Preparation of Low-Cost Magnesium Oxychloride Cement Using Magnesium Residue Byproducts from the Production of Lithium Carbonate from Salt Lakes

Abstract

Magnesium oxychloride cement (abbreviated as MOC) was prepared using magnesium residue obtained from Li2CO3 extraction from salt lakes as raw material instead of light magnesium oxide. The properties of magnesium residue calcined at different temperatures were researched by XRD, SEM, LSPA, and SNAA. The preparation of MOC specimens with magnesium residue at different calcination temperatures (from 500 °C to 800 °C) and magnesium chloride solutions with different Baume degrees (24 Baume and 28 Baume) were studied. Compression strength tests were conducted at different curing ages from 3 d to 28 d. The hydration products, microstructure, and porosity of the specimens were analyzed by XRD, SEM, and MIP, respectively. The experimental results showed that magnesium residue’s properties, the BET surface gradually decreased and the crystal size increased with increasing calcination temperature, resulting in a longer setting time of MOC cement. Additionally, the experiment also indicated that magnesium chloride solution with a high Baume makes the MOC cement have higher strength. The MOC specimens prepared by magnesium residue at 800 °C and magnesium chloride solution Baume 28 exhibited a compressive of 123.3 MPa at 28 d, which met the mechanical property requirement of MOC materials. At the same time, magnesium oxychloride cement can be an effective alternative to Portland cement-based materials. In addition, it can reduce environmental pollution and improve the environmental impact of the construction industry, which is of great significance for sustainable development.

Perspective of Using Magnesium Oxychloride Cement (MOC) and Wood as a Composite Building Material: A Bibliometric Literature Review

“…MOC cement also has various other applications, such as the use of composite building materials based on MOC for stabilization or solidification of sewage sludge [ 41 ]. Other research directions explore the possibility of obtaining good building materials using seawater [ 42 ] or different compounds from the salt lakes [ 43 ] and also how the MOC composite responds to the salt attack [ 44 ].…”

“…The traditional active magnesia used for MOC materials is calcined from magnesite at 700–900 °C. For example, China is one of the countries with the wealthiest magnesite resources in the world, but even if the resources are rich and the grade is high, the distribution is shallow [ 43 ]. This can have a big influence on the production costs and, in the end, on the final price of the MOC cement.…”

High-Bond-Strength, Water-Resistant Magnesium Oxychloride Cement-Based Inorganic Adhesive Inspired by Adsorbed Heavy Metal Ions

“…MOC is a mixture of magnesium oxide (MgO) and magnesium chloride (MgCl 2 ) along with water, which hardens in air. Its raw material, magnesium chloride, can be derived from further processing of salt lake waste, while magnesium oxide is derived from the calcination of dolomite or magnesite. − Unlike silicate cement clinker, magnesite can be calcined at 600–1300 °C to obtain the activated magnesium oxide, which can be used to manufacture MOC. , Therefore, the development and use of MOC does not only reduce energy consumption and CO 2 emissions but also further increase the recycling of waste to alleviate the global warming crisis. Unlike calcium silicate hydrate (C–S–H) or calcium aluminum silicate hydrate (C-A–S-H) of silicate cement, , the main physical structures of MOC are 3-phase, 5-phase, 2-phase, and 9-phase, , where the main phases present at room temperature are 3-phase and 5-phase, and they improve the mechanical strength of MOC composites in the form of needle rods and short rods.…”