Modeling and Design of Membrane Integrated Processes for HCl and Metals Recovery from Pickling Solutions

Abstract

Hydrochloric acid pickling is a common practice in steel manufacturing industry. During the process, acid is consumed to dissolve surface oxides and metals are accumulated in the solution. This fact leads to a process efficiency decrease. Continuous regeneration of pickling solutions enhances process rate and performance, but also minimises the highly expensive and environmentally risky wastewater disposal. The recovery of valuable substances (e.g. acid and metals) can be accomplished by coupling diffusion dialysis (DD) and membrane distillation (MD) technologies. In the present work, a steady state process simulator for the integrated process has been developed. The aim is to analyze and predict performances of a small pilot-scale unit to be installed and operated within a hot-dip galvanizing plant. A parametric analysis of the model is performed varying the hydrochloric acid concentration. In this way, refilling with fresh acid, as done in the normal operations, is avoided and operations are carried out under the optimal working conditions.