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锌基合金中锌铜铝总量在98%以上,其他杂质在1%左右,铁、铅、镉在0.3%以下。试样分解后,控制pH 5～6,用氟化物掩蔽铁、铝和锡,硫酸和二氯化钡共沉淀铅,碘化钾掩蔽镉,硫脲掩蔽铜,以二甲苯酚橙作指示剂,用EDTA滴定锌。滴定锌后的溶液中加过氧化氢解蔽硫脲铜络合物,然后用EDTA滴定铜。实践证明:在80%以上锌、5%左右铜同用二甲苯酚橙作指示剂,终点变化敏锐,方法简便可靠。
The total amount of zinc, copper and aluminum in zinc-based alloy is above 98%, other impurities are about 1%, and iron, lead and cadmium are below 0.3%. After the samples were decomposed, the pH was controlled from 5 to 6, coprecipitated with iron, aluminum and tin with fluoride, lead and cadmium with cadmium and thiourea masked with sulfuric acid and barium chloride, copper as the indicator with xylenol orange as indicator, EDTA titration zinc. Titration solution of zinc after adding hydrogen peroxide thiourea copper complex, and then titration with EDTA copper. Practice has proved that: in more than 80% of zinc, about 5% of copper with xylenol orange as an indicator, the endpoint changes sharply, the method is simple and reliable.