Hydrogen reduction of heterogenite to make sub-micron cobalt metal powder for hard metal applications

This short communication pertains to the synthesis of heterogenite (HCoO2) and its reduction to submicron cobalt metal powder. Heterogenite was prepared from a commercially produced wet cobalt hydroxide, Co(OH)3, which was dried at 110 °C to make heterogenite. HCoO2 thus prepared had 24% higher bulk density than mixed valance cobalt oxide, Co3O4 (CoOCo2O3). The reduction of heterogenite in hydrogen was studied via a design-of-experiment approach. The effect of three parameters i.e. time of reduction, temperature of reduction and hydrogen flow rate was studied on the reduction of heterogenite to cobalt metal powders of submicron sizes. The main advantage of using HCoO2 containing about 63% Co as feed for making cobalt metal powder will be the higher productivity and capability of making different sizes of cobalt metal powders such as sub-micron, half-micron and extra-fine.

► Heterogenite with 63.4% Co content was prepared from a commercially produced Co(OH)3. ► Co3O4 has the higher Co content at 73.4% than HCoO2 but has 24% less bulk density. ► Due to its higher density; HCoO2 has the highest mass of Co per unit volume. ► A furnace boat loaded with HCoO2, will carry approximately 7% more Co than Co3O4. ► This is important from an industrial standpoint.