Abstract

Ash accumulation is a relevant problem due to the widespread use of coal-fired power plants and a very limited number of ash utilization technologies. Plasma processing of ash is a promising method of ash valorization for production of various useful products, which is limited by high energy consumption. In the current study, a mixture of waste ash from power plant and black carbon was processed using an original direct current plasma arc experimental setup in ambient air which allows lower energy consumption due to the absence of the vacuuming system. Four types of samples at different plasma exposure times were produced and together with the initial ash were studied by thermal analysis, X-ray diffractometry and scanning electron microscopy. The X-ray diffraction analysis identified the resulting phases of graphite, silicon carbide, and aluminum nitride in the synthesis products; at the same time, at the arc discharge energy increased from 26 to 105 kJ, the intensities of the maxima that correspond to metal and nonmetal oxides in the composition of the initial ash decreased to nearly zero. To remove graphite, the processed samples were annealed at 750 °C in air and studied. It was found that the applied approach made it possible to obtain a mixture of silicon carbide and aluminum nitride powders in direct current arc plasma initiated in ambient air, which reduced the energy consumption for ash processing by electric arc.

Graphical Abstract

中文翻译：

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通过直流电弧等离子体处理灰渣并生产SiC和AlN

摘要

由于燃煤发电厂的广泛使用以及灰烬利用技术的数量非常有限，灰烬积累是一个相关的问题。灰分的等离子体处理是用于生产各种有用产品的灰分增值的一种有前途的方法，其受到高能耗的限制。在当前的研究中，使用原始直流等离子弧实验装置在环境空气中处理了发电厂产生的废灰和黑碳的混合物，由于没有真空系统，因此可以降低能耗。制备了四种在不同等离子体暴露时间下的样品，并通过热分析，X射线衍射和扫描电子显微镜研究了初始灰分。X射线衍射分析确定了石墨，碳化硅，合成产品中的氮化铝；同时，在电弧放电能量从26 kJ增加到105 kJ时，对应于初始灰分成分中的金属和非金属氧化物的最大值的强度降低到几乎为零。为了去除石墨，将经过处理的样品在750°C的空气中退火并进行研究。发现所应用的方法使得有可能在环境空气中引发的直流电弧等离子体中获得碳化硅和氮化铝粉末的混合物，这减少了电弧灰分处理的能耗。为了去除石墨，将经过处理的样品在750°C的空气中退火并进行研究。发现所应用的方法使得有可能在环境空气中引发的直流电弧等离子体中获得碳化硅和氮化铝粉末的混合物，这减少了电弧灰分处理的能耗。为了去除石墨，将经过处理的样品在750°C的空气中退火并进行研究。发现所应用的方法使得有可能在环境空气中引发的直流电弧等离子体中获得碳化硅和氮化铝粉末的混合物，这减少了电弧灰分处理的能耗。

图形概要