Characterization and Leaching of Coal Fly Ash

Abstract

Physical characteristics, chemical composition and leaching behaviour of a waste fly ash from a coal-fired power station are reported. Particle size distribution was studied by the following techniques: sedimentation in a liquid medium; sedimentation in an air flow; and Fraunhofer diffraction of a laser beam. Results obtained by the different methods are in good agreement. Mineralogical content and chemical composition were determined by X-ray diffraction, electronic microprobe and X-ray fluorescence. Acid leaching of the samples was investigated, using the following strong acids in sequence: HCl + HNO3, H2F 2, HClO4. Analysis of leachates by atomic absorption shows trace metals In, Tl, Ge, Cu, Ga, Pb, Ni, Co, Mn, Cd, Zn, Cr. In this work fly ashes from a Spanish power plant are characterized according to the type of particles, size distribution and chemical composition by means of physical methods. Three particle size fractions are leached by acids and analysis of trace elements in the leaching liquor is carried out. The concentration of trace metals is somewhat higher in the particles of smallest size.

Gallium

“…Other suitable methods include X-ray diffraction, scanning electron microscopy (SEM), X-ray fluorescence, and transform infrared spectrometry using a spectrometer equipped with a liquid nitrogencooled indium-antimonide/mercury-cadmium-telluride sandwich detector (Gutierrez et al 1993, Strang et al 1989). Trace concentrations of gallium present in tissues and biological fluids can be determined using several analytical methods.…”

Hydrochloric Acid Leaching of Philippine Coal Fly Ash: Investigation and Optimisation of Leaching Parameters by Response Surface Methodology (RSM)

“…This method involves dissolution of the target components in a sample by lixiviants such as acids or bases. In the past, acid leaching has been used to extract hazardous elements from CFAs to decontaminate them before disposal [20][21][22][23][24]. More recently, these methods were improved to facilitate the selective extraction of valuable elements from CFA, such as Fe, Al and REEs [25][26][27][28][29][30][31][32].…”

Coal fly ash and synthetic coal fly ash aggregates as reactive media to remove zinc from aqueous solutions

“…CF frequently contains trace elements, such as As, Cd, Cu, Pb, Zn, and Se, which can have environmental impacts if released (e.g., groundwater quality) [26][27][28].…”