Highly selective separation of vanadium over iron from stone coal by oxalic acid leaching

Highly selective separation of vanadium over iron from stone coal by oxalic acid leaching

In this paper, a novel method was proposed to selectively extract vanadium from stone coal by oxalicacid leaching. Vanadium was leached, but the iron impurity wasmaintained in the leaching residue. Theeffects of leaching conditions on the leaching efficiency of vanadium and iron were investigated foroxalic and sulfuric acid leaching, respectively. For oxalic acid leaching, 71.5% of the vanadium can berecovered with only 3.4% of the iron impurity leached under the leaching conditions: a dosage of H+ of12 mol/kg, a leaching time of 6 h, a leaching temperature of 368 K (95 8C) and a water–mineral ratio of1.5 L/kg. However, under the same conditions, 74.1% of the vanadium and 13% of the iron were leachedduring sulfuric acid leaching. The XRD and FTIR analyses showed that both oxalic and sulfuric acidleaching can destroy the crystal lattice structure of muscovite, resulting in the leaching efficiency ofvanadium without much difference. Further, the SEM-EDS and XPS analyses indicated that very littlepyrite dissolved during oxalic acid leaching, but that much more pyrite dissolved during sulfuric acidleaching. Therefore, oxalic acid leaching can achieve a highly selective separation of vanadium over ironfrom stone coal.

In this paper, a novel method was proposed to selectively extract vanadium from stone coal by oxalicacid leaching. Vanadium was leached, but the iron impurity wasmaintained in the leaching residue. Theeffects of leaching conditions on the leaching efficiency of vanadium and iron were investigated foroxalic and sulfuric acid leaching, respectively. For oxalic acid leaching, 71.5% of the vanadium can berecovered with only 3.4% of the iron impurity leached under the leaching conditions: a dosage of H+ of12 mol/kg, a leaching time of 6 h, a leaching temperature of 368 K (95 8C) and a water–mineral ratio of1.5 L/kg. However, under the same conditions, 74.1% of the vanadium and 13% of the iron were leachedduring sulfuric acid leaching. The XRD and FTIR analyses showed that both oxalic and sulfuric acidleaching can destroy the crystal lattice structure of muscovite, resulting in the leaching efficiency ofvanadium without much difference. Further, the SEM-EDS and XPS analyses indicated that very littlepyrite dissolved during oxalic acid leaching, but that much more pyrite dissolved during sulfuric acidleaching. Therefore, oxalic acid leaching can achieve a highly selective separation of vanadium over ironfrom stone coal.