US4954262A
Expired / Lapsed
US
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Method and apparatus for recovering sulfuric acid from a titanium sulfate waste liquor
Assignee: AGC Inc
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Filing: 1989-10-31
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Granted: 1990-09-04
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Expires: 2009-10-31
Abstract
Abstract A method for recovering sulfuric acid from a titanium sulfate waste liquor by diffusion dialysis in a diffusion dialytic cell provided with anion exchange membranes, which comprises subjecting the titanium sulfate waste liquor to precision filtration to remove a solid content having a particle size of at least 0.1 μm to a level of not more than 100 μg/l, and placing the filtered liquor to face water with an anion exchange membrane interposed therebetween so that sulfuric acid in the titanium sulfate waste liquor is recovered by diffusion dialysis.
Inventors
- 👤 Yoshiharu Aoki
- 👤 Toshikatsu Hamano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:49
CPC Classifications
B; B01; B01D; B01D61/00; B01D61/24; B01D61/243; C; C01; C01B; C01B17/00; C01B17/69; C01B17/90; C01B17/901; C01B17/902; B01D2325/00; B01D2325/42
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
105 words
A method for recovering sulfuric acid from a titanium sulfate waste liquor by diffusion dialysis in a diffusion dialytic cell provided with anion exchange membrane, which comprises; subjecting the titanium sulfate waste liquor to precision filtration to remove a solids content having a particle size of at least 0.1 μm to a level of not more than 100 μg/l; and placing the filtered liquor to face water with an anion exchange membrane interposed therebetween so that sulfuric acid in the titanium sulfate waste liquor is recovered by diffusion dialysis at a temperature sufficiently low to substantially preclude adherence of titanium oxide particles to said membrane.
Claim 2
Independent Claim
105 words
A method for recovering sulfuric acid from a titanium sulfate waste liquor by diffusion dialysis in a diffusion dialytic cell provided with anion exchange membrane, which comprises; subjecting the titanium sulfate waste liquor to precision filtration to remove a solids content having a particle size of at least 0.1 μm to a level of not more than 100 μg/l; and placing the filtered liquor to face water with an anion exchange membrane interposed therebetween so that sulfuric acid in the titanium sulfate waste liquor is recovered by diffusion dialysis at a temperature sufficiently low to substantially preclude adherence of titanium oxide particles to said membrane.
Claim 3
Dependent Claim
27 words
The method according to claim 1, wherein the titanium sulfate waste liquor and water are supplied in a flow ratio by volume of from 2/1 to 0.5/1.
Claim 4
Dependent Claim
31 words
The method according to claim 1, wherein the precision filtration is conducted by a precision filter having a porous filtering surface having a pore diameter of not more than 0.1 μm.
Claim 5
Dependent Claim
26 words
The method according to claim 3, wherein the precision filter is a hollow fiber or spiral type ultrafilter, a millipore filter or a porous tube filter.
Claim 6
Dependent Claim
63 words
The method according to claim 1, wherein the titanium sulfate waste liquor is placed to face water in a multistage diffusion dialytic cell provided with anion exchange membranes, and the titanium sulfate waste liquor is supplied from the first stage to the last stage of the multistage diffusion dialytic cell, while water is supplied countercurrently from the last stage to the first stage.
Claim 7
Dependent Claim
35 words
The method according to claim 5, wherein the multistage diffusion dialytic cell has two stages, and the recovery ratio of sulfuric acid of the first stage to the second stage is from 0.3 to 3.0.
Claim 8
Dependent Claim
21 words
The method according to claim 1, wherein the anion exchange membranes are periodically treated by an aqueous solution containing a bactericide.
Claim 9
Dependent Claim
27 words
The method according to claim 7, wherein the aqueous solution containing a bactericide is an aqueous formalin solution containing from 0.01 to 20% by weight of formaldehyde.
Claim 10
Dependent Claim
42 words
The method according to claim 1, wherein the temperature of the diffusion dialytic cell is lowered to a temperature lower than the temperature corresponding to the desired remaining acid concentration in the titanium sulfate waste liquor as defined in attached FIG. 1.
Claim 11
Dependent Claim
48 words
The method according to claim 9, wherein the temperature of the diffusion dialytic cell is maintained at a level of not higher than 30° C, and the concentration of free sulfuric acid in the titanium sulfate waste liquor is reduced to a level of not higher than 2.0N.
Claim 12
Dependent Claim
24 words
The method according to claim 1, wherein the anion exchange membranes have an ion exchange capacity of from 2 to 5 meq/g dry resin.
Claim 13
Dependent Claim
36 words
The method according to claim 1, wherein the titanium sulfate waste liquor is a waste liquor from a process for producing titanium oxide by a sulfuric acid method, which contains titanium dioxide as a solid content.
References Cited (Backward Citations)
US4111866A
Cited
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