Abstract

Most of the worldwide sodium nitrate production is supplied from natural deposits in Chile, South America; the rest is provided essentially as a by-product from nitric acid plants. Sodium nitrate is used as a fertilizer and in a number of industrial applications, primarily as an oxidizing agent. These latter include the manufacture of glass, explosives, and charcoal briquettes, and the production of potassium compounds. Consumption of sodium nitrate for industrial uses has been rather steady, but production for use as fertilizer has declined. Various technical and industrial grades are available, in addition to the agricultural grade. Surface mining methods are used to mine the Chilean nitrate ore. Mineral recovery and processing procedures are described, as are the various purification steps. Synthetically produced sodium nitrate results from absorption of waste nitrous oxide gases in an alkaline solution.

Sodium nitrite, NaNO₂, is a versatile industrial chemical having applications that are widely based on its oxidizing properties or its ability to yield nitrous acid on acidification. It is hygroscopic and quite soluble in water, but not in most organic solvents. Sodium nitrite is a moderately strong oxidizer and toxic by ingestion. It can react violently with some chemicals, evolves toxic NO_x on decomposition, and can promote burning when exposed to fire. It may be derived from the reduction of sodium nitrate, but is typically manufactured by the absorption of nitrogen oxides into solutions of sodium hydroxide or sodium carbonate. Dry and liquid forms of the product in several grades are offered in bulk and a variety of packaging options. Dry products may be treated with an anticake. Typical assays are 99% NaNO₂ for dry and 42% NaNO₂ for liquid products. The product is used in azo dyes, rubber chemicals, heat treating and heat-transfer salts, some meat curing, metal finishing, organic chemical syntheses, and as a corrosion inhibitor.