Abstract: In sulfuric acid medium，the leaching of low-grade pyrolusite was investigated with formaldehyde and glucose as compound reductant.Mass concentration of formic acid in the leaching solution was quantitatively analyzed by high perfor- mance liquid chromatography（HPLC）.Effects of dosages of reductants and their reaction times，the whole leaching time， leaching temperature，volume fraction of sulfuric acid，stirring rate，and liquid-solid ratio on the extraction ratio and mass concentration of formic acid were studied.The optimal conditions were determined as 90% and 60% theoretical amounts（mass fraction） of formaldehyde and glucose respectively，their reaction time ratio of 1∶2，the whole leaching time of 3 h，temperature of 90 ℃，volume fraction of sulfuric acid of 18%，stirring rate of 300 r/min，and liquid-solid ratio of 12 mL/g.Under these conditions leaching efficiency of manganese was 94.68% together with 1.86 mg/mL（mass concentration） of the formic acid

Key words: formaldehyde, glucose, pyrolusite, leaching efficiency