a belt conveyor to a linear vibrating sieve and then enters a roll crusher for coarse crushing (first crushing) to break down large particles. The crudely crushed salt is then conveyed by a belt conveyor to another roll crusher for second crushing. The doubly crushed salt enters a spiral washer for the first washing, where brine is used to dissolve and remove soluble impurities such as Mg²⁺ on the salt particle surface, while insoluble impurities such as suspended sediment are removed with the overflow liquid. The salt after the first washing is dehydrated by a dewatering vibrating sieve and then conveyed by a spiral conveyor to a roll crusher for third crushing. The crushed salt is then conveyed to a intensive washer and mixed with injected washing liquid to form a salt slurry, which is pumped to a countercurrent washer for the second washing. The salt is then washed a third time in a mixing tank. The triply washed raw salt is dehydrated by a centrifuge, dried, and packaged to produce CWS.
The washing liquid (brine) in the process has a concentration of approximately 24°Bé and can be reused. When its concentration rises to 27~27.5°Bé, it loses its washing effect due to excessively high Mg²⁺ and SO⁴²⁻ contents. At this point, the brine can be used for the production of refined salt or discharged into solar salt pans.