Process for the treatment of metal-containing water and recovery of metals therefrom

A process for the treatment of contaminated water containing iron, copper, aluminum and other metals and the recovery of copper, aluminum and spinel ferrite therefrom comprising:

• (a) precipitating and recovering copper from the contaminated water in a copper precipitation stage, wherein the precipitation is carried out at a pH of about 1 to about 2 at which copper precipitates from the water, comprising:
• (i) adding to the contaminated water at least one oxidizing agent in an amount to increase the oxidation-reduction potential of the water to a positive potential sufficient to convert iron to the ferric ion form wherein iron remains dissolved in the water at a pH of about 1 to about 2;
• (ii) adding a sufficient amount of aqueous acid or base or a mixture thereof to the contaminated water having iron in the form of ferric ion to adjust the pH of the water to a pH of about 1 to about 2 at which precipitation of copper occurs in the presence of an organic or inorganic sulfur compound;
• (iii) adding a sufficient amount of at least one organic or inorganic sulfur compound or mixture thereof, said sulfur compound having a sulfhydryl group or an ionized sulfhydryl group or a sulfur compound which is capable of producing a sulfhydryl group or an ionized sulfhydryl group, to form a copper precipitate in the water at the adjusted pH;
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• (iv) removing the copper precipitate from the water to form an aqueous supernatant substantially free of said copper;
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• (v) optionally repeating steps (a)(i) to (a)(iv) to precipitate and recover at least one other metal in at least one metal precipitation stage from the aqueous supernatant of (a)(iv) at a preselected pH at which said one other metal precipitates from the aqueous supernatant to form a precipitated metal and an aqueous supernatant substantially free of said one other metal;
• (b) precipitating and recovering aluminum from the contaminated water or from the aqueous supernatant formed in (a)(iv) or (a)(v) in an aluminum precipitation stage wherein the precipitation is carried out at a pH of about 5 at which aluminum precipitates from the water or aqueous supernatant, comprising:
• (i) adding to the water or aqueous supernatant at least one reducing agent to adjust the oxidation-reduction potential of the aqueous supernatant to a less positive or a negative potential sufficient to convert iron to the ferrous ion form wherein iron remains dissolved in the aqueous supernatant as a ferrous ion at a pH of about 5 at which aluminum precipitate is formed;
• (ii) adding aqueous acid or base or a mixture thereof to the water or aqueous supernatant having the iron in the form of ferrous ion to adjust the pH to about 5, thereby causing an aluminum precipitate to form;
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• (iii) removing the aluminum precipitate from the water or aqueous supernatant substantially free of copper to form an aqueous supernatant substantially free of copper and aluminum;
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• (c) precipitating iron and recovering spinel ferrite from the aqueous supernatant formed in (b) in a precipitation stage wherein the precipitation is carried out at a pH of about 9 to about 12 at which spinel ferrite precipitates from the aqueous supernatant comprising:
• (i) adding to the aqueous supernatant formed in (b) at least one reducing agent to adjust the oxidation-reduction potential of the aqueous supernatant to a less positive or negative potential sufficient to convert iron in the aqueous supernatant to the ferrous ion form;
• (ii) adding a stoichiometric amount of water soluble ferrous salt to the aqueous supernatant formed in (b) to provide a ferrous ion-containing water having a sufficient amount of ferrous ion to produce metal ferrite from the other metals in the ferrous ion-containing water;
• (iii) adding an amount of aqueous base to the ferrous ion-containing water sufficient to adjust the pH of the ferrous ion-containing water to about 9 to about 12;
• (iv) subjecting the ferrous ion-containing water having a pH of about 9 to about 12 to an oxidizer for a sufficient amount of time to form spinel ferrite precipitate;
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• (v) removing the spinel ferrite precipitate from the water to form water substantially free of metals.

A process for the treatment of contaminated water which contains non-ferrous and non-ferric main group, transition, lanthanide or actinide metals or mixtures thereof, and optionally iron and aluminum, and the recovery of spinel therefrom by three stages comprising:

• (a) precipitating and recovering from the contaminated water at least one non-ferrous or non-ferric metal precipitate in at least one metal precipitation stage, each metal precipitation stage being carried out at a pre-selected pH at which said metal is precipitated from the water or at a preselected pH at which said metal is precipitated from the water in the presence of an inorganic and/or organic sulfur compound, wherein the sulfur compound has a sulfhydryl group or an ionized sulfhydryl group or a sulfur compound which is capable of producing a sulfhydryl group or an ionized sulfhydryl group, and removing the metal precipitate from the water leaving an aqueous supernatant;
• (b) optionally precipitating and recovering aluminum from aluminum-containing contaminated water or from aluminum-containing aqueous supernatant formed in (a), in a metal precipitation stage wherein the precipitation is carried out at a pH of about 4 to about 6 at which pH aluminum is precipitated from the water or aqueous supernatant and is removed from the water or aqueous supernatant to form an aqueous supernatant substantially free of aluminum;
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• (c) precipitating iron and recovering spinel ferrite from the contaminated water or from the aqueous supernatant formed in precipitation stages (a) or (b) in a precipitation stage wherein the precipitation is carried out at a pH of about 9 to about 12 under controlled oxidation at which spinel ferrite is precipitated from the water or aqueous supernatant to form water substantially free of metals.

A process for the treatment of contaminated water or an aqueous supernatant derived from contaminated water and the recovery of spinel ferrite therefrom comprising:

• (a) precipitating and recovering from contaminated water or from an aqueous supernatant derived from contaminated water at least a portion of at least one non-ferrous or non ferric metal precipitate exclusive of aluminum, in at least one metal precipitation stage, each metal precipitation stage being carried out at a pre-selected pH at which said metal precipitates from the water, each precipitation and recovery stage comprising:
• (i) adding to contaminated water containing iron or to an aqueous supernatant derived from contaminated water containing iron at least one oxidizing agent to increase the oxidation-reduction potential of the water to a positive potential sufficient to convert iron in the contaminated water, to the ferric ion form wherein iron remains dissolved in the water at said pre-selected pH;
• (ii) adding aqueous acid or base or a mixture thereof to contaminated water or to an aqueous supernatant derived from contaminated water or to the water or aqueous supernatant having iron in the form of ferric ion of step (i) to adjust the pH of the water to said pre-selected pH at which precipitation of said at least one metal occurs in the presence of an organic or inorganic sulfur compound;
• (iii) adding a sufficient amount of at least one organic or inorganic sulfur compound or mixture thereof, said sulfur compound having a sulfhydryl group or an ionized sulfhydryl group or a sulfur compound which is capable of producing a sulfhydryl group or an ionized sulfhydryl group, to form a precipitate of said at least one metal in the contaminated water or aqueous supernatant at the adjusted pH;
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• (iv) removing the precipitate of said at least one metal from the contaminated water or aqueous supernatant to form an aqueous supernatant derived from contaminated water or aqueous supernatant and free of at least a portion of said at least one metal;
• (b) adding to the aqueous supernatant formed in (a)(iv) at least one reducing agent to adjust the oxidation-reduction potential of the aqueous supernatant to a less positive or a negative potential sufficient to convert iron in the aqueous supernatant, to the ferrous ion form;
• (c) adding a stoichiometric amount of water soluble ferrous salt to the aqueous supernatant of step (b) having a less positive or a negative potential to provide a ferrous ion-containing water having a sufficient amount of ferrous ion to produce metal ferrite from metals dissolved in the ferrous ion-containing water;
• (d) adding an amount of aqueous base to the ferrous ion-containing water sufficient to adjust the pH of the ferrous ion-containing water to about 9 to about 12;
• (e) subjecting the ferrous ion-containing water having a pH of about 9 to about 12 to an oxidizer for a sufficient amount of time to form spinel ferrite precipitate;
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• (f) removing the spinel ferrite precipitate from the water to form water substantially free of metals.

A process for the treatment of contaminated water or an aqueous supernatant derived from contaminated water and the recovery of spinel ferrite therefrom comprising:

• (a) precipitating and recovering aluminum from contaminated water containing aluminum or from an aqueous supernatant derived from contaminated water containing aluminum, in a metal precipitation stage wherein the precipitation is carried out at a pH of about 4 to about 6 at which aluminum precipitates from the water or aqueous supernatant, comprising:
• (i) adding to contaminated water containing iron or aqueous supernatant containing iron at least one reducing agent to adjust the oxidation-reduction potential of the water or aqueous supernatant to a less positive or a negative potential sufficient to convert iron in the water or aqueous supernatant to the ferrous ion form wherein iron remains dissolved in the water or aqueous supernatant as a ferrous ion at the pH at which aluminum precipitate is formed;
• (ii) adding aqueous acid or base or a mixture thereof to contaminated water or to aqueous supernatant or to the contaminated water or aqueous supernatant of step (i) having iron in the form of ferrous ion to adjust the pH to about 4 to about 6, thereby causing an aluminum precipitate to form;
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• (iii) removing the aluminum precipitate from the water or aqueous supernatant to form an aqueous supernatant derived from contaminated water and substantially free of aluminum;
• (b) adding to the aqueous supernatant formed in (a)(iii) at least one reducing agent to adjust the oxidation-reduction potential of the aqueous supernatant to a less positive or a negative potential sufficient to convert iron in the aqueous supernatant, to the ferrous ion form;
• (c) adding a stoichiometric amount of water soluble ferrous salt to the aqueous supernatant of step (b) having a less positive or a negative potential to provide a ferrous ion-containing water having a sufficient amount of ferrous ion to produce metal ferrite from metals dissolved in the ferrous ion-containing water;
• (d) adding an amount of aqueous base to the ferrous ion-containing water sufficient to adjust the pH of the ferrous ion-containing water to about 9 to about 12;
• (e) subjecting the ferrous ion-containing water having a pH of about 9 to about 12 to an oxidizer for a sufficient amount of time to form spinel ferrite precipitate;
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• (f) removing the spinel ferrite precipitate from the water to form water substantially free of metals.