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一般文献对于铌钽铁矿中氧化锡的测定,都用焦硫酸钾熔融试样,以酒石酸和硫酸浸出熔块,分离氧化硅后,通硫化氢,沉淀锡,灼烧为氧化锡;再以焦硫酸钾熔融,酒石酸浸出;再通硫化氢,将沉淀灼烧为氧化锡。根据这个重量法所得的结果,因吸附杂质太多,往往偏高,故不能采用。如果将重量法所得的氧化锡以过氧化钠熔融,用水浸出,在盐酸溶液中还原后,按照碘量法测定锡,结果虽较准确,但手续繁,需时冗长(约廿余小时),亦不符合快速的要求。因此,我们改用过氧化钠与氢氧化钠混合熔样,借盐酸水解铌钽,加入氯化钠促使铌钽水解完全,将溶液还原后,以碘量法测定锡,很快就得出准确结果,现将方法介绍如下:
General Literature For the determination of tin oxide in a tantalum coltan, the sample is melted with potassium pyrosulfate, the frit is leached with tartaric acid and sulfuric acid, the silicon oxide is separated, the hydrogen sulfide is precipitated, the tin is precipitated, and the mixture is tinned with Potassium pyrosulfate melted, leaching tartaric acid; and then pass hydrogen sulfide, the precipitate was fired as tin oxide. According to the results of this gravimetric method, due to excessive adsorption of impurities, tend to be high, it can not be used. If the gravimetric method of tin oxide with sodium peroxide melting, leaching with water, hydrochloric acid solution reduction, according to the iodometric method for the determination of tin, the result is more accurate, but the procedure is complicated, takes a long time (about 20 hours) Does not meet the fast requirements. Therefore, instead of mixing niobium and tantalum with hydrochloric acid, we use a mixture of sodium hydroxide and sodium hydroxide, hydrolyze niobium and tantalum with hydrochloric acid, hydrolyze niobium and tantalum completely with sodium chloride, measure the tin by iodometric method after reducing the solution, and quickly obtain accurate As a result, the method is described below: