Method for removing metals from acid mine drainage
First Claim
1. A method for removing metals from metal-containing acidic mine wastewater, consisting essentially of the steps of:
- (a) dispersing lignin derivatives in said wastewater;
(b) dispersing an alkali coagulant in said wastewater, thereby increasing the pH of said wastewater to about 4.5 to 8.5;
(c) after steps (a) and (b), dispersing an alkaline composition in the wastewater, thereby increasing the pH of said wastewater to about 9 to 10 and causing the formation of a floc; and
(d) separating metal-containing flocs formed in said wastewater from said wastewater.
1 Assignment
0 Petitions
Accused Products
Abstract
A method for removing metal contaminants from acidic mine wastewater using lignin derivatives, such as lignosulfonates and kraft lignin, an alkali coagulant, such as a lime compound, and an alkaline composition for increasing the pH. The lignin derivatives are dispersed in the wastewater and the coagulant is added, increasing the pH to about 4.5–8.5 and causing the formation of a floc. The alkaline composition is then added to bring the pH to about 9 to 10, causing the further formation of a floc. Optionally, air oxidation is carried out, reducing the pH to about 8.1–8.6. Optionally, a ferric or ferrous salt may also be added. The flocs comprise metal-lignin colloids, metal hydroxides and metal salts. The flocs coagulate to form a sludge. Optionally, fly ash or diatomaceous earth may be added to increase the density and stability of the sludge. The sludge that is formed contains the metals and is separated from the treated water by filtration.
35 Citations
34 Claims
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1. A method for removing metals from metal-containing acidic mine wastewater, consisting essentially of the steps of:
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(a) dispersing lignin derivatives in said wastewater; (b) dispersing an alkali coagulant in said wastewater, thereby increasing the pH of said wastewater to about 4.5 to 8.5; (c) after steps (a) and (b), dispersing an alkaline composition in the wastewater, thereby increasing the pH of said wastewater to about 9 to 10 and causing the formation of a floc; and (d) separating metal-containing flocs formed in said wastewater from said wastewater. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for removing metals from metal-containing acidic mine wastewater, consisting essentially of the steps of:
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(a) dispersing lignin derivatives in said wastewater; (b) dispersing an alkali coagulant in said wastewater, thereby increasing the pH of said wastewater to about 4.5 to 8.5; (c) after steps (a) and (b), dispersing an alkaline composition in the wastewater, thereby increasing the pH of said wastewater to about 9 to 10 and causing the formation of a floc; (d) after step (c), causing oxidation of said wastewater; and (e) separating metal-containing flocs formed in said wastewater from said wastewater. - View Dependent Claims (20, 21, 22)
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23. A method for removing metals from metal-containing acidic mine wastewater, consisting essentially of the steps of:
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(a) dispersing lignin derivatives in said wastewater; (b) dispersing an alkali coagulant in said wastewater, thereby increasing the pH of said wastewater to about 4.5 to 8.5; (c) after steps (a) and (b), dispersing an alkaline composition in the wastewater, thereby increasing the pH of said wastewater to about 9 to 10 and causing the formation of a floc; (d) adding fly ash or diatomaceous earth to said wastewater; and (e) separating metal-containing flocs formed in said wastewater from said wastewater. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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30. A method for removing metals from metal-containing acidic mine wastewater, consisting essentially of the steps of:
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(a) dispersing lignin derivatives in said wastewater; (b) dispersing an alkali coagulant in said wastewater, thereby increasing the pH of said wastewater to about 4.5 to 8.5; (c) after steps (a) and (b), dispersing an alkaline composition in the wastewater, thereby increasing the pH of said wastewater to about 9 to 10 and causing the formation of a floc; (d) after step (c), causing oxidation of said wastewater; (e) adding a ferric or ferrous salt; and (f) separating metal-containing flocs formed in said wastewater from said wastewater. - View Dependent Claims (31, 33)
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32. A method for removing metals from metal-containing acidic mine wastewater, consisting essentially of the steps of:
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(a) dispersing lignin derivatives in said wastewater; (b) dispersing an alkali coagulant in said wastewater, thereby increasing the pH of said wastewater to about 4.5 to 8.5; (c) after steps (a) and (b), dispensing an alkaline composition in the wastewater, thereby increasing the pH of said wastewater to about 9 to 10 and causing the formation of a floc; (d) after step (c), causing oxidation of said wastewater, wherein said oxidation reduces the pH of said water to about 8.7–
8.9;(e) adding a ferric salt to said water after said step of air oxidation, reducing the pH to 8.0–
8.6; and(f) separating metal-containing flocs formed in said wastewater from said wastewater.
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34. A method for removing metals from metal-containing acidic mine wastewater, consisting essentially of the steps of:
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(a) dispersing lignin derivatives in said wastewater; (b) dispersing an alkali coagulant in said wastewater, thereby increasing the pH of said wastewater to about 4.5 to 8.5; (c) after steps (a) and (b), dispersing an alkaline composition in the wastewater, thereby increasing the pH of said wastewater to about 9 to 10 and causing the formation of a floc; (d) adding a ferric salt; and (e) separating metal-containing flocs formed in said wastewater from said wastewater.
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Specification