US4145398A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bauxite digestion by caustic alkali with improved heat transfer in tubular reactors
Assignee: Vereinigte Aluminium Werke AG
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Filing: 1976-12-27
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Granted: 1979-03-20
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Expires: 1996-12-27
Abstract
Abstract A first substance and a liquid are conveyed along a conduit at least part of which is arranged in heat-exchange relationship with a second substance. Upstream of this part of the conduit, a suspension of the first substance in the liquid is formed wherein the first substance has an average particle size between 10 and 150 microns and a concentration between 1 and 6 volume percent. The suspension is conveyed along the conduit under conditions of turbulent flow. In this manner, the efficiency of the heat-exchange between the suspension and the second substance is increased. The method may be used to increase the heat-exchange efficiency in the extraction of bauxite so that an apparatus of given size can extract greater quantities of bauxite or, conversely, so that a given quantity of bauxite can be extracted with an apparatus of smaller size.
Inventors
- 👤 Ludolf Plass
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:33
CPC Classifications
C; C01; C01F; C01F7/00; C01F7/02; C01F7/04; C01F7/06; C01F7/062; C01F7/0626; Y; Y10; Y10S; Y10S165/00; Y10S165/903; Y10S423/00; Y10S423/06; Y10S423/09
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
141 words
A process for the continuous extraction of bauxite with soda lye, comprising the steps of forming a suspension of particulate bauxite in soda lye wherein the concentration of bauxite is between substantially 1 and 6 volume %, said buaxite having an average particle size between substantially 10 and 150 microns; conveying said suspension along at least one conduit at a pressure between substantially 10 and 200 atmospheres, said suspension being coveyed at a flow rate between substantially 0.5 and 7 meters per second so as to establish and maintain turbulent flow with a corresponding Reynolds Number of the order of 10 5 ; and heating said suspension to temperatures between substantially 200° and 300° C. by conveying a heated medium in countercurrent flow to said suspension along another conduit substantially concentrically arranged with and in heat-exchange relationship with said one conduit.
Claim 2
Dependent Claim
141 words
A process for the continuous extraction of bauxite with soda lye, comprising the steps of forming a suspension of particulate bauxite in soda lye wherein the concentration of bauxite is between substantially 1 and 6 volume %, said buaxite having an average particle size between substantially 10 and 150 microns; conveying said suspension along at least one conduit at a pressure between substantially 10 and 200 atmospheres, said suspension being coveyed at a flow rate between substantially 0.5 and 7 meters per second so as to establish and maintain turbulent flow with a corresponding Reynolds Number of the order of 10 5 ; and heating said suspension to temperatures between substantially 200° and 300° C. by conveying a heated medium in countercurrent flow to said suspension along another conduit substantially concentrically arranged with and in heat-exchange relationship with said one conduit.
Claim 3
Dependent Claim
37 words
A process as defined in claim 1, said extraction causing the formation of red mud; and wherein the step of forming said suspension comprises introducing at least a portion of said red mud into said soda lye.
Claim 4
Dependent Claim
78 words
In a process for the continuous extraction of bauxite with caustic liquor such as soda lye wherein the bauxite and liquor are conveyed along a confining path under pressure and heated to a final temperature by heat-exchange with a heated substance, the improvement comprising the step of forming a suspension of said bauxite in said liquor wherein said bauxite has an average particle size between substantially 10 and 150 microns, whereby the efficiency of said heat-exchange is improved.
Claim 5
Dependent Claim
78 words
In a process for the continuous extraction of bauxite with caustic liquor such as soda lye wherein the bauxite and liquor are conveyed along a confining path under pressure and heated to a final temperature by heat-exchange with a heated substance, the improvement comprising the step of forming a suspension of said bauxite in said liquor wherein said bauxite has an average particle size between substantially 10 and 150 microns, whereby the efficiency of said heat-exchange is improved.
Claim 6
Dependent Claim
21 words
A process as defined in claim 3, wherein the concentration of said bauxite is between subtantially 1 and 6 volume %.
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) | 1982-03-19 | 1982-09-18 | 1983-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-03-19 | 1986-09-18 | 1987-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-03-19 | 1990-09-18 | 1991-03-20 | $7700.00 | Window Closed / Lapsed |