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山西煤矸石中铝元素矿物赋存形态及酸浸溶出规律

Mineral occurrence and acid leaching characteristic of aluminum for coal gangue in Shanxi Province

  • 摘要: 山西作为全国煤炭大省,在煤炭开采和分选过程中产生大量工业固废煤矸石,回收铝元素是其资源化高值利用的重要方式。研究主要采用X射线荧光光谱、X射线衍射光谱、扫描电镜−能谱等方法,对山西主要煤田所产煤矸石中铝含量及其矿物赋存形态和空间分布特性进行了分析;基于多元线性回归方法,考察了不同化学组成煤矸石经焙烧−酸浸处理后Al2O3溶出情况,以期阐明成分波动对煤矸石中铝溶出特性的影响规律。结果表明:山西煤矸石中Al2O3质量分数为13.9%~ 42.5%,主要以高岭石、伊利石和白云母等铝硅酸盐矿物的形式赋存;其中,晋北地区由于特殊的古地质成因,导致局地产出高铝煤矸石, Al2O3质量分数超过30%。煤矸石在焙烧−酸浸过程中,焙烧温度显著影响其活化效率,活化最佳温度为700 ~ 850 ℃;酸浸后Al2O3溶出量主要与煤矸石中Al2O3含量相关,相关系数可达0.97以上,即煤矸石中Al2O3含量越高,酸浸Al2O3溶出量越高。除此之外,煤矸石中Al2O3溶出量还与其SiO2含量、K2O含量和C含量呈现一定相关性,其中Al2O3溶出量与SiO2含量的负相关性较强,与K2O含量的负相关性较弱,随着C含量的增加,Al2O3溶出量和C含量的由负相关转向正相关。这可能是煤矸石本身元素含量特性、不同矿物活化温度差异、浸出过程固液接触面积变化等因素造成的。

     

    Abstract: Shanxi Province, a major coal-producing region in China, generates a substantial amount of industrial waste (such as coal gangue) during coal mining and washing processes. Recovering aluminum from coal gangue represents a significant method for its high-value utilization. The content, mineralogical occurrence and spatial distribution characteristics of aluminum for coal gangue from major coalfields in Shanxi was measured by X-ray fluorescence spectroscopy, X-ray diffraction spectroscopy, and scanning electron microscopy-energy dispersive spectroscopy to analyze. Furthermore, the effect of chemical compositions on the leaching characteristics of aluminum from coal gangue treated with calcination and acid leaching was analyzed using multiple linear regression. The resulted indicated that the Al2O3 content in Shanxi's coal gangue ranges from 13.9% to 42.5%, predominantly existing in the form of aluminosilicate minerals such as kaolinite, illite and muscovite. Notably, due to unique paleo-geological formations, the northern region of Shanxi produces the aluminum-rich coal gangue with Al2O3 content exceeding 30%. The calcination temperature significantly influences the activation efficiency of coal gangue, and the optimal temperature ranges between 700 ℃ and 850 ℃. The aluminum leaching amount is primarily related to the Al2O3 content of coal gangue, with a correlation coefficient exceeding 0.97.It indicate that the higher aluminum leaching amounts with higher Al2O3 content of coal gangue. Additionally, the aluminum leaching amount also shows correlations with the contents of SiO2, K2O, and C of coal gangue. A strong negative correlation exists between aluminum leaching amount and SiO2 content and a weaker negative correlation with K2O content. In comparison, there is a complex relationship between C content and aluminum leaching amount, which change from negative to positive correlation as the increasing of C content. This may be attributed to the intrinsic elemental characteristics of the coal gangue, differences in activation temperatures of various minerals and changes in the solid-liquid contact area during the leaching process.

     

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