Separation and Recycling Nitric Acid – Metals Waste Waters from a Brass Pickling by Diffusion Dialysis – Selective Physico - Chemical Methods

Abstract

This research work applies a clean technology to treatthe concentrated waste waters of a brass pickling bath. This last contains high concentration mixture of nitricacid and dissolved metals (Cu++, Zn++and Pb++). Now the studied industrial plant neutralizes HNO andprecipitates the metals with these 3 major drawbacks:

Loss of an expensive acid ( 50 % of the initialquantity ) Pollution of the treated and rejectedeffluents by nitrates

Production of a problematic ( filtration , storage ,fate …) metal hydroxides sludge ;

To solve these problems we apply a clean hybridtechnology:

The diffusion dialysis with anion exchangemembranes AMX; the result is excellent. Weseparate and purify HNO with a high efficiency.

The remaining metals mixture contains Cu++ and Pb++ which are processed by chemical (selective precipitation ) and physico – chemical (cementation ,…) methods...