Phase and morphological transformation stages during carbothermal reduction nitridation process: From coal gasification slag wastes to Ca-α-SiAlON powders

Tang, Yun; Yin, Hongfeng; Yuan, Hao; Shuai, Hang; Xin, Yalou

doi:10.1016/j.apt.2016.08.008

Cited by 32 publications

(6 citation statements)

References 29 publications

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“…Most contemporary studies have focused on the utilisation of CGFS, which is carried by the coarse gas to the top of the gasifier furnace; CGFS comprises approximately 20% of CGS, and it has a high carbon content (between 20% and 40%) and fine particle size (66% in mass was <0.074 mm) [ 5 ]. CGFS is used as a raw material for cement; as a supplement in combustion fuels [ 6 ]; as an additive in wall materials [ 7 ]; as solid amendments [ 8 ]; and as some high-value utilisation products such as active carbon [ 9 ], sodium silicate [ 10 ], ceramic powders [ 11 , 12 ], and carbon–silicon composites [ 13 ]. However, CGCS, which is discharged at the bottom of the gasifier and accounts for approximately 80% of the total CGS, has been rarely investigated.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Ultra-High Performance Concrete with Coal Gasification Coarse Slag as River Sand Replacement

Zhu¹,

Lian

Zhai

et al. 2022

Materials

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Coal gasification coarse slag (CGCS) is a by-product of coal gasification. Despite its abundance, CGCS is mostly used in boiler blending, stacking, and landfill. Large-scale industrial applications of CGCS can be environment-friendly and cost saving. In this study, the application of CGCS as a substitute for river sand (RS) with different replacement ratios in ultra-high performance concrete (UHPC) was investigated. The effects of CGCS replacement ratios on the fluidity and mechanical properties of specimens were examined, and the effect mechanisms were explored on the basis of hydration products and the multi-scale (millimetre-scale and micrometre-scale) microstructure analysis obtained through X-ray diffraction (XRD), scanning electron microscopy, and X-ray energy-dispersive spectroscopy. With an increase in the CGCS replacement ratio, the water–binder ratio (w/b), flexural strength, and compressive strength decreased. Specimens containing CGCS of ≤25% can satisfy the strength requirement of non-structural UHPC, with flexure strength of 29 MPa and compressive strength of 111 MPa at day 28. According to the XRD results and multi-scale microstructure analysis, amorphous glass beads in CGCS positively influenced ettringite generation due to the pozzolanic activity. Porous carbon particles in CGCS showed strong interfacial bonding with cement slurry due to internal hydration; this bonding was conducive to improving the mechanical strength. However, CGCS hindered hydration in the later curing stage, leading to an increase in the unreacted cement and agglomeration of fly ash; in addition, at a CGCS replacement ratio of up to 50%, an apparent interfacial transition zone structure was observed, which was the main contributor to mechanical strength deterioration.

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Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Ultra-High Performance Concrete with Coal Gasification Coarse Slag as River Sand Replacement

Zhu¹,

Lian

Zhai

et al. 2022

Materials

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“…Currently, one of the main approaches for handling slag is backfilling to the mine or landfilling elsewhere. [ 4 ] A small part of slag is recycled and utilized as building materials or by mixing with asphalt. [ 5,6 ] The disposal of such a large quantity of solid waste leads to severe environmental pollution and space wastage.…”

Section: Introductionmentioning

confidence: 99%

Recovered Carbon from Coal Gasification Fine Slag as Electrocatalyst for Oxygen Reduction Reaction and Zinc–Air Battery

et al. 2021

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The coal gasification industry produces a large amount of coarse and fine slag. Such slag, which is composed mainly of carbon residues and inorganic species, e.g., silicon, calcium, magnesium, and aluminum, becomes a tough problem because of the environmental concerns and high reusage cost. Benefiting from the carbon‐rich feature, such cheap byproducts of the coal gasification industry can be used as precursors to prepare porous carbons for energy conversion and storage. Herein, new porous carbons are prepared by treating carbon‐rich fine slag by direct acid etching and ammonia activation. The oxygen reduction reaction performance of as‐developed porous carbons as electrocatalysts is evaluated in alkaline media. Then, such porous carbons are further utilized as air cathodes for a zinc–air battery and reach a power density of 88 mW cm−2 at the current density of 154.9 mA cm−2. All these results indicate that fine slag, a byproduct of the coal gasification industry, has a great potential to be reused as a high‐value electrocatalyst and electrode for energy conversion and storage.

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“…Many promising ways to optimize the utilization of coal slag have been explored. It was reported that the coal slag can be used to synthesize structural materials, e.g., Si–Al–O–N ceramics, silica-based mesoporous materials, − highly porous active carbons, etc. Some researchers found that the coal gasification slag can be used in anaerobic digestion to remove resistance genes. , Coal gasification slags can be also applied to fabricate building bricks , and are recommended to add to pig manure for effective composting .…”

Section: Introductionmentioning

confidence: 99%

Characteristics of High-Carbon-Content Slag and Utilization for Coal-Water Slurry Preparation

Guo

Zhang

et al. 2020

Energy Fuels

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Fine slag and coarse slag are the byproducts of the entrained-flow gasifier, which may contain a considerable amount of carbonaceous residue. In this study, the characteristics of slags (LHA, LHB, and GT) from three commercial gasifiers were collected and studied. The coal-water slurry (CWS) blended with these different slags (5 wt %) was investigated in detail, including the apparent viscosity, contact angle, and zeta potential. The experimental results showed that the fine slag contained the residue carbon at normally higher than 15 wt % and the combustible content in coarse slag was mainly concentrated in the particle size of 20–60 mesh. According to the reactivity index, the residue carbon in slags from LHB and GT showed higher reactivity compared to that of raw coal at 1300 °C. The addition of slag would cause little increase of the apparent viscosity. The addition of fine and coarse slag in CWS was better than the addition of fine slag alone. CWS blended with slags would decrease the contact angle of the samples. All the results showed the feasibility of the high-carbon-content slag for coal water slurry preparation to achieve residual carbon utilization.

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Phase and morphological transformation stages during carbothermal reduction nitridation process: From coal gasification slag wastes to Ca-α-SiAlON powders

Cited by 32 publications

References 29 publications

Mechanical Properties of Ultra-High Performance Concrete with Coal Gasification Coarse Slag as River Sand Replacement

Mechanical Properties of Ultra-High Performance Concrete with Coal Gasification Coarse Slag as River Sand Replacement

Recovered Carbon from Coal Gasification Fine Slag as Electrocatalyst for Oxygen Reduction Reaction and Zinc–Air Battery

Characteristics of High-Carbon-Content Slag and Utilization for Coal-Water Slurry Preparation

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