Abstract: The mass fraction of SiO₂ was more than 60% in the residue of pyrolusite after manganese was extracted through reduction roasting and acid leaching, and it was a better siliceous raw material because of less other impurities.Sodium hydroxide solution was adopted in leaching silicon from acid leaching residue of pyrolusite at atmospheric pressure.The effects of reaction temperature，reaction time，sodium hydroxide concentration，and liquid-solid ratio etc.on the leaching ratio of SiO₂ were investigated by means of orthogonal and single-factor experiments.Results showed that the main factors that affected the leaching ratio of SiO₂ followed by：leaching temperature，liquid-solid ratio，leaching time，and sodium hydroxide concentration.The leaching ratio of SiO₂ could be up to 70.9%，when the reaction temperature was 120 ℃，liquid-solid（ratio of liquid volume to mass of leaching residue of pyrolusite,mL/g） ratio was 2∶1，reaction time was 5.5 h，and sodium hydroxide concentration was 20 mol/L.

Key words: acid leaching residue of pyrolusite；silica, sodium hydroxide