Technology for Extracting Manganese from Vanadium Converter Slag After Leaching Vanadium

New technology is developed for preparing pure vanadium pentoxide from vanadium-containing metallurgical slag. As a result of the selective extraction of vanadium from calcined slag, solid residues containing from 7 to 10% of manganese are formed, which are suitable for extraction. A study of the mineralogical composition of solid residues shows that manganese is found in cakes in the form of MnCO₃. An aqueous solution of sulfuric acid is adopted as the leaching agent. According to our data, the maximum solubility of manganese sulfate was 484–500 g/dm³ at T = 25 °C, 5 g/dm³ H₂SO₄. Considering these data, a study is made of leaching Mn from solid residues with aqueous solutions of H₂SO₄. Extraction of Mn from solid residues into the solution is 75%, and additional extraction of vanadium remaining in cake is up to 50%. The complex solutions obtained by leaching, containing Fe³⁺, V⁵⁺, Al³⁺, Si⁴⁺, are purified by feeding them to a fresh portion of cake at pH 4–4.5 and Mn is precipitated from solution by using (NH₄)₂CO₃ to form MnCO₃. The washed and calcined residue contains pure Mn₃O₄. The main production scheme for comprehensive treatment of vanadium slag with preparation of V₂O₅, Mn₃O₄, MgO, (NH₄)₂SO₄ from solution, and complex master alloys from solid residues is presented.