Design modifications and adaptation of an oxidising multiple hearth roaster for reduction roasting

Significant differences exist between the design and operation of the react ors meant for oxidation roasting and reduction roasting. Also, reduction pr ocess is often associated with handling of hazardous/toxic gases. A pilot s cale Multiple Hearth Roaster (MHR) was originally procured for oxidation ro asting of ores and concentrate. In this paper, the stepwise procedure for c onverting an oxidising MHR for carrying out reduction roasting is discussed in detail. The MHR which has been converted for reduction roasting can ope rate below 800 degrees c with a reduction potential [CO/ (CO + CO2)] of les s than 0.6 under a positive pressure of 1-5 nlm WG.