Recovering Metals in Fly Ash Derived from Heavy Oil by Combination of Leaching and Ion Exchange Processes

摘要

Recovery of metal such as V, Ni and Fe from oil fly ash is important for efficient use of natural resources and protection of environment. Leaching of metals from fly ash followed by ion exchange of leached metals has been examined to develop a process which can selectively recover V and Ni from the fly ash. Experiment of leaching with water, HC1, H_2SO_4 and NaOH leads us to propose a two-step leaching process as an effective and mild operation. The first step is leaching with water for removal of Ni, Mg, Al and Zn and the second step is leaching with acidic solution for the recovery of V. The metals V and Ni are then separated from other metals in each leached liquor by ion exchange. Advantage of this separation process is that acidic leachant can be reused, which contribute to save separation energy.