Method for extracting vanadium from low-grade vanadium-containing raw material and recycling wastewater

The invention relates to the technical field of vanadium extraction metallurgy, and discloses a method for extracting vanadium from a low-grade vanadium-containing raw material and recycling wastewater. The method comprises the following steps: (1) adding a low-grade vanadium-containing raw material and calcium sulfite into water for pulping, then adding sulfuric acid for leaching, adjusting the pH value of a system to 2-3 after the reaction is finished, and carrying out solid-liquid separation to obtain residues and leachate; (2) adjusting the pH value of the leachate to 5.5-7 for vanadium precipitation, and filtering to obtain a vanadium precipitate and primary wastewater; (3) adding water, sulfuric acid and a phosphorus removal agent into the vanadium precipitate for reaction, and performing solid-liquid separation to obtain filter residues and vanadium liquid; (4) adding urea into the vanadium liquid to precipitate vanadium, filtering to obtain vanadium hydroxide and secondary wastewater, and calcining th