Process for recovery of spent etchant

Details Process for recovery of spent etchant Process for recovery of spent etchant

1990-07-03

1992-04-28

Silverman, Stanley S.

Liquid purification or separation

Processes

Making an insoluble substance or accreting suspended...

210727, 210912, 210729, 210732, C02F 162

Patent

active

051086204

ABSTRACT:
A chelation process and apparatus for treating an acid solution, namely nitric acid photoengraving etchant, having a high concentration of magnesium and having a heavy metal contaminant produced by zinc leached during etching. The process requires adjusting pH of a batch quantity of the etch solution to a value permitting chelating to occur and mixing carbamic sodium salt hydrate chelating agent with the solution in quantity sufficient to cause precipitation from the solution of a carbamic salt compound precipitate of the contaminant, and separating the precipitate from the remaining solution by filter press for removal from the solution for safe environmental disposal. The remaining liquor is safely sewered. The apparatus is mobile for use on photoengraving premises.

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