Natural and Derived Sodium and Potassium Salts

Sodium chloride, or common salt, is among the earliest chemical commodities produced by man, prompted, by its essential requirement in the diet and the scattered accessibility of available land- based supplies. The word salary itself is derived from the Roman “salarium”, which was a monetary payment given to soldiers for salt purchase to replace the original salt issue. While the initial production and harvesting of sodium chloride was from dietary interests, today this application represents less than 5% of the consumption, and uses as a chemical intermediate far exceed this (Table 4.1). The wide availability of sodium chloride has contributed to the derivation of nearly all com-pounds containing sodium or chlorine from this salt, and to the establishment of many large industrial chemical operations adjacent to major salt deposits. Three general methods are in common use for the recovery of sodium chloride, which in combination were employed for the world-wide production of 167 million tonnes of this commodity in 1976 and slightly less in 1981 (Table 4.2).