Mass Integration for Recovery of Zinc from Galvanizing and Metal Finishing Industry Using Supertargeting Approach

Abstract

This paper presents an optimization technique, based on Supertargeting Approach, for the synthesis of solvent extraction and ion exchange network, which broadly falls under Mass Exchange Network (MEN). Supertargeting approach has been successfully applied for targeting and designing of Heat Exchange Network (HEN). The present work is related to the recovery of zinc from spent pickle liquor and the rinse water, an effluent of galvanizing and metal finishing industry. Three Mass Separating Agents (MSAs): tributyle phosphate (S1), triisooctyle amine (S2) and di-2-ethyl hexyl phosphoric acid (S3) for solvent extraction; two resins: a strong acid cation resin (I1) and a strong base anion resin (I2) for ion exchange; two solutions: 4% HCl (H1) & 4% NaOH (H2) for regeneration of resins, I1 & I2, and water for rinsing after regeneration of resins have been proposed to recover zinc from spent liquor and rinse water. The minimum composition difference of zinc, , between operating condition and equilibrium condition is found to be a key optimization variable. This paper describes the targeting as well as designing procedures for optimization of present MEN. The optimum targeted total annual cost (TAC) and  of MEN have been computed to be Rs. 17851660/yr and 0.0002 respectively. During the design stage, it has been possible to achieve the targeted results. The optimum MEN consists of 6 units - four packed and two tray type columns.