Recycling Zinc and Preparing High-Value-Added Nanozinc Oxide from Waste Zinc-Manganese Batteries by High-Temperature Evaporation-Separation and Oxygen Control Oxidation

In this work, zinc was recycled and nanozinc oxide with high added values was prepared from waste zinc-manganese batteries by high-temperature evaporation-separation and oxygen control oxidation. Air was used as both the oxidant and the carrier gas. Because of the relatively fast oxidation rate of zinc, this Article attempts to balance the evaporation rate and oxidation rate of zinc by adding foreign materials to contend for the oxygen or covering the zinc with porous materials to isolate the oxygen. The results showed that the oxidation rate was still fast and the effect of contending for the oxygen by adding carbon powder or lead powder was not satisfied. The zinc hull was oxidized fast in the crucible and mixed with other oxides together, while covering the porous material (wire mesh, fiber felt) can accomplish the purpose of oxygen controlling. Zinc can be evaporated and separated from the zinc hull and oxidized during the zinc evaporation process, which is a benefit for producing pure nanozinc oxides. Under the experimental condition of 1123 K heating temperature, 3 kPa air pressure, and blowing air at 723 K, using fiber mat to cover the zinc hull, the recovery efficiency of zinc is ∼98.99%, and the uniform morphology of tetrapod-shaped nanozinc oxide was prepared successfully. This study provides a novel and environmentally friendly method for the resource utilization of zinc from waste zinc-manganese batteries.