Petrological Characteristics and Trace Element Partitioning of Gasification Residues from Slagging Entrained-Flow Gasifiers in Ningdong, China

Abstract

In order to better understand the petrological characteristics of gasification residues and trace element partitioning during entrained-flow gasification processes, oil-immersion microscopy, X-ray diffraction, scanning electron microscopy combined with an energy dispersive detector, inductively coupled plasma mass spectrometry, a Milestone DMA-80 Hg analyzer, and pyrohydrolysis in conjunction with a fluorine ion-selective electrode were employed to study samples collected from three commercial-scale slagging entrained-flow gasifiers in Ningdong, China. Petrological analysis indicated that dominant organic components in the residues were inertiods, fusinoids, tenuinetworks, and crassisnetworks. In addition, vitroplast and cenosphere were observed in coarse residues produced from water–slurry coal gasification. The main inorganic components were quartz, calcite, spinel, and a large amount of Al–Si glass. After gasification, most trace elements were significantly enriched in the residues. Critical trace elements Li, Be, Sc, V, Cr, Sr, REEs, Th, Nb, Ta, Zr, and Hf were enriched in the coarse residues. Critical trace elements Zn, Sb, Pb, and Bi were enriched in the fine residues, which was in accord with volatilization–condensation mechanism. The partitioning of trace elements was elucidated on the basis of their relative enrichment. Fluorine showed various partitioning behavior in three gasification processes. Mercury was the most volatile element. Generally, trace elements from the GE gasification process were less volatile; elements from the opposed four-burner gasification were more volatile; and the volatile behavior of trace elements from the Gaskombimat Schwarze Pumpe gasifier was intermediate.

Green Synthesis Method and Application of NaP Zeolite Prepared by Coal Gasification Coarse Slag from Ningdong, China

“…Ningdong energy and chemical base is one of the most advanced bases for developing clean coal technology in China. In 2018, the base generated nearly 8 million tons of CGS [3]. At present, there is no good treatment method, and it can only be landfilled after high-standard anti-seepage treatment on the ground, which is quite different from the systematic utilization of fly ash [4][5][6][7][8].…”

“…At present, there are many researches on the resource utilization of fly ash and slag in the world [7,8,10]. However, since the CGS is obtained in a high-pressure vaporization furnace under a reducing atmosphere (CO, H 2 ) and 1400-1500 • C, its structure and composition are greatly different from those of fly ash and slag [3,5,9]. Therefore, it is difficult to realize the utilization of CGS by the same method.…”

“…This study is based on China Ningdong coal gasification coarse slag (CGCS) [3,15,16]. We hope to find a feasible way for the utilization of CGCS with the increasingly severe environmental pressure.…”

Clean coal geology in China: Research advance and its future

“…The authoritative background values of trace elements in Chinese coals were obtained by Dai et al (2012a, b) and an evaluation formula of enrichment coefficients of trace elements was established by Dai et al (2014). Recently, the emphases of researches on trace elements are on their behavior during coal utilization (Tang et al 2018a;, their health impacts (Dai et al 2014;Finkelman and Tian 2018), and recovery of valuable trace elements (Dai et al 2006b;Seredin and Dai 2012;Dai et al 2014Dai et al , 2016Dai and Finkelman 2017). This last topic is illustrated by the fact that germanium has achieved industrial extraction (Tang and Huang 2004).…”

Changes and Distribution of Modes of Occurrence of Seventeen Potentially-Hazardous Trace Elements during Entrained Flow Gasification of Coals from Ningdong, China

“…In the GE-FR, more than 60% of the Cr was in the carbonates and iron and manganese oxides (likely calcite or some oxidized species), while about 70% of the Cr was in the sulfides in the GSP-FR ( Figure 14A,B). Tang et al [40] showed that spinel was identified in the gasification residues, but Cr-bearing spinel was not determined by SEM-EDX due to the low concentration of Cr. In this study, Cr identified in the carbonates and iron and manganese oxides is probably associated with spinel (note that spinel was not identified by XRD or SEM-EDX).…”