**3. Results**

The white volatile that condensed in the cold beaker at the end of the quartz tube during the roasting process is shown in Figure 3a, b, and its XRD pattern is presented in Figure 3c. The XRD pattern and ICP-AES analysis indicated that the white volatiles corresponded to As2O3 powder with 89.12% purity, which confirms that the arsenic removal in an oxygen atmosphere is mainly carried out via Equation (1). The arsenic content in the ore after roasting at different temperatures is listed in Table 3.

$$2\text{FeAsS} + 5\text{O}\_2(\text{g}) = \text{Fe}\_2\text{O}\_3 + \text{As}\_2\text{O}\_3(\text{g}) + 2\text{SO}\_2(\text{g})\tag{1}$$

**Figure 3.** (**a**) Arsenic removal from mixed ore by roasting in resistance furnace with quartz tube under air atmosphere and 1000 ◦C; (**b**) Collected As2O3 powers condensed in cold beaker; (**c**) XRD spectra of collected As2O3 powers condensed in cold beaker.


**Table 3.** Arsenic removal rate of ore subjected to roasting.

Table 3 summarizes how arsenic can be removed from arsenopyrite-bearing iron ore by roasting in an air atmosphere or nitrogen atmosphere. The arsenic removal rate increases with the increase of temperature from 700 to 1000 ◦C. The arsenic removal rate by roasting method in an air atmosphere is less than that in the nitrogen atmosphere. The arsenic removal rate in the air atmosphere is poor at 700–800 ◦C, and the arsenic removal rate is about 12%, while the rate is 76.8–95.68% in the nitrogen atmosphere.
