Deposition characteristics and growth mechanism of flue gas in the treatment of zinc-containing dust by rotary hearth furnace

The Rotary Hearth Furnace (RHF) process is an effective method for treating zinc-containing dust to recover valuable metals, but the significant deposition of flue gas during processing limits production efficiency. This study provides detailed insights into the mechanism of flue gas deposition in the treatment of zinc-containing dust in RHF through X-ray fluorescence spectrometer, X-ray diffraction, scanning electron microscopy, theoretical thermodynamic calculation and flue gas deposition experiments under high-temperature roasting. The results show that the deposits consist of ZnO, NaCl, KCl, K2SO4, Na2SO4, and ZnCl2. During the flue gas deposition process, ZnCl2 firstly precipitates and aggregates other deposited particles as a binding phase to form agglomerates. Under the driven by the thermophoresis of the flue gas, the agglomerates contact the heated surface, creating the initial deposition layer. The rough surface of this layer accelerates the deposition of chloride compounds from the flue gas. As the flue gas flows, the deposition layer continues to grow, leading to an increase in layer thickness and the eventual formation of periodic dense deposits.