<p>The implementation of embedded selective catalytic reduction (SCR) denitration in chain grate during iron ore pelletizing process obviates additional flue gas heating. However, the influence of gas components and alkali metal on SCR denitration requires attention. The SCR denitration behavior in the preheating section of chain grate was investigated, and the combined influence mechanisms of H₂O(g), SO₂, and potassium were revealed. The results show that the presence of H₂O(g) and SO₂ in the flue gas decreases the NO conversion rate of the catalyst from 96.3% to 79.5%, while potassium adsorbed on the catalyst surface further reduces the NO conversion rate to 74.1%. H₂O(g), SO₂, and potassium in the flue gas form sulfate and potassium salt on the catalyst surface, blocking the pore structure, thereby decreasing the gas adsorption capacity of the catalyst. Moreover, SO₂ and potassium engage in competitive adsorption and reaction with NH₃ and NO at the active sites on the catalyst surface, reducing the content and activity of the catalyst effective component. Increasing the flue gas temperature can promote the decomposition of ammonium sulfate and ammonium bisulfate on the catalyst surface, but it has little effect on potassium. Additionally, potassium will exacerbate sulfur poisoning of the catalyst. Hence, the embedded SCR denitration process requires electrostatic precipitation to eliminate the adverse impacts of potassium and thermal regime optimization to raise flue gas temperature to 350&#xa0;°C, thereby increasing NO conversion rate exceeding 85%.</p>