**4. Conclusions**

The main elements (Cu, Fe and S) in sulfide concentrates have a significant influence on the arsenic distribution among gas, slag and matte phases. When the Cu content in concentrate increases, the fractional distribution of arsenic in smelting products increases, except in the gas phase. As the Fe content increases, the proportion of arsenic reporting to the gas phase increases, however, there are opposite changes in the matte and slag phases. When the S content in the initial concentrate increases, the fractional distribution of arsenic in both the matte and slag phases decreases sharply, and reporting to the gas phase increases. Through optimization of the ore proportions, the concentrate composition was changed from its initial proportions (Cu 24.4%, Fe 26.8%, S 28.7%, and other 20%) to optimized proportions (Cu 19%, Fe 32%, S 29%, and other 20%), and the distribution of arsenic among three phases was improved from the initial (gas 82.01%, slag 12.08%, matte 5.91%) to an optimized distribution (gas 94.37%, slag 3.45%, matte 2.18%). The mass fraction of arsenic in matte was reduced from 0.07% to 0.02%. The optimized result could provide direct guidance for actual production.

**Author Contributions:** Q.W. (Qinmeng Wang) carried out the research and wrote the paper. X.G. and Q.T. designed the research. Q.W. (Qiongqiong Wang) and X.G. reviewed and contributed to the final manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** The authors appreciate the financial support from the National Natural Science Foundation of China (No.51904351 and No.51620105013), Innovation-Driven Project of Central South University (No.2020CX028) and Hunan Natural Science Fund for Distinguished Young Scholar (No.2019JJ20031).

**Conflicts of Interest:** The authors declare no conflict of interest.

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