Simultaneous NO_x and SO₂ removal during wet flue gas desulfurization, using copper smelter slag slurry combined with yellow phorphorus

Abstract

The study of copper slag has attracted the attention of scholars from both China and around the world. But few have paid attention to its applications in the simultaneous removal of SO2 and NOx in wet flue gas desulfurization (WFGD), becasue WFGD technique is inappropriate for directly treating NOx owing to the low solubility of NO. This work aims to improve NOx removal efficiency in WFGD technology using copper slag slurry associated with the oxidation of NOx by yellow phosphorus. Different operating conditions, including dispersion of P4, solid‐liquid ratio, initial pH value of copper slag slurry, reaction temperature, oxygen content, and gas flow rate, were compared regarding the efficiency of SO2 and NOx simultaneous removal. The characterizations were carried out on the liquid and solid part of fresh and spent copper slag slurry after filtration. The results indicated that a great amount of metals ions, such as Fe3+ and Zn2+, were leached by reacting with produced acids (H2SO4, HNO3, and H3PO4), which had a liquid‐phase catalytic oxidation on SIV species (SO32−/HSO3−), leading to promotion in absorption for SO2. The copper slag played a significant role in dispersing the yellow phosphorus and promoting ozone generation, thus improving NOx removal efficiency. The reaction pathway can be divided into three parts: (a) ozone generation induced by yellow phosphorus, (b) the oxidation of NO by O3 and then dissolution in aqueous solution, and (c) the dissolution of SO2 and the liquid‐phase oxidation for SO2 through metal ions produced by the reaction between acid and copper slag.

Recent Advances in Elimination of SO2 and NOx from Flue Gas Employing Phosphorus Sludge and Phosphate Rock

“…•− free radicals are key factors of efficient removal of SO 2 . 34 The NO 2 obtained from NO oxidation can induce S(IV) to produce a large amount of SO 3 Given the advantages of P 4 as an efficient inducer of oxidants, various composite absorbents based on yellow phosphorus have been developed to remove SO 2 and NO x For instance, the "P 4 + alkali" absorbent, 18 "P 4 + red mud" absorbent, 50 "P 4 + sulfate of potash" absorbent, 59 and "P 4 + copper smelter slag slurry" absorbent 60 are currently being studied by scholars. Table 3 shows the performances of and key information on desulfurization and denitrification technologies developed based on phosphorus.…”