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Coal based solid waste has been recognized as a sustainable raw material for the preparation of high added value materials for wastewater treatment. In this paper, a preparation route was designed for the rapid, efficient, and low-cost preparation of MCM-41 zeolite using coal gasification fine slag as raw material. Functionalization modification of MCM-41 was carried out by grafting amino groups on its surface to improve its application performance. Moreover, the prepared functionalized material is used for bidirectional adsorption of anionic and cationic dyes. The experimental results indicate that MCM-41 zeolite with highly ordered pore structure was rapidly prepared using the advantages of fast heating and strong permeability of microwave synthesis method, with a specific surface area of up to 862.03 m 2 /g. Amine functionalized MCM-41 exhibits strong adsorption capacity for both cationic and anionic dyes, with maximum adsorption capacities for methylene blue and Congo red being 292.40 mg/g and 354.61 mg/g, respectively. The study of adsorption kinetics and adsorption mechanism indicate that the adsorption process is mainly controlled through chemical adsorption, including electrostatic attraction, hydrogen bonding, and π-π interactions. The results of this study will provide useful references for the use of coal based solid waste to prepare functional materials for the treatment of organic wastewater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Gasification converts coal into syngas (CO and H 2) for downstream utilization. The most important reaction in an autothermal gasifier is the char−H 2 O/CO 2 reaction. The evolution of C(O) complexes on the coal char surface directly determines the pathways and rates of CO and H 2 generation. This study mainly used a fixed bed reactor to prepare Zhundong coal char with different reaction levels in H 2 O and CO 2 , and its surface carboxyl, lactone, phenolic hydroxyl, and hydroxyl functional groups were systematically analyzed by using Boehm titration, FT-IR, and XPS. The results show that the contents of the four oxygen-containing groups in raw coal are in the order of carboxyl＞lactone＞phenol hydroxyl＞hydroxyl. In H 2 O gasification, the lactone groups were more susceptible to H 2 O resulting in a significant increase in carboxyl content at the early stage of the reaction. The hydroxyl, as a very active group in the reaction, and the amount of its generation and consumption was very obvious. The phenolic hydroxyl−the least thermally stable group among these four types of groups, was unable to participate in the inter-transformation between oxygen-containing functional groups during the gasification. During CO 2 gasification, the hydroxyl was rapidly consumed at the initial stage of the reaction and then shown a slow growth trend, and the newly generated hydroxyl would continue to undergo dehydrogenation to form new functional groups. At the end of the reaction, the transformation of other oxygen-containing functional groups into more stable carbonyl groups leads to a sudden increase in the content of carboxyl and lactone. In this work, Boehm titration was introduced into the determination of oxygen-containing functional groups on the surface of char during gasification in H 2 O/CO 2. • Evolution of oxygen-containing functional groups on coal char surface during gasification was revealed. • The evolution of oxygen-containing groups in H 2 O/CO 2 was significantly different. • H 2 O has more noticeable effect in increasing aromatic C=C of char than CO 2 during gasification. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of aliphatics in coal on the formation of light aromatics (benzene, toluene, ethylbenzene, xylene and naphthalene, called BTEXN) from coal pyrolysis and catalytic upgrading using on-line Py-GC/MS, n-hexane was used to extract Shengli lignite (SL) and Pingshuo bituminous coal (PS). The extracts of the two coals (SLE and PSE) were analyzed by GC × GC-MS. Results show that aliphatics account for 85% of SLE and 68% of PSE. It brings about that the total yields of BTEXN from SL residue and PS residue pyrolysis are decreased by 29% and 18% compared with raw coals. This is because the aliphatics could provide small-molecule free radicals to stabilize the light aromatic cracking fragments and promote the formation of BTEXN during pyrolysis. The amounts of the alkyl benzene series, phenols, and polycyclic aromatic hydrocarbons from pyrolysis gaseous tar are significantly increased after extraction and they will undergo catalytic cracking to form BTEXN over USY zeolite, resulting in that the total yield of BTEXN from residue is almost same as that from raw coal during catalytic upgrading. • N-hexane extraction effected the formation of light aromatics from coal pyrolysis. • Extract mainly contained aliphatics that promoted aromatics formation from pyrolysis. • Extraction made pyrolysis products like alkyl benzenes, phenols and PAHs increased. • Residue coal had a high yield of BTEXN after catalytic upgrading over USY zeolite. [ABSTRACT FROM AUTHOR]

The formed activated carbon is a promosing carbon based absorbent for CO 2 adsorption in fossil energy industrial process. In this paper, the preparation method of commercial formed activated carbon and the partial steam gasification of coal via the addition of K 2 CO 3 and melamine were combined to prepare cylindrical activated carbon with high abrasive resistance and well-developed pore structure. The CO 2 adsorption capacity and mechanism of the prepared carbons were also explored. The results showed that the steam gasification reactivity of coal was enhanced by the addition of K 2 CO 3 and melamine. The prepared cylindrical carbons had the abrasive resistance higher than 95% and their specific surface area reached 1451 m2/g after K was added to coal. Nearly 70% of microporous proportion was obtained for the cylindrial carbons from the N doped and K-N co-doped coals as 1.3 times as that from undoped carbon. Both the CO 2 chemisorption and physical adsorption were improved by the K/N doping. It was concluded that the N species content and narrow micropore volume (<1 nm) showed the more important role on CO 2 total and physical adsorption capacity respectively. Good cyclic stability of CO 2 adsorption was also observed for the doped cylindrical carbons. • The preparation method of commercial formed AC and the coal partial steam gasification are combined. • K-N co-doped cylindrical AC with high abrasive resistance is prepared for CO 2 adsorption. • The activation time for cylindrical carbons can be seriously shortened by the doping of K and N. • Both the pore structure and nitrogen species are improved by doping of K and N. • K-N co-doped cylindrical AC have the good CO 2 adsorption capacity and cyclic stability. [ABSTRACT FROM AUTHOR]

Coal is one of the most important primary energy sources all over the world. Dry coal beneficiation is a hot topic in the mineral processing field because of severe environmental pollution and shortage of water resources. A dense-phase pulsed fluidized bed (DPPFB) is proposed for the dry coal beneficiation of fine coal; an active pulsating airflow was introduced into an air dense medium fluidized bed (ADMFB). In this study, the kinetic characteristics of the particles in a DPPFB were investigated by computational particle fluid dynamics. The results show that the bubbles present in the DPPFB were much smaller than those in the ADMFB, and the motion of the dilute-phase region replaced the motion of the large bubbles. Because of the action of the pulsating airflow, the motion of the heavy medium became uniform and steady. The back-mixing phenomenon caused by the circulation motion of the heavy medium was suppressed significantly. [ABSTRACT FROM AUTHOR]

• A VFB-LIBS online system was applied for the in-situ detection of released AMs. • The concentration of released AMs in gaseous phase was quantitatively measured. • The temporal release of AMs can be limited in the whole pyrolysis. • The higher content of C = O in coal, the stronger limitation on the release of AMs. • The inhibition of OCFG was not selective for the release of K and Na. Co-pyrolysis of coal and biomass is a promising technology for clean and efficient utilization of these two carbon resources. In this study, a visual fixed bed (VFB) combined with laser-induced breakdown spectroscopy (LIBS) was applied to investigate the effect of O-containing functional groups (OCFG) in coal on the release of alkali metals (AMs) during the co-pyrolysis of coal and biomass. The results showed that low temperature pre-oxidation increased the content of OCFG in coal, especially C=O and O–C=O groups, and limited the release of AMs during the co-pyrolysis. The higher pre-oxidation degree, the stronger limitation on the release of AMs. The increase of OCFG declined the maximum release concentrations of AMs and the temporal release of AMs in the whole pyrolysis process rather than some period. The release ratio of AMs can be maximally reduced about 39% by the OCFG. The relationship between release of AMs and structure of chars during the pyrolysis was also investigated. It was obtained that the layering placement of biomass and coal showed the less volatilization of AMs than the mixing placement of them. This study provided the theoretical basis for mitigating equipment corrosion problems caused by AMs in industrial applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Visual fixed bed combined with LIBS was applied for the detection of released alkali metals. • The concentration of released alkali metals was quantitatively measured. • Synergy effect between RS and YCW suppressed significantly the release of alkali metals. • Relation between disorder degree of char and release concentration of alkali metals was obtained. In this article, a visual fixed bed (VFB) combined with laser-induced breakdown spectroscopy (LIBS) was innovatively applied to investigate the in-situ release characteristics of alkali metals during fast co-pyrolysis of coal and biomass. The concentration of released alkali metals in gas phase was measured and used to reflect their temporal release behavior. The results showed that the release of alkali metals first increased and then decreased over time. The pyrolysis temperature, mass ratio of biomass to coal, and minerals in coal had little effect on the temporal release trends but seriously affected the release concentration extremity of alkali metals. Moreover, the interaction between coal and biomass caused the less release of alkali metals during the co-pyrolysis than biomass pyrolysis. This study benefited the better understanding on the release of alkali metals and the further industrial application of coal and biomass co-pyrolysis. [ABSTRACT FROM AUTHOR]

The iron-based waste catalysts (IWC) from Fisher-Tropsch synthesis, as a kind of waste containing abundant hydrocarbons and iron species, can be treated by the co-pyrolysis technology to realize the clean, efficient utilization of waste and coal. In this study, the synergistic effect and co-pyrolysis characteristics of IWCs and a bituminous coal were investigated by TG-MS and Py-GCMS. The results show that the co-pyrolysis of IWCs and coal occurs primarily in the range of 200–500 °C. The tar composition from the co-pyrolysis of coal and IWC 1 composed of paraffins is mainly aliphatic acids and olefins, while the co-pyrolysis of coal and IWC 2 with higher content of mineral matters principally yields aromatics and phenols. The strength of synergistic effect between coal and IWCs is enhanced by the increasing mass ratio of IWCs to coal and affected by the co-pyrolysis temperature, but the effects of temperature in the range of 200–400 °C and 400–500 °C are almost opposite. These changes of strength are related to the content of paraffins and iron species in IWCs, promoting or limiting the release of volatiles and changing the content of tar components, especially the content of aliphatic acids. The gas composition is also affected by the interaction. This study provides a basis for the further clean co-utilization of iron based waste catalysts from FT synthesis process and coal. • Co-pyrolysis of iron based waste catalysts and coal improves the yield of volatiles from coal. • The variation of weight difference with temperature was used to judge the interaction. • Co-pyrolysis temperature has different effects on the synergies in different stages. • The strength of synergies is attributed to the content of iron species and paraffins in waste. [ABSTRACT FROM AUTHOR]

• The interactions of Si, Al, and Ca in gasification were analyzed deeply. • The gasification rate of Ca-Si-Al coal quadrupled that of demineralized coal. • Factsage software was combined with in-situ XRD to reveal the change of minerals. • CaSiO 3 , Ca 2 SiO 4 , and Ca 2 Al 2 SiO 7 played a catalytic role in gasification. Clarifying the effect of other inert minerals on the catalytic performance of Ca in coal gasification is critical and meaningful to understand the deactivation mechanism of catalyst. In this work, four coal samples, demineralized coal (Dem-coal), coal loaded Ca (Ca + Dem-coal), coal containing Si and Al ((Si, Al)-coal), and coal loaded Ca, Si, and Al (Ca+(Si, Al)-coal), were prepared to analyze the impact of interactions on gasification reactivity. The gasification activity of coal samples with CO 2 agent at 900 °C was evaluated via thermal gravimetric analyzer (TGA). An in-situ heating stage microscope was applied to record the change of morphology of coal particles in the whole process. Besides, Factsage thermodynamic calculations were combined with in-situ X-ray diffraction (XRD) results to investigate the evolution of minerals including Ca, Si, and Al. The results indicate that Ca presenting in the form of CaO exhibits excellent catalytic performance. Si and Al existing in the form of SiO 2 crystals and amorphous structure respectively, hinder the process severely. Noticeably, the interactions of Si, Al, and Ca has a catalytic effect on coal gasification, though the gasification reactivity of Ca+(Si, Al)-coal is a bit lower than that of Ca + Dem-coal. In-situ XRD results confirmed the formation of CaSiO 3 , Ca 2 SiO 4 , and Ca 2 Al 2 SiO 7 , suggesting that these Ca complexes are catalytically active, but the catalytic performance of them is inferior to that of CaO. The evidence proved powerfully that it is not the reactions among Ca, Si, and Al which caused the deactivation of Ca catalyst. [ABSTRACT FROM AUTHOR]

• The reaxFF-MD simulation method was used on deconvolution of volatile–char interaction. • C-O reduced energy barrier of carbocyclic structural rearrangement to produce cyclopentadienyl group. • Thermodynamic competitive evolution of O-containing structure to CO/CO 2 under interaction was discussed. • Phenol hydroxyl group was likely to interact with coal molecules under electrostatic induction effect. • TEM photographed the primary soot and irregularly shaped mature soot aggregates. Information on energy states, evolutionary paths, microstructure, and chemical bonding properties of reactants and products under volatile–char interaction cannot be directly obtained through laboratory experiments. In this study, simulation experiments of volatile–char interaction were performed by ReaxFF-MD method based on interaction experiment of O-containing model compounds. The CO/CO 2 generation paths from different O-containing structures during the volatile–char interaction were obtained, and the corresponding thermodynamic parameters were calculated by using DFT. The peculiarities of C–O active site structure greatly reduce the energy barrier for the carbocyclic structural rearrangement of the six-carbon ring, leading to the formation of five-carbon ring cyclopentadienyl group. The electrons provided by the active sites of coal fragments effectively promote the activation of phenol hydroxyl group, resulting in the decrease of ΔE LUMO-HOMO and acceleration of interaction process. This study deepens the understanding of chemical site adsorption effect of O-containing compounds in the interaction process from the microscopic level. [ABSTRACT FROM AUTHOR]

Interzeolite transformation (IZT) has been used to produce zeolite with novel structure and composition. However, the complicated interactions between synthesis parameters and the resultant zeolites remained ambiguous. Herein, we synthesized zeolite SSZ-13 via an IZT strategy by using coal fly ash-derived analcime as parent zeolite. The effects of feeding H 2 O/SiO 2 , OH-/SiO 2 , and SiO 2 /Al 2 O 3 ratios on the crystallization of zeolite SSZ-13 were examined. The crystallinity, pore structure, building units, and chemical environment of the products were investigated by XRD, SEM, XRF, N 2 adsorption-desorption, FT-IR, and NMR, respectively. Zeolite SSZ-13 with high crystallinity and regular pore structure can be obtained under feeding H 2 O/SiO 2 ratios of 17.5–25, OH-/SiO 2 ratios of 0.2–0.6, and Al 2 O 3 /SiO 2 ratios of 30–40. The absence of external water limited the mass transfer between reactants. While excessive water lessened the driving force for synthesizing zeolite SSZ-13 with regular structure. Small amounts of OH- ions triggered the dissociation of zeolite analcime. But high concentrations of OH- ions blocked the condensation of Si reactants and nucleation of zeolite SSZ-13. Increasing SiO 2 /Al 2 O 3 ratio boosted the nucleation frequency. Insufficient contents of external Si species delayed nucleation and formed amorphous aluminosilicate impurities. The superfluous SiO 2 /Al 2 O 3 ratio caused the overgrowth of zeolite SSZ-13 with irregular structures. Our findings benefited in understanding the interaction among synthesis parameters and the crystallization mechanism of IZT. It also gained new strategies for synthesizing high-silica zeolite using Al-rich natural and industrial aluminosilicate solid wastes. [Display omitted] • Zeolite SSZ-13 was synthesized transforming from coal fly ash-derived analcime. • Effects of H 2 O/SiO 2 , OH−/SiO 2 , and SiO 2 /Al 2 O 3 ratios on SSZ-13 were examined. • Added water determined mass transfer of reactants and crystallization driving force. • OH− ions triggered dissociation of analcime but inhibited nucleation of SSZ-13. • High Si contents boosted nucleation frequency but impacted product purity. [ABSTRACT FROM AUTHOR]

• Reaction characteristics of a single coal particle flame for different coal ranks were studied. • Flame structures for three coal ranks at different oxygen concentration (X i,O2) were obtained. • Na* and K* in single coal particle flames with different reaction stages were analyzed. • Alkalis alkali metal spectral intensity was feasible to calculate flame temperature. In this work, the combustion progress and alkali metals radiation characteristic of the different coal ranks (NaoMaoHu (NMH) lignite coal, YangChangWan (YCW) bituminous coal and SiHe (SH) anthracite coal) are studied in a visualization drop tube furnace (VDTF) by a high-speed camera and a hyper-spectral camera. The effects of different coal ranks on the alkali metal (Na*, K*) radiation characteristics in the volatile and char reaction stage are explored at the oxygen concentration (X i,O2) ranging from 0.2 to 1.0. In addition, the flame temperature of the different coal ranks is further calculated by alkali metal spectral intensity. The results show that in the volatile reaction stage, the NMH Coal is homogeneously ignited and the coal particle shows the fragmentation behavior. The YCW coal shows a hetero-homogeneous ignition, and SH Coal particles are heterogeneously ignited with a black spot in the center of the particle. During the char reaction stage, the three coal particles are ignited heterogeneously. As the reaction proceeds, the flame size and brightness of the three coal particles first increase and then decrease. The Na* and K* peak intensity and volatile reaction time of the different coal ranks have the relationship that NMH Coal > YCW Coal > SH Coal, because the volatile content of YCW Coal and SH Coal is lower than that of NMH Coal. Besides, the trend of flame temperature variation agrees with the alkali metal spectral intensity for different coal ranks. When X i,O2 is 0.2, only one release peak of Na* and K* occurs, and the flame temperature varies from 1600 K to 1950 K. When X i,O2 is greater than 0.4, the three coal particles show two Na* release peaks and the flame temperature varies from 1650 K to 2100 K. This paper provides insight on the effects of flame temperature and alkali metals radiation characteristics on reaction process of different coal ranks. [ABSTRACT FROM AUTHOR]

• Volatile–char interaction inhibited the occurrence of deacidification and deketoization reactions. • PAHs occupied the active site was the main cause for coal char deactivation. • Phenolic hydroxyl group were more favorable for diaryl ether dissociation showing the strongest inhibition. • Inhibition behavior on reactivity follows the order: Phenolic hydroxyl > Carboxyl > Aldehyde > Ether group. Volatile–char interaction is a significant contributor to low equipment reliability and energy efficiency of gasifier equipment. In this work, volatile–char interaction during the coal/biomass co-gasification process is explored based on a two-stage fixed bed reactor decoupling, the variations in liquid–gas-solid three-phase product composition and reactivity are discussed in detail, and the contributing behaviors of different O-containing compounds to coal char deactivation were analyzed. The essence of volatile–char interaction is the process of deoxidation, dehydrogenation and ring-opening repolymerization of tar compounds, and inhibits decarboxylation and deketoization. The PAHs generated by the polymerization of O-containing compounds occupy the active sites and is the main reason for coal char deactivation during gasification. And the functional groups are phenolic hydroxyl, carboxyl, aldehyde and ether in the order of action strength. This study provides the potential for directional regulation of product distribution to reduce interaction intensity, which is helpful for gasifier design and operation optimization. [ABSTRACT FROM AUTHOR]

• Structural features of residue char from maceral concentrate gasification were revealed. • The shrinkage ability of inertinite char residual is stronger than that of vitrinite. • The fresh vitrinite char has lower order degree and more active sites. • The amount of vitrinite residual char active sites decreases rapidly during gasification. Gasification fine slag contains a high content of carbon, which causes waste of resources and environmental hazards. In essence, fine slag is a comprehensive reflection of the separate gasification of various macerals in coal. In this study, different macerals concentrates were firstly prepared from Yangchangwan (YCW) and Meihuajing coal (MHJ). The structure and pyrolysis characteristics of different macerals as well as the morphology and molecular structure of gasification residue carbon at different conversion levels were then investigated by a series of characterization techniques. The results show that the aromatic degree of inertinite concentrates of both coals is greater than that of vitrinite. During the active pyrolysis stage of 200–600 °C, the weight loss rate of vitrinite is higher than that of inertinite, and the weight loss rate reaches maximum at about 445 °C. Maximum thermal weight loss rate of YCW and MHJ vitrinite is 1.39 and 1.43 times higher than that of inertinite. The shrinkage ability of inertinite char is stronger than that of vitrinite and the surface of inertinite residue carbon is rougher and rich in porous structures during gasification, resulting in a higher final gasification carbon conversion level. The fresh vitrinite char obtained from pyrolysis has lower order degree and more active sites. As the gasification proceeds, the content of active sites in vitrinite gasification residue carbon decreases rapidly, while inertinite remains relatively stable. This research innovatively links the properties of macerals with the structure of residue carbon, which is helpful to deepen the understanding of the correlation between coal microstructure and reactivity. [ABSTRACT FROM AUTHOR]

In this study, the volatile–char interaction in coal and cow manure co-pyrolysis process was decoupled by adding internals in a two-stage fixed bed reactor, and the effect of vapor-residence time on coal char reactivity at 850 °C was investigated. The results indicated that the volatile–char interaction inhibited coal char reactivity, but the inhibition showed an opposite rule with the vapor-residence time in different co-pyrolysis modes. The reformed gas-phase volatiles entered the macromolecular framework of coal and generated PAHs, increasing the aromatization degree and large aromatic rings numbers of char, resulting in the reduction of the O-containing functional groups and the behavioral effects of C–O and C O being particularly pronounced. The interaction promoted the release of Na/K, and the release behavior changed when only volatile−volatile interaction existed in the co-pyrolysis samples. The reduction of O-containing functional groups resulted in the loss of active sites number after the interaction, AAEM showed limited catalytic behavior. The O-containing functional groups and cross-linking structure act as active sites in the interaction process. This work is beneficial to enrich and develop the synergistic transformation theoretical system of carbon-containing energy materials, and provides theoretical support for promoting the industrial application of related technologies. • The interaction behaviour in the biomass and coal co-pyrolysis process was decoupled. • Multifaceted characterization of the in-situ interacting char carbon chemical structure. • The increase of vapor-residence time promoted the precipitation of Na and K. • The interaction process was not conducive to the cracking of alkyl aryl ether. • C–O, C O content and cross-linking structure act as active sites in the interaction. [ABSTRACT FROM AUTHOR]

Here, the OH* and CH* chemiluminescence characteristics of a single coal particle flame combustion in a visual drop-tube furnace (VDTF) for different oxygen fraction, X i,O2 , in O 2 /CO 2 atmosphere were investigated using an optical diagnostic technique. The results indicate that the combustion of single coal particles is composed of a volatile reaction stage followed by a volatile-char reaction stage. During volatile reaction stage, the single coal particle burns in an enveloped flame. The flame becomes brighter and the flame length increases gradually. In addition, the OH* and CH* intensity shows peak values with axial distance along the furnace, with that of OH* appearing earlier as the oxygen fraction increases. In the volatile-char reaction stage, the flame length fluctuates slightly, and OH* and CH* peak position are spread over a smaller range of distance. The value of X i,O2 affects the reaction rate as it promotes the diffusion of oxygen to the interior of coal particle, as the intensity of OH* and CH* increasing rapidly for X i,O2 > 0.4. This indicates that the rate of reaction is controlled by X i,O2. Furthermore, the peak intensity ratio of OH* and CH* increases linearly with X i,O2. • O 2 /CO 2 atmosphere of single coal particle was studied in visual drop-tube furnace (VDTF). • Single coal particle combustion characteristic was studied using optical diagnostic technique. • OH* and CH* chemiluminescece distributions at different X i,O2 were obtained. • Effects of X i,O2 on distribution characteristics of OH* and CH* were further analyzed. • Quantitative relation among the OH* and CH* peak intensity, OH*/CH* and X i,O2 were studied. [ABSTRACT FROM AUTHOR]

Co-gasification of coal and coal indirect liquefaction residue (LR) could mitigate the environmental pollution caused by solid waste accumulation to a great extent. Therefore, in this work, anthracite coal and LR were co-gasified to solve the above-mentioned derived problems. The effects of LR addition on ash fusibility and fluidity were investigated by ash fusion temperature analyzer (AFTA), XRD, SEM-EDS and FactSage software. The results showed that with the increase of LR proportion, the ash fusion temperatures (AFTs) could be effectively reduced. The formation of mullite with skeleton structure was the main reason for the higher AFTs in Sihe coal ash (AS0). The addition of LR increased the Fe content in the mixed sample, thereby inhibiting the formation of mullite phase and promoting the formation of low-temperature eutectic (hercynite and fayalite) resulting in the continuous decrease of AFTs. According to the quantitative calculation of change rate of ash cone height during AFTs test, the melting mechanism was described. Due to the high AFTs of AS0, the ash melting behavior followed the "softening-melting" mechanism; however, for the sample with LR added, the ash melting behavior conformed to the "melting-dissolution" mechanism. Finally, flow temperature (FT) and T mullite were fitted (FT = 1.35*T mullite -336.94), and there was a good linear relationship. [Display omitted] • Explored the co-gasification process of LR and coal on ash fusibility and fluidity. • AFTs decreased significantly with the increasing of LR proportion. • By adding LR, low-temperature eutectics such as hercynite and fayalite formed. • The ash melting process was distinguished based on the ash cone height variation. • The FT of each sample was well fitted with T mulite. [ABSTRACT FROM AUTHOR]