US3833463A
Expired / Lapsed
US
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Method of decolorizing waste process liquid discharged by a paper mill
Assignee: OI Glass Inc
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Filing: 1972-10-26
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Granted: 1974-09-03
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Expires: 1992-10-26
Abstract
Abstract Discolored process waste liquid from a paper mill containing ecologically undesirable color bodies is subjected to a sequence of process steps serving, in aggregate, to reduce and/or eliminate the color bodies, said sequence of steps including (1) a carbonation of the waste liquid to adjust the pH to approximately neutral, (2) an addition of lime mud (principally calcium carbonate) which in the presence of carbon dioxide tends to form soluble calcium bicarbonate, (3) an optional secondary carbonation to counteract lime mud alkalinity and promote high calcium concentration, (4) a mixing clarifier addition of a slurry of lime (principally calcium oxide and calcium hydroxide), raising the pH and precipitating calcium carbonate, clarifier bottom slurry being recycled to lime slurry and bled to kiln, and (5) a carbonation of clarifier effluent with carbon dioxide to lower the pH and to react with remaining calcium to form and remove calcium carbonate and conjoint agglomeration of residual color bodies, yielding an essentially color-free effluent. The process also envisions recycling of various streams, thereby providing continuousness of the process.
Inventors
- 👤 H Croom
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:59
CPC Classifications
D; D21; D21C; D21C11/00; D21C11/04; C; C02; C02F; C02F1/00; C02F1/66; C02F2103/00; C02F2103/26; C02F2103/28; Y; Y02; Y02P; Y02P40/00; Y02P40/40; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/917; Y10S210/928
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
21 words
mixing into said carbonated liquid an amount of lime mud consisting essentially of calcium carbonate, CaCO3, forming soluble calcium bicarbonate, Ca(HCO3)2,
Claim 2
Dependent Claim
12 words
The method as claimed in claim 1 which includes the following steps:
Claim 3
Dependent Claim
19 words
mixing into said neutralized waste an amount of lime mud consisting essentially of calcium carbonate, CaCO3, forming calcium bicarbonate,
Claim 4
Dependent Claim
39 words
mixing into said carbonated and neutralized liquid an amount of lime mud consisting essentially of calcium carbonate, said carbonate at the essentially neutral pH and in the presence of carbon dioxide being essentially converted to soluble calcium bicarbonate, Ca(HCO3)2,
Claim 5
Dependent Claim
21 words
adjusting the pH of the step (2) liquid to counteract the pH elevation caused by the addition of the calcium carbonate,
Claim 6
Dependent Claim
23 words
The method as claimed in claim 1, wherein step (1) carbonation with CO2 yields a pH ranging from about 5.5 to about 8.3.
Claim 7
Dependent Claim
37 words
combining said resultant solution with a slurry, of at least one of the group calcium oxide and calcium hydroxide, thereby raising the pH sufficient to initiate precipitation of calcium carbonate and conjoint agglomeration of color bodies, and
Claim 8
Dependent Claim
27 words
recarbonating the step (2) liquid throughput to counteract the alkalinity of the added calcium carbonate and promote a formation of a liquid throughput rich in calcium ion,
Claim 9
Dependent Claim
9 words
separating the precipitate and color bodies from the liquid.
Claim 10
Dependent Claim
28 words
The method as claimed in claim 1, wherein said lime mud is introduced in plentiful excess, stoichiometrically based on the amount of carbon dioxide employed in step (1).
Claim 11
Dependent Claim
46 words
combining the step (3) throughput liquid with a slurry of at least one of the group calcium oxide and calcium hydroxide sufficient in amount to raise the pH to the saturation concentration of calcium carbonate, effecting precipitation of calcium carbonate and conjoint agglomeration of color bodies,
Claim 12
Dependent Claim
50 words
combining, with the resultant of the preceding step, an amount of at least one of the group calcium oxide and calcium hydroxide sufficient to raise the pH to the saturation point of calcium carbonate, resulting in the initiation of precipitation of calcium carbonate and conjoint agglomeration of color bodies, and
Claim 13
Dependent Claim
9 words
separating the precipitate and color bodies from the liquid.
Claim 14
Dependent Claim
18 words
The method as claimed in claim 1 which includes the step of carbonating the product of step (2).
Claim 15
Dependent Claim
30 words
recycling the liquid of step (4) to the source of said slurry composed of at least one of the group calcium oxide and calcium hydroxide for reintroduction in step (4),
Claim 16
Dependent Claim
34 words
carbonating the separated effluent from step (4) to effect (a) precipitation of residual calcium salt, (b) conjoint agglomeration separation of residual color bodies and (c) further reduction of the pH of the effluent liquid,
Claim 17
Dependent Claim
13 words
recirculating carbonated liquid in contact with said precipitate to stabilize said liquid and
Claim 18
Dependent Claim
5 words
clarifying the step (4) liquid,
Claim 19
Dependent Claim
30 words
The method as claimed in claim 1, wherein the product of mixing lime mud into the carbonated liquid is recarbonated before combining with the slurry as recited in step (3).
Claim 20
Dependent Claim
37 words
The method as claimed in claim 6, wherein a part of the secondary carbonation product and a part of the product of step (2) are recirculated to the source of lime mud for reintroduction in step (2).
Claim 21
Dependent Claim
24 words
carbonating, by the addition of carbon dioxide, the clarifier effluent of the preceding step to lower the pH and further precipitate residual calcium carbonate,
Claim 22
Dependent Claim
13 words
recarbonating step (5) liquid as needed to reduce the pH to approximately 7.5.
Claim 23
Dependent Claim
32 words
The method as claimed in claim 1, wherein a portion of the product of step (3) is continuously recirculated into the slurry of one of the group calcium oxide and calcium hydroxide.
Claim 24
Dependent Claim
14 words
recarbonating effluent from the preceding step to adjust the pH to approximate neutrality and
Claim 25
Dependent Claim
30 words
The method as claimed in claim 7, wherein the slurry product of step (3) is continuously recirculated into the slurry of one of the group calcium Oxide and calcium hydroxide.
Claim 26
Dependent Claim
7 words
separating precipitated calcium carbonate and color bodies.
Claim 27
Dependent Claim
21 words
The method as claimed in claim 9, wherein an amount of slurry is bled off and burned in a lime kiln.
Claim 28
Independent Claim
30 words
A method of treating discolored paper mill process waste liquid to remove color bodies which impart objectionable coloration to said waste liquid, said method comprising the following steps in sequence:
Claim 29
Dependent Claim
48 words
The method as claimed in claim 11, wherein the steps recited are carried out continuously with recirculation of lime mud addition product of step (2) to lime mud source and recirculation of step (3) liquid to the source of one of the group calcium oxide and calcium hydroxide.
Claim 30
Independent Claim
30 words
A method of treating discolored paper mill process waste liquid to remove color bodies which impart objectionable coloration to said waste liquid, said method comprising the following steps in sequence:
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) | 1977-09-02 | 1978-03-04 | 1978-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-02 | 1982-03-04 | 1982-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-02 | 1986-03-04 | 1986-09-03 | $7700.00 | Window Closed / Lapsed |