Obtaining (gamma) MnO2 for use in batteries from different manganese compounds

Abstract

This project proposes the evaluation and the improved use of manganese minerals in Brazil through the development of processes that converge towards obtaining gamma-MnO2 (nsutite) used in the manufacture of Le-clanche and Alkaline type batteries. In phase 1 proposals were made for methods of obtaining y-MnO2, with a structure of nsutite from different raw materials. Two of them achieved good performance, but only one of them is recommended for development. Conversion of the natural mineral from the Raizama Mine in the municipality of Cavalcanti, GO, was carried out. The mineral is essentially composed of Hollandite (BaMna016). The mineral was ground up and submitted to enclosed heating, transforming it into Hausmannite (Mn3O4). This was followed by aqueous leaching with the significant elimination of Barium. The conversion of Hausmannite into nsutite was successfully achieved. However, the method proved not to be economically viable. Studies concentrated on the conversion of synthetic rhodochrosite of high purity, through heating in an oven with alternating flows of (water vapor + air) and (water vapor + oxygen). Virtually pure synthetic nsutites were obtained, with the structure of y-MnO2 and with a density of around 1.2 g per cm3. In phase 2, the intention is to build a rotating heating vessel with sections for the heating of rhodochrosite in an atmosphere of (air + water), with a chimney for the escape of gases, as well as density increasing sections, on a production scale of some 100 Kg/hour. (AU)