A co-optimized control method of key parameters during operating state migration in zinc electrolysis process

Abstract

Electrolysis is the primary energy-consuming process in zinc hydrometallurgy. Time-of-use pricing policy has caused changes in the optimal operating conditions of the electrolysis cell, necessitating adjustments to key parameters such as current density and the acid-to-zinc ratio to migrate it to the desired operational state. However, while the current density can be switched instantaneously, adjustments to the acid-to-zinc ratio occur slowly, leading to a prolonged mismatch between these key parameters, increasing energy consumption. To address this problem, this paper proposes a co-optimized control method of key parameters during the operating state migration in zinc electrolysis process. First, a co-optimization model is established with current density and acid-to-zinc ratio as decision variables. Next, a cascade control framework is designed in which the current density controller is subordinate to the acid-to-zinc ratio controller, transforming the problem of solving the co-optimization model into a parameter optimization problem for the acid-to-zinc ratio controller. Finally, a fitness function representing energy efficiency, control performance, and zinc yield during the operating state migration in zinc electrolysis process is designed, and a heuristic algorithm is employed to find the optimal parameters for the acid-to-zinc ratio controller. This achieves the optimal trajectory migration of the operating state in the zinc electrolysis process. Simulation experiments demonstrate that the proposed method can reduce energy consumption during the operating state migration without compromising production efficiency, offering a new approach to energy-saving in the zinc electrolysis industry.