Sustainable Mining and Metallurgy

Taking a wet desulfurization wastewater treatment project of ultra-high temperature subcritical gas power generation as an example, the desulfurization wastewater of this project was treated by triple-box chemical precipitation method, and the process conditions of pH value, coagulant aid and sludge production were optimized. The results showed that with the increase of lime milk dosage, the pH value of neutralization tank wastewater increased gradually, and the conductivity of wastewater decreased gradually. When the dosage of lime milk solution was 24g/L, the concentration of Mg²⁺ and SO^2-₄ ions in the desulfurization wastewater decreased significantly, while the concentration of Ca²⁺ ions increased, which exceeded the national standard requirements. In order to remove Ca²⁺ ions, sodium carbonate solution was added, and the optimum dosage of sodium carbonate was 6.9g/L; the flocculation effect of non-ionic coagulant aid in the treatment of desulfurization wastewater is better than that of anionic and cationic coagulant aid. The sludge yield increased with the increase of pH value of desulfurization wastewater. When the pH value was 11, the sludge yield reached the maximum. The main components of the sludge were CaSO₄·2H₂O, Mg(OH)₂ and Ca(OH)₂.