| 摘要 |
PURPOSE:To manufacture manganese dioxide, by treating slag formed as a by-product in the manufacture of ferromanganese with sulfuric acid so as to remove impurities thereby forming manganese sulfate soln., then by electrolyzing the manganese sulfate soln. CONSTITUTION:Slag is finely pulverized and is made into a slurry with water. Necessary amount of sulfuric acid is reacted with the slurry by adding it drop by drop. The reaction procduct diluted with water is neutralized with, for example, slaked lime to 6.0-8.5, preferably to 7.0-7.5pH, then divalent iron is converted to trivalent iron by blowing air into the soln., and the solid matter is removed by filtration. The filtrate is concentrated by heating to crystallize CaSO4, which is separated by filtration just before manganese sulfate is crystallized. The manganese sulfate soln. is concentrated in a vacuum evaporator to crystallize the manganese sulfate, which is centrifugally separted and is washed with water. The crystal hereby obtained is dissolved in water and is used as an electrolyte. The concn. of the soln. is 8-25mol/ l in terms of Mn<2+> and 0.3-1.2mol/l in terms of sulfuric acid. Electrolysis is performed at 40-98 deg.C bath temp., at 0.5-10A/dm<2> current density to form manganese dioxide. |
