Extraction and separation of vanadium and nickel from fly ash produced in heavy fuel power plants

In Jordan, large amounts of fly ash (FA) are produced as a result of burning heavy fuel in power plants. Extraction of metals from FA is an important industrial/environmental issue to assess metals’ mobility and applications. Large amounts of metals (V, Ni, Fe, Ca, Mg, Na, and K) were easily leached from FA under acidic, basic, and neutral conditions and this makes disposal of this material an important environmental issue. Extraction and separation of vanadium (V) and nickel (Ni) from FA is achieved using Akita's procedure with some modifications. In the first step, Ni is selectively eluted from FA using NH4OH solution and then precipitated using Na2S. The Ni/V ratio in final precipitate was 27. On the other hand, V is extracted from Ni-free-FA using Na2CO3 solution, recovered by 0.1 M tri-ethylamine/toluene, and precipitated by NH4Cl. The V/Ni ratio in the final precipitate was 55. The adopted method showed a reasonable recovery for both metals from FA, 56 and 45% from Ni and V, respectively. The earlier attempts indicated that separation of V/Ni by precipitation using OH− or CO32− was not successful where both the metals did not precipitate from solution in the presence of other elements.

► Large amounts of fly ash are produced as a result of burning diesel fuel in power stations.
► Ni is selectively eluted from the FA using NH3 solution and was precipitated as NiS.
► V is extracted from Ni-free-FA by Na2CO3 solution and precipitated by NH4Cl.
► The proposed method herein showed a high recovery (97%) for both metals.