滴定法和光度法在铌铁合金测定中的应用

The Application of Titration and Spectrophotometry in the Determination of Nb-Fe Alloy

试样以过氧化钠熔融后,用热水浸取、定容,过滤使铝、磷与铌、钽、铁、钛等元素沉淀分离。经分离后的铝,在p H4.5酸性介质中加入过量的EDTA标准溶液,以PAN为指示剂,用硫酸铜标准溶液滴定过剩的EDTA,与铝配位络合的EDTA用氟化铵取代释放后,再用硫酸铜标准溶液滴定求得铝量。滤液中磷在过氧化钠熔融时已被氧化,在有铁离子存在的情况下,于硝酸介质中,用钼酸铵-酒石酸钾钠混合溶液掩蔽硅并使磷生成磷钼黄,以氟化钠-氯化亚锡掩蔽铁,并将磷钼黄还原为磷钼蓝,测定吸光度求得磷量。在草酸介质中,变色酸与钛生成红色络合物,用光度法测定吸光度值求得含钛量。实验证明,该方法有较好的精密度和准确度,能满足冶金生产的需求。

After the sample was dissolved with sodium peroxide,the hot water was used to leach and fix to the constant volume,and then through filtering the aluminium and phosphorus were separated from the precipitation of niobium,tantalum,iron,titanium elements. For the separated aluminium,in the acid medium with PH 4. 5,the excessive EDTA standard solution was added,and taking PAN as indicator,the standard solution of copper sulfate was used to titrate the excessive EDTA,then after the EDTA coordinated with aluminum was replaced with ammonium fluoride,the content of aluminium was titrated and determined with the standard solution of copper sulfate. The phosphorus in filtrate had been oxidized in the fusion of sodium peroxide,in the presence of iron ions,and in the medium of nitric acid,the ammonium molybdate-potassium sodium mixed solution was used to mask silicon and cause phosphorus to become molybdophosphate,and then sodium fluoride-stannous chloride was used to mask the iron and reduce molybdophosphate into phospho-molybdenumblue,and now the content of phosphorus was obtained by determining the absorbance. In the oxalic acid medium,the chromotropic acid and titanium generated a red complex,and the content of titanium was obtained through determining the absorbance by spectrophotometry. The experiments showed that,this method had a good precision and accuracy,could meet the requirements of metallurgical production.