METHOD FOR RECOVERING AND UTILIZING ZINC FROM WASTE ZINC ELECTROPLATING LIQUID

摘要

PURPOSE:To recover and reutilize zinc contained in a waste liq. and to reduce the material consumption by neutralizing a waste acidic zinc electroplating liq. with sodium carbonate to deposit basic zinc carbonate which is washed with water and supplied to a plating bath as a zinc source. CONSTITUTION:A waste acidic bath zinc electroplating liq. is neutralyzed with Na2CO3 or Na2CO3 and NaOH to deposit basic zinc carbonate. After the deposited crystal is washed with water and the water-soluble impurities are removed, the crystal in a slurry or the crystal which is separated and dried into solid powder is supplied to a plating bath and reutilized as a zinc source. Before the waste plating liq. is neutralized, an oxidizing agent and then zinc powder are previously added to deposit dissolved impurities of heavy metals having lower ionization tendency than zinc and to remove the impurities. Zinc can be recovered in high purity and reutilized by this method, and the cost of treating the waste can be reduced.