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Separation of tungsten from ammonium molybdate solutions

a technology of ammonium molybdate and tungsten, which is applied in the direction of molybdeum compounds, iron compounds, chromates/bichromates, etc., can solve the problems of difficult work, difficult to separate tungsten from molybdenum in aqueous solutions, and difficult to work with tungsten

Inactive Publication Date: 2013-09-19
ORCHARD MATERIAL TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This patent describes a way to separate tungsten from molybdenum and ammonium molybdate solutions. The method involves dissolving molybdenum trioxide in water and adding certain metal generating compounds to create a tungsten-containing precipitate. Calcium, iron, and manganese are the preferred metal generating compounds used in this process.

Problems solved by technology

In its raw form, tungsten is a steel-gray metal that is often brittle and hard to work, but, if pure, it can be worked easily by forging, drawing, extruding or sintering.
The separation of tungsten from molybdenum in aqueous solutions presents a challenge due to the similarity of the chemical properties of these two metals.
These processes cannot be applied for the separation of tungsten from ammonium molybdate solutions.
The procedure was performed according to the publication by the inventors hereof and it was found that the process took as long as seven days, making any industrial application of the process impractical and undesirable.
However, preliminary purification is recommended and methyl alcohol, which is highly toxic, is used to precipitate the ammonium molybdate.
The process is difficult to commercialize because it requires significant amounts of tin (IV) oxide hydrate.
It is difficult to imagine a practical way of rejuvenation of tin oxide and further utilization of tungsten.

Method used

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  • Separation of tungsten from ammonium molybdate solutions
  • Separation of tungsten from ammonium molybdate solutions
  • Separation of tungsten from ammonium molybdate solutions

Examples

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example 1

[0054]Calcium acetate and calcium hydroxide were used to experimentally verify the general concept of the feasibility of using calcium to precipitate tungsten from ammonium molybdate solutions.

[0055]Required aliquots of either calcium acetate solution or calcium hydroxide (as set forth in Table 4) were added to 100 mL of the ammonium molybdate solution at room temperature (25° C.). The pH was kept at about 10.1. The slurry was agitated for three hours and the precipitate was filtered and washed. The solutions were submitted for analysis. The results are set forth in Table 4.

TABLE 4Precipitation of Tungsten with Calcium CompoundsVol-ume,MoW% WMlg / Lmgg / LmgRemovedMo / WFeedSolutionFiltrate100263263000.34934.90754CalciumAcetateAddition =4 mLFiltrate174115200100.08915.5421290CalciumAcetateAddition =5 mLFiltrate174510887400.09817.1865189Ca(OH)2Addition =0.3 gFiltrate170478812600.07713.1886203Ca(OH)2Addition =0.3 gFiltrate186193358980.10018.6611930

example 2

[0056]In this example, ferric molybdate was used for tungsten precipitation. A sample of ferric molybdate was prepared by dissolving 100 grams of ferric sulfate (20 grams iron) in water and then adding to an ammonium molybdate solution. The slurry was agitated for an hour and the precipitate was filtered and washed. The weight of the wet cake containing 5% iron was 400 grams. An ammonia digestion of 440 grams of leached cake was started by sequential additions of cake and ammonium hydroxide maintaining the pH at 8.5 to 8.7 at approximately 60° C. Thirty minutes after the last addition, 100 grams of the ferric molybdate cake was added (about 5 g Fe / L) and the slurry was agitated for another 30 minutes. The slurry was filtered and the cake was washed. Afterwards, 200 mL aliquots were heated to 60° C. and ferric molybdate additions of 2, 4, 8, and 16 grams were made (0.5, 1.0, 2.0, and 4.0 g Fe / L). After one hour of agitation, the slurries were filtered. The solutions and the solids th...

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Abstract

Disclosed is process for the separation of tungsten from molybdenum and more particularly from ammonium molybdate solutions. The method comprises dissolving technical grade molybdenum trioxide in an aqueous ammonium hydroxide solution and further adding certain metal generating compounds to the aqueous solution thereby generating a tungsten-containing precipitate. Calcium, iron and manganese are the preferred metal generating compounds of the invention. Certain temperature and pH values of the system, as disclosed, are preferred for the precipitation of the tungsten from the ammonia molybdate solution.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application is a U.S. National Stage application under 35 U.S.C. §365 of PCT Application No. PCT / US2011 / 23852 filed Feb. 7, 2011, which claims priority under 35 U.S.C. §120 to U.S. Non-provisional patent application Ser. No. 12 / 875,385 filed on Sep. 3, 2010; which priority Under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 61 / 302,378 filed on Feb. 8, 2010, the subject matter of which are hereby incorporated by reference in their entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]The present invention was not developed with the use of any Federal Funds, but was developed independently by the inventors.BACKGROUNDField and Background of the Invention[0003]Tungsten was discovered and isolated in the late 18th century. Tungsten is found in the minerals wolframite (iron-manganese tungstate, FeWO4 / MnWO4), scheelite (calcium tungstate, (CaWO4), ferberite (FeWO4) and hithnerite (MnWO4). I...

Claims

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Application Information

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IPC IPC(8): C22B34/34
CPCC01G49/0018C22B34/34
Inventor SHEKHTER, LEONID N.LITZ, JOHN E.WEI, XIONGMCHUGH, LAWRENCE F.
Owner ORCHARD MATERIAL TECH