Efficient Preparation of Metallic Bismuth from Pressure-Leaching Residue of Bismuth Sulfide Concentrate

As the leading technology for producing bismuth ingots from bismuth sulfide concentrate, pyrometallurgical smelting has the shortcomings of high energy consumption, gas pollution, and dust emissions. Hydrometallurgical treatment has been widely regarded because of its low carbon, energy efficiency, and eco-friendly characteristics. In this paper, metallic bismuth is prepared through "transformation pretreatment-methanesulfonic acid (MSA) leaching-bismuth electrodeposition" from a bismuth-based acid-leaching residue, and the separation of bismuth from associated minerals such as pyrite and molybdenite is realized. First, Bi2O(OH)2SO4 of bismuth-containing acid-leaching residue is transformed to acid-soluble Bi2O3 in NaOH solution. The transformed product is leached in MSA solution, and the obtained bismuth methanesulfonate-leaching solution is electrodeposited to generate bismuth metal. Under the optimal parameters, the total recovery ratio of bismuth from a bismuth-based acid-leaching residue to bismuth metal can reach 97%. The final-leaching residue is mainly composed of elemental sulfur and sulfide ores (pyrite, molybdenite, etc.), which can be separated and recovered by the flotation process. The purity of bismuth metal from electrodeposition is higher than 99.96%, and the waste electrolyte can be recycled to the acid-leaching procedure as the leaching agent. The proposed technology in this work can also be applied to treating bismuth-containing secondary materials and low-grade complex sulfide ores. It is expected to have bright application prospects in bismuth hydrometallurgy and sustainable metallurgy.