Patent US3816095A successfully refreshed from Google Patents.
US3816095A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for recovering chromium values from chromite ore
Assignee: Honeywell International Inc
•
Filing: 1972-03-09
•
Granted: 1974-06-11
•
Expires: 1992-03-09
Abstract
Abstract A method for recovering chromium values from chromite ore which initially involves pelleting a mixture of chromite ore and soda ash, preferably without the inclusion of recycled leached chromite ore residue or other refractory diluent, employing water, or preferably an electrolyte such as an aqueous solution of sodium hydroxide, potassium hydroxide, sodium aluminate, sodium silicate, sodium chromate or a mixture thereof as the pelleting liquid. To reduce the tendency of the pellets to melt and fuse during the roasting step, the chromite ore is heated under oxidizing conditions, either before or after being incorporated into the pellets, to an extent sufficient to oxidize at least 40% of the contained ferrous oxide to the ferric state. The pellets are next roasted under oxidizing conditions, preferably in a static bed, then disintegrated and extracted to obtain an aqueous solution of the soluble sodium chromate thus formed.
Inventors
- 👤 C Bruen
- 👤 W Low
- 👤 E Smalley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 03:04
CPC Classifications
C; C22; C22B; C22B34/00; C22B34/30; C22B34/32; C22B1/00; C22B1/02; Y; Y02; Y02P; Y02P10/00; Y02P10/20
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
30 words
The method of claim 1 wherein the chromite ore is heated in an oxidizing atmosphere within the range of about 500* to 925* C. for at least about 20 minutes.
Claim 2
Dependent Claim
13 words
The method of claim 1 wherein water is used as a pelleting liquid.
Claim 3
Dependent Claim
40 words
The method of claim 1 wherein a pelleting liquid is used which is an aqueous solution containing at least 5% of a compound selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium aluminate, sodium silicate and sodium chromate.
Claim 4
Dependent Claim
29 words
The method of claim 4 wherein the solution is added in an amount sufficient to contribute about 0.5 to 25% of the selected compound to the pellet, dry basis.
Claim 5
Dependent Claim
33 words
The method of claim 1 wherein there is included in the dry mix, a quantity of a refractory diluent in an amount up to 200% of the weight of the chromite ore used.
Claim 6
Dependent Claim
17 words
The method of claim 1 wherein the green pellets are dried at temperatures up to 500* C.
Claim 7
Independent Claim
115 words
A method for producing green pellets of chromite ore comprising mixing said chromite ore with sodium carbonate in the proportion of 80% to 200% of the stoichiometric amount of said sodium carbonate required to produce sodium chromate from the chromium value of the ore, pelleting the mixture using a pelleting liquid, drying the pellets at a temperature within the range of 100* to 500* C., and oxidizing at least 40% of the ferrous iron contained in the chromite ore to the ferric state by heating said pellets at a temperature between about 500* and 925* C. under an oxidizing atmosphere for a period of time sufficient to convert said ferrous iron to the ferric state.
Claim 8
Dependent Claim
41 words
The method of claim 8 wherein the drying of the green pellets and the oxidation of the contained ferrous iron in the dry pellets to ferric iron is carried out in graduated temperature zones of a travelling grate or hearth furnace.
Claim 9
Dependent Claim
11 words
The process of claim 8 wherein the pelleting liquid is water.
Claim 10
Dependent Claim
37 words
The method of claim 8 wherein the pelleting liquid is an aqueous solution containing 5 to 55% of a compound selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium aluminate, sodium silicate and sodium chromate.
Claim 11
Dependent Claim
30 words
The method of claim 11 in which the solution is added in an amount sufficient to contribute about 0.5 to 25% of the selected compound to the pellet, dry basis.
Claim 12
Dependent Claim
12 words
The method of claim 11 wherein the selected compound is sodium hydroxide.
Claim 13
Dependent Claim
36 words
The method of claim 8 wherein there is included in the dry mix, a quantity of a refractory diluent in an amount equal to between 0 and 150% of the weight of the chromite ore used.
Claim 14
Dependent Claim
12 words
The method of claim 14 wherein the refractory diluent is recycled residue.
Claim 15
Dependent Claim
12 words
The method of claim 14 wherein the refractory diluent is pyrites cinder.
Claim 16
Dependent Claim
54 words
A green pellet composed of a mixture of chromite ore having at least 40% of the ferrous iron contained in the chromite ore oxidized to the ferric state, and sodium carbonate in the proportion of 80 to 200% of the stoichiometric amount required to produce sodium chromate from the chromium value of the ore.
Claim 17
Dependent Claim
25 words
A green pellet of claim 17 containing an inert refractory diluent in an amount up to 200% of the weight of the chromite ore used.
Claim 18
Dependent Claim
14 words
The green pellet of claim 18 wherein the inert refractory diluent is pyrites cinder.
Claim 19
Dependent Claim
14 words
The green pellet of claim 18 wherein thE inert refractory diluent is recycled residue.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-10 | 1977-12-10 | 1978-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-10 | 1981-12-10 | 1982-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-10 | 1985-12-10 | 1986-06-11 | $7700.00 | Window Closed / Lapsed |