US 5,002,645 AGranted

Process of separating and recovering metal values from a waste stream

AssigneeSaginaw Valley State University

InventorsGeorge W. Eastland, Jr., Robert L. Wright, Thomas A. Vivian

Life of this patent

Estimating the term…

Loading patent…

Abstract

Described is a method of separating and recovering metal values from a waste stream containing metal hydroxides comprising the steps of providing an aqueous waste stream containing metal values including chromium; subjecting the waste stream to an oxidation process to convert the chromium to chromium (VI); precipitating the other metal values in the aqueous stream by adjusting the pH of the stream to cause the precipitations; and separately recovering the chromium (VI) from the remaining metal values. The process described pertains to separating and recovering metal values such as those from an electroplating process or an electroless process wherein the metals may be iron, cobalt, zinc, cadmium, nickel, copper, silver, aluminum and chromium. The chromium recovery step is performed by oxidizing chromium (III) to chromium (VI) preferably in the presence of a manganese catalyst and preferably utilizing ultrasound waves. The remaining metal values are separated by the use of a chelating ion exchange resin.

Claims13

Dependent claims

A process for separating and recovering Cr(VI) from a waste stream containing chromium and at least one metal value selected from the group consisting of copper, nickel, cobalt, zinc, cadmium and iron, comprising the steps:

(1) providing an aqueous Cr(III) waste stream having an alkaline pH further containing at least one metal value selected from the group consisting of copper, nickel, cobalt, zinc, cadmium and iron, thereby maintaining the non-chrome metal values in a precipitated state;
(2) subjecting the stream of Step 1 to an oxygen oxidation process from an oxygen source to convert the Cr(III) to Cr(VI) in the presence of a manganese catalyst and using an effective amount of ultrasonic waves to assist the conversion of Cr(III) to Cr(VI);
(3) isolating the Cr(VI) from the other metal values in the aqueous stream in Step 2 by a process of solid-liquid separation;
(4) recovering the Cr(VI) as chromic acid from the liquid portion of Step 3 using a cation exchange resin;
and
(5) dissolving the solids portion from Step 3 containing the other metal values and separating the values one from the other using an ion exchange column.

3 more elements

Dependencies are inferred from the claim text.