Analysis and optimization of water systems for water conservation and emission reduction in pyrometallurgical copper smelting processes

Copper, as a foundational material for the global transition to new energy industries, is facing increasing demand. The rapid development of the copper industry is accompanied by substantial consumption of minerals, energy, and water resources, while also generating significant volumes of wastewater and other pollutants, imposing severe environmental pressure. Water serves as both a critical resource and an essential medium in metallurgical processes, with its consumption directly linked to wastewater generation. Therefore, this study takes a typical pyrometallurgical copper smelting enterprise as a case to systematically analyze the characteristics of water metabolism throughout the entire process, identify key water-saving stages, propose water network optimization strategies, and promote the green transformation and sustainable development of the copper industry. Using material flow analysis, the study quantifies the relationships among water consumption, wastewater discharge, and recycling from a holistic process perspective. It integrates all water-use processes into a water balance system, establishes an optimization model and evaluation index system for the water network of the copper smelting enterprise, and proposes a hierarchical water-use strategy based on a "graded treatment-cascading utilization-closed-loop reuse" framework. The results show that after optimization, the enterprise's fresh water consumption decreased from 15.74 m³/t to 12.51 m³/t, a reduction of 20.52%. The recycled water usage increased from 949.67 m³/t to 1 274.54 m³/t, a rise of 34.21%. Water resource efficiency improved by 68.04%, the water recycling rate increased from 98.2% to 98.7%, system reclaimed water usage rose from 1.30 m³/t to 4.05 m³/t, and wastewater discharge decreased from 5.05 m³/t to 4.43 m³/t. This study reveals the characteristics of water flow in copper smelting processes, proposes hierarchical water-use strategies and water network optimization methods, providing a feasible technical pathway for efficient water resource management and near-zero discharge. Future work could further integrate intelligent monitoring and control technologies to achieve dynamic optimization and refined management of water systems.