基于高温活化钼尾矿地质聚合物胶凝材料制备与抗压强度

钼尾矿具有高结晶度的矿物相和低品位的金属元素,开发利用性难,环境危害大。本文基于钼尾矿的矿物学特性,结合X射线衍射仪和扫描电子显微镜研究了热处理温度和时间对钼尾矿物相成分和微观形貌特征的影响,揭示了钼尾矿热活化改性机理;基于最优热处理温度,成功制备出碱激发地质聚合物(AAG)胶凝材料,并研究了热处理时间对其固化时间和抗压强度的影响。研究结果显示:850 ℃热处理2 h显著提高了钼尾矿中活性硅(铝)组分的含量;钼尾矿颗粒的表面粗糙度随着热处理时间增加而增大,其火山灰活性得到显著提高;由经过850 ℃热处理2 h的钼尾矿制备的AAG在室温条件下固化时间显著降低,相较于由未处理钼尾矿制备的AAG,固化时间由168 h缩短至48 h,且养护14 d后的抗压强度提高了2倍,达到了35.7 MPa。研究结果拓宽了可用于合成地质聚合物的原料来源,为钼尾矿在建筑材料方向的利用提供了一种可行的活化改性方案。

Preparation and Compressive Strength of Geopolymer Cementitious Material Based on High Temperature Activated Molybdenum Tailings

Molybdenum tailings are difficult to develop and utilize because of their high crystallinity mineral phase and low-grade metal elements. In order to realize the resource utilization of molybdenum tailings, based on the mineralogical characteristics of molybdenum tailings, the effects of heat treatment temperature and time on the phase composition and microstructure were studied, and the thermal activation modification mechanism of molybdenum tailings was developed. Based on the optimal heat treatment temperature, molybdenum tailings based alkali-activated geopolymer (AAG) cementitious material was successfully prepared, and the effect of heat treatment time on its curing time and compressive strength was studied. The results show that heat treatment at 850 ℃ for 2 h promotes the decomposition of muscovite and calcite in molybdenum tailings, and some low crystalline garnet and quartz phases transforme into amorphous aluminosilicate (ferrite), which significantly improve the content of active silicoaluminate in molybdenum tailings. The surface roughness of molybdenum tailings particles increases with the increase of heat treatment time, and the pozzolanic activity is significantly improved. Thecuring time of AAG prepared by molybdenum tailings after heat treatment at 850 ℃ for 2 h is shortened to 48 h from 168 h, which is significantly lower than that of AAG with untreated molybdenum tailings at room temperature, and the compressive strength after curing for 14 d increases by 2 times, reaching 35.7 MPa. The research results greatly broaden the raw material sources of geopolymer, and provide a feasible modification scheme for the utilization of molybdenum tailings.