Li Xianhai, Zhao Yongqing, Luo Yunping, Ding Chengmei, Hu Biao
Mining College, Guizhou University, Guiyang, 550025, China.
National & Local Joint Laboratory of Engineering for Effective Utilization of Regional Mineral Resources from Karst Areas, Guiyang, 550025, China.
Sci Rep. 2024 Dec 28;14(1):31230. doi: 10.1038/s41598-024-82593-3.
Coal gangue (CG) is an industrial solid waste produced by coal mining and separation that is considered to have a significant effect on the soil or water environment when exposed to the air, exacerbating ecological pollution. The comprehensive utilization of CG has always been a difficult problem due to the complex mineralogical characteristics. Producing concrete aggregates with CG is an effective strategy for utilising CG resources synthetically. This work studied the mineralogical characteristics of CG discharged from a coal mine in Guizhou Province, China, and the feasibility of producing concrete coarse aggregate by using CG particles. The results indicated that some CGs were mainly composed of coal particles, whereas others were mainly composed of noncoal particles. Based on their apparent characteristics, texture, and cross-sectional characteristics, the CG samples at this sampling point could be divided into 8 categories, and the mass ratio suitable for concrete aggregate production was less than 50%. The average pore size of CG was 5.5 nm smaller than that of the industrial (IS) aggregate, but its porosity and total pore area were 2.31% and 4.5 m/g greater than those of the IS aggregate, respectively. CG aggregate concrete achieved a compressive grade of C40 at the appropriate mix ratio, but the mechanical properties of CG aggregate concrete were lower than those of IS aggregate concrete. The compressive strength of the concrete with the addition of coarse aggregate decreased by 17.26% at 7 days (7 d) of curing and 29.16% at 28 days (28 d) of curing compared with that of the concrete with the addition of the IS coarse aggregate. In addition, roasting at 500 °C for 2 h could increase the microhardness of this CG 40.06% higher than that without roasting. The separation of raw CG was a prerequisite for the preparation of concrete aggregate with CG, and also a direction to realize the comprehensive utilization of CG resources efficiently. Moreover, the roasting modification of this CG was an effective way to improve the mechanical performance of CG particles as concrete aggregates.
煤矸石（CG）是煤炭开采和选煤过程中产生的一种工业固体废弃物，暴露于空气中时被认为会对土壤或水环境产生重大影响，加剧生态污染。由于其复杂的矿物学特性，煤矸石的综合利用一直是个难题。利用煤矸石生产混凝土骨料是综合利用煤矸石资源的有效策略。本研究对中国贵州省某煤矿排出的煤矸石的矿物学特性以及利用煤矸石颗粒生产混凝土粗骨料的可行性进行了研究。结果表明，部分煤矸石主要由煤颗粒组成，而其他煤矸石主要由非煤颗粒组成。基于其表观特征、质地和横截面特征，该采样点的煤矸石样品可分为8类，适合生产混凝土骨料的质量比小于50%。煤矸石的平均孔径比工业（IS）骨料小5.5nm，但其孔隙率和总孔面积分别比IS骨料大2.31%和4.5m²/g。煤矸石骨料混凝土在合适的配合比下达到了C40的抗压强度等级，但煤矸石骨料混凝土的力学性能低于IS骨料混凝土。与添加IS粗骨料的混凝土相比，添加粗骨料的混凝土在养护7天（7d）时抗压强度降低了17.26%，在养护28天（28d）时降低了29.16%。此外，在500℃下焙烧2小时可使该煤矸石的显微硬度比未焙烧时提高40.06%。原煤矸石的分选是用煤矸石制备混凝土骨料的前提，也是高效实现煤矸石资源综合利用的一个方向。此外，对该煤矸石进行焙烧改性是提高煤矸石颗粒作为混凝土骨料力学性能的有效方法。
