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Chrome/6 Recovery from Spent Concentrated Solutions

IP.com Disclosure Number: IPCOM000086657D
Original Publication Date: 1976-Oct-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Sulich, J: AUTHOR

Abstract

This process permits the recovery of chrome-6 from waste chrome concentrates using concentrated solutions of selected oxidants. The recovered chrome-6 may be reused or sold rather than disposed of in land fills, which is the present practice.

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Chrome/6 Recovery from Spent Concentrated Solutions

This process permits the recovery of chrome-6 from waste chrome concentrates using concentrated solutions of selected oxidants. The recovered chrome-6 may be reused or sold rather than disposed of in land fills, which is the present practice.

The process consists of the stoichiometric addition of a concentrated waste solution of a selected oxidant to the spent chrome concentrate. The oxidant converts chrome-3 present to the chrome-6 form, oxidizes any organics present and raises other metals in the waste concentrate, e.g., ferrous ions, to their higher valence states. When the oxidizing reaction is completed, solid lime or concentrated lime water is added to precipitate out the soluble sulfates as calcium sulfate, the ferric ion as ferric hydroxide and any residual chrome-3 as chromic hydroxide. Next, a filtration or clarification step removes the precipitated sediments from the mother liquor, which contains the chrome-6 in soluble form.

By adjusting the pH of the mother liquor, it can deliver either primarily chromate, a 1:1 mixture or primarily dichromate. The mother liquor, properly assayed can be used to make up fresh batches of concentrated solutions, if it meets the necessary quality standards, or it can be further processed to deliver the more easily and compactly stored crystals by well-known evaporation techniques.

In situations where chrome-3 enriched sludge or waste water exists, spent solutions of co...