中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 35 No. 6 June 2025 |
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
3. Shanxi Key Laboratory of Copper-based New Materials, Yuncheng 044000, China）
Abstract:Highly efficient removal of impurity Bi element from scrap brass can facilitate the recycling process of brass. The effects of melting temperature, holding time and Mg-Ca alloy content on the removal effect of impurity Bi element were investigated by compound-separation method. The mechanism of the compound-separation method was revealed for removing the Bi element from a thermodynamic point of view. The results showed that the Bi content was decreased from 1.95 wt.% to 0.178 wt.% at the optimum process parameters of melting temperature of 980 °C, holding time of 20 min, and Mg-Ca alloy content of 6 wt.%, achieving a removal rate of 90.9%. A small amount of Ca-Bi compound remained in the brass matrix after refining. NaF flux can effectively wet and adsorb Ca-Bi compounds due to its low viscosity and the function of lowering the surface tension, which facilitate the agglomeration and flotation of Ca-Bi compounds to the melt surface, thereby ensuring the sufficient removal of Bi element.
Key words: scrap brass; Bi-rich phase; Mg-Ca alloying; compound-separation method
