To reduce the release of arsenic from non-ferrous metal (especially copper) smelting flue gases as well as to recover arsenic, the dry quenching process has been successfully applied to remove arsenic. However, the formation of arsenate hindered the separation of arsenic, thus reducing the collection efficiency. To tackle the bottleneck, the strategy of mineral phase regulation was proposed by the conversion from arsenate to sulfate, metal sulfate and gaseous arsenic were formed and separated each other. Chalcopyrite served as a potential sulfation regulator due to the gradual production of active sulfur (S2 dimer and S monomers) at high temperatures. At a chalcopyrite dosage of 60%, the separation efficiency of arsenic from the metals reached 93.78% and the residual arsenic content in the arsenic-copper particulate matter was decreased from 40.38% to 3.12% at 700 °C. The separation of arsenic and metal was attributed to the release of active sulfur from chalcopyrite, which enhanced the conversion of arsenate to sulfate. The separated arsenic enters the following section in the form of gaseous As2O3, which is beneficial to the dry quenching collection of arsenic. This provides theoretical and technical support for the clean production of nonferrous metal smelting and the control of arsenic pollution in flue gas.