Study of using light-burned dolomite ores as raw material to produce magnesium oxysulfate cement

Abstract

Magnesium oxysulfate cement (MOS) prepared by light-burned dolomite has excellent performance in terms of light weight, high strength and low carbon dioxide emission. In this research, dolomite ores are used to produce MOS cement at different calcination temperatures and calcination times; the parameters investigated are the rate of loss on ignition, free lime (f-CaO), dihydrate gypsum (CaSO 4 Â2H 2 O) and impact of active magnesium oxide (α-MgO) content exerted on the setting time and compressive strength of the MOS cement. X-ray diffraction analysis, scanning electron microscopy, the time of colour change for citric acid and hydration-heat release rate were adopted to assess the effects of calcination temperature, calcination time and the molar ratio of α-magnesium oxide/magnesium sulfate on the MOS cement. The experimental results showed that the MOS cement prepared by dolomite ores at the calcination temperature of 850°C for 30 min with the α-magnesium oxide/magnesium sulfate molar ratio of 4 demonstrates better mechanical properties than those made in other circumstances. In addition, the main strength phase of MOS cement with tri-sodium citrate dihydrate (Na 3 C 6 H 5 O 7 •2H 2 O) generated by light-burned dolomite ores is the needle-like 5Mg(OH) 2 •MgSO 4 •7H 2 O crystal phase. Notation M MgO molecular weight of magnesium oxide M H2O molecular weight of water m 1 , m 2 mass of magnesium oxide before and after reacting with water for 3 h at a temperature of 105°C, respectively W 1 , W 2 mass of dolomite before and after calcinating, respectively ω(CaO) content of calcium oxide ω(MgO) content of magnesium oxide ΔG gibbs free energy Cite this article Chen Y, Wu C, Yu H et al. (2018) Study of using light-burned dolomite ores as raw material to produce magnesium oxysulfate cement.

Water-to-Cement Ratio of Magnesium Oxychloride Cement Foam Concrete with Caustic Dolomite Powder

“…When bischofite was dissolved in water, MgCl 2 -H 2 O of a certain concentration was formed. The ratio of m f added to the bischofite was a function of the Ba: f (m f /m Bi ) = f (Ba), which can be calculated according to Equation (17). As shown in Table 3, the actual measured function is expressed as f (m f /m Bi ) = f (Ba).…”

“…The MgO content in dolomite is one-third of that of magnesite; therefore, the mechanical performance of MOC prepared with dolomite raw material is poor [14], especially magnesium oxychloride cement foam concrete (MOCFC) made from porous material [15]. Dolomite has already been tested as a raw material for producing MgO-based cements such as magnesium oxychloride cement [16], magnesium oxysulfate cement [17] and magnesium phosphate cement [13]. However, few studies have been conducted using CDP and LMP as the raw materials to produce MOC material, and only a few scholars have probed the performance of MOC made from mixed materials [18].…”

Half-decomposition of salt-bearing dolomite

“…Half-calcined dolomites (HCDs) are of industrial importance as a source of MgO for construction, 1,2 catalysis, 3,4 and biomaterials; 5 as an absorbent for pollutant gases (H 2 S, SO x , and CO 2 ); 6–10 and as a scrubber for several metal elements (Ag, As, B, Ba, Co, Cr, Hg, Mn, Ni, Pb, Sn, Sr, Ti, and V) and anions (F − , PO 4 3− , and AsO 4 3− ) in wastewater. 11–14 Studies have demonstrated that the performance of HCDs is closely related to their microstructures.…”

Mechanistic Study of the Effects of Magnesia Reactivity on Setting and Hardening of Basic Magnesium Sulfate Cement

“…Li et al (2020) compared the BMS cement prepared by MgO derived from the calcination of brine precipitation products and LBM, and the former showed a higher early strength. Chen et al (2018) investigated the BMS cement prepared using light burnt dolomite and found that the BMS cement prepared using magnesia at a calcination temperature of 850°C had the highest strength. In our previous report (Wu et al 2018), the magnesium-rich by products obtained in the production of lithium carbonate from salt lake were used to prepare BMS cement.…”