Reductive leaching of low-grade manganese ore with bamboo sawdust: Study of bamboo sawdust and glucose degradation

Abstract

This study was conducted to identify the pathways by which bamboo sawdust (BSD) degrades into sugar (predominantly glucose) and the resultant glucose degrades into an organic acid during Mn leaching. Synthetic Mn ore (SMO) and low-grade Mn ore (LGMO) were leached with BSD as a reductant in sulfuric acid. Mn was determined by complexometric titration with ethylenediaminetetraacetic acid. Sugar derivatives and organic acids were determined by high-performance liquid chromatography. The samples were leach liquor treated in 4.0 M H2SO4 at 100 °C and sampled every 15 min until 360 min. BSD, which contained cellulose (56.11%) and hemicellulose (28.6%), and cellulose was degraded into glucose as the major sugar. The highest glucose concentration produced in the SMO and LGMO leaching system were 28.54 ppm and 19.45 ppm, respectively. The produced glucose reduced the Mn ores and was also degraded into organic acids, predominantly formic acid. The highest concentration of extracted Mn was 0.15 ppm for SMO and 0.06 ppm for LGMO. The highest formic acid concentration was less than 0.005 ppm for both ores. The results indicate that the formed glucose preferentially participated in Mn reduction rather than undergoing degradation. Thus, complete extraction of Mn could not be achieved because O2 competed with Mn to degrade glucose into an organic acid.