Clean Process to Utilize the Potassium-Containing Phosphorous Rock with Simultaneous HCl and KCl Production via the Steam-Mediated Reactions

Yunshan Wang; Lufang Shi; Houli Li; Yixiao Wang; Zhiying Wang; Xuebin An; Mingzhu Tang; Gang Yang; Jun He; Jing Hu; Yong Sun

doi:10.1021/acsomega.2c02362

Clean Process to Utilize the Potassium-Containing Phosphorous Rock with Simultaneous HCl and KCl Production via the Steam-Mediated Reactions

ACS Omega. 2022 Jul 7;7(28):24561-24573. doi: 10.1021/acsomega.2c02362. eCollection 2022 Jul 19.

Authors

Yunshan Wang¹, Lufang Shi², Houli Li³, Yixiao Wang⁴, Zhiying Wang³, Xuebin An¹, Mingzhu Tang³, Gang Yang¹, Jun He^{5

6}, Jing Hu⁴, Yong Sun^{7

6}

Affiliations

¹ National Engineering Research Center of Green Recycling for Strategic Metal Resources, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
² Each Energy Technology (Suzhou) Co., Ltd., Suzhou 215021, China.
³ School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China.
⁴ Key Laboratory of Carbonaceous Wastes Processing and Process Intensification of Zhejiang Province, University of Nottingham Ningbo China, Ningbo 315100, China.
⁵ Nottingham Ningbo China Beacons of Excellence Research and Innovation Institute, Ningbo 315021, China.
⁶ Department of Chemical and Environmental Engineering, University of Nottingham Ningbo China, Ningbo 315100, China.
⁷ School of Engineering, Edith Cowan University, 270 Joondalup Drive, Joondalup, Western Australia 6027, Australia.

Abstract

In this paper, a clean process based on the steam-mediated reactions for simultaneous HCl and KCl production using the potassium (K)-containing phosphorous rock as a precursor is proposed. Through hydrochloric acid (HCl) leaching, not only the generation of H₃PO₄ and CaCl₂ (via further precipitation) were realized but also the acid-insoluble residue [phosphorous-rock slag (PS)] rich in elements, that is, K, Al, Si, and so on, in the form of microcline (KAlSi₃O₈) and quartz (SiO₂) was obtained and became readily available for further HCl and KCl generation. Over 95% of the elements, that is, K, Al, and Si, come into the final products, and the overall acid consumption (based on HCl) is significantly reduced (90%) due to recovery of acids. The impacts of the key operational parameters such as temperature, duration, and reagent impregnate ratio were rigorously analyzed via a supervised machine learning approach, and the optimal conditions were determined [reaction temperature, X₁, 850 °C; reaction duration, X₂, 40 min; and impregnate ratio (PS over CaCl₂), X₃, 2.5] with approximately ±10% uncertainties. Thermodynamic analysis indicates that the introduction of steam to PS + CaCl₂ not only enhances the chemical potential for the formation of HCl and KCl but also provides the transport advantage in continuously removing the generated products, that is, HCl and KCl, out of the system. Molecular simulation indicates that the presence of both steam and SiO₂ in the PS matrix plays critical roles in decomposing PS + CaCl₂ at high temperature. The shrinking core model shows that both the intrinsic kinetics and transport are influential with the activation energy being around 14.63 kJ/mol. The potential reaction pathway is postulated.