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US 5,205,939 AGranted
Removal of silver from aqueous systems
AssigneeNalco Chemical Company
InventorAllen R. Syrinek
Life of this patent
Estimating the term…
Abstract
High molecular weight cationic flocculents in combination with water soluble dithiocarbamates remove dissolved and colloidal silver from aqueous suspensions thereof.
Claims6
A process for removing dissolved and colloidal silver from an alkaline aqueous liquid which comprises the sequential steps of:
- a) treating the alkaline aqueous liquid with at least 3 ppm of a water soluble cationic acrylamide co-polymer which contains from 3 to 50 mole per-cent of diallyldimethyl ammonium chloride and has a molecular weight of at least 1,000,000 to flocculate the colloidal silver;
- b) filtering the flocculated alkaline aqueous liquid to form silver rich filtered solids and a filtrate;
- c) treating the filtrate produced in step (b) with at least 10 ppm of a water soluble C.sub.1 -C.sub.4 alkyl substituted dithiocarbamate to react with the dissolved silver to form a colloidal suspension of silver;
- d) treating the filtrate produced in step (c) with at least 0.1 ppm of said water soluble cationic copolymer to flocculate the colloidal silver, and then;
- e) filtering the flocculated filtrate produced in step (d) to produce silver rich filtered solids and a filtrate having a silver content of less than 2 ppm.
2 more elements
A process for removing dissolved and colloidal silver from an alkaline aqueous liquid which comprises the sequential steps of:
- a) treating the alkaline aqueous liquid with at least 10 ppm of a water soluble C.sub.1 -C.sub.4 alkyl substituted dithiocarbamate to react with the dissolved silver to form a colloidal dispersion of silver;
- b) treating the alkaline aqueous liquid produced in step (a) with at least 0.1 ppm of a water soluble cationic acrylamide copolymer which contains from 3 to 50 mole per-cent of diallyldimethyl ammonium chloride and has a molecular weight of at least 1,000,000 to flocculate the colloidal silver, and then;
- c) filtering the flocculated alkaline aqueous liquid produced in step (b) to produce silver rich filtered solids and a filtrate having a silver content below 2 ppm.
Dependencies are inferred from the claim text.