For the iron ore contains iron silicate,10ml nitric acid,3mL hydrofluoric acid,3mL perchloric acid is adopted for dissolution and drying by distillation,and 10mL mixtures of sulfuric and phosphoric acid is adopted for dissolution until reflux,the sodium tungstate is used as the indicator,and the stannous chloride is used for reduction,when the sodium tungstate is reduced to pale yellow,then reduce it to blue by titanium trichloride,added 100mL water and when blue faded,using sodium diphenylaminesulfonate is used as the indicator,and titrate with potassium dichromate until purple red color is obtained as the destination.The nitric acid,hydrofluoric acid,perchloric acid is used for predissolving,which make iron silicate dissolved completely,so the problem that this type of insoluble ore is overcome,the method is simple and practicable,the results are accurate.%对于含硅酸铁的铁矿,采用10 mL硝酸,3mL氢氟酸,3 mL高氯酸溶解蒸干,再用10 mL硫磷混酸溶解至回流,以钨酸钠为指示剂用氯化亚锡还原至浅黄色再用三氯化钛还原至蓝色,加水100 mL左右,待蓝色褪尽,以二苯胺磺酸钠为指示剂,用重铬酸钾滴至紫红色为终点.试验以硝酸、氢氟酸、高氯酸预溶,使硅酸铁彻底溶解,克服此类矿物难以溶解的难题,方法简便易行,结果准确.
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