The heavy metals present in the sludge can undergo a reaction with sulfur, leading to their conversion into metal sulfides through hydrothermal sulfidation. Sulfur ions, possessing a strong sulfidation capability, can operate within a wider pH range at elevated temperatures. The high temperature environment promotes the sulfidation process of zinc within heavy metal-laden sludge. Increasing the temperature of microwave hydrothermal sulfidation and extending the sulfidation duration for heavy metal-containing sludge can enhance the growth of crystal size in the artificially synthesized zinc sulfide. Zinc sulfide predominantly takes the form of ZnS, which facilitates the subsequent flotation recovery of zinc.