| 摘要 |
1321937 Manganese dioxide BROKEN HILL PTY CO Ltd 14 Dec 1971 [30 Dec 1970] 58102/71 Heading C1A MnO 2 is produced in a cyclic process which comprises the following steps: (A) leaching a manganese containing material with HCl; (B) neutralizing unreacted acid with a base; (C) removing impurities; (D) treating with Cl 2 at a pH maintained above 0À5 by the addition of a base thereby precipitating MnO 2 ; (E) separating the MnO 2 and; (F) regenerating the base and HCl by hydrolysis of the remaining liquid phase at a temperature of at least 400‹ C. and then recycling them. The leaching is expedited by the presence of inert chlorides, MgCl 2 and MnCl 2 being exemplified, and the Cl 2 may be partially produced in the leaching stage and step (C) may be carried out with the removal of impurities such as Fe, Al and Si by precipitation with the use in step (B) of MgO as base. The precipitation of MnO 2 may be carried out in the presence of nuclei of carbon black and/or MnO 2 and carbon black may be added to the precipitated MnO 2 to produce a mixture suitable for use in dry cells. In the flow diagram shown, Cl 2 from the leaching stage is used with MgO in the MnO 2 precipitation stage, MnCl 2 being present in the HCl solution during leaching. |
