Understanding Crude Salt and Initial Impurities
Crude salt, obtained from methods like solar evaporation ponds or solution mining, contains various impurities that must be removed for industrial or consumer use. These impurities include dirt, clay, insoluble minerals (such as calcium sulfate), and organic matter, which can affect the salt's purity, color, and usability.
The initial purification focuses on physical separation techniques to eliminate these contaminants without altering the salt's core composition (primarily sodium chloride, NaCl).
Common impurities in crude salt:
- Insoluble particles like sand and mud from evaporation ponds.
- Soluble ions such as magnesium and sulfate from underground brines.
- Biological residues, including algae or microorganisms.
By addressing these early, we prevent downstream issues in refinement, ensuring the salt meets standards for food, chemical, or de-icing applications. For example, table salt requires over 99% purity, starting from crude salt that might be only 80-90% NaCl.