花岗岩尾矿制备可加工微晶玻璃的结构调控与复相增强机理研究

A great deal of granite tailings are not only fail to use effectively, but also pollute the environment seriously．Thus increasing the utilization of granite tailings is an urgent and important issue．It is a high value-added application to prepare glass-ceramics by the use of granite tailings. On the basis of our previous research, the bulk crystallization method will be used to prepare high-strength and high-hardness mica/ diopside-based machinable glass-ceramics with granite tailings as the main raw materials. Firstly, by adjusting the composition of the basic glasses, the kinds and contents of the nucleating agents, and the heat treatments, the precipitation of mica/diopside crystals and their morphologies will be controled. The influence of glass structure, bond and distribution of ligand units on the crystallization behavior will be investigated. Secondly, through the crystallization kinetics calculation, the crystallization ability of the base glass and the target crystal growth mechanism can be determined. Then, the effect of crystallinity and microstructure on the flexural strength, microhardness, fracture toughness, and machinability of the glass-ceramics will be investigated, in order to reveal the mechanism of enhancement of mica/diopside-based glass-ceramics. Through the further optimization of composition, the amount of granite tailings will be increased, so as to increase the efficiency of resource utilization of granite tailings. The implementation of this project is expected to provide theoretical guidance for the preparation of glass-ceramics with large amounts of tailings, and create a huge economic and social benefits.

花岗岩尾矿排放量大且资源化利用率很低，对生态环境造成巨大的破坏，因此亟需寻求一种有效的处理方式，而采用花岗岩尾矿制备微晶玻璃正是一种高附加值的利用途径。本项目在前期研究的基础上，以花岗岩尾矿为主要原料，拟采用整体析晶法制备高强度、高硬度的云母/透辉石基可加工微晶玻璃。首先通过调整基础组成、晶核剂的种类及含量和热处理制度，控制云母/透辉石晶相的析出，研究基础玻璃结构及各种离子配位体构成和分布情况对析晶性能的影响规律。其次通过析晶动力学计算，判断基础玻璃的析晶能力，揭示目标晶体的生长机制。进一步研究晶相含量和显微结构对微晶玻璃抗折强度、显微硬度、断裂韧性和可加工性能的影响规律，探索云母/透辉石基微晶玻璃的复相增强机理。最后通过组成优化，提高花岗岩尾矿掺量，从而提高花岗岩尾矿的资源化利用效率。项目的研究为大宗量利用尾矿制备微晶玻璃提供理论指导，可创造较好的经济和社会效益。

花岗岩尾矿是花岗岩在开采、加工过程中产生的固体废弃物，排放量大且资源利用率很低，对生态环境造成巨大的破坏。而采用花岗岩尾矿制备建筑微晶玻璃是一种高效、经济和环保的解决途径。传统建筑微晶玻璃硬度大，耐腐蚀，但存在韧性差、加工困难等技术难题，严重制约了各类尾矿建筑微晶玻璃的实际应用。.本项目采用花岗岩尾矿作为主要原料，基于SiO2-Al2O3-MgO-CaF2-K2O玻璃体系，选用CaF2作为晶核剂，系统研究了SiO2/Al2O3、SiO2/MgO、 CaO/MgO比值（mol%）以及热处理工艺制度对玻璃析晶行为、微观结构及机械性能的影响规律。揭示了云母相与增强相（镁橄榄石、透辉石）的相对含量、晶粒尺寸、形态以及分布对微晶玻璃样品强度、硬度、断裂韧性和可加工性能之间的作用机制。发现随云母晶体含量的增加，微晶玻璃的维氏硬度逐渐降低，但其断裂韧性和可加工性显著提升。层状晶体的增加有利于微晶玻璃断裂韧性和可加工性能的提升。当SiO2/Al2O3、SiO2/MgO和CaO/MgO比值分别为17.82、3.73和0.243时，经过900℃热处理，得到的微晶玻璃维氏硬度超过6.3GPa，断裂韧性超过2.51 MPa·m1/2，且具有良好的可加工性能。在本项目的支持下，成功制备出主晶相为透辉石、镁橄榄石和带云母的高强度高韧性微晶玻璃材料，其中花岗岩尾矿掺量高达50%以上。本项目的实施促进了花岗岩尾矿微晶玻璃的实际应用，对加强大宗固废高附加值综合利用，推动绿色低碳循环经济发展具有重要意义。