Ferrous dithionite process and composition for removing dissolved heavy metals from water
AssigneeRomar Technologies, Inc.
InventorRobert G. Guess
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Abstract
A process for removing dissolved heavy metal from an aqueous solution is provided where the aqueous solution is mixed with a source of ferrous ion and dithionite ion in a first step at acidic pH to reduce and permit removal of the heavy metal. Solution from the first step is reacted in a second step with hydroxide slurrys obtained from third and fourth steps. A second solution from the second step is reacted in a third step with an alkali composition and a third solution. The third solution is reacted with a chelating agent for iron and an oxidizer in a fourth step. A solution of chelated iron from the fourth step is disposed of.
Claims54
The process for removing dissolved heavy metals from aqueous solutions containing said heavy metals which comprises:
- (a) in a first reaction step, admixing and reacting a first aqueous solution containing dissolved heavy metal ions with a source of ferrous ion and dithionite ion at a pH between about 1 and 7 to effect reduction and precipitation of said heavy metals from said first solution, separating said reduced heavy metals from said first solution, to form a first liquid effluent from said first reaction step, (b) in a second step, admixing said first liquid effluent with an aqueous composition selected from the group consisting of water and an acidic aqueous solution of heavy metals to produce a second liquid effluent, (c) in a third reaction step, admixing and reacting said second liquid effluent with a water soluble alkali composition to produce a slurry and a third liquid effluent, and (d) recycling said slurry to at least one of said first reaction step, said second step, or said third reaction step.
Dependencies are inferred from the claim text.