## 1 Introduction
An oxidative pretreatment-thiosulfate leaching-electrodeposition process was employed, which avoided the emission of harmful gases, such as sulfur dioxide and ammonium; the maximum recovery of Ag using this process was 95.4%. However, both these methods have challenges, such as a long metal recovery cycle and difficulty in treating acid-containing wastewater [1]. Furthermore, a pyro-hydrometallurgical process [10], sulfation roasting-water adsorption, was proposed to treat CAS, and was first conducted to recover selenium. Subsequently, water leaching-iron powder cementation was adopted to extract Cu from the roasted residue. Afterwards, selective chloride leaching-H\({}_{2}\)C\({}_{2}\)O\({}_{4}\) reduction was applied to \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Resource** & **Ag** & **Au** & **As** & **Pb** & **Bi** \\ \hline La Caridad Copper Refinery [8] & 15.4 & 0.04 & 5.00 & 14.80 & 1.20 \\ Qinghai Copper Industry Co. [9] & 5.00 & 0.15 & 2.12 & 28.5 & 4.61 \\ Sarkuysan Copper, Turkey [5] & 2.80 & 0.23 & 3.93 & 12.93 & 0.15 \\ Medium-scale copper smelter in western China [10] & 5.36 & 0.16 & 2.38 & 28.65 & 3.86 \\ Yunnan [11] & 4.79 & 0.18 & 6.21 & 3.18 & 3.15 \\ Toyama, Japan [12] & 17.00 & 1.04 & 0.41 & 35.10 & – \\ Tehran, Iran [13] & 7.07 & 0.08 & 0.42 & 4.42 & 0.08 \\ Noranda (Canada) [14] & 19.50 & 0.18 & 1.14 & 8.00 & 0.77 \\ IMI Refinery (UK) [14] & 5.50 & 0.07 & 3.50 & 22.00 & 0.50 \\ INCO (USA) [14] & 6.37 & 0.12 & 0.50 & 1.70 & 0.14 \\ La Caridad Copper Refinery (Mexico) [8] & 15.40 & 0.04 & 5.00 & 14.80 & 1.20 \\ Rio Tinto Minera Copper Refinery, Huelva (Spain) [15] & 14.54 & 0.38 & 3.41 & 2.89 & 0.76 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Composition of CAS from various refineries (wt. %). extract Au from the copper-leaching residue. Finally, sulfite leaching-Na\({}_{2}\)S\({}_{2}\)O\({}_{4}\) reduction was employed to recover Ag from the gold-leaching residue, and the barren leachate was recycled for use in silver leaching with the addition of a small quantity of lixiviant. The use of this integrated pyroo-hydrometallurgical process resulted in recovery yields of 98.7% of Au, 98.6% of Ag, and 99.8% of Pb from the mud. In the traditional pyrometallurgical process, Pb, Bi, As, and other base metals are mainly removed during oxidation refinement in a silver separation furnace. This removal depends on the different affinities of each metal element for oxygen to enable sequential oxidation, subsequent transfer into the slag or dust, and separation from the precious metals [19]. However, this process generates a large amount of soot and precious metal-containing slag. Therefore, vacuum distillation was introduced to replace the oxidation-blowing process of precious metals in the traditional firing method; since then, it has also been industrially applied [20]. This process relies on the difference in physicochemical properties between base metals and noble metals to volatilize the group with a higher vapor pressure in order to enrich the noble metals. However, anode slime with a high arsenic content will produce a high concentration of arsenic oxide fume during smelting, which can cause serious and irreversible damage to the environment and human health [21]. Arsenic emission has always been a challenge for lead and copper smelting enterprises. Arsenic continually accumulates in each step of the traditional pyrometallurgical process and has not been effectively opened up [22]. The current pyrometallurgical process uses reduction melting, which inevitably generates arsenic oxide fume and dust. Therefore, this paper we used a vacuum carbothermal reduction method to treat anode slime. During the low-temperature vacuum carbothermal reduction, arsenic is volatilized as arsenic oxide and recovered as volatiles, and no soot is generated in the process. The arsenic content in the residue was reduced from 9.35% to 0.48%, realizing 94.89% arsenic removal [23].