Method for preparing elemental sulfur and metal arsenic from arsenic sulfide slag

The invention discloses a method for preparing elemental sulfur and metal arsenic by utilizing arsenic sulfide slag. The method comprises the following steps: providing the arsenic sulfide slag; mixing the arsenic sulfide slag with lignin and acid liquor, and heating to a first preset temperature to obtain preheated ore pulp; introducing steam and oxygen into the preheated ore pulp, reacting for a first preset time at a second preset temperature and a preset oxygen partial pressure, and then carrying out solid-liquid separation treatment to obtain a leaching solution and leaching residues; heating and melting the leached residues at a third preset temperature, and carrying out hot filtration to obtain elemental sulfur; and adding a reducing agent into the leachate, reacting at a fourth preset temperature for a second preset time, and carrying out solid-liquid separation treatment to obtain metal arsenic and arsenic-precipitated liquid. According to the method, arsenic is transferred into the solution through