Rapid Determination of Lead in Barium-bearing Ores by EDTA Compleximetry

For the determination of lead content in barium-bearing samples by the EDTA volumetric method, the lead analysis result is low due to the presence of lead sulfate and barium sulfate double salt formed during the analysis process. The interference of the barium can be eliminated by using the lead and barium chromate volumetric method, but the analysis process is complicated and time-consuming. Consequently, a rapid determination method based on the improved EDTA volumetry has been established and is documented in this paper. Barium-bearing ores are dissolved in a hydrochloric acid system with sulfuric acid precipitation to remove soluble barium ions. The acid solution is then evaporated and the lead sulfate separated by precipitation from other impurities with sulfuric acid solution. The lead sulfate precipitations are dissolved by acetic acid-sodium acetate buffer solution at pH of 5.7. The content of lead is analyzed by EDTA complexometric titration. Through the experiment, the amount of hydrochloric acid was 40 mL and the interference from barium was eliminated by 2 drops of 50% sulfuric acid. Lead sulfate was separated and measured after 20 min when the sample was decomposed. The influence of barium content on samples, to determine lead content was also studied. According to different barium contents of lead ore samples, the precisions (RSD, n=7) wer 0.1%-0.8%, and the results were consistent with those of the national standard method. The results show that the method can shorten the sample processing workflow, which can satisfy plant commissioning and processing requirements.