NOVELTY - Electrolytic manganese dioxide is prepared by placing manganese oxide powder with size of greater than or equal to 150 meshes, pyrite powder, and sulfuric acid in leaching reaction tank according to weight ratio of 10000 g:1000-1200 g:1000-2000 g, stirring at 60-100 rpm, reacting at 85-90 degrees C for 2-3 hours, adjusting stirring speed to 30-50 rpm and temperature to 90-95 degrees C, introducing sulfur dioxide (SO2) gas according to ratio of 10000 g:0.5-3 mol, reacting for 1-1.5 hours, extracting crude manganese sulfate solution slurry, adding sulfuric acid (H2SO4) at normal temperature, and neutralizing solution.    USE - Preparation of electrolytic manganese dioxide for button-type zinc/manganese dioxide alkaline battery (claimed).    ADVANTAGE - Production process is simplified, production efficiency and product performance and quality are improved, and production cost is reduced.    DETAILED DESCRIPTION - Electrolytic manganese dioxide is prepared by placing manganese oxide powder with size of greater than or equal to 150 meshes, pyrite powder, and sulfuric acid in leaching reaction tank according to weight ratio of 10000 g:1000-1200 g:1000-2000 g, stirring at 60-100 rpm, reacting at 85-90 degrees C for 2-3 hours, adjusting stirring speed to 30-50 rpm and temperature to 90-95 degrees C, introducing sulfur dioxide (SO2) gas according to ratio of 10000 g:0.5-3 mol, reacting for 1-1.5 hours, extracting crude manganese sulfate solution slurry, adding sulfuric acid (H2SO4) at normal temperature, neutralizing solution using ammonium bicarbonate until pH is 4.5, stopping addition of ammonium bicarbonate, detecting concentration of bivalent iron ion in solution in which manganese oxide powder with size of greater than or equal to 600 meshes is added when concentration of bivalent iron is greater than or equal to 60 ppm until bivalent iron ion content in mixed solution is 60 ppm, continuously adding bivalent iron ion into ammonium bicarbonate to adjust pH value to 6.5, detecting concentration of trivalent iron ion in mixed in which ammonium bicarbonate is continuously added when concentration of trivalent iron ion is greater than or equal to 60 ppm until trivalent iron ion content is less than or equal to 60 ppm, filtering to remove dregs and obtain crude thick manganese sulfate slurry solution, heating crude manganese sulfate solution to 85-90 degrees C, slowly adding barium sulfide at a speed of 2-5 g/L/minute, detecting copper (Cu), lead (Pb), nickel (Ni), cobalt (Co), and arsenic (As) concentrations every 30 minutes, adding barium sulfide until concentrations of Cu, Pb, Ni, Co, and As are less than or equal to 2 ppm, less than or equal to 2 ppm, less than or equal to 3 ppm, less than or equal to 3 ppm, and less than or equal to 0.5 ppm, respectively, adding manganese oxide powder with size of greater than or equal to 300 meshes until concentration of Mo is less than or equal to 0.003 ppm, adding 20-25 g filter aid per 100 L slurry solution, stirring for 20-30 minutes, filtering to remove precipitate to obtain filtrate, adding high molecular electrolyte to filtrate according to ratio of 2-5 g:100 L, leaving to stand for 1 day, removing impurity in electrolytic bath by electrolytic process to obtain manganese sulfate solution in which electrolytic conditions are electrolysis temperature of 85-96 degrees C, anode current density of 60-75 A/m2, electrolyte H2SO4 concentration of 0.28-0.36 mol/L, manganese concentration of 0.7-1 mol/L, and electrolysis time of 10-12 days, mill grinding using roller at rotating speed of 200-500 rpm and air quantity of 120-20 m3/hour, rinsing, passing product through 40 mesh sieve and 60 mesh sieve, sieving coarse particles and other impurities using permanent magnets in magnetic separator to remove heavy metals, and mixing.