Das Projekt "Metal recycling during the treatment of liquid effluent arising from electrolytic strip zinc plating" wird vom Umweltbundesamt gefördert und von Verein Deutscher Eisenhüttenleute durchgeführt. General Information: Workings base on updating and analysis of existing knowledge from literature and operational experience concerning metal recovery from electrolytic galvanizing waste water as also process water. Different alternative technical procedures have been analysed and evaluated under technical and economic points of view. Solvent extraction was ascertained as best possible method for selective metal recovery from low concentrated aqueous solutions. The qualification of solvent extraction for selective metal recovery from process water of electrolytic strip galvanizing was shown by preliminary laboratory tests within a batch reactor. A qualified extract ant phase was ascertained in laboratory experiments and its composition was optimized for the treated types of process water. Chemical reaction periods, periods for phase separation, extraction efficiency, distribution equilibrium, separation efficiency and the necessary number of extraction steps have been ascertained with use of operational process water. On the base of these trials in the batch reactor a mixer-settler laboratory plant for continuous metal recovery was designed, constructed and taken into operation. In the following continuous laboratory trails were carried out to prove the qualification of the mixer-settler principle. After optimizing of operating method and parameters for the mixer-settler laboratory plant detailed results for the achievable grade of metal reduction and for maximum selectivity have been yield. Endurance trials were carried out to assay and optimize the extraction efficiency at the mixer-settler laboratory plant. Detailed results for maximum metal reduction in the process water stream were yield under review of a high metal enrichment in the stripping agent. Further aims were a low organic load of treated process water and stripping agent by the used extract ant phase as also the determination of the solvent stability. The operational concept of the new planned mixer-settler technical plant, which went into operation at Krupp Hoesch Stahl AG in Dortmund, was proved by endurance trials. The several weeks lasting trials were carried out with process water of the electrolytic strip galvanizing plant. Operational parameters of the mixer-settler technical plant were optimized for production of recyclable metal solutions and operational chemicals consumption was determined. An operational plant concept for metal recovery during strip galvanizing was finally developed on this basis.