Study on the role of copper converter slag in simultaneously removing SO2 and NOx using KMnO4/copper converter slag slurry

Jiacheng Bao; Kai Li; Ping Ning; Chi Wang; Xin Song; Yansu Luo; Xin Sun

doi:10.1016/j.jes.2021.02.004

Study on the role of copper converter slag in simultaneously removing SO₂ and NO_x using KMnO₄/copper converter slag slurry

J Environ Sci (China). 2021 Oct:108:33-43. doi: 10.1016/j.jes.2021.02.004. Epub 2021 Feb 25.

Authors

Jiacheng Bao¹, Kai Li¹, Ping Ning², Chi Wang³, Xin Song¹, Yansu Luo¹, Xin Sun⁴

Affiliations

¹ Faculty of Environment Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China.
² Faculty of Environment Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China. Electronic address: ningping@kust.edu.cn.
³ Faculty of Chemical Engineering, Kunming University of Science and Technology, Kunming 650500, China.
⁴ Faculty of Environment Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China. Electronic address: sunxin@kust.edu.cn.

PMID: 34465435
DOI: 10.1016/j.jes.2021.02.004

Abstract

To achieve "waste controlled by waste", a novel wet process using KMnO₄/copper converter slag slurry for simultaneously removing SO₂ and NO_x from acid-making tail gas was proposed. Through the solid-liquid separation for copper slag slurry, the liquid-phase part has a critical influence on removing NO_x and SO₂. Also, the leached metal ions played a crucial role in the absorption of SO₂ and NO_x. Subsequently, the effects of single/multi-metal ions on NO_x removal was investigated. The results showed that the leached metal from copper converter slag (Al³⁺, Cu²⁺, and Mg²⁺) and KMnO₄ had a synergistic effect on NO_x removal, thereby improving the NO_x removal efficiency. Whereas Fe²⁺ had an inhibitory effect on the NO_x removal owing to the reaction between Fe²⁺ and KMnO₄, thereby consuming the KMnO₄. Besides, SO₂ was converted to SO₄^2- completely partly due to the liquid catalytic oxidation by metal ions. The XRD and XPS results indicated that the Fe (II) species (Fe₂SiO₄, Fe₃O₄) in copper slag can react with H⁺ ions with the generation of Fe²⁺, and further consumed the KMnO₄, thereby resulting in a decrease in the NO_x removal. The characterization of the slags and solutions before and after reaction led us to propose the possible mechanisms. The role of copper slag is as follows: (1) the alkaline substances in copper slag can absorb SO₂ and NO₂ by KMnO₄ oxidation. (2) copper slag may function as a catalyst to accelerate SO₂ conversion and improve NO_x removal by synergistic effect between leached metal ions and KMnO₄.

Keywords: Copper slag slurry; Denitrification; Desulfurization; Metal ions; Reaction mechanism.

MeSH terms

Copper*
Metals
Oxidation-Reduction
Sulfur Dioxide*

Substances

Metals
Sulfur Dioxide
Copper