Resource treatment of coking sulfur paste: Characterization analysis and composition of impurities

Abstract

Coking sulfur paste (CSP) generated from coking oven gas desulfurization process is an extremely harmful pollutant. In this article, modern analytic methods, such as X‐ray fluorescence, X‐ray diffraction, Fourier transform infrared, thermo gravimetric‐differential scanning calorimetry and scanning electron microscope, were utilized to analyze CSP. Results showed that sulfur in CSP mainly existed in the form of elemental sulfur, which is presented mostly in the form of rhombic sulfur (Sα). The rest of sulfur existed in the form of NH4SCN, (NH4)2S2O3, FeSO4. There were also microelements in CSP, such as Fe, Br, Ca, P, Mo and Cl, whose contents were less than 2.50%. Impurities in CSP could be divided into three categories: water‐soluble impurities (WI), dichloromethane‐soluble impurities (DI) and other impurities (OI), accounting for 4.2%, 12.16% and 2.61%, respectively, among the whole CSP. WI is consisted of NH4SCN, (NH4)2S2O3, FeSO4, PDS and hydroquinone accounting for 58.39%, 9.05%, 24.67%, 3.70%, and 3.37%, respectively, of the total WI. DI mainly contained polycyclic aromatic hydrocarbons, including benzenes, naphthalenes, fluorenes, phenanthrenes, anthraquinones and pyrenes. Carbon in OI existed mainly in the form of C–C and C–H, oxygen in OI existed in the form of C=O and C–OH groups. A composite extraction process was proposed to deal with CSP in this paper, which separated sulfur from impurities in CSP at normal temperature efficiently, based on the existing conditions of coking enterprises. © 2018 American Institute of Chemical Engineers Environ Prog, 38:e13023, 2019