Preparation of magnesium potassium phosphate cement using by-product MgO from Qarhan Salt Lake for low-carbon and sustainable cement production

Yongshan Tan; Zhibin Zhang; Jing Wen; Jinmei Dong; Chengyou Wu; Ying Li; Dingyi Yang; Hongfa Yu

doi:10.1016/j.envres.2022.113912

Preparation of magnesium potassium phosphate cement using by-product MgO from Qarhan Salt Lake for low-carbon and sustainable cement production

Environ Res. 2022 Nov;214(Pt 2):113912. doi: 10.1016/j.envres.2022.113912. Epub 2022 Jul 19.

Authors

Yongshan Tan¹, Zhibin Zhang², Jing Wen³, Jinmei Dong⁴, Chengyou Wu⁵, Ying Li⁶, Dingyi Yang², Hongfa Yu⁷

Affiliations

¹ College of Civil Science and Engineering, Yangzhou University, Yangzhou, 225127, China. Electronic address: ystan@nuaa.edu.cn.
² College of Civil Science and Engineering, Yangzhou University, Yangzhou, 225127, China.
³ Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, 810008, China. Electronic address: wj580420@isl.ac.cn.
⁴ Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, 810008, China.
⁵ School of Civil Engineering, Qinghai University, Xining, 810016, China.
⁶ Construction Fifth Engineering Bureau Co.,Ltd, Changsha, 410014, China.
⁷ Department of Civil and Airport Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.

PMID: 35863442
DOI: 10.1016/j.envres.2022.113912

Abstract

Herein, to reduce CO₂ emissions and energy consumption and to promote the recycling of waste resources, two types of boron-containing MgO by-products, which were obtained by lithium extraction from Qarhan Salt Lake, China, were used as substitutes for dead-burned MgO to prepare magnesium phosphate potassium cement (MKPC) as a rapid repair material. First, the phase composition and particle-size distribution of the MgO by-product were investigated. The effects of different MgO sources, molar ratio of MgO to KH₂PO₄ (M/P), and curing age on the setting time and mechanical properties of MKPC were then studied. Based on the results, the mix proportion of MKPC was optimized. Finally, X-ray diffractometry, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), differential thermogravimetric (DTG) analysis, and mercury intrusion porosimetry were used to characterize the phase and microstructure evolution of MKPC prepared with different MgO contents. The results demonstrated that the by-product MgO prolonged the setting time of MKPC to more than 40 min. In addition, in the initial stage of hydration, the compressive strength of the MgO by-product was slightly lower than that of the dead-burned MgO; however, with increasing age, the mechanical properties of MKPC prepared by by-product MgO were excellent (up to 60 MPa). The phase and microstructure results revealed that the main hydration product of MKPC prepared using the three types of MgO was MgKPO₄·6H₂O. Combined with the physical and chemical properties of the raw materials, it was confirmed that the larger particle size and the coexisting impurities from the salt lake were the main reasons for the longer setting time of the MKPC prepared by the by-product MgO. We believe that this research will be of great significance for the preparation of low-carbon, low-cost, and high-performance MKPC materials.

Keywords: Boron-containing by-product MgO; Mechanical properties; Microstructure; Retarding mechanism; Setting time.

Publication types

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

MeSH terms

Carbon
Lakes
Magnesium Compounds
Magnesium Oxide*
Magnesium*
Phosphates
Potassium
Potassium Compounds
X-Ray Diffraction

Substances

Magnesium Compounds
Phosphates
Potassium Compounds
Magnesium Oxide
magnesium phosphate
Carbon
potassium phosphate
Magnesium
Potassium