US4018680A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for separating iron, zinc and lead from flue dust and/or flue sludge
Assignee: Von Roll AG
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Filing: 1976-02-24
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Granted: 1977-04-19
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Expires: 1996-02-24
Abstract
Abstract There is disclosed a process for separating iron, zinc and lead from flue dust and/or flue sludge, wherein the three following reaction stages are performed in the aqueous phase: A. Oxidation of the iron and filtration of the resulting first turbid liquid; B. Suspension and acidification of a first filtration residue and subsequent filtration of the resulting second turbid liquid, whereby a second filtration residue containing mainly iron sludge is obtained; C. Neutralization of the filtrate and subsequent filtration of the resulting third turbid liquid, whereby a third filtration residue containing the precipated heavy metals is obtained.
Inventors
- 👤 Rudolf Kupfer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 17:50
CPC Classifications
C; C22; C22B; C22B7/00; C22B7/02; C21; C21B; C21B3/00; C21B3/04; C22B3/00; C22B3/20; C22B3/22; C22B7/04; Y; Y02; Y02P; Y02P10/00; Y02P10/20; Y02W; Y02W30/00; Y02W30/50; Y10; Y10S; Y10S75/00; Y10S75/961
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
248 words
A process for separating iron, zinc and lead from a weakly alkaline flue dust and/or flue sludge wherein said flue dust and/or flue sludge are suspended in aqueous phase comprising the sequential steps of treating said aqueous suspension with sufficient hydrogen peroxide so as to oxidize iron whereby said treated aqueous suspension comprises a first liquid phase and a first solid phase; separating said first liquid phase and said first solid phase by filtration so as to produce a first filtrate and a first solid residue; suspending said first solid residue in an aqueous phase and treating said aqueous suspension of said first solid residue with sufficient hydrochloric acid so as to change the pH of said aqueous suspension of said first solid residue to about 5 whereby said treated aqueous suspension of said first solid residue comprises a second liquid phase and a second solid phase; separating said second liquid phase and said second solid phase by filtration so as to produce a second solid residue, consisting essentially of iron sludge and a second filtrate; treating said second filtrate with sufficient milk of lime so as to change the pH of said second filtrate to about 8.3 whereby said treated second filtrate comprises a third liquid phase and a third solid phase; a separating said third liquid phase and said third solid phase by filtration so as to produce a third solid residue comprising lead and zinc, and a third filtrate substantially free of dissolved heavy metals.
Claim 2
Dependent Claim
248 words
A process for separating iron, zinc and lead from a weakly alkaline flue dust and/or flue sludge wherein said flue dust and/or flue sludge are suspended in aqueous phase comprising the sequential steps of treating said aqueous suspension with sufficient hydrogen peroxide so as to oxidize iron whereby said treated aqueous suspension comprises a first liquid phase and a first solid phase; separating said first liquid phase and said first solid phase by filtration so as to produce a first filtrate and a first solid residue; suspending said first solid residue in an aqueous phase and treating said aqueous suspension of said first solid residue with sufficient hydrochloric acid so as to change the pH of said aqueous suspension of said first solid residue to about 5 whereby said treated aqueous suspension of said first solid residue comprises a second liquid phase and a second solid phase; separating said second liquid phase and said second solid phase by filtration so as to produce a second solid residue, consisting essentially of iron sludge and a second filtrate; treating said second filtrate with sufficient milk of lime so as to change the pH of said second filtrate to about 8.3 whereby said treated second filtrate comprises a third liquid phase and a third solid phase; a separating said third liquid phase and said third solid phase by filtration so as to produce a third solid residue comprising lead and zinc, and a third filtrate substantially free of dissolved heavy metals.
Claim 3
Dependent Claim
15 words
A process in accordance with claim 1 wherein said hydrochloric acid comprises concentrated hydrochloric acid.
Claim 4
Dependent Claim
316 words
A process for separating iron, zinc and lead from a weakly alkaline flue dust and/or flue sludge wherein said flue dust and/or flue sludge are suspended in an aqueous phase comprising the sequential steps of treating said aqueous suspension with sufficient hydrogen peroxide so as to oxidize iron whereby said treated aqueous suspension comprises a first liquid phase and a first solid phase; separating said first liquid phase and said first solid phase by filtration so as to produce a first filtrate and a first solid residue; suspending said first solid residue in aqueous phase and treating said aqueous suspension of said first solid residue with sufficient hydrochloric acid so as to change the pH of said aqueous suspension of said first solid residue to about 5 whereby said treated aqueous suspension of said first solid residue comprises a second liquid phase and a second solid phase; separating said second liquid phase and said second solid phase by filtration so as to produce a second solid residue, consisting essentially of iron sludge and a second filtrate; treating said second filtrate with sufficient soda solution so as to change the pH of said second filtrate to between about 6.0 and 6.5 whereby said treated second filtrate comprises a third liquid phase and a third solid phase; separating said third liquid phase and said third solid phase by filtration so as to produce a third solid residue, consisting essentially of lead sludge, and a third filtrate; treating said third filtrate with sufficient milk of lime so as to change the pH of said third filtrate to about 8.3 whereby said treated third filtrate comprises a fourth liquid phase and a fourth solid phase; and separating said fourth liquid phase and said fourth solid phase by filtration so as to produce a fourth solid residue consisting essentially of zinc, and a fourth filtrate substantially free of dissolved heavy metals.
Claim 5
Dependent Claim
316 words
A process for separating iron, zinc and lead from a weakly alkaline flue dust and/or flue sludge wherein said flue dust and/or flue sludge are suspended in an aqueous phase comprising the sequential steps of treating said aqueous suspension with sufficient hydrogen peroxide so as to oxidize iron whereby said treated aqueous suspension comprises a first liquid phase and a first solid phase; separating said first liquid phase and said first solid phase by filtration so as to produce a first filtrate and a first solid residue; suspending said first solid residue in aqueous phase and treating said aqueous suspension of said first solid residue with sufficient hydrochloric acid so as to change the pH of said aqueous suspension of said first solid residue to about 5 whereby said treated aqueous suspension of said first solid residue comprises a second liquid phase and a second solid phase; separating said second liquid phase and said second solid phase by filtration so as to produce a second solid residue, consisting essentially of iron sludge and a second filtrate; treating said second filtrate with sufficient soda solution so as to change the pH of said second filtrate to between about 6.0 and 6.5 whereby said treated second filtrate comprises a third liquid phase and a third solid phase; separating said third liquid phase and said third solid phase by filtration so as to produce a third solid residue, consisting essentially of lead sludge, and a third filtrate; treating said third filtrate with sufficient milk of lime so as to change the pH of said third filtrate to about 8.3 whereby said treated third filtrate comprises a fourth liquid phase and a fourth solid phase; and separating said fourth liquid phase and said fourth solid phase by filtration so as to produce a fourth solid residue consisting essentially of zinc, and a fourth filtrate substantially free of dissolved heavy metals.
Claim 6
Dependent Claim
22 words
A process in accordance with claim 3 wherein said soda solution comprises a 10% aqueous solution of Na 2 CO 3 .
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) | 1980-04-18 | 1980-10-18 | 1981-04-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-18 | 1984-10-18 | 1985-04-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-18 | 1988-10-18 | 1989-04-19 | $7700.00 | Window Closed / Lapsed |