Preparation of Low Ratio Magnesium Ccement by Acid Leaching Treatment of Boron Mud

Abstract

The effects of liquid-solid ratio and reaction time on the leaching rate of magnesium at room temperature were investigated, as well as the effects of the molar ratio of MgO/MgCl₂, the amount of water added, and the amount of acid-impregnated slag dosed on the compressive strength and water resistance of LR-MOC. The results showed that the magnesium element in the boron mud could be maximally leached under the conditions of 1:1 concentration of hydrochloric acid at room temperature, liquid-solid ratio of 2.5 mL·g⁻¹, and reaction time of 5 h, and the main products were amorphous SiO₂ as well as a small amount of magnesium olivine which had not been completely reacted. The LR-MOC prepared using the acid-soaked mixture could reach a softening coefficient of 0.85 for 28 d of water immersion when the molar ratio of MgO/MgCl₂ was 2.2, the amount of water added was 0 g, and the acid-soaked slag dosing was 40 wt%, which also led to an appreciable late-strength, with an increase of 19.4% in compressive strength at 28 d compared to that at 7 d. Unlike previous studies, LR-MOC prepared in this way has a final strength phase that is not the more easily hydrolysed 3-phase but the lath-like 5-phase. For this phenomenon, we analyzed the mechanism and found that, during the acid leaching process, a part of amorphous SiO₂ dissolved in the acid leaching solution formed a silica sol, in which Mg²⁺ played a bridging role to make the silica sol more stable. With the addition and hydrolysis of MgO, the silica sol gel coagulation slows down, providing a capping layer to inhibit the hydrolysis of the 5-phase crystals and providing some strength after coagulation. The amorphous SiO₂ in the other part of the acid-impregnated slag generated M-S-H gel with Mg²⁺ and OH⁻, which synergised with the dense structure composed of interlocking crystals to improve the water resistance of LR-MOC.

References

[1] Yu J, Lin L, Qian J, et al.. Preparation and Properties of a Low-Cost Magnesium Phosphate Cement with the Industrial by Products Boron Muds[J]. Construction and Building Materials, 2021, 302: 124 400

[2] Hu F, Fu L, Zhang Q, et al.. Efficient Synthesis of Forsterite via High-Temperature Thermochemical Reactions from Boron Mud Waste without Briquetting[J]. Particuology., 2024, 87: 124-132

[3] Yin Y X. Environmental Problems and Resource Utilisation of Boron Mud[J]. China Comprehensive Utilisation of Resources, 2020, 38(02): 72-75

[4] Ning Z Q, Zhai Y C, Xie H W, et al.. Recovery of Silica from Sodium Silicate Solution of Calcined Boron Mud[J]. Rare Metals, 2016, 35: 204-210

[5] Shen R, Yang H B, Li H, et al.. Preparation of Magnesium Carbonate Trihydrate Whiskers Using Boron Mud[J]. Journal of Artificial Crystals, 2014, 43(04): 991-996

[6] Ma X, Ma H, Jiang X, et al.. Preparation of Magnesium Hydroxide Nanoflowers from Boron Mud via Anti Drop Precipitation Method[J]. Materials Research Bulletin, 2014, 56: 113-118

[7] Liu D X. Development of High-Strength Boron Mud Shale Ceramic Granules[J]. Coal Ash, 2016, 28(05): 34-35 43

[8] Fu X J, Chu M S, Zhao J Q, et al.. Experimental Study on Application of Boron Mud Secondary Resource to Oxidized Pellets Production[J]. High Temperature Materials and Processes, 2017, 36(7): 649-655

[9] Cao J, Wang Y Y, Wang X M. Effect of Boron Mud Blending on the Properties of Magnesium Phosphate Cement[J]. Transactions of Nonferrous Metals Society of China (Smelting Component), 2023(09): 159–166

[10] Tong Y, Liu J X, Xia F, et al.. Hydrothermal Curing Mechanism and Compressive Strength of Boron Mud[J]. Chinese Journal of Environmental Engineering, 2015, 9(12): 6 090-6 096

[11] Hu P, Zhang Y, Lu F, et al.. Preparation of Layered Double Hydroxides Using Boron Mud and Red Mud Industrial Wastes and Adsorption Mechanism to Phosphate[J]. Water and Environment Journal, 2017, 31(2): 145-157

[12] Xue R Y, Li R. Study on the Treatment of Simulated Printing and Dyeing Wastewater by Boron Mud Acid Leaching Mud[J]. Environmental Protection and Circular Economy, 2019, 39(11): 29-31

[13] Xiao L P, Li J X, Wang T. Adsorption Performance of Boron Mud on Acidic Wastewater Containing Copper[J]. Environmental Science & Technology, 2020, 43(07): 94-100

[14] Bo J, Zhang Y, Zhang Y. Leaching Magnesium Oxide in Boron Mud by Water with Pressurized CO₂[J]. Hydrometallurgy, 2017, 171: 142-148

[15] Chang J, Ning Z, Xie H, et al.. Leaching Kinetics of Magnesium Extraction from Boron Mud in Ammonium Bisulfate Solutions[J]. The Canadian Journal of Chemical Engineering, 2023, 101: 6 764-6 773

[16] Hu F, Fu L, Zhang Q, et al.. Efficient Synthesis of Forsterite via High-Temperature Thermochemical Reactions from Boron Mud Waste Without Briquetting[J]. Particuology, 2024, 87: 124-132

[17] Liu Y, Zhang T, Wang B, et al.. Preparation of Environment-Friendly SiO₂ Aerogel Based on Waste Boron Mud and Its Adsorption Behavior for Toluene[J]. Water Science and Technology, 2023, 87(2): 469-491

[18] Ning Z Q, Zhai Y C, Song Q S. Extracting B2O3 from Calcined Boron Mud Using Molten Sodium Hydroxide, 2015, 34: 744-751

[19] Ning Z Q, Song Y T, Zhao R Y, et al.. A New Process for Extracting Silicon and Boron from Boron Clay[J]. Journal of Northeastern University (Natural Science), 2022, 43(07): 959-965

[20] Wang L J, Ning Z Q, Xie H W, et al.. Study on Magnesium Extraction from Acid Leached Activated Boron Mud[J]. Chinese Journal of Rare Metals, 2022, 46(09): 1 207-1 214

[21] Bo J. Basic Research on the Application of Pressurised Carbonation of Boron Mud to Extract Magnesium, 2018, Beijing, Institute of Process Engineering, Chinese Academy of Sciences

[22] Jiang T, Zhang Q W, Jing Y J, et al.. Boron Mud Activation Roasting-Leaching Integrated Recovery of Silicon, Magnesium Valuable Components[J]. CIESC Journal, 2014, 65(10): 4 110-4 117

[23] Song Z J, Liu L, Yu P P, et al.. Preparation and Performance of Chitosan/Citric Acid Modified Magnesium Oxychloride Cement[J]. Journal of Wuhan University of Technology -Materials Science Edition, 2023, 38(06): 1 326-1 334

[24] Qin L Q. Flame-Retardant Mechanism of Magnesium Oxychloride in Epoxy Resin[J]. Journal of Wuhan University of Technology -Materials Science Edition, 2009, 24(01): 127-131

[25] Ge S J, Zhang X, Wang H N, et al.. Effect of High Activity MgO on the Physical Phase and Properties of Low-Temperature Magnesium Chloride-Oxygen Cement[J]. Journal of the Chinese Ceramic Society, 2019, 47(07): 865-873

[26] Huang Q, Li Y, Chang C G, et al.. The Salt Attack Performance of Magnesium Oxychloride Cement Exposure to Three Kinds of Brines[J]. Journal of Wuhan University of Technology -Materials Science Edition, 2020, 35(01): 155-166

[27] Ba H, Guan H. Influence of MgO/MgCl₂ Molar Ratio on Phase Stability of Magnesium Oxychloride Cement[J]. Journal of Wuhan University of Technology-Mater. Sci. Ed., 2009, 24(3): 476-481

[28] Li Z, Chau C K. Influence of Molar Ratios on Properties of Magnesium Oxychloride Cement[J]. Cement and Concrete Research, 2007, 37(6): 866-870

[29] Li K, Wang Y, Zhang X, et al.. Raw Material Ratio Optimisation of Magnesium Oxychloride Cement Using Response Surface Method[J]. Construction and Building Materials, 2021, 272: 121 648

[30] Li H, Sun Q, Wu C P, et al.. Preparation of Porous Silica from Boron Clay and Characterisation of Its Properties[J]. Bulletin of the Chinese Ceramic Society, 2014, 33(08): 2 124-2 127

[31] Yang X M, Hu S, Wen Y, et al.. Process Conditions for the Preparation of Magnesium Oxide from Boron Mud[J]. Journal of Materials Science and Engineering, 2014, 32(05): 727-731

[32] Yang M, Chen Q F, Wu X J. Study on the Preparation of Refined Magnesium Chloride from Boron Mud Leached by Hydrochloric Acid Method[J]. Journal of Shenyang Normal University(Natural Science Edition), 2016, 34(02): 144-147

[33] Liang X M. Research on the Mechanism of the Effect of Silica Fume on the Water Resistance of Magnesium Chloride Cement, 2017, Dalian, Dalian University of Technology

[34] Sun Q, Li H, Zheng S L, et al.. Preparation and Photocatalytic Properties of TiO₂ Nanoparticles/Boron Mud Demineralised Silica Slag Composites[J]. Journal of Synthetic Crystals, 2014, 43(04): 893-897

[35] Li H, Sun Q, Wu C P, et al.. Preparation of Porous Silica from Boron Clay and Characterisation of Its Properties[J]. Bulletin of the Chinese Ceramic Society, 2014, 33(08): 2 124-2 127

[36] Bao B. Preparation and Formation Mechanism of Highly Reactive Silica, 2022, Kunming, Kunming University of Science and Technology

[37] Li Z G, Ji Z S. Research Progress on Deformation and Cracking of Magnesium Chloride-Oxygen Cement Products[J]. Bulletin of the Chinese Ceramic Society, 2012, 31(02): 291-294 300

[38] Ning Y Y, Zhang L Q, Ding X Q. Influence of Several Factors on the Properties of Magnesium Chloride Cement[J]. Bulletin of the Chinese Ceramic Society, 2016, 35(07): 2 287-2 290

[39] Chen X, Zhang T, Bi W, et al.. Effect of Tartaric Acid and Phosphoric Acid on the Water Resistance of Magnesium Oxychloride (MOC) Cement[J]. Construction and Building Materials, 2019, 213: 528-536

RIGHTS & PERMISSIONS

Wuhan University of Technology and Springer-Verlag GmbH Germany, Part of Springer Nature