Green method for preparation NaVO2 from vanadium-chromium slag based on Na2CO3 roasting and water leaching

An effective and environment-friendly method for preparing NaVO 2 , which can be used as an energy storage material, from Na 2 CO 3 roasted vanadium-chromium slag was proposed using water as the leaching medium. Vanadium-chromium slag with 30 % Na 2 CO 3 was heated in air and argon atmospheres from 30 °C to 1000 °C, respectively. The results show that vanadium compounds converted to NaVO 3 while chromium compounds to Na 2 CrO 4 under air. NaVO 3 and Na 2 CrO 4 were water-soluble making the separation of vanadium and chromium complicated. NaVO 3 and Na 2 CrO 4 were water-soluble making the separation of vanadium and chromium complicated. Heating vanadium-chromium slag in an argon atmosphere caused Fe 2 VO 4 to react with Na 2 CO 3 , forming NaVO 2 and NaFeO 2 below 1000 °C. However, chromium compounds unreacted in argon. NaFeO 2 was insoluble, while NaVO 2 was water-soluble with a leaching efficiency exceeding 70 %. Notably, the characteristic peak of V(III) in NaVO 2 was first found to be −532.00 ppm by the liquid 51 V NMR spectrum. This method represents a novel, green strategy for the resource utilization of vanadium-chromium slag, involving Na 2 CO 3 roasting in an argon atmosphere to produce NaVO 2 . It offers a promising approach to reduce the cost of NaVO 2 battery production and support its commercialization.