Process for the removal of toxic cyanide and heavy metal species from alkaline solutions
AssigneeCognis Corporation
InventorsMichael J. Virnig, Phillip L. Mattison, George A. Wolfe, J. Michael Sierakoski, Murdoch Mackenzie, Keith E. Weerts
Life of this patent
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Abstract
Toxic cyanide and anionic metal species are removed from aqueous alkaline solutions by contacting the aqueous alkaline solutions with a compound which is capable of being protonated at a pH of 9 or above.
Claims26
A process for removing anionic metal species, cyanide species, or a combination thereof from an aqueous alkaline solution containing said anionic metal or cyanide species comprising the steps of:
- ( 1) contacting a water immiscible extractant phase comprising an extractant which is capable of being protonated at a pH of 9 or above with an aqueous buffer solution having a pH of from about 8.5 to about 10.5 to form a pre-treated extractant phase;
- (2) contacting said aqueous alkaline solution with said pre-treated extractant to remove said anionic metals from said aqueous alkaline solution;
- (3) separating said anionic metal-barren aqueous solution from said extractant phase.
A continuous process for removing anionic metal species, cyanide species, or a combination thereof from an aqueous alkaline effluent comprising the steps of:
- (1) contacting a water immiscible extractant phase comprising an extractant which is capable of being protonated at a pH of 9 or above with an aqueous buffer solution having a pH of from about 8.5 to about 10.5 to form a pre-treated extractant phase;
- (2) contacting said aqueous alkaline effluent with said pre-treated extractant phase to extract said anionic metals from said aqueous alkaline effluent and form a loaded extractant phase;
- (3) separating said anionic metal-barren aqueous alkaline effluent from said loaded extractant phase;
- (4) contacting said loaded extractant phase with a strongly alkaline solution to remove said anionic metals and form a regenerated extractant phase;
- (5) acidifying said buffer solution from step (1) to pH 8.5 to 10.5;
- and (6) recycling said acidified buffer solution from step (5) and said regenerated extractant phase from step (4) to step (1).
A process for extracting anions from an alkaline aqueous solution comprising the steps of:
- (1) contacting an extractant phase which is capable of being protonated at a pH of 9 or above with an aqueous buffer solution having a pH of from about 8.5 to about 10.5 to form a buffered extractant phase;
- (2) separating said buffered extractant phase from said aqueous buffer solution;
- (3) contacting said buffered extractant phase with said alkaline aqueous solution to extract said anions.
Dependencies are inferred from the claim text.