Effect of water hardness on purity of NaCl

In Iran, salt production industry is usually based on washing salt rock with water for purification. So in this project the effect of water hardness on the purification of the salt was studied using water with different degrees of hardness. We tested the amount of Ca, Ma and other heavy metal impurities in the sample salt using an analytical method, atomic absorption spectroscopy. The results were compared with each other and with quantities set by the institute for standards and industrial research of Iran. By statistical test (Anova: Single Factor) it can be found that a significant change in purity of salt is obtained by changing hardness of waters used for purification and the salts leached with softer waters have higher significant purity from 96.98 to 98.83 mass percent and higher quality than those leached with harder waters. The amount of heavy metals, as defined according to the Iranian salt standard, were also determined. The amounts of Fe, Cd and Cu were found to be less than standard. Pb was at or in higher amounts than the standard level.