METHOD OF EXTRACTING SODIUM SULPHATE AND METAL NITRATES Russian patent published in 2017 - IPC C01D5/16 C01B21/48 

FIELD: chemistry.

SUBSTANCE: invention relates to processing of mineral waste of chemical production. For extraction of sodium sulphate and nitrates of metals from aqueous solutions of sodium sulphate, containing as impurities sodium nitrate and sodium nitrite, solutions are reacted with sodium bisulphate or concentrated sulphuric acid. Initial solution at 1 mol sodium nitrate and sodium nitrate is mixed with 1 mol sodium bisulphate or 0.5 mol sulphuric acid. Sodium sulphate is extracted by evaporation of water. Wet mixture of salts is dried. Dry residue is heated for at least 15 minutes at temperature 140–200 °C. Gaseous reaction products are trapped with aqueous solutions of hydroxides or carbonates of alkali or alkali-earth metals. Metal nitrates are separated from obtained solution. Metal hydroxides used are sodium hydroxide, or potassium hydroxide, or calcium hydroxide, metal carbonates are sodium carbonate or potassium carbonate.

EFFECT: invention provides production of commercial purified sodium sulphate and nitrates of metals with content of basic substance not less than 99 %.

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