Mechanical Salt Refinery

Raw salt procured from solar salt field is fed into a raw salt RCC hopper. Regulated quantity of salt through a feed regulator falls on to Belt Conveyor which transports and discharges raw salt through a Vertical Bucket Elevator (VBE), as the need be, either into a Prewashery or into a Wet Mill. Crushed salt is subjected to upgradation in a multi-stage cleansing system which comprises of a series of special design vessels, like, Elutriation Tank, Washing Tank, Thickener, etc. These are integrated with devices for continuous reduction in load of sand and grit in the salt slurry. The lighter insolubles drift away with the over flows. These cause improvement in both the physical and chemical attributes of common salt. Salt, thus upgraded, is then subjected to centrifuging and blending with crystal habitat modifiers. The blended salt is then fed in a continuous type Fluidized Bed Dryer. The feed material and hot air come in contact with each other and drying takes place. The exhaust air carries the moisture removed from the product away. Dried product is collected at the bottom of the other end of the FBD. The exhaust gas is passed through cyclone separator for recovery of salt fines.

Dried salt is graded in Vibro Sieving machine. Oversize crystals are crushed in Pin-mill or in roller crusher as per the requirement and routed back in the system through the fluidized bed dryer. The salt crystal having sizes mostly between (-) 850 to (+) 150 microns are mixed in a Blender with suitable quantity of additives including a free flowing agent and conveyed by means of Screw Conveyors to packaging machines for being packed in consumer packs. The crystal size of (-) 150 microns, collected from the dryer cyclone, are packed in laminated HDPE bags in 25 / 50 kgs lot. Magnetic separators are provided at various stages of processing for removal of iron particles.

The spent brine, collected after washing of salt is sent to settling pond where it is regenerated on removal from it the excess load of calcium, magnesium & insoluble impurities. The brine thus improved is used again for upgradation of the common salt.