氯化钠电位滴定法测定贵铅中银

用能量色散X射线荧光光谱仪(EDX)和X射线衍射仪(XRD)对贵铅进行扫描分析,结果表明贵铅中主要含有铅、银、铋、铁、锑、铜、砷、碲等,且银的主要物相是银锑合金、银铋合金、单质银以及银砷合金。在应用硝酸对贵铅进行溶样处理过程中发现,锑的水解会产生灰白色沉淀物,考虑到酒石酸可以和锑发生络合反应,有效防止锑的化合物水解,据此,采用硝酸-酒石酸混酸溶解样品,建立了电位滴定法测定贵铅中银的方法。对实验条件进行了优化,并对贵铅样品中的共存杂质元素进行了干扰试验,结果表明其对测定的干扰可以忽略。按照实验方法对3个贵铅样品中银进行测定,6次平行测定结果的相对标准偏差(RSD)均在0.18%~0.21%之间,加标回收率在99%~101%之间。将实验方法应用于贵铅实际样品分析,并与火试金法-重量法测定结果进行对照,二者有较好的一致性。

Determination of silver in noble lead by sodiumchloride potentiometric titration

The noble lead sample was scanned and analyzed by energy dispersion X-ray spectrometer (EDX) and X-ray diffractometer (XRD). The results showed that the noble lead was mainly composed of lead, silver, bismuth, iron, antimony, copper, arsenic and tellurium. Moreover, the phases of silver mainly included silver-antimony alloy, silver-bismuth alloy, elemental silver and silver-arsenic alloy. The noble lead sample was treated and dissolved with nitric acid. It was found that gray white precipitate could be formed due to the hydrolysis of antimony. Based on the complex reaction between tartaric acid and antimony, the hydrolysis of antimony compounds could be effectively prevented by adding tartaric acid. Consequently, a determination method of silver in noble lead by potentiometric titration was established after dissolving the sample with mixed nitric acid and tartaric acid. The experimental conditions were optimized. The interference test of coexisting impurity elements in noble lead sample was conducted. The results showed that the interference of coexisting elements could be ignored. The proposed method was applied for determination of silver in three noble lead samples. The relative standard deviations (RSD, n=6) of determination results were between 0.18% and 0.21%. The recoveries were between 99% and 101%. The noble lead actual sample was analyzed according to the experimental method. The results were in good agreement with those obtained by fire assaying-gravimetric method.