富硅镁冶金废渣机械力化学效应及其含镁矿物在水泥基材料中的水化特性研究

Mechanochemistry is used to describe the chemical conversions in solids induced by a mechanical process such as milling or grinding. The mechanical processing usually results in variety of crystal defects such as increased number of grain boundaries, dislocations, vacancies and interstitial atoms, stacking faults, and deformed and ruptured chemical bonds. This work aims to assess the possibility of using the metallurgical slag with rich silica-magnesia (MgO-SiO2-Fe2O3-Al2O3) such as the nickel slag as a hydraulic binder in application of mechanochemistry. It will be used with high-energy grinding for activation method to research the mechanochemical effects for the metallurgical slag with rich silica-magnesia of the crystal structure, lattice distortion, microscopic strain, split phase composition, polymerization degree of [SiO4], alumina polyhedron structure, surface behavior, particle size distribution and other physical and chemical properties. The dynamic model of ion dissolution rate in chemical environment will be established. It will be revealed the relationship between the mechanochemical effects of the metallurgical slag with rich silica-magnesia, hydration reactivity (ion dissolution rate, the rate of hydration, hydration products) and macroscopic properties (mechanical properties, volume stability). The research results will promote the use of low activity slag such as the metallurgical slag with rich silica-magnesia in cement-based materials by studying regular pattern of the mechanochemical effects to increase the magnesium dissolution. The hydration properties of the mineral phase with magnesia and its effects on the microstructure and long-term strength and volume change in the cement-based materials will be illustrated. These basic studies will expand the scope of mechanochemistry, provide the theoretical basis for high energy grinding-chemical dissociation processes and the new process application in cement concrete expansion agent, valuable metals extracting and other areas.

以亟待充分利用的镍工业冶金废渣(镍渣)为代表的富硅镁冶金废渣(MgO-SiO2-Fe2O3-Al2O3)为研究对象，以高能粉磨实现机械力化学效应，达到提高废渣活性的目的。探明机械力化学作用下富硅镁冶金废渣中硅酸盐矿相的晶体结构、晶格畸变、分相组成、[SiO4]聚合度、铝氧多面体结构、表面特性、粒度分布等物理化学变化规律，建立其硅酸盐矿相在化学环境介质中离子溶出动力学模型。揭示机械力化学效应-水化活性(离子溶出速率、水化速率、水化产物)-宏观性能(力学性能、体积稳定性)之间的关系。通过研究机械力化学促进镁离子溶出规律，结合其对水泥基材料微观结构和长期强度及体积变化的影响，阐明富硅镁冶金废渣中含镁矿物的水化特性，促进低活性废渣在水泥基材料中的应用。研究成果可为高能粉磨-化学解离工艺应用于低活性工业废弃物奠定理论基础，并为富硅镁冶金废渣应用于有价金属提取、水泥混凝土膨胀剂等方面开拓新的应用领域。

我国仍有大量的低活性冶金废渣亟待有效利用。冶金废渣年排放量达4.4亿吨，其利用率为60%，每年约有1.8亿吨没有得到利用，主要为钢渣及镍冶金废渣。由于镍铁冶金废渣和低碱度钢渣的MgO、 SiO2含量较高，故称为富硅镁冶金废渣。该类废渣目前处理技术主要以堆存、填埋为主，对生态环境构成了潜在威胁。项目以亟待充分利用的镍工业冶金废渣(镍渣)为代表的富硅镁冶金废渣(RSMS)为研究对象，以高能粉磨实现机械力化学效应，达到提高废渣活性的目的。研究了机械力化学作用下富硅镁冶金废渣中硅酸盐矿相的晶体结构、晶格畸变、分相组成等物理化学变化规律，建立了硅酸盐矿相在化学环境介质中离子溶出动力学模型。研究表明：高能球磨可以进一步细化镍渣，使大颗粒块状粉体破裂、表面粗糙化并提高镍渣的反应活性，长时间球磨可使水化样品诱导期和加速期两个阶段的水化放热量显著增大。高能球磨4h时镍渣蒸压试块的强度是未高能球磨时的4.5倍，球磨4h后蒸压试块水化产物的X射线谱图中出现了硬硅钙石、 托勃莫来石和镁水化物等衍射峰。.项目揭示了机械力化学效应-水化活性(离子溶出速率、水化速率、水化产物)-宏观性能(力学性能、体积稳定性)之间的关系。镍渣中不含有f-MgO或含量较低，MgO的存在形式取决于镍渣的碱度，镍渣属于低碱度镍渣，该类镍渣中的MgO容易与其他氧化物化合成镁橄榄石、镁黄长石、斜顽辉石等硅酸盐矿物，这些矿物水化反应后形成矿物骨架，结构稳定而不发生膨胀。镍渣取代部分硅酸盐水泥熟料后，随着镍渣掺量的增加，水泥浆体凝结时间不断延长，且水化反应放热量逐渐减少。但镍渣细度的提高， 能改善浆体的凝结时间， 同时提高浆体的水化放热量。.研究成果为富硅镁冶金废渣应用于水泥混凝土矿物掺合料、集料、蒸压加气混凝土、水泥砂浆、水泥基复合材料等方面应用领域提供理论基础。