Leaching of heavy metals vanadium and nickel from gasified petroleum coke ash

In order to improve the leaching rate of V and Ni in gasified petroleum coke ash, the leaching behavior of heavy metals V and Ni in gasified petroleum coke ash treated with carbon burning at 600 ℃ was studied by wet process. V and Ni were extracted from ash residue by three methods: acid leaching, alkali leaching and alkali-acid leaching. The experimental conditions of reaction temperature, concentration and time were optimized, and the leaching rates of the two heavy metals were compared. The results showed that the leaching rates of V and Ni were 60.30% and 90.70%, respectively, when the ash particle size was 70 to 90 μm, the reaction temperature was 160 ℃, the reaction time was 3 h, and the mass percentage of H₂SO₄ was 40.00% in the acid leaching process. Acid leaching is more beneficial to the extraction of Ni. Alkaline leaching method can significantly improve the specific surface area of ash residue. When the reaction temperature was 150 ℃, the reaction time was 3 h, and the mass percentage of lye was 7.00%, the specific surface area of ash residue can reach 97 m²/g, the leaching rate of V was 88.10%, and Ni was not leached. By alkali-acid leaching, almost all of the V and Ni in the ash residue entered the solution, the leaching rate of V and Ni in ash residue were 99.80% and 99.40% respectively, which can maximize the leaching of V and Ni.