The invention relates to the field that biquaternary ammonium compounds are applied in silicate mineral flotation, and discloses a collector which applies the biquaternary ammonium compound with the constitutional formula shown as the formula I in bauxite or ironstone reverse flotation desiliconization. In the formula I, R<1> and R<2> are alkyls with 6-18 carbon atoms; R<3>, R<4>, R<5> and R<6> are respectively methyl, ethyl, -(CH2CH2O)nH, or -(CH(CH3)CH2O)nH, wherein, n is equal to 1-6; R<7> is alkylene with 2-6 carbon atoms; and X is Cl, Br or I. The collector of the invention has strong ability to collect quartz, kaolinite, illite and pyrophyllite, and is applicable to the silicate mineral separation from the bauxite or ironstone by reverse flotation, the suitable pH range of the flotation pulp is 5-13, and the dosage is equal to 50-500 g/t according to the content change of the silicate mineral in ores.