<p>Utilization of slag with high sulfur content to produce ceramsites and meanwhile recovering SO₂ from the flue gas is a green and high effective way. In this paper, kiln slag with 7.34&#xa0;wt.% sulfur, discharging from zinc extraction process of metallurgical dust in the rotary kiln, was prepared into ceramsites. Two temperature regions of sulfur release existed during the sintering process. One is in a low-temperature region at 400–600&#xa0;°C with oxidation of iron sulfide, and the other is a high-temperature region at 1000–1150&#xa0;°C with decomposition of calcium sulfate, respectively, releasing 45.94 and 27.4% of sulfur in the ceramsites. During 600–1000&#xa0;°C, reactions of sulfation and formation of calcium sulfate occurred. Therefore, recycling flue gas from the high-temperature region into the low-temperature region were proposed for enriching the SO₂ concentration in the flue gas, and thereby improving quality of ceramsites and efficiency of producing sulfuric acid or zinc sulfate from flue gas.</p> Graphical Abstract <p></p>