Emissions of black plumes from the chimneys of brick making kilns; a compositional study of the blackish particulates

Abstract

Abstract In Pakistan brick making industries use indigenous unprocessed coal for kiln heating. Beside coal, waste hydrocarbons are intermittently added, particularly during the refueling in order to maintain a smooth combustion inside the kiln. Presently, it is presumed that the blackish smoke is the combustion product of waste rubber/waste oil. To verify the hypothesis, Whatman grade 1 filter paper was placed at the chimney exit for the sample collection. A powerful scanning electron microscope (SEM) having a built in energy dispersive spectroscopy (EDS) unit, X-ray fluorescence (XRF), X-ray diffraction (XRD), N2 adsorption isotherms, and thermogravimetric (TGA) analytical techniques were utilized to verify the chemical composition of the sample. The SEM image at a ×30,000 magnification displays many roundish masses having size between 2 - 0.5 microns. The elements in these spherical particles were carbon, oxygen, and sulfur (EDS analysis). What we know is that these detected elements are common coal compositions usually referred as cenosphere. Moreover, XRF analysis of a calcined sample highlighted a noticeable decrease in SO3 entity (common in coal). N2- adsorption isotherm shows that the surface area of the flying coal particles is too low, whereas the appearance of the spherical objects in SEM images is like a fullerene, a carbon allotrope. XRD and TGA analysis supports the initial inference that these emissions contain fine coal particles. These coal particulates are hazardous and should be bagged in a separate cleaning tower system.