One-pot extraction and purification of vanadium from industrial by-products using ionic liquids followed by simultaneous in-situ vanadium and solvent recovery
File(s)
Author(s)
Mohammad Dezashibi, Amir
Type
Thesis
Abstract
Abstract
The recovery of ultra-pure vanadium(V) from gasifier ash produced by a gasification unit has been investigated by a purely hydrometallurgical technique which uses a task- specific ionic liquid, tetramethylammonium hydroxide (TMA+OH-), for the selective extraction of vanadium(V) from the ash matrix containing 24 elements.
The leaching kinetics behaviour of vanadium(V) was investigated from the gasifier at high pH and the effects of the following conditions were investigated: temperature, ionic liquid concentration, liquid-to-solid ratio, and oxidant concentration. An oxidant was used because vanadium was only partially oxidised under the reductive environment of the gasification units. The extraction of silicon and aluminium compounds was almost negligible due to the unfavourable chemical interaction with the ionic liquid, solving one of the biggest challenges in the hydrometallurgical extraction of vanadium(V). Recoverable and unrecoverable vanadium phases were identified and characterised in the gasifier ash which accurately explained and predicted the leaching efficiency. The results may be used to predict the equilibrium vanadium(V) extraction yield of samples from other sources. Control experiments were also conducted to mimic the extraction behaviour of vanadium(V) from phases consisting of M-V-O with M being an alkali or a transition metal.
Highly concentrated and pure vanadium(V) solutions were obtained that encouraged the development of a technique for the recovery of both the leached vanadium(V) and the ionic liquid. Membrane electrolysis technology was utilised to separate the ionic liquid cations from the leach liquor and to regenerate it in the cathode chamber of the electrochemical reactor. In the anode chamber, vanadium(V) was deposited as a novel vanadium compound onto the surface of the anode which was later recovered in a ternary mixture and purified as V2O5 for the final product.
In order to keep the process sustainable i.e., eliminate the use of oxidant, a method was developed by which partially oxidised vanadium was electrochemically oxidised through a heterogenous reaction mechanism. The electrochemically oxidised ash was then used as a feedstock to leach vanadium(V). This third step is optional and can be integrated into the leaching and recovery steps.
The process which is called the ionoLeach process was developed as a green and selective method for the extraction and purification of vanadium(V) from wastes/by-products using ionic liquids as solvents with no ongoing chemical use. The process uses heat, electricity, water and vanadium-bearing waste and produces hydrogen gas, oxygen gas and ultra-pure V2O5.
A techno-economic assessment was performed based on the parameters that were calculated in this research. Three scenarios were considered to find the best possible path in terms of IRR, NPV and capital investment for the recovery of the vanadium(V).
The recovery of ultra-pure vanadium(V) from gasifier ash produced by a gasification unit has been investigated by a purely hydrometallurgical technique which uses a task- specific ionic liquid, tetramethylammonium hydroxide (TMA+OH-), for the selective extraction of vanadium(V) from the ash matrix containing 24 elements.
The leaching kinetics behaviour of vanadium(V) was investigated from the gasifier at high pH and the effects of the following conditions were investigated: temperature, ionic liquid concentration, liquid-to-solid ratio, and oxidant concentration. An oxidant was used because vanadium was only partially oxidised under the reductive environment of the gasification units. The extraction of silicon and aluminium compounds was almost negligible due to the unfavourable chemical interaction with the ionic liquid, solving one of the biggest challenges in the hydrometallurgical extraction of vanadium(V). Recoverable and unrecoverable vanadium phases were identified and characterised in the gasifier ash which accurately explained and predicted the leaching efficiency. The results may be used to predict the equilibrium vanadium(V) extraction yield of samples from other sources. Control experiments were also conducted to mimic the extraction behaviour of vanadium(V) from phases consisting of M-V-O with M being an alkali or a transition metal.
Highly concentrated and pure vanadium(V) solutions were obtained that encouraged the development of a technique for the recovery of both the leached vanadium(V) and the ionic liquid. Membrane electrolysis technology was utilised to separate the ionic liquid cations from the leach liquor and to regenerate it in the cathode chamber of the electrochemical reactor. In the anode chamber, vanadium(V) was deposited as a novel vanadium compound onto the surface of the anode which was later recovered in a ternary mixture and purified as V2O5 for the final product.
In order to keep the process sustainable i.e., eliminate the use of oxidant, a method was developed by which partially oxidised vanadium was electrochemically oxidised through a heterogenous reaction mechanism. The electrochemically oxidised ash was then used as a feedstock to leach vanadium(V). This third step is optional and can be integrated into the leaching and recovery steps.
The process which is called the ionoLeach process was developed as a green and selective method for the extraction and purification of vanadium(V) from wastes/by-products using ionic liquids as solvents with no ongoing chemical use. The process uses heat, electricity, water and vanadium-bearing waste and produces hydrogen gas, oxygen gas and ultra-pure V2O5.
A techno-economic assessment was performed based on the parameters that were calculated in this research. Three scenarios were considered to find the best possible path in terms of IRR, NPV and capital investment for the recovery of the vanadium(V).
Version
Open Access
Date Issued
2023-01-17
Date Awarded
01/09/2023
License URL
Advisor
Hallett, Jason
Fennell, Paul
Kelsall, Geoff
Sponsor
Engineering and Physical Sciences Research Council
Shell
Publisher Department
Chemical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)