Enhancing the vanadium recovery from heavy fuel fly ash by using Tri Sodium Citrate as a chelating agent in Alkaline Solution

Sodium carbonate exhibits high selectivity for vanadium and low vanadium recovery rate (43%) from the fly ash of Al-Dura thermal power plant (Baghdad, Iraq) under standard conditions (35°C , 12 hrs, 1M Na2CO3, L/S=10). The recovery increases to 57% in the presence of 0.005M KMnO4. This study explores the role of tri-sodium citrate (0.1M) as a chelating agent in enhancing recovery, achieving up to 85% recovery under the same conditions. Vanadium was precipitated as ammonium metavanadate (NH4VO3) by adjusting pH to 5 using NH4Cl and heating to 50°C for 6 hrs. The precipitate was roasted at 650°C for 2 hrs to obtain vanadium pentoxide (76% purity). The controlling step in vanadium recovery is the chemical reaction rate on the surface of fly ash, as determined by the unreacted-core model. The activation energy for the reaction is (8.47kJ/mole) at a temperature range (35-60°C).