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矿石中铋的络合滴定法,试样通常以盐酸、硝酸分解并蒸干,用较大浓度硝酸浸取,然后稀释并分液,调节PH1～2,以硫脲或二甲酚橙为指示剂,用EDTA标准溶液滴定.多年生产实践表明,此法简易快速,结果基本稳定.由于原法装容量瓶,干过滤、分液等步骤,消耗整个操作时间的1/3.用25毫升稀硝酸(5+95)浸取直接滴定.均因铋未完全转入溶液,使滴定终点回头,试样含铋量越高,回头越严重.通过试验,加入一定量高氯酸加热驱赶硝酸后,用水稀释,用抗坏血酸还原铁(Ⅲ),以硫脲掩蔽铜,以半二
Ore bismuth complex titration, the sample is usually hydrochloric acid, nitric acid decomposition and evaporated to dryness, with a larger concentration of nitric acid leaching, and then diluted and liquid separation, adjusting PH1 ~ 2, thiourea or xylenol orange as an indicator Agent, with EDTA standard solution titration.Production of many years of practice shows that this method is simple and fast, the results are basically stable.Because the original method of loading volumetric flask, dry filtration, liquid separation steps, consumption of the entire operation time 1 / 3. With 25 ml thin Nitric acid (5 +95) leaching direct titration, both because the bismuth is not completely transferred to the solution, the titration end point back, the higher the sample containing bismuth, the more serious back.Through experiments, adding a certain amount of perchloric acid heated to drive the nitric acid , Dilute with water, reduce iron (III) with ascorbic acid, mask the copper with thiourea, in half