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以乙酸铅作沉淀剂,用EDTA滴定过量铅离子测定钨的方法,前人已作了不少工作,但因准确度不高而未能应用到生产上。1982年我们在做钨的探索实验时,发现钨酸铅沉淀既严重地吸附铅离子(3毫克左右),又因形成多聚钨酸盐(polytungstates)而影响方法的准确度。因此,要使钨的络合滴定法应用到生产上,首先必须解决好上述问题。对前一问题,前文已经解决了;对后一问题,在最近的试验中发现,如在碱性溶液中加入3克氟化钠,即可抑制多聚钨酸盐的形成,因而解决了结果偏低的问题,使方法的回收率提高到
Lead acetate as a precipitating agent, with EDTA titration of excess lead ions tungsten method, predecessors have done a lot of work, but because of the accuracy is not applied to the production. In 1982, when we conducted tungsten exploration experiments, we found that lead tungstate precipitation adsorbs both lead ions (about 3 mg) and the accuracy of the method due to the formation of polytungstates. Therefore, to make tungsten complexation titration method applied to the production, we must first solve the above problems. The previous issue has been solved; in the latter case, it has been found in recent tests that the formation of polytungstates can be suppressed by adding 3 g of sodium fluoride in alkaline solution, thus solving the problem Low problem, the method of recovery to