Patent US481739A successfully refreshed from Google Patents.
Patent US4044095A successfully refreshed from Google Patents.
US4044095A
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Process for recovery of alumina from high-silica ore
Assignee: Alcoa Corp
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Filing: 1975-10-20
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Granted: 1977-08-23
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Expires: 1995-10-20
Abstract
Abstract Back reactions of dissolved alumina from a high caustic-lime digest of anorthosite and other alumina-containing siliceous materials can be eliminated or mitigated by control of particle size of digestible material; and time and temperature of separation of the alumina-bearing liquid from the solid residues. In one embodiment the back reaction is further controlled by adjustment of the caustic concentration of the digest effluent.
Inventors
- 👤 Lawrence Keith Hudson
- 👤 Kenneth I. Savage
- 👤 John M. Stinson, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 02:28
CPC Classifications
C; C01; C01F; C01F7/00; C01F7/02; C01F7/04; C01F7/06; C01F7/062; C01F7/0633
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
93 words
In a process for extraction of alumina from particulate aluminous material of high silica content by a digest with highly concentrated NaOH and lime to form a sodium-aluminate solution and an insoluble sodium-calcium-silicate residue, the improvement which comprises: a. digesting said material having a particle size distribution range of at least 80% by weight -35 to +325 mesh and at a temperature of at least 200° C; and b. separating said insoluble sodium-calcium-silicate residue at a temperature in the range of 120° to 200° C in a time period not exceeding 60 minutes.
Claim 2
Dependent Claim
93 words
In a process for extraction of alumina from particulate aluminous material of high silica content by a digest with highly concentrated NaOH and lime to form a sodium-aluminate solution and an insoluble sodium-calcium-silicate residue, the improvement which comprises: a. digesting said material having a particle size distribution range of at least 80% by weight -35 to +325 mesh and at a temperature of at least 200° C; and b. separating said insoluble sodium-calcium-silicate residue at a temperature in the range of 120° to 200° C in a time period not exceeding 60 minutes.
Claim 3
Dependent Claim
16 words
The process of claim 1 wherein said particle size range is from -65 to +325 mesh.
Claim 4
Dependent Claim
17 words
The process of claim 1 wherein said separation temperature is the atmospheric boiling point of the effluent.
Claim 5
Dependent Claim
20 words
The process of claim 1 wherein said separation is made in a time period of from 1 to 20 minutes.
Claim 6
Dependent Claim
48 words
The process of claim 1 wherein the solution and residue from said digest are diluted with a stream having an Na 2 O content in the range of 90 to 110 grams per liter and having an alumina/Na 2 O ratio in the range of 0.36 to 0.66.
Claim 7
Dependent Claim
138 words
In a process for the extraction of alumina from alumina-containing siliceous materials by a digest with NaOH and lime to form a sodium-aluminate solution and an insoluble sodium-calcium-silicate residue, the improvement which comprises: a. grinding said materials to a particle size distribution of at least 80% by weight from -35 mesh to +325 mesh; b. digesting the ground material in said NaOH and lime at a temperature of at least 200° C to form a slurry of dissolved sodium aluminate and an insoluble calcium silicate residue; c. cooling said slurry to a temperature below 200° C but above 120° C; d. separating the residue from the liquid portion of the slurry in a time period of from 1 to 20 minutes while maintaining the temperature above 120° C; and e. recovering alumina from the liquid by subsequent precipitation.
Claim 8
Dependent Claim
138 words
In a process for the extraction of alumina from alumina-containing siliceous materials by a digest with NaOH and lime to form a sodium-aluminate solution and an insoluble sodium-calcium-silicate residue, the improvement which comprises: a. grinding said materials to a particle size distribution of at least 80% by weight from -35 mesh to +325 mesh; b. digesting the ground material in said NaOH and lime at a temperature of at least 200° C to form a slurry of dissolved sodium aluminate and an insoluble calcium silicate residue; c. cooling said slurry to a temperature below 200° C but above 120° C; d. separating the residue from the liquid portion of the slurry in a time period of from 1 to 20 minutes while maintaining the temperature above 120° C; and e. recovering alumina from the liquid by subsequent precipitation.
Claim 9
Dependent Claim
22 words
The process of claim 6 wherein said alumina-containing material is anorthosite and separation is made at the boiling point of the slurry.
Claim 10
Dependent Claim
87 words
In a process for extraction of alumina from particulate aluminous material of high silica content by digest with highly concentrated NaOH and lime to form a sodium-aluminate solution and an insoluble sodium-calcium-silicate residue, the improvement which comprises: a. digesting material having a particle size distribution range of at least 80% by weight -35 to +325 mesh and at a temperature of at least 200° C; and b. separating said insoluble sodium-calcium-silicate residue at a temperature below about 80° C in a time period not exceeding 60 minutes.
Claim 11
Dependent Claim
87 words
In a process for extraction of alumina from particulate aluminous material of high silica content by digest with highly concentrated NaOH and lime to form a sodium-aluminate solution and an insoluble sodium-calcium-silicate residue, the improvement which comprises: a. digesting material having a particle size distribution range of at least 80% by weight -35 to +325 mesh and at a temperature of at least 200° C; and b. separating said insoluble sodium-calcium-silicate residue at a temperature below about 80° C in a time period not exceeding 60 minutes.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-22 | 1981-02-21 | 1981-08-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-22 | 1985-02-21 | 1985-08-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-22 | 1989-02-21 | 1989-08-23 | $7700.00 | Window Closed / Lapsed |