US3911077A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tungsten recovery from tungsten ore concentrates by caustic baking
Assignee: GTE Sylvania Inc
•
Filing: 1974-09-03
•
Granted: 1975-10-07
•
Expires: 1994-09-03
Abstract
Abstract Tungsten is recovered from scheelite ore concentrates, or other tungsten concentrates which may, or may not contain scheelite in the form of sodium tungstate and in yields up to 99.5 percent or more by a process in which ground ore substantially below 200 mesh in particle size is first added to a 50 percent sodium hydroxide solution while being agitated to such an extent that the resulting mixture becomes a semi-solid as the temperature is raised above 80*C. The semi-solid is then baked at 135 to 145*C for about 1 to 2 hours, followed by adding sufficient water to the semi-solid to form a slurry having a sodium hydroxide concentration below 6 molar, separating the causticinsoluble sludge from the slurry and washing the sludge with a dilute sodium hydroxide solution to remove residual sodium tungstate.
Inventors
- 👤 Brice E Martin
- 👤 Joseph E Ritsko
- 👤 Jr Robert E Long
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:09
CPC Classifications
C; C22; C22B; C22B34/00; C22B34/30; C22B34/36; C01; C01G; C01G41/00; C22B3/00; C22B3/04; C22B3/12; Y; Y02; Y02P; Y02P10/00; Y02P10/20
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
54 words
A METHOD FOR RECOVERING SOLUBLE SODIUM TOUNGSTATE FROM TUNGSTEN ORE CONCENTRATES COMPRISING LEACHING THE CONCENTRATE IN SODIUM HYDROXIDE SOLUTION TO PRODUCE SOLUBLE TUNGSTATE AND CUSTIC INSOLUBLE CALCIUM HYDROXIDE-CONTAINING SLUDGE, DILUTINF THE LEACH SOLUTION WITH WATER SEPATATING THE LEACH SOLUTION FROM THE SLUDGE, AND CRYSTALLIZING THE SODIUM TUNGSTATE FROM THE SOLUTION WHEREIN THE IMPROVEMENT COMPRISES:
Claim 2
Independent Claim
54 words
A METHOD FOR RECOVERING SOLUBLE SODIUM TOUNGSTATE FROM TUNGSTEN ORE CONCENTRATES COMPRISING LEACHING THE CONCENTRATE IN SODIUM HYDROXIDE SOLUTION TO PRODUCE SOLUBLE TUNGSTATE AND CUSTIC INSOLUBLE CALCIUM HYDROXIDE-CONTAINING SLUDGE, DILUTINF THE LEACH SOLUTION WITH WATER SEPATATING THE LEACH SOLUTION FROM THE SLUDGE, AND CRYSTALLIZING THE SODIUM TUNGSTATE FROM THE SOLUTION WHEREIN THE IMPROVEMENT COMPRISES:
Claim 3
Dependent Claim
88 words
CARRYING OUT LEACHING BY FIRST BAKING A SEMI-SOLID MITURE OF THE CONCENTRATE IN SODIUM HYDROXIDE SOLUTION HAVING A CONCENTRATION OF AT LEAST 10 MOLAR AT A TEMPERATURE OF FROM 90*C TO A MOISTURE LEVEL OF FROM 10 TO 25 PERCENT TO CONVERT SUBSTANTIALLY ALL OF THE INSOLUBLE TUNGSTATES TO SODIUM TUNSTATE, FOLLOWED BY ADDING SUFFICIENT WATER TO THE SEMI-SOLID TO FORM A SLURRY OF SLOKDS IN SOLUTION HYDROXIDE LEACH SODIUM HAVING A CONCENTRATION BELOW ABOUT 6 MOLAR TO ACHIEVE A SUBSTANTIALLY COMPLETE SOLUBILITY OF SODIUM TUNGSTATE THEREIN, AND
Claim 4
Dependent Claim
88 words
CARRYING OUT LEACHING BY FIRST BAKING A SEMI-SOLID MITURE OF THE CONCENTRATE IN SODIUM HYDROXIDE SOLUTION HAVING A CONCENTRATION OF AT LEAST 10 MOLAR AT A TEMPERATURE OF FROM 90*C TO A MOISTURE LEVEL OF FROM 10 TO 25 PERCENT TO CONVERT SUBSTANTIALLY ALL OF THE INSOLUBLE TUNGSTATES TO SODIUM TUNSTATE, FOLLOWED BY ADDING SUFFICIENT WATER TO THE SEMI-SOLID TO FORM A SLURRY OF SLOKDS IN SOLUTION HYDROXIDE LEACH SODIUM HAVING A CONCENTRATION BELOW ABOUT 6 MOLAR TO ACHIEVE A SUBSTANTIALLY COMPLETE SOLUBILITY OF SODIUM TUNGSTATE THEREIN, AND
Claim 5
Dependent Claim
25 words
SEPARATING THE LEACH SOLUTION FROM THE SLIDGE PRIOR TO THE TIME WHEN SUBSTANTIAL REVERSAL OF TE REACTION AND REFORMATION OF INSOLUBLE TUNGSTATES BEGINS TO OCCUR.
Claim 6
Dependent Claim
25 words
SEPARATING THE LEACH SOLUTION FROM THE SLIDGE PRIOR TO THE TIME WHEN SUBSTANTIAL REVERSAL OF TE REACTION AND REFORMATION OF INSOLUBLE TUNGSTATES BEGINS TO OCCUR.
Claim 7
Dependent Claim
25 words
separating the leach solution from the sludge prior to the time when substantial reversal of the reaction and reformation of insoluble tungstates begins to occur.
Claim 8
Dependent Claim
25 words
separating the leach solution from the sludge prior to the time when substantial reversal of the reaction and reformation of insoluble tungstates begins to occur.
Claim 9
Dependent Claim
46 words
The method of claim 1 in which the concentration of the leach solution formed by the addition of water to the semi-solid is below 4.5 molar and is adjusted to within the range of about 4.5 to 5.5 molar by the addition of sodium hydroxide thereto.
Claim 10
Dependent Claim
38 words
The method of claim 1 in which the ore concentrate is added to the leach solution in an amount to achieve a mole ratio of from about 4 to 6 moles of sodium hydroxide per mole of tungsten.
Claim 11
Dependent Claim
33 words
The method of claim 1 in which the ore concentrate is ground to substantially below 200 mesh particle size, and in which baking is carried out for from about 1 to 4 hours.
Claim 12
Dependent Claim
20 words
The method of claim 4 in which baking is carried out at a temperature of from about 130* to 145*C.
Claim 13
Dependent Claim
29 words
The method of claim 1 in which the sludge is washed with a solution containing from 0 to 6 molar concentration of sodium hydroxide to remove residual sodium tungstate.
Claim 14
Dependent Claim
33 words
The method of claim 1 in which following crystallization of the sodium tungstate, the excess sodium hydroxide solution is separated therefrom and concentrated and recycled to the baking of a new ore concentrate.
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) | 1978-10-06 | 1979-04-07 | 1979-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-06 | 1983-04-07 | 1983-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-06 | 1987-04-07 | 1987-10-07 | $7700.00 | Window Closed / Lapsed |