Abstract
Common salt produced from the sea water that had been treated with caustic soda and milk of lime for precipitation of magnesium hydroxide, showed an abnormal caking tendency as compared with the salt produced from salt-field brine. The author, therefore, investigated the caking strength and examined the manufacturing process in order to reduce this caking tendency. Results obtained were as follows:
1. The common salt produced from the de-magnesium sea water proved to have a greater caking tendency than the salt produced from the salt-field brine. The caking strength was 1-5kg/-cm2 for the storage period of 6-12 months.
2. This high caking tendency is attributed to the fact that mother liquid containing less magnesium ion on the surface of salt crystals tends to dry when it is placed in low humidity, and when it is cooled it tends to precipite ateastrakanite (MgS04·Na2S04·4H20, hydrated double salt) transformed from loeweite and vanthoffite. This caused the salt to cake considerably.
