Processing nonferrous metal hydroxide sludge wastes

Claim 1

A method for separately recovering nonferrous metals from hydroxide sludge wastes which contain as the main nonferrous metals, chromium, copper, zinc, and nickel, comprising the steps of: a. chlorinating the aqueous waste sludge suspension at temperatures of about 20° to 80° C. and pH values between 4 and 13, acidifying the chlorinated waste with sulfuric acid to reach a pH value from 1.0 to 3.0, separating the insoluble components therefrom to produce a solution containing Cr(VI) and treating this aqueous solution in a fixed bed anion exchanger at pH values of <3 to separate the Cr(VI) therefrom; b. separating the copper from the aqueous solution remaining from step a) by liquid-liquid extraction at a pH from 1.5 to 2.5 using an extraction liquid selected from the group consisting of substituted hydroxybenzophenonoximes diluted with petroleum; c. separating the zinc at a pH about 2 to 3 from the aqueous solution containing chloride and sulfate remaining from (b) by liquid-liquid extraction using as the extraction means an organophosphoric acid having the formula (OR).sub.2 POOH wherein R is alkyl; d. precipitating and separating the aluminum in the form of hydroxide from the aqueous solution remaining from step c) by filtration thereof and separating the nickel from the filtrate by liquid-liquid extraction wherein the extracting agent is the sodium salt of the diluted di-(2-ethylhexyl-) phosphoric acid with a highly boiling aromatic solvent, the amount of di-(2-ethylhexyl-)phosphoric acid in the mixture being 40% by volume.

Claim 2

A method for separately recovering nonferrous metals from hydroxide sludge wastes which contain as the main nonferrous metals, chromium, copper, zinc, and nickel, comprising the steps of: a. chlorinating the aqueous waste sludge suspension at temperatures of about 20° to 80° C. and pH values between 4 and 13, acidifying the chlorinated waste with sulfuric acid to reach a pH value from 1.0 to 3.0, separating the insoluble components therefrom to produce a solution containing Cr(VI) and treating this aqueous solution in a fixed bed anion exchanger at pH values of <3 to separate the Cr(VI) therefrom; b. separating the copper from the aqueous solution remaining from step a) by liquid-liquid extraction at a pH from 1.5 to 2.5 using an extraction liquid selected from the group consisting of substituted hydroxybenzophenonoximes diluted with petroleum; c. separating the zinc at a pH about 2 to 3 from the aqueous solution containing chloride and sulfate remaining from (b) by liquid-liquid extraction using as the extraction means an organophosphoric acid having the formula (OR).sub.2 POOH wherein R is alkyl; d. precipitating and separating the aluminum in the form of hydroxide from the aqueous solution remaining from step c) by filtration thereof and separating the nickel from the filtrate by liquid-liquid extraction wherein the extracting agent is the sodium salt of the diluted di-(2-ethylhexyl-) phosphoric acid with a highly boiling aromatic solvent, the amount of di-(2-ethylhexyl-)phosphoric acid in the mixture being 40% by volume.