METHOD OF REDUCING SODIUM CONTENT OF WATER CONTAINING DISSOLVED SODIUM IONS

摘要

The invention provides a method of reducing the sodium content of a water containing dissolved sodium ions, particularly a water with a sodium ion content of at least 100 ppm. Examples of such waters are effluents such as acid mine drainage and river waters. The method includes the steps of: (i) removing sodium, calcium and magnesium ions from the water by contacting the water with a cation exchange resin/s to capture sodium, calcium and magnesium ions thereon, (ii) treating the cation exchange resin/s of step (i) with nitric acid to produce an eluant containing sodium ions, calcium ions, magnesium ions nitrate ions and nitric acid, (iii) adding a carbonate to the eluant to precipitate the calcium and magnesium ions as calcium and magnesium carbonates; (iv) separating the precipated carbonates from the eluant; and (v) treating the eluant from step (iv) to obtain a sodium and/or potassium nitrate product.