EDTA滴定法测定高铋银精矿中铋

银精矿中铋元素含量直接影响到冶炼工艺的选取和金属平衡管理,是评价银精矿的重要指标,但对于高铋银精矿中大于5%(质量分数)铋的测定方法还鲜见报道,因此迫切需要一种快速、准确的检测高铋银精矿中铋的方法。采用波长色散X射线荧光光谱仪(WDXRF)、高频红外碳硫分析仪对高铋银精矿试样进行半定量成分分析,确定其主要含有银、铅、铋、铜、锑、铁、硫、硅、碳等元素。在此基础上,对溶样体系及共存元素的干扰和消除方法进行了探讨,结果表明,以盐酸-硝酸-高氯酸-氢溴酸体系溶解试样后溶液清亮,终点明显;利用盐酸挥发去除样品中硫,硝酸和高氯酸加热至冒浓烟除碳;采用氢溴酸挥发2次的溶样方式可基本将砷、锡、硒挥发完全,大部分锑也会被挥发出去,残留的少部分锑可通过加入5mL 100g/L酒石酸溶液的方式来掩蔽;加入5mL饱和硫脲溶液可掩蔽铜;加入0.2g抗坏血酸可掩蔽铁(Ⅲ);其他共存元素的干扰试验表明,试样中的银、铅、锌、镉、镁、钼对测定的干扰可忽略。用饱和乙酸铵溶液和硝酸(4+96)调节样品溶液pH值至1.5～1.7,以EDTA标准滴定溶液滴定铋,建立了EDTA滴定法测定高铋银精矿中铋的方法。按照实验方法对3个高...

Determination of bismuth in bismuth-riched silver concentrate by EDTA titration

The content of bismuth in silver concentrate directly affects the selection of smelting process and metal balance management, and it is an important index for the evaluation of silver concentrate. However, the determination methods of bismuth in bismuth-riched silver concentrate with bismuth content of higher than 5% (mass fraction) are rarely reported. Therefore, it is necessary to develop a rapid and accurate determination method of bismuth in bismuth-riched silver concentrate. The semi-quantitative composition analysis of bismuth-riched silver concentrate sample was conducted using wavelength dispersive X-ray fluorescence spectrometer (WDXRF) and high frequency infrared carbon-sulfur analyzer. It was found that the sample mainly contained silver, lead, bismuth, copper, antimony, iron, sulfur, silicon and carbon. On the basis of this, the sample dissolution system as well as the interference and elimination method of coexisting elements was discussed. The results showed that the sample solution was clear after dissolution in hydrochloric acid-nitric acid-perchloric acid-hydrobromic acid system, and the endpoint was obvious. The sulfur in sample was removed by hydrochloric acid volatilization. The carbon in sample was removed by heating nitric acid and perchloric acid to fuming. The volatilization of arsenic, tin and selenium in sample was complete by twice dissolution with hydrobromic acid. Most of antimony was also removed, and the residual antimony could be masked by adding 5mL of 100g/L tartaric acid solution. The copper was masked by adding 5mL of saturated thiourea solution, and the iron (III) could be masked by adding 0.2g of ascorbic acid. The interfere tests of other coexisting element showed that the interference of silver, lead, zinc, cadmium, magnesium and molybdenum in sample could be ignored. The pH of sample solution was adjusted to 1.5-1.7 with saturated ammonium acetate solution and nitric acid (4+96). The content of bismuth was titrated with EDTA standard titration solution. The determination method of bismuth in bismuth-riched silver concentrate by EDTA titration was established.The recovery tests of bismuth in three bismuth-riched silver concentrate samples were conducted according to the experimental method, and the recoveries were between 98% and 102%. The proposed method was applied for the determination of bismuth in five bismuth-riched silver concentrate samples, and the relative standard deviations (RSD, n=11) of the determination results were between 0.39% and 0.87%. The determination results were consistent with those obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES).