Zheng Yangfan, Cui Jiayan, Gao Pengxiao, Lv Junfan, Chi Lin, Nan Hongyan, Huang Yuandong, Yang Fan
School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, China.
School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, China.
Materials (Basel). 2023 Nov 16;16(22):7193. doi: 10.3390/ma16227193.
Coal gangue is a solid waste with low carbon content discharged during the course of the coal mining process. The resource utilization of coal gangue could solve environmental problems caused by its excessive production, such as soil contamination and land occupation. This study proposed to produce high-strength thermal insulation bricks using coal gangue as the primary material and three other mineral powders as auxiliary materials, including K-feldspar, CaCO and fly ash. A systematic analysis was conducted to explore the optimum raw material addition ratio and optimum sintering temperature; then, the intrinsic structure of thermal insulation bricks and their sintering formation mechanisms were revealed. The results showed that the optimal ratios of coal gangue, K-feldspar, CaCO and fly ash were 65 wt%, 15 wt%, 10 wt% and 10 wt%, respectively; the compressive strength of the thermal insulation brick produced under this ratio was 22.5 MPa; thermal conductivity was 0.39 W m k. During sintering processes, mineral powders sufficiently fused to form a skeleton, and the CO derived from CaCO formed pores. The optimum sintering temperature was 1150 °C, because at this temperature, K-feldspar had the best effect in promoting the conversion of CaCO to Ca-feldspar. The high level of the relative crystallinity of Ca-feldspar (about 76.0%) helped raise the Si-O network's polymerization degree (NBO/T = 1.24), finally raising the compressive strength of thermal insulation bricks. The innovative method of using coal gangue to make thermal insulation bricks not only solved the environmental pollution caused by coal gangue but also provided excellent construction materials with high practical application value.
煤矸石是煤炭开采过程中排放的一种低碳固体废弃物。煤矸石的资源利用可以解决因其产量过高而导致的环境问题，如土壤污染和土地占用。本研究提出以煤矸石为主要原料，钾长石、碳酸钙和粉煤灰三种矿物粉末为辅助原料生产高强度保温砖。进行了系统分析，以探索最佳原料添加比例和最佳烧结温度；然后，揭示了保温砖的内部结构及其烧结形成机制。结果表明，煤矸石、钾长石、碳酸钙和粉煤灰的最佳比例分别为65 wt%、15 wt%、10 wt%和10 wt%；在此比例下生产的保温砖抗压强度为22.5 MPa；导热系数为0.39 W/(m·K)。在烧结过程中，矿物粉末充分熔融形成骨架，碳酸钙分解产生的二氧化碳形成气孔。最佳烧结温度为1150℃，因为在此温度下，钾长石对促进碳酸钙转化为钙长石的效果最佳。钙长石的相对结晶度较高（约76.0%）有助于提高硅氧网络的聚合度（NBO/T = 1.24），最终提高保温砖的抗压强度。利用煤矸石制作保温砖的创新方法不仅解决了煤矸石造成的环境污染问题，还提供了具有高实际应用价值的优质建筑材料。
