| 摘要 |
545,724. Manganese dioxide. SOC. METALLURGICA ITALIANA and GUARESCHI, -P. Oct. 8, 1941, No. 13012. Convention date, Oct. 8, 1940. [Class 1 (iii)] [Also in Group XXXVI] Pure metallic manganese and MnO 2 are obtained from pyrolusite or other source by treatment with sulphuric acid in the presence of a reducing agent such as a ferrous salt which converts the MnO 2 to MnO, the reducing agent being then precipitated as ferric hydrate by neutralization of the solution by CaCO 3 or NH 3 in the presence of ammoniacal salts or by means of the spent catholyte from the electrolysis step, the solution being then electrolyzed in a partioned cell. The precipitate contains the iron, antimony, arsenic etc.; copper, zinc, cadmium &c. present are precipitated by addition to the solution of pure electrolytic manganese in powder form. MnO 2 may be added to the solution before the neutralization step. The ferric hydrate may be regenerated by dissolving it in H 2 SO 4 in the presence of SO, or an alkaline sulphide, or the spent anolyte obtained from the electrolysis may be employed for this purpose ; this may also be used for the solution of the mineral. |
