Concentrations of heavy metals in fly ash from a coal-fired power plant with respect to the new Finnish limit values

Abstract

In Finland, the new limit values for heavy metals in fertilizers used in agriculture and in forestry came into force in March 2007, and for materials used as earth construction agents, in June 2006. From the utilization point of view, it was notable that the total heavy metal concentrations (Cd, Cu, Pb, Cr, Mo, Zn, As, Ni, Ba, and Hg) in fl y ash from a coal-fi red power plant were lower than those limit values. The concentrations of the easily soluble elements Ca, Mg, Na, P, and Zn in the fl y ash were between 3.5 and 35 times higher than those found in the coarse mineral soils of Finland. Fly ash is a potential agent for soil remediation and for improving soil fertility. If inorganic materials and by-products are utilized in earthworks, the content of harmful compounds must be low and the harmful components must be tightly bound to the matrix. Therefore, a fi ve-stage sequential extraction procedure was used to evaluate the extractability of different elements in fl y ash into the following fractions: (1) the water-soluble fraction, (2) the exchangeable fraction (CH 3 COOH), (3) the easily reduced fraction (NH 2 OH-HCl), (4) the oxidizable fraction (H 2 O 2 + CH 3 COONH 4 ), and (5) the residual fraction (HF + HNO 3 + HCl).

Occupational Risk Evaluation of Using Bottom Ash and Fly Ash as a Construction Material

“…However, the high LOI (15.6%; d.w.) and TOC (140 g=kg; d.w.) values in the fly ash indicate that this ash fraction contains both volatile fractions and unburned organic material. If the LOI values in the bottom and fly ash are compared to those reported in the literature (Lahtinen 2001;Dahl et al 2008;Korpijärvi et al 2009), the observations are in relatively good agreement with the LOI and TOC values in the ashes from Finnish power plants. According to Table 1, the particle size distributions of the bottom ash and fly ash differ significantly.…”

Characterization and comparison of leaching behaviors of fly ash samples from three different power plants in Turkey

“…In previous studies [7,14,43,[59][60][61][62] they were stated that the leaching behavior of the elements depends strongly on the alkalinity of the fly ashes and the leach solution pH changed in the course of the leaching process. For this reason, the pH values of the fly ash and leach solution mixtures were continuously measured in the same conditions with leaching processes.…”

Leaching behavior of selected trace elements in coal fly ash samples from Yenikoy coal-fired power plants

“…340i portable water meter and final pH was found as 13.2. The basic character of ash leachate is generally attributed to the free calcium, soluble metal salts, oxides, hydroxides, and carbonates [4,32].…”