Basic nickel carbonate part I: microstructure and phase changes during oxidation and reduction processes

A significant industrial problem associated with the production of nickel from basic nickel carbonate has been identified. Fundamental studies of the change of phase, product surface, and internal microstructures taking place during oxidation and reduction processes at temperatures between 110 °C and 900 °C have been carried out. The various elemental reactions and fundamental phenomena that contribute to the change of the physical and chemical characteristics of the samples during the processes taking place in Ni metal production through gas/solid-reduction processes have been identified and thoroughly investigated. The following phenomena affecting the final-product microstructure were identified as follows: (1) chemical changes, i.e., decomposition, reduction reactions, and oxidation reactions; (2) NiO and Ni recrystallization and grain growth; (3) NiO and Ni sintering and densification; and (4) agglomeration of the NiO and Ni particles