Water-leaching characteristic of valuable trace metals (U, V, and Ga) from (NH4)2SO4-treated coal ash: A coprecipitation behavior at high temperature

Zhe Yang; Wei Zhang; Yumei Li; Changxiang Wang; Sen Yang; Zhi Tang; Danqing Liu; Yilian Li

doi:10.1016/j.jhazmat.2020.122113

Water-leaching characteristic of valuable trace metals (U, V, and Ga) from (NH₄)₂SO₄-treated coal ash: A coprecipitation behavior at high temperature

J Hazard Mater. 2020 Apr 15:388:122113. doi: 10.1016/j.jhazmat.2020.122113. Epub 2020 Jan 15.

Authors

Zhe Yang¹, Wei Zhang¹, Yumei Li², Changxiang Wang¹, Sen Yang¹, Zhi Tang¹, Danqing Liu², Yilian Li³

Affiliations

¹ School of Environmental Studies, China University of Geosciences, Wuhan, 430074, China.
² School of Environmental Studies, China University of Geosciences, Wuhan, 430074, China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430074, China.
³ School of Environmental Studies, China University of Geosciences, Wuhan, 430074, China. Electronic address: yl.li@cug.edu.cn.

PMID: 31972436
DOI: 10.1016/j.jhazmat.2020.122113

Abstract

Coal ash (CA) becomes the most significant industrial solid waste and attracts much attention due to its potential environmental risk and reuse as the supplementary material. In this study, experiments were conducted to investigate the mode of occurrence and the leaching behavior of valuable trace metals (U, V, and Ga) from CA and (NH₄)₂SO₄-treated CA (NCA), based on the recovery of aluminum. Integrations of Fe- and K-oxide with Si-Al glass increased the ash strength and obstructed the activation of NH₄⁺ on amorphous Al-bearing phases, resulting in a limited improvement in the leaching efficiency of trace metals. On the other side, a higher liquidus temperature, contributing to the dissolutions of Al³⁺ and Ca²⁺, could promote the leaching of U from NCA as well, whereas the water-leaching behaviors of V and Ga involved a sophisticated trend with temperature > 40℃. Water-leached V/Ga tended to transfer into Fe-Mn oxide-bound and residual V/Ga owing to the noticeable hydrolysis of Fe and Ti ions that facilitated the formation of coprecipitation. However, 0.1 M H₂SO₄ could re-dissolve that coprecipitation, and thus leaching efficiencies of U, V, and Ga were 1.9, 1.3, and 5.0 times higher than those by directly leaching CA, respectively.

Keywords: (NH(4))(2)SO(4)-treated coal ash; Coprecipitation; Valuable trace metals; Water-leaching.

Publication types

Research Support, Non-U.S. Gov't