Improvement on Method of SnCl_2-TiCl_3-K_2Cr_2O_7

In order to understand the measurement of iron content in iron ore theoretically,the experimental conditions of SnCl2-TiCl3-K2Cr2O7 were researched and analysized.The method of SnCl2-TiCl3-K2Cr2O7 was that hydrochloric acid plus sodium fluoride under the thermal decomposition,so that iron oxides and silicates have become iron oxide into the solution.First of all,the stannous chloride makes the ferric ions reduced to two-valent iron,other ferric iron reduced to ferrous iron by titanium trichloride to generate tungsten with sodium tungstate as the indicator.Next,potassium dichromate standard solution was oxidated until the blue colour was disappeared.Droplets of potassium dichromate standard set by adding parathion mixed acid with diphenylamine sulfonante as indicator.The experimental conditions were optimized through improving the reduction acidity,reduction temperature,time of dissolved sample and reagent dosage.The results show that reduction acidity was 4.0 mol·L-1;the reduction temperature was between 60 and 70 ℃;the volume of concentrated hydrochloric acid was 30 mL;the time of dissolved sample was 25 min.It supplied an opitimized condition on the method of SnCl2-TiCl3-K2Cr2O7.