Micro-X-ray spectral determination of the chipboard dust samples elemental composition

Abstract

The paper determines the composition of dust from electrostatic precipitators of EAF gas cleaners during long-term storage in dumps in order to obtain information on classifying dust as hazardous waste. Determination of the heavy metals content in waste was performed by atomic absorption flame spectrophotometry on an AAS-1N spectrophotometer. The content of the amount total iron and the determination of its various oxidation states was carried out by redox titration with potassium bichromate in an acidic medium. A comprehensive metallo-graphic study of dust samples included macroanalysis (at x16 magnification), microanalysis of the structure of the end section of pellets from fresh dust from EAF electrostatic precipitators using optical microscopy (x 50, x 500). A detailed analysis of the microstructure of the selected samples was carried out using a JSM-6490 scanning electron microscope in the mode of secondary elastically scattered electrons. The X-ray spectral analysis of the selected samples was carried out using energy and wave spectrometers attached to a JSM-6490 scanning electron microscope. Chemical analysis of dust samples showed that there are no significant differences in the content of total iron in the presented dust samples, although there is some decrease in the depth of the dump. A stronger decrease in the transition from the surface of the dump to the depth is noted by the content of Fe3O4. All samples are magnetic, which indicates a significant content of magnetic nitrous oxide-iron oxide in the dust, most likely in an unbound state. The presence of zinc and lead impurities in the melting charge, evaporating at the operating temperatures of the furnace, leads to their oxidation by the air flow, as a result of which they can be in the final dust both in the form of free oxides and in the form of composite structures with iron oxides. It has been established that the results of the chemical analysis of electrostatic precipitator dust samples, their qualitative composition and the content of toxic heavy metals, in general (according to the average value of 10 determinations) correspond to the given technical conditions of the enterprise for this type of waste, the excess was obtained in terms of the zinc content in all considered iron-containing wastes. A distinctive feature of heavy metals present in the waste is extremely low mobility in buffer media and practical insolubility in water.