提钛尾渣对氯氧镁水泥耐水性的影响

为了改善氯氧镁水泥(MOC)的耐水性,资源化利用固废提钛尾渣,向MOC中掺入提钛尾渣,利用维卡仪、万能试验机、离子色谱仪、X射线衍射仪、扫描电镜、压汞仪等检测设备分析了提钛尾渣对MOC凝结时间、抗压强度、氯离子溶出率、相组成、微观形貌和孔结构的影响。结果表明:未处理的提钛尾渣提高了MOC的总孔隙率和有害大气孔(直径>100 nm)含量,降低了MOC的抗压强度和耐水性。经磨细工艺处理后的提钛尾渣改善了MOC体系中氧化镁颗粒的分散性,促进了5Mg(OH)₂·MgCl₂·8H₂O生长发育,降低了MOC的总孔隙率,提高了MOC的抗压强度和耐水性。MOC中掺入20%(轻烧粉质量计)经磨细工艺处理后的提钛尾渣后,其28 d抗压强度和浸水28 d的强度保留系数最高,分别可达102.4 MPa和0.88,浸泡液中氯离子浓度可低至11.2 mmol/L。

Effects of Titanium Extraction Tailings on Water Resistance of Magnesium Oxychloride Cement

To improve the water resistance of magnesium oxychloride cement (MOC) and transform the solid waste-titanium extraction tailings (TETS) powder into resources, the TETS powder was added into MOC as an admixture. The effect of TETS powder on the setting time, compressive strength, dissolution rate of chloride ion, phase composition, microstructure and pore structure was analyzed by Vicat, electronic servo testing machine, ion chromatograph, X-ray diffractometer, scanning electron microscope and mercury intrusion porosimetry, etc. The results show that untreated TETS increases the total porosity and the large pores (>100 nm in diameter) content of the MOC matrix, resulting in a decrease in the compressive strength and water resistance of MOC. TETS powder treated by grinding can improve the dispersion of MgO particles in the MOC system, promote the growth and development of 5Mg(OH)₂·MgCl₂·8H₂O crystals, and reduce the total porosity of MOC, resulting in an increase in the compressive strength and water resistance of MOC. The 28 d compressive strength and 28 d strength retention coefficient of MOC containing 20% TETS powder treated by grinding (by weight of light-burned magnesia) reach to 102.4 MPa and 0.88, respectively. Meanwhile, the concentration of chloride ion in soaking liquid decreases to 11.2 mmol/L.