Deposition Characteristics of Secondary Dust in Flue Gas from a Rotary Hearth Furnace

抄録

The rotary hearth furnace (RHF) process is widely employed for the efficient recycling of iron- and zinc-bearing dusts. However, the formation and deposition of secondary dust in the flue gas system significantly impair its operational availability. In this study, a laboratory-scale simulation of the RHF reduction process was conducted to collect and characterize the secondary dust formed under different temperature conditions. The distribution patterns and deposition behavior of secondary dust were systematically investigated. Results indicate that dust deposition predominantly occurs in the medium-temperature zone (873 ~ 1073K), where ZnO and alkali metal chlorides are the dominant components, accounting for up to 76.1% of the total deposited mass. The particle size of the secondary dust first decreases and then increases with decreasing flue gas temperature. The elemental composition of the secondary dust includes Zn, Pb, K, Na, Sn, In, O, and Cl. Specifically, the Zn content decreases from 73 mass% to 44 mass%, while Cl increases sharply from 0.2 mass% to 41 mass% as the temperature drops. Minor increases in K and Pb concentrations and a slight decrease in Na are also observed. Thermodynamic modeling was applied to interpret the phase transformations and deposition mechanisms at various temperature intervals. This study provides fundamental insights into the generation and deposition behavior of secondary dust in RHF systems, offering theoretical guidance for the mitigation of dust-related issues and improvement of process reliability in industrial applications.