Method for recycling spent carbon cathode of aluminum electrolysis

A method for recycling spent carbon cathode of aluminum electrolysis, comprising the following steps:

• 1) mixing spent carbon cathode particles with a sulfuric acid solution to obtain a first slurry, and performing first leaching to obtain a second slurry, wherein a concentration of the sulfuric acid solution is 0.5-8 mol/L;
• 2) evaporating and concentrating the second slurry to obtain a third slurry;
• 3) adding concentrated sulfuric acid to the third slurry to obtain a fourth slurry;
• 4) performing first-stage roasting on the fourth slurry at 150-300° C., and then performing second-stage roasting at 300-600° C. to obtain roasted carbon;
• 5) mixing the roasted carbon with a leaching agent to perform second leaching, wherein the leaching agent is water or a mixed solution of water and a first pH regulator;
• 6) adding a second pH regulator in the second leaching to control a pH value of a fifth slurry obtained at an end of the second leaching to be less than 6 or greater than 8;
• and
• 7) performing solid-liquid separation to obtain a solid phase, and drying the solid phase to obtain a carbon material.