OBTAINING AQUEOUS SOLUTION FROM INSOLUBLE METAL OXIDE

摘要

This method of obtaining an aqueous solution of metal values from an insoluble metal oxide is possible where the metal has a lower oxidation number in the solution than in the insoluble oxide, for example manganese (+2 and +4 respectively). The oxide, such as MnO2, is treated with hot mineral acid such as HCl in the presence of coal. After some hours, the liquid comes to contain most of the manganese as dissolved Mn(II) ion.