Manganese is an important industrial raw material,as well as a strategic element of smelting steel.Manganese oxide ores are stable in acid or alkaline conditions,so the extraction of manganese must be carried out under reducing conditions.Recently,reductive leaching technologies of manganese oxide ores are developing rapidly.There are some advantages for hydrometallurgical treatment of pyrolusite directly compared to pyrometallurgical and hydrometallurgical method indirectly,such as low power consumption,simple equipment requirement,less environment pollution.At present,because of friend-environment,high leaching efficiency and low cost operation,there are a lot of reports about using biomass as reductant to leach manganese oxide ores,such as sawdust[1],cane molasses[2],molasses alcohol wastewater[3] and corncob[4].Waste tea-leaf is a rich resource in China which is a renewable and non-hazardous reductant compared with other reducing agents.There are many reducing components in waste tea-leaf such as polysaccharide,tea polyphenols,cellulose,organic acids,and so on,which could be hydrolyzed into release glucose in acid condition.Hence,the extraction rate of manganese should be improved significantly.The aim of this work was to develop a new leaching process of the manganese oxide ores by sulfuric acid in the presence of waste tea-leaf as reductant.The dynamics of the leaching process was also investigated[5,6].In this study,Manganese oxide ores from Gabon and China were leached by waste tea-leaf in dilute sulfuric acid solution.The effects of waste tea-leaf dosage,concentration of sulfuric acid,liquid-solid ratio,leaching temperature and reaction time on leaching process were studied.The results showed that leaching efficiency of Gabonese manganese oxide ores reached almost 100% under the optimal conditions which were determined as manganese oxide ores to waste tea-leaf weight ratio of 10:4,sulfuric acid concentration of 2.5mol/L,liquid-solid ratio of 7.5:1,leaching temperature of 368K for 8h.While that of Chinese manganese oxide ores reached 99.8%,and the optimal conditions were obtained as follows: manganese oxide ores to waste tea-leaf weight ratio of 10:1,sulfuric acid concentration of 1.7mol/L,liquid-solid ratio of 7.5:1,leaching temperature of 368K and time of 8h.The leaching process followed the kinetic model 1-2/3X-(1-X)2/3=kt with an apparent activation energy of 38.5 kJ/mol and 20.7 kJ/mol respectively,which concluded that the leaching processes are controlled by internal diffusion.