Characterization and abatement of SOx, NOx and PCDD/Fs in iron ore sinter machine wind legs

Abstract

It was observed that SOx and NOx, in large concentrations, are getting released from certain wind boxes below the sinter machine. The particulates released from specific wind legs were characterized using Quantitative Evaluation of Materials by Scanning Electron Microscopy (QEMSCAN). Particulates with spherical, cubical, needle and bar-like morphologies containing K, Na, Cl were found. Nitrogen-based solids were found in clutter-like morphology. Some particles had a mixture of the above, SOx and NOx. A method of dissolving SOx, NOx and breaking them down into harmless substances was explored in this research. The deposits in the wind legs were dissolved in demineralized water and solutions of sodium bicarbonate, urea, and di-sodium borate deca-hydrate (borax) to estimate the absorbance of K, Na, Cl, Ca, Mg, S, and N based compounds present. Demineralized water and sodium bicarbonate were found to be the most effective sorbents of SOx and NOx. The filtrates were examined under QEMSCAN and found that SOx and NOx are not present. Based on the above finding, a solution of sodium bicarbonate and water 0.01% v/v was sprayed into a wind box and found that SOx and NOx have got reduced by about 55%. To maximize the capture of SOx and NOx, the solution was optimized at 0.02% v/v. With this novel technique, capital intensive Desulphurization (De-SOx) and Denitrification (De-NOx) installation can be avoided. Additionally, an economical solution to the Polychlorinated dibenzo para-dioxins and polychlorinated dibenzofurans (PCDD/Fs) emission was explored in this research. Various physicochemical mechanisms of forming harmful substances are described in this paper.