Enhancing selective dissolution of manganese by mechanochemical process for iron ore upgrading

Currently exploited iron ores have high-manganese content. Conventional leaching of manganese takes about 2 h at 80 C followed by precipitation. Thus, it consumes high energy and a relatively long-time. In this paper, the mechanochemical method was investigated for reducing manganese in iron ore at a shorter time and at room temperature. The number and size of balls were studied during the milling process in the presence of sulfuric and/or oxalic acid either as a single acid or as a mixture. The higher the ball's number and size the higher the iron and manganese dissolution. The sulfuric-oxalic acid mixture is better than the usage of single acid for reducing the manganese at about 10 min. The iron concentrate, containing 54% Fe and 2.9% Mn from a feed containing 57% Fe and 7.5% Mn, is obtained using 15 balls of size 3.3 cm and 2%:4% sulfuric to oxalic ratio and dosage. Moreover, the mechanochemical is advantageous over conventional leaching as it continuously cleans the surface, creates new surfaces, controls iron dissolution, is conducted at room temperature and shorter time (about 10% of the time needed for the leaching process), and direct production of iron concentrate without subsequent processes like precipitation.