Comparison of Hydrogen Reduction of Different Lead-Bearing Materials for Lead Recovery

Abstract

Understanding the fundamental knowledge of lead reduction from lead-bearing materials using hydrogen is essential for developing a carbon neutral lead production process. Recycling of lead from secondary resources using hydrogen as a reducing agent is industrially important to promote circular economy, resource efficiency, and reduction of carbon footprint. The current study evaluates and compares the general reduction mechanism of PbO with a more complex lead-containing compound, PbO-SiO2 glass/slag. Isothermal reductions were carried out on pelletized PbO and PbO-SiO2 (70wt% PbO and 30wt% SiO2) using hydrogen at 350 to 800 °C (for PbO) and 300 to 700 °C (for PbO-SiO2). The results from microstructural observation showed that uniform, globular, non-wetting lead droplets formed on the surface of PbO pellets. The lead droplets covered the whole surface, which appeared to inhibit further reduction. In the case of PbO-SiO2, the viscous nature of the glass/slag appeared to significantly hinder diffusion of hydrogen within the pellet, resulting in a low reduction rate.