Effects of slag and deoxidizers on recovery of Mn from high-sulfur electrolytic manganese metal scrap

The effect of the initial (Al + Si)/MnO molar ratio and slag composition on MnO recovery from electroslag by remelting at 1773 K was investigated. High-purity aluminum metal and silicon were employed as the deoxidizers to effectively promote the recovery of manganese metal (MM). The reduction of MnO in slag, through the interaction between molten MM with a deoxidizer and the Na2O-enriched electroslag melt, was assessed both thermodynamically and kinetically. The sulfur content of high-sulfur rejected electrolytic manganese metal (EMM) scrap decreased to 0.58% with high-temperature pretreatment. The mass ratio between slag and high-sulfur rejected EMM scrap is 2/3. When the Al2O3 content in the initial slags decreased and the Na2O content increased, the MnO reduction ratio increased. The residual MnO concentration of the slag reduced with increasing the Al-Si deoxidizer content. When the (Al + Si)/MnO molar ratio reached 0.83, the MnO concentration in the final slag was only 3%. A deoxidizer mainly containing aluminum and a small amount of Si could be added to recover MnO from the slag, resulting in the improvement in the cleanliness of final Mn metal.