Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group viib metal
Patent
1997-12-05
1999-04-06
Bos, Steven
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group viib metal
423 54, 423 63, 423593, C01G 4700, C01G 3700, C01G 3900, C01G 4100
Patent
active
058914072
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the production of pure ammonium metallates of the metals W, Mo, V, Cr and Re, wherein alkaline metal salt solutions are adjusted to a pH value in the range from 5 to 9 by reaction with CO.sub.2, these metal salt solutions are passed through an anion exchanger in carbonate form, wherein, in addition to the alkaline metal carbonate solution, the metallate form of the ion exchanger is formed, the ion exchanger is then washed until free of alkali and is then eluted by means of aqueous ammonia to form ammonium metallate solutions and the anion exchanger in the OH form, wherein the anion exchanger is converted into the carbonate form by means of CO.sub.2 treatment and is recycled.
In order to produce pure ammonium metallates, in particular of the refractory metals W, Mo and V as precursors for recovery of the metals, the raw materials are generally treated with alkaline NaOH or Na.sub.2 CO.sub.3 solutions. An excess of alkali is used in this operation in order to achieve the greatest possible yields of the valuable metal. In the subsequent processing stage, the pH value of these solutions must be reduced. Since this is generally achieved by using mineral acids, this inevitably results in the formation of neutral salts, which must be disposed of.
Once the alkaline metallate solutions obtained in this manner have been digested and purified, they are converted into the ammonium metallates.
This is principally achieved by solvent extraction processes (Ulmanns Encyclopadie der technischen Chemie, 4th edition, volume 24, 1983, page 466) or recovery using solid ion exchangers (Uranium Mining and Metallurgy, volume 10(3), August 1991).
The reduction in pH is also achieved in these two processes by the addition of mineral acids, inevitably resulting in the formation of considerable quantities of neutral salts which must be disposed of.
An improved solvent extraction process is disclosed in SU-A 1 792 993 and SU-A 1 792 994 (Derwent 94-133033/16 and 94-133084/16). According to this process, acidification is performed with CO.sub.2, resulting in the formation of Na.sub.2 CO.sub.3, which may be returned to the process. In the process described, the metallate anion is converted into an organic phase and then only partially re-extracted with NH.sub.3 solution. However, up to approx. 50% of the stoichiometric quantity of the extracting agent remain blocked by the metallate anion.
The object of the present invention is to provide a process which avoids environmental pollution by the neutral salts and the disadvantages of incomplete utilisation of the extracting agent.
This object is achieved by a process for the production of pure ammonium metallates of the metals W, Mo, V, Cr and Re, wherein alkaline metal salt solutions are adjusted to a pH value in the range from 5 to 9 by reaction with CO.sub.2, these metal salt solutions are passed through an anion exchanger in carbonate form, wherein, in addition to the alkaline metal carbonate solution, the metallate form of the ion exchanger is formed, the ion exchanger is then washed until free of alkali and is then eluted by means of aqueous ammonia to form ammonium metallate solutions and the anion exchanger in the OH form, wherein the anion exchanger is converted into the carbonate form by means of CO.sub.2 treatment and is recycled, wherein the anion exchanger used is a solid anion exchanger.
The solid anion exchanger used is preferably a moderately basic ion exchanger. These are those ion exchangers which contain tertiary and quaternary ammonium groups as the active components. Better results are achieved with weakly basic ion exchangers, i.e. those predominantly containing tertiary ammonium groups as the active components. These may be almost completely eluted with aqueous NH.sub.3.
The best results are achieved if the alkaline metal salt solutions are reacted with CO.sub.2 at pressures ranging from standard pressure to 50 bar, preferably from standard pressure to 10 bar.
The exchanger may also advantageously be laden with CO.sub.2 b
REFERENCES:
patent: 4051221 (1977-09-01), Pannekeet et al.
patent: 4079116 (1978-03-01), Ronzio et al.
patent: 4279869 (1981-07-01), Coulson
Ullmanns, Encyklopa die der technischen Chemie, Band 24, p. 466, no date.
Uranium Mining and Metallurgy, vol. 10, No. 3, Aug. 1991, pp. 39-47.
Patents Abstracts of Japan, C-37, Dec. 26, 1980, vol. 4, No. 190 Recovering Molybdenum from Water Containing the Same.
6001 Chemical Abstracts, 110:60551e (1989), Feb. 20, No. 8, Columbus, Ohio "Preparation of ammonium paratungstate with high-purity using two-step ion exchange method", no month.
Derwent Chemical Patent Index, *MEEN, M25, 94-133033/16, SU1792993-A1, "Extn. of tungsten from carbonate solns. with improved efficiency", Mosc. Mendeleev Chem Techn Inst Feb. 15, 1991.
Derwent Chemical Patent Index, *MEEN, M25, 94-133034/16, SU1792994-A1, "Extn. of tungsten from carbonate solns. includes extn. with salt of quat. ammonium base in organic dilutent to improve process efficiency", Mosc. Mendeleev Chem Techn Inst Mar. 15, 1991. resin regenerate anionite washing solution adjust total ammonia level sodium", Khabirov, V, SU1032810A.
Zhu, Yujun, "Extraction of ammonium paratungstate by ion exchange", Beijing Res. Inst. Chem. Eng. Metall., CNNC, Beijing, Pweop. Rep. China, Youkuangye (1991), 10(3), 39-47, no month.
Gutknecht Wilfried
Mathy Wolfgang
Bos Steven
Cohen Jerry
H.C. Starck GmbH & Co. KG
LandOfFree
Process for producing pure ammonium metallates does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for producing pure ammonium metallates, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing pure ammonium metallates will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1368498