Tytuł pozycji:
Microstructures and Microwave-Absorbing Properties of ZnO Smoke from Zinc Leach Residue Treated by Carbothermal Reduction
Much zinc residue is produced during the traditional processes involved in zinc hydrometallurgy in the leaching stage: its composition is complex and valuable metals are difficult to recover therefrom. If not handled properly, it can lead to a waste of resources and environmental pollution. To solve this problem, zinc leach residue specimens were treated using the carbothermal reduction method (CTR) that is easy to operate and has a high energy utilisation rate. The methods, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM) were used for analytical characterisation. Based on this, this research investigated a structure-function relationship between microstructures and microwave-absorbing properties of ZnO smoke from CTR-treated zinc leach residue. The results demonstrate that microstructures and macro-properties of ZnO smoke obtained at different temperatures differ greatly. Under conditions including a calcination temperature of 1250°C, holding time of 60 min, and addition of 50% and 10% of powdered coal and CaO separately, the ZnO content in the obtained smoke is 99.14%, with regular micron-sized ZnO particles therein. For these particles, the minimum reflection loss (RLmin) reached –25.56 dB at a frequency of 15.84 GHz with a matching thickness of 5 mm. Moreover, frequency bandwidth corresponding to RL < –10 dB can reach 2.0 GHz. ZnO smoke obtained using this method is found to have excellent microwave-absorbing performance, which provides a new idea for high-value applications of zinc-rich residue.
1. This work was supported by the Joint Fund between Shenyang National Laboratory for Materials Science and The State Key Laboratory for Advanced Processing and Recycling of Non-ferrous Metals for “One-step harmless treatment of zinc and silver-rich residue using the smelting-volatilisation method” (Grant no. 18LHZD001), The Department of Industry and Information Technology of Gansu Province for a “Technical study on the harmless treatment of zinc and silver-rich residue using the fuming process” (Grant no. GGLD-2019-046), and a Gansu Major Science and Technology Project for “Development and industrialisation of key technologies for enrichment of rare metals in zinc hydrometallurgy” (Grant no. 19ZD2GD001).
2. Opracowanie rekordu ze środków MNiSW, umowa Nr 461252 w ramach programu "Społeczna odpowiedzialność nauki" - moduł: Popularyzacja nauki i promocja sportu (2021).
