Recycling of High-Purity Strontianite and Hematite from Strontium-Bearing Sludge

Rui Bian; Ting Su; Yu Chen; Zhan Qu; Suiyi Zhu; Xi Tian; Yang Huo

doi:10.1021/acsomega.0c01539

Recycling of High-Purity Strontianite and Hematite from Strontium-Bearing Sludge

ACS Omega. 2020 Jun 8;5(23):14078-14085. doi: 10.1021/acsomega.0c01539. eCollection 2020 Jun 16.

Authors

Rui Bian¹, Ting Su¹, Yu Chen², Zhan Qu¹, Suiyi Zhu^{1

3}, Xi Tian³, Yang Huo⁴

Affiliations

¹ School of Environment, Northeast Normal University, Changchun 130117, China.
² Jilin Institute of Forestry Survey and Design, Changchun 130022, China.
³ Changchun Institute of Technology, Changchun 130117, China.
⁴ Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.

Abstract

Sr-bearing sludge is a hazardous waste that is commonly generated by nuclear power plants and mineral refining operations. In this work, Sr-bearing sludge was simulated and then cleanly recycled into high-purity strontianite with hematite nanoparticles as a byproduct via a novel hematite precipitation route. The sludge contained 26.1% Fe, 3.5% Sr, and Si impurities. After dissolution in 1.2 M nitric acid, the sludge was treated hydrothermally with the addition of glycol to precipitate Fe effectively. Without the addition of glycol, only 52% Fe was hydrothermally precipitated in the form of hematite aggregates. With the addition of glycol at the optimal M _glycol/M _nitrate molar ratio of 0.4, nearly 100% Fe was removed in the form of hematite nanoparticles with an average diameter of 50 nm, whereas over 98% of Sr was retained in the leachate. The generated hematite was highly purified with an Fe₂O₃ content of 95.23%. Sr was present at a high concentration of 3.9 g/L in the treated leachate and further precipitated in the form of strontianite with a purity of 96.8% through Na₂CO₃ addition. Tertiary butanol (TeB) exhibited a similar Fe removal rate as glycol even though its optimal M _TeB/M _nitrate molar ratio was 0.1, which was approximately one-fourth the optimal M _glycol/M _nitrate molar ratio. Fe removal involved spontaneous Fe³⁺ hydrolysis under hydrothermal conditions and was promoted by increasing the pH of the redox reaction between nitrate and glycol and/or TeB. The method reported here successfully enabled the resource recycling of Sr-bearing sludge to generate high-purity strontianite and hematite products without producing any secondary waste.