All of which the economic element iron ore called iron ore. There are many kinds of iron ore, used in the main have magnetite iron (Fe3O4), hematite (Fe2O3) and siderite (FeCO3), etc. Iron ore samples with HCL, one of the iron into Fe3 +. In strong acid conditions, Fe3 + can through the SnCl2 Fe2 + for reduction. Sn2 + will Fe3 + reduction, the methyl orange can also be Sn2 + reductive into hydrogenated methyl orange and fade, thus the methyl orange to instruct a Fe3 + reduction destination. Sn2 + still can continue to make hydrogenated methyl orange reductive into N, N-dimethyl benzene 2 amine and to amino benzene sulfonic acid sodium.