Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group vb metal
Reexamination Certificate
2001-08-10
2004-07-20
Silverman, Stanley S. (Department: 1751)
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group vb metal
C423S065000, C423S067000, C423S544000, C429S205000, C252S062200, C205S496000
Reexamination Certificate
active
06764663
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a process for the preparation of a vanadyl/vanadous sulphate crystal product or solution from a vanadium bearing ore material, and to various intermediate steps in the process.
Vanadyl/vanadous sulphate solutions or electrolytes are becoming more and more important in various applications, including in the battery industry. A problem with the solutions, however, is that they are highly acidic and hazardous. Accordingly, there may be serious problems in transporting these products around the world.
Additionally, there are many vanadium bearing ores that would be useful as a starting material for producing vanadyl/vanadous sulphate solutions. However, as far as we know, there is to date no commercially viable process for producing vanadyl/vanadous sulphate solutions from vanadium bearing one.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, a process for the preparation of vanadyl/vanadous sulphate crystals from a vanadyl/vanadous sulphate solution, and subsequent reconstitution of the crystals to form a solution, comprises the step of:
1) providing a starting material in the form of a vanadyl/vanadous sulphate solution having a specified chemical composition.
2) evaporating the solution to crystallization by applying heat; and
3) re-dissolving the crystals by the addition of a specified volume of de-ionized water with constant stirring and, if necessary, with the addition of heat to form a clear solution having substantially the same chemical composition as the starting material.
The necessity of applying heat in step 3) is dependent on the evaporation in step 2). If the vanadyl/vanadous sulphate solution is evaporated at its boiling point, the water of crystallization is removed from the crystals and heat is required for dissolution of the crystals in step 3). If however, the vanadyl/vanadous sulphate solution is evaporated at below its boiling point, for instance below 90° C., the water of crystallization is not removed from the crystal structure and no heat is required for dissolution of the crystals in step 3).
The invention encompasses a process for the preparation of a vanadyl/vanadous sulphate solution from vanadyl/vanadous sulphate crystals by dissolving the crystals in a specified volume of de-ionized water with constant stirring, and, if necessary, with the addition of heat.
The vanadyl/vanadous sulphate solution is prepared by forming a vanadous sulphate solution from a vanadyl sulphate solution electrolyzed with sulphuric acid, and combining the vanadous sulphate solution with a further portion of vanadyl sulphate solution, preferably in equal volumes and/or concentrations, and if desired filtering the resultant solution and adding phosphoric acid as required.
The vanadyl sulphate solution is preferably formed by reacting sulphuric acid, diluted with de-ionized water as required, with vanadium pentoxide and oxalic acid under suitable reaction conditions.
The sulphuric acid solution preferably has a molarity of about 2.8 to about 8.5 depending upon the specified molar concentration of the vanadyl sulphate solution.
The oxalic acid is preferably pure oxalic acid, in particular 99% pure or greater.
The vanadium pentoxide is also preferably pure, in particular having a V
2
O
5
content of 99.5% or greater.
The vanadyl sulphate solution produced may have any desired molar concentration, for example 2M, 4M up to a maximum of 6M.
The pure V
2
O
5
is preferably produced by forming a slurry containing ammonium-poly-vanadate (APV), contacting the slurry with ammonia gas to precipitate out ammonium-meta-vanadate (AMV), and calcining the AMV in a kiln to form pure V
2
O
5
.
Ammonium sulphate is preferably added to assist in precipitating the AMV from the APV slurry.
The ammonia gas is preferably added to the slurry very slowly to completely dissolve the APV before crystallization of the AMV.
The APV is preferably produced from a titaniferous magnetite ore.
According to a further aspect of the invention, there is provided a process for producing a vanadyl/vanadous sulphate crystal product or solution from a vanadium bearing ore material, in particular a titaniferous magnetite ore starting material incorporating, as appropriate, one or more of the above method steps.
The invention also extends to the use of a vanadyl/vanadous sulphate solution produced according to any one or more of the above method steps or reconstituted from a vanadyl/vanadous sulphate crystal product produced according to any one or more of the above method steps as an electrolyte in a vanadium redox battery.
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patent: 5368762 (1994-11-01), Sato et al.
patent: 5587132 (1996-12-01), Nakajima et al.
patent: 2002/0048546 (2002-04-01), Tanaka et al.
patent: 2002/0119090 (2002-08-01), Tanaka et al.
patent: 0 517 217 (1997-03-01), None
patent: 157555 (1919-01-01), None
MellorA Comprehensive Treatise on Inorganic and Theoretical Chemistry vol. 1Xpublished by Longmans, Green & Co. Ltd. London GB, pp. 822 and 823, Sep. 1947.*
E. Sum et al: Investigation of the V(V) /V (IV) System for use in the Positive Half -Cell of a Redox Battery,Journal of Power Sources, 16pp. 85-95, 1985.
E. Sum et al.: A Study of the V(II)/V (III) Redox Couple for Redox Flow Cell Applications.Journal of Power Sources, 15, pp. 179-190, 1985.
Dormehl Andries Gerhardus
Monaghan Patrick Albert
Strydom Ivan
Highveld Steel and Vanadium Corporation Limited
Pauley Petersen & Erickson
Silverman Stanley S.
Vanoy Timothy C
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