Original Article

Recovery of nickel, cobalt and copper from nickel slag by a new process of reduction-sulfurizing smelting

¹ State Key Laboratory of Ni & Co Associated Minerals Resources Development and Comprehensive Utilization, Jinchang, Jin Chuan Group Co., Ltd., 737104, Gansu, PR China
² School of Materials Science and Engineering, State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, Gansu, PR China

^* e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 26 June 2025
Accepted: 30 October 2025

Abstract

An innovative technology was proposed for recovering valuable metals from nickel slag by employing nickel sulfide concentrate as a sulfurizing agent and granulated coal as a reduction agent to convert Co, Ni, and Cu into sulfides. Thermodynamic analysis confirmed the feasibility of this “reduction-sulfurization” approach. Industrial-scale pilot tests were conducted using the nickel slag. The results demonstrated that Co, Ni and Cu in the nickel slag could be effectively sulfurized by FeS₂ in the nickel sulfide concentrate under the reducing atmosphere. After smelting, Matte was enriched from the nickel slag and settled at the bottom. The physical separation of the cleaned slag and matte phase were carried out at high temperature. Compared to the nickel slag, the cleaned slag showed remarkable reductions in Co, Ni, and Cu content exceeding 50%, 60%, and 25%, respectively. This work establishes a scalable and cleaner reduction-sulfurization route that lowers emissions and costs while enabling sustainable recovery of Co-Ni-Cu from nickel slag.