US4374805A
Expired / Lapsed
US
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Reductants for reducing metals in acid media
Assignee: UNC RESOURCES Inc
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Filing: 1980-05-07
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Granted: 1983-02-22
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Expires: 2000-05-07
Abstract
Abstract Metals such as iron, uranium, vanadium, molybdenum and rare earths are reduced to lower oxidation states in various acid media using silicon metal or an iron-silicon alloy. In particular, ferric iron and hexavalent uranium in wet-process phosphoric acid are reduced to the ferrous and tetravalent states, respectively, using silicon metal or an iron-silicon alloy to provide a feed acid which is suitable for extraction with an extractant which is selective for tetravalent uranium such as a mixture of mono- and di-(alkylphenyl) esters of orthophosphoric acid.
Inventors
- 👤 Ralph E. Worthington
- 👤 Michael A. Smith
- 👤 John M. Tobias
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 16:11
CPC Classifications
C; C01; C01G; C01G49/00; C01G43/00; C22; C22B; C22B3/00; C22B3/20; C22B3/44; C22B34/00; C22B34/20; C22B34/22; C22B34/30; C22B34/34; C22B5/00; C22B5/02; C22B5/04; C22B59/00; C22B60/00; C22B60/02; C22B60/0204; C22B60/0217; C22B60/0252; C22B60/026; C22B60/0278; C22B60/0282; Y; Y02; Y02P; Y02P10/00; Y02P10/20
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
65 words
A process for reducing iron from the ferric to the ferrous state in wet-process phosphoric acid comprising contacting wet-process phosphoric acid containing ferric iron with a reductant selected from the group consisting of silicon metal and iron-silicon alloy containing about 5 to 80% silicon by weight to reduce at least a portion of said ferric iron in said wet-process phosphoric acid to the ferrous state.
Claim 2
Dependent Claim
65 words
A process for reducing iron from the ferric to the ferrous state in wet-process phosphoric acid comprising contacting wet-process phosphoric acid containing ferric iron with a reductant selected from the group consisting of silicon metal and iron-silicon alloy containing about 5 to 80% silicon by weight to reduce at least a portion of said ferric iron in said wet-process phosphoric acid to the ferrous state.
Claim 3
Dependent Claim
26 words
The process of claim 1 wherein the temperature of said wet-process phosphoric acid is above 60° C. and a stoichiometric amount of iron-silicon alloy is employed.
Claim 4
Dependent Claim
30 words
The process of claim 1 wherein the temperature of said wet-process phosphoric acid is below 60° C. and 10 to 200 times the stoichiometric amount of iron-silicon alloy is employed.
Claim 5
Dependent Claim
17 words
The process of claim 3 wherein excess iron-silicon alloy is removed from the reduced wet-process phosphoric acid.
Claim 6
Dependent Claim
25 words
The process of claim 4 wherein said excess iron-silicon alloy after removal from said reduced wet-process phosphoric acid is recycled to reduce further fresh acid.
Claim 7
Dependent Claim
10 words
The process of claim 1 wherein said reductant is powdered.
Claim 8
Dependent Claim
19 words
The process of claim 1 wherein the temperature of said wet-process phosphoric acid is about 50° to 80° C.
Claim 9
Dependent Claim
98 words
A process for reducing iron from the ferric to the ferrous state in wet-process phosphoric acid comprising agitating wet-process phosphoric acid containing about 25 to 35% P 2 O 5 and ferric iron with a powdered reductant selected from the group consisting of silicon metal and iron-silicon alloy containing about 5 to 20% silicon by weight at a temperature of about 50° C. to 80° C. until at least a portion of said ferric iron is reduced to the ferrous state in said wet-process phosphoric acid and then removing any excess, unreacted reductant from said wet-process phosphoric acid.
Claim 10
Dependent Claim
98 words
A process for reducing iron from the ferric to the ferrous state in wet-process phosphoric acid comprising agitating wet-process phosphoric acid containing about 25 to 35% P 2 O 5 and ferric iron with a powdered reductant selected from the group consisting of silicon metal and iron-silicon alloy containing about 5 to 20% silicon by weight at a temperature of about 50° C. to 80° C. until at least a portion of said ferric iron is reduced to the ferrous state in said wet-process phosphoric acid and then removing any excess, unreacted reductant from said wet-process phosphoric acid.
Claim 11
Dependent Claim
86 words
A process for the recovery of uranium from wet-process phosphoric acid derived from the sulfuric acid acidulation of uncalcined phosphate rock comprising contacting wet-process phosphoric acid containing ferric iron and uranium values with a reductant selected from the group consisting of silicon metal and iron-silicon alloy containing about 5 to 80% silicon by weight to reduce ferric iron to ferrous iron and any hexavalent uranium to tetravalent uranium and contacting the reduced wet-process phosphoric acid with an organic extractant selective for uranium in the tetravalent state.
Claim 12
Dependent Claim
86 words
A process for the recovery of uranium from wet-process phosphoric acid derived from the sulfuric acid acidulation of uncalcined phosphate rock comprising contacting wet-process phosphoric acid containing ferric iron and uranium values with a reductant selected from the group consisting of silicon metal and iron-silicon alloy containing about 5 to 80% silicon by weight to reduce ferric iron to ferrous iron and any hexavalent uranium to tetravalent uranium and contacting the reduced wet-process phosphoric acid with an organic extractant selective for uranium in the tetravalent state.
Claim 13
Dependent Claim
33 words
The process of claim 9 wherein said organic extractant is an about 10 to 40% by volume solution of a mixture of mono- and di-(alkylphenyl) esters of orthophosphoric acid in an inert diluent.
Claim 14
Dependent Claim
20 words
The process of claim 10 wherein said organic extractant is a mixture of mono- and di-(octylphenyl) esters or orthophosphoric acid.
Claim 15
Dependent Claim
93 words
A process for reducing a metal to a lower oxidation state in an acid comprising contacting an acid selected from the group consisting of phosphoric acid, sulfuric acid and hydrochloric acid containing the metal selected from the group consisting of iron, uranium, vanadium, molybdenum and a rare earth with a reductant selected from the group consisting of silicon metal and iron-silicon all containing about 5 to 80% silicon by weight in the presence of fluoride ion to reduce at least a portion of said metal in said acid to a lower oxidation state.
Claim 16
Dependent Claim
93 words
A process for reducing a metal to a lower oxidation state in an acid comprising contacting an acid selected from the group consisting of phosphoric acid, sulfuric acid and hydrochloric acid containing the metal selected from the group consisting of iron, uranium, vanadium, molybdenum and a rare earth with a reductant selected from the group consisting of silicon metal and iron-silicon all containing about 5 to 80% silicon by weight in the presence of fluoride ion to reduce at least a portion of said metal in said acid to a lower oxidation state.
Claim 17
Dependent Claim
20 words
The process of claim 12 wherein the fluoride ion is present in an amount of about 1 to 50 grams/liter.
Claim 18
Dependent Claim
20 words
The process of claim 12 wherein the fluoride ion is present in an amount of about 5 to 50 grams/liter.
Claim 19
Dependent Claim
20 words
The process of claim 12 wherein the acid is selected from the group consisting of sulfuric acid and hydrochloric acid.
Claim 20
Dependent Claim
19 words
The process of claim 12 wherein the reduction is carried out at a temperature of 50° to 80° C.
Claim 21
Dependent Claim
17 words
The process of claim 12 wherein the fluoride ion is added to the acid as hydrogen fluoride.
Claim 22
Dependent Claim
123 words
A process for reducing a metal to a lower oxidation state in an acid comprising agitating an acid selected from the group consisting of phosphoric acid, sulfuric acid and hydrochloric acid containing a metal selected from the group consisting of iron, uranium, vanadium, molybdenum and a rare earth with a powdered reductant selected from the group consisting of silicon metal and iron-silicon alloy containing about 5 to 20% silicon by weight in the presence of fluoride ion in an amount of at least 1 gram/liter at a temperature of about 50° C. to 80° C. until at least a portion of said metal is reduced to a lower oxidation state in said acid and then removing any excess, unreacted reductant from said acid.
Claim 23
Dependent Claim
123 words
A process for reducing a metal to a lower oxidation state in an acid comprising agitating an acid selected from the group consisting of phosphoric acid, sulfuric acid and hydrochloric acid containing a metal selected from the group consisting of iron, uranium, vanadium, molybdenum and a rare earth with a powdered reductant selected from the group consisting of silicon metal and iron-silicon alloy containing about 5 to 20% silicon by weight in the presence of fluoride ion in an amount of at least 1 gram/liter at a temperature of about 50° C. to 80° C. until at least a portion of said metal is reduced to a lower oxidation state in said acid and then removing any excess, unreacted reductant from said acid.
References Cited (Backward Citations)
US2830872A
Cited
US2859092A
Cited
US2860031A
Cited
US3479139A
Cited
US3711591A
Cited
US3835214A
Cited
US3978196A
Cited
US4087512A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-02-21 | 1986-08-23 | 1987-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-21 | 1990-08-23 | 1991-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-21 | 1994-08-23 | 1995-02-22 | $7700.00 | Window Closed / Lapsed |