Mechanism of High-Pressure Forming Coupled with Controlled Pore-Forming Enhancement of Copper Slag Biomass Reduction for Lead and Zinc

The copper slag biomass direct reduction process (CSB-DR) uses straw to replace traditional fossil energy, which has the advantage of reducing carbon emissions. This method can realize green and efficient utilization of copper slag. However, copper slag usually contains a certain amount of lead and zinc (1–3%). Directly reduced iron (DRI) prepared from copper slag cannot be directly applied to iron and steelmaking processes. The DRI needs to be further refined and removed. In the direct reduction process of copper slag biomass, owing to the pore-creating effect of the pore-forming agent, increasing the agglomeration pressure effectively improved the reduction efficiency and lead–zinc removal efficiency of the copper slag biomass composite pellets. In this study, the trends of porosity, metallization rate, and lead–zinc removal rate of DRI were analyzed by changing the agglomeration pressure of copper slag biomass composite pellets, and the performance of DRI prepared from copper slag biomass composite pellets was analyzed via micro/nano simulations using the reduction mechanism and the lead–zinc removal mechanism. The results showed that the metallization rate and the lead–zinc removal rate of DRI increased with increasing pelletizing pressure. When the granule-forming pressure is 30 MPa, the removal rate of Pb can reach 97.95%, the removal rate of Zn can reach 96.22%, and the compressive strength can reach 1097.03 N/cm2.