skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: The leaching behavior of cadmium, arsenic, zinc, and chlorine in coal and its ash from coal-fired power plant

Abstract

The leaching experiment of feed coal (c) and its laboratory high-temperature ash (HA), fly ash (FA), and bottom ash (BA) from a Chinese coal-fired power plant were carried out using column leaching under different pH conditions (pH = 2.0, 4.0, 6.0, and 7.5, respectively) and different leaching durations (up to 80 h). The leaching behaviors of As, Cd, Zn, and Cl were investigated. The results showed that the elements occurring in water-soluble, ion-exchangeable, and Fe-Mn oxide phases are potentially leachable, whereas those in association with organic matter and silicate are less likely to be leached. The cumulative percent of Zn, As, Cl, and Cd leached from C and ash samples increase with decrease in pH. The leaching rate of As and Cl in C and ash samples are higher in comparison with Zn and Cd. However, the maximum concentrations of Cd in the leachate from C, HA, FA, and BA are in excess of or very close to the maximum standard concentrations permitted in the Chinese Standards for Drinking Water and Surface Water. The ultimate concentrations of As, Cd, and Cl in the leachates did not attain equilibrium after the leaching of 80 h; therefore, longer leaching experiments are necessarymore » to evaluate the impact of these hazardous trace elements on aqueous environment.« less

Authors:
; ; ; ; ;  [1]
  1. China University of Mining & Technology, Beijing (China). Dept. of Resource & Earth Science
Publication Date:
OSTI Identifier:
20712186
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Engineering Science; Journal Volume: 23; Journal Issue: 1
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; COAL; FLY ASH; LEACHING; CADMIUM; ARSENIC; ZINC; CHLORINE; ASHES; PH VALUE; BENCH-SCALE EXPERIMENTS; TRACE AMOUNTS

Citation Formats

Zhao, F.H., Peng, S.P., Zheng, B.S., Tang, Y.G., Cong, Z.Y., and Ren, D.Y. The leaching behavior of cadmium, arsenic, zinc, and chlorine in coal and its ash from coal-fired power plant. United States: N. p., 2006. Web. doi:10.1089/ees.2006.23.68.
Zhao, F.H., Peng, S.P., Zheng, B.S., Tang, Y.G., Cong, Z.Y., & Ren, D.Y. The leaching behavior of cadmium, arsenic, zinc, and chlorine in coal and its ash from coal-fired power plant. United States. doi:10.1089/ees.2006.23.68.
Zhao, F.H., Peng, S.P., Zheng, B.S., Tang, Y.G., Cong, Z.Y., and Ren, D.Y. Sun . "The leaching behavior of cadmium, arsenic, zinc, and chlorine in coal and its ash from coal-fired power plant". United States. doi:10.1089/ees.2006.23.68.
@article{osti_20712186,
title = {The leaching behavior of cadmium, arsenic, zinc, and chlorine in coal and its ash from coal-fired power plant},
author = {Zhao, F.H. and Peng, S.P. and Zheng, B.S. and Tang, Y.G. and Cong, Z.Y. and Ren, D.Y.},
abstractNote = {The leaching experiment of feed coal (c) and its laboratory high-temperature ash (HA), fly ash (FA), and bottom ash (BA) from a Chinese coal-fired power plant were carried out using column leaching under different pH conditions (pH = 2.0, 4.0, 6.0, and 7.5, respectively) and different leaching durations (up to 80 h). The leaching behaviors of As, Cd, Zn, and Cl were investigated. The results showed that the elements occurring in water-soluble, ion-exchangeable, and Fe-Mn oxide phases are potentially leachable, whereas those in association with organic matter and silicate are less likely to be leached. The cumulative percent of Zn, As, Cl, and Cd leached from C and ash samples increase with decrease in pH. The leaching rate of As and Cl in C and ash samples are higher in comparison with Zn and Cd. However, the maximum concentrations of Cd in the leachate from C, HA, FA, and BA are in excess of or very close to the maximum standard concentrations permitted in the Chinese Standards for Drinking Water and Surface Water. The ultimate concentrations of As, Cd, and Cl in the leachates did not attain equilibrium after the leaching of 80 h; therefore, longer leaching experiments are necessary to evaluate the impact of these hazardous trace elements on aqueous environment.},
doi = {10.1089/ees.2006.23.68},
journal = {Environmental Engineering Science},
number = 1,
volume = 23,
place = {United States},
year = {Sun Jan 15 00:00:00 EST 2006},
month = {Sun Jan 15 00:00:00 EST 2006}
}
  • Coal (C), fly ash (FA) and bottom ash (BA) from the thermoelectric plant of Shengtou, Shanxi Province along with the coal`s high temperature ash (HTA) produced in the laboratory were leached under different conditions and leaching times. The leaching behaviors of As, Cr, Cd, Pb, Ni, Co, Cu, Zn, Hg, Ba, Mn, Cl, hazardous minor and trace elements, were investigated in detail. The pH values of the leaching solutions were 2.0, 4.0, 6.0 and 7.5. The total leaching time was 80 hours. The sampling time intervals were 5 hours from the beginning up to 30 hours and then 10 hourmore » intervals from 30 to 80 hours. The results showed the pH values of leaching solutions, leaching times, element species and their occurrences in C, HTA, FA, BA have a significant impact on the leaching behavior. Among these elements, Cl, Hg, Ba, As, and Cd in C, HTA, FA, BA, Cr in HTA, FA, are more strongly leached. Under the leaching conditions the concentrations of Co, Cu, Ni and Pb in C, HTA, FA, BA remained unchanged. The leaching susceptibility of all elements is stronger in acid solution than in base solution and the more acid the leaching solution, the stronger is the susceptibility.« less
  • Trace elements were extracted from a coal-fired power plant electrostatic precipitator ash with nitric acid, hydrochloric acid, citric acid, redistilled water, and ammonium hydroxide as extractants. Effluent waters at this plant were sampled to assess the elevation of trace element concentrations compared with intake waters. The results showed a positive correlation between those elements most extractable by water (B, F, Mo, and Se) or acid (As, B, Cd, F, Mo, and Se) and those elements most elevated in effluent waters (As, B, F, Mo, and Se).
  • The two finest, most respirable coal fly ash fractions collected from the smokestack of a power plant were more mutagenic than two coarser fractions. Mutagenicity was evaluated in the histidine-requiring bacterial strains TA 1538, TA 98, and TA 100 of Salmonella typhimurium. Ash samples collected from the hoppers of an electrostatic precipitator in the plant were not mutagenic. The mutagens in coal fly ash were resistant to x-ray or ultraviolet irradiation, possibly as a result of stabilization by fly ash surfaces. All mutagenic activity is lost with heating to 350/sup 0/C.
  • Understanding the leaching behavior of arsenic (As) and selenium (Se) in coal fly ash is important in evaluating the potential environmental impact of coal fly ash. Batch experiments were employed to systematically investigate the leaching behavior of As and Se in two major types of coal fly ashes, bituminous coal ash and sub-bituminous coal ash, and to determine the underlying processes that control As and Se leaching. The effects of pH, solid/liquid (S/L) ratio, calcium addition, and leaching time on the release of As and Se were studied. Overall, bituminous coal ash leached significantly more As and Se than sub-bituminousmore » coal ash, and Se was more readily leachable, in both absolute concentration and relative fraction, than As for both types of fly ashes. Adsorption/desorption played a major role on As and Se leaching from bituminous coal ashes. However, calcium precipitation played the most important role in reducing As and Se leaching from sub-bituminous coal ashes in the entire experimental pH range. The leaching of As and Se from bituminous coal ashes generally increased with increases in the S/L ratio and leaching time. However, for sub-bituminous coal ashes, the leaching of As was not detected under most experimental conditions, while the leaching of Se increased with increases in the S/L ratio and leaching time. As{sup V} and Se{sup IV} were found to be the major species in all ash leachates in this study. 46 refs., 7 figs., 1 tab.« less