Jincheng Coal Research Articles

The effects of Na2O/K2O flux on ash fusion characteristics for high silicon-aluminum coal in entrained-flow bed gasification

Composite additives are widely used to regulate coal ash fusion characteristics to meet the requirement of entrained-flow bed gasification. In this paper, the effects and corresponding mechanisms of the Na2O/K2O ratio on ash fusion behavior of high silicon-aluminum coal (Jincheng coal, JC) were investigated. The results showed that at the same total mass fractions of Na2O and K2O (15%), the JC ash fusion temperatures (AFTs) decreased quickly and then increased slowly with increasing Na2O/K2O ratio, the lowest AFT reached when Na2O/K2O ratio was at 9/6. The variations in volume and morphology of mixed JC ashes during heating indicated the AFT variation. The mineral change from KAlSi2O6 (MP: 1686 °C) to NaAlSiO4 (MP: 1100 °C) with increasing Na2O/K2O mass ratio mainly resulted in a decrease in the AFT. This indicated that the Na2O/K2O synergy flux effect was related to the formation of a NaAlSiO4–KAlSiO4 eutectic structure. The AFT variation with increasing Na2O/K2O ratio was also explained by the fact that a quick increase and then a slow decrease in the temperature at which all solid phase changes into liquid-phase was calculated by FactSage.

In-situ analysis of the sintering behavior of coal ash and a phosphorus-rich biomass ash under gasification condition

The relatively high contents of some ash-forming elements (Na, K, Ca, Mg, P) in biomass ash can cause serious ash-related problems (deposition, slagging, corrosion, etc.) during the co-gasification of coal and biomass, influencing the stable operation of gasifier. The sintering behavior of Jincheng coal ash (JCA) and a phosphorus-rich Jatropha seed cake ash (JSCA) were investigated by in-situ heating stage microscopy, while the sintering mechanism was revealed by phase studies employing X-ray powder diffraction and thermodynamic modelling. Results indicated that the sintering temperature of blended ashes reached the minimum at the 20 wt% blending ratio of JSCA in the coal-biomass ash mixture. The high sintering temperatures of JCA and JSCA were due to the extensive mullite and quartz crystallization in the high acidic JCA system and the widespread formation of K–Ca phosphate and K–Mg phosphate in the high basic JSCA system, respectively. The transition of the phosphorus from fluxing effect to refractory effect on the sintering of ash mixture was identified at the 20 wt% blending ratio of JSCA. It was also found that the role of mullite and quartz decreased, while the role of anorthite, gehlenite, leucite, and calcium phosphate increased with increasing JSCA content, leading to the lowest sintering temperature. Finally, the variation trend of sintering temperatures against the JSCA additions was in accord with the change of the liquidus temperatures that was calculated by thermodynamic modelling. These observations can be used for the potential prediction of the ash sintering temperature in the coal-biomass gasifier.

The influence of the high potassium biomass on the ash fusion characteristics of coal

The influence of high potassium biomass (corn straw (CS)) on ash fusion temperature (AFTs) of Jincheng coal (JC) was explored by X-ray fluorescence (XRF), intelligent ash fusion point tester, X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS). The results show that the method of adding CS can effectively reduce the AFTs of JC. The main mineral composition of JC ash at high temperatures is refractory Al6Si2O13, which is why JC has a higher AFTs; the main mineral composition of CS ash at high temperatures is its ash with a large amount of Ca/Mg-containing aluminosilicates and glassy substance containing metal potassium (K), which is why CS has a lower AFTs. With the increasing of the proportion of CS added, Al6Si2O13 as the main mineral component in JC ash gradually converts into a series of new Ca/K-containing aluminosilicates (such as, diopside (CaMgSi2O6), leucite (KAlSi2O6), etc.), which results in the reduction of the AFTs of JC. Meanwhile, the Ca/K-containing aluminosilicates has a low-temperature co-fusion effect. In addition, SiO2 and Al2O3 together in coal ash have excellent K-fixing efficiency confirmed by the formation of stable K-containing aluminosilicates.

Sintering behavior of ash from combustion of Jincheng coal and pine sawdust blends

Sintering behaviour of ash specimens from blends of Jincheng (JC) coal and pine sawdust (PS) was investigated using a pressure-drop sintering device combined with scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD) analysis, and FactSage modeling. The sintering temperatures consistently displayed a decreased trend when the PS was added into JC. In addition, the ashing temperature had an important influence on the sintering temperature of ash. The SEM analysis revealed a fine, irregular, and fibrous texture in the ash specimens from the lower ashing temperature. Regular block-shape particles were present in the ash from the higher ashing temperature. The EDS results showed that more Ca and Fe appeared with the increase of ashing temperature and more K and Na appeared, while Ca and Fe decreased with the addition of PS. The XRD analysis revealed that low-temperature minerals melted or co-fused with 10% PS addition into coal, while the high-temperature minerals formed with increased ashing temperature. The FactSage calculation indicated that the alkali and alkali earth metal species mainly existed in the forms of aluminosilicates and silicates. Calcium, magnesium, and potassium played a vital role during the sintering of the blends with PS.

Clinical characteristics of pneumoconiosis complicated with chronic obstructive pulmonary disease

Objective: To analyze the pulmonary function and clinical features of coal worker's pneumoconiosis complicated with chronic obstructive pulmonary disease (COPD) , coal worker's pneumoconiosis and COPD, in order to improve the diagnosis and treatment of coal worker's pneumoconiosis complicated with chronic obstructive pulmonary disease. Methods: Selected patients in respiratory department of General Hospital of Jincheng Coal Industry Group were classified as pneumoconiosis complicated with COPD group (n=52) , pneumoconiosis group (n=70) and COPD group (n=50) . Clinical data were collected and compared between three groups, including age, history of smoking, BMI, pulmonary function, CAT score and complication with Hypoxemia and respiratory faliure. Results: The mean age, smoking index and BMI of the three groups were not significantly different. The FEV1% pred, FEV(1)/FVC%, DLco-SB%, FVC% pred were significantly lower in pneumoconiosis complicated with COPD group than pneumoconiosis group (P<0.05) ; The FEV(1)% pred, DLco-SB%, FVC% pred were significantly lower in pneumoconiosis complicated with COPD group than COPD group (P<0.05) , but, the FEV(1)/FVC% was no significant different between pneumoconiosis complicated COPD group and COPD group (P>0.05) ; The CAT score for clinical symptoms of pneumoconiosis complicated with COPD group was significantly higher than that of pneumoconiosis group (P<0.05) , but there was no significant difference between pneumoconiosis complicated COPD group and COPD group (P>0.05) . The rate of hypoxemia in coal workers' pneumoconiosis combined with chronic obstructive pulmonary disease was 78.8%, which was higher than that of coal workers' pneumoconiosis group (61.4%) and chronic obstructive pulmonary disease group (72%) ; The respiratory failure rate of coal worker's pneumoconiosis combined with chronic obstructive pulmonary disease group was 44.2%, which was higher than that of coal worker's pneumoconiosis group (4.3%) and chronic obstructive pulmonary disease group (16%) . Conclusion: In pneumoconiosis patients, once complicate with COPD, the pulmonary function indexes are worse, the clinical symptoms are heavier, and the probability of hypoxemia and respiratory failure are higher. Compared with the COPD group, the patients with pneumoconiosis complicated with COPD have more restrictive ventilation dysfunction and diffuse dysfunction, and the clinical symptoms are heavier, and the probability of combined respiratory failure is higher.

Influence of the Direct Coal Liquefaction Residue on the Fusion Characteristics of Jincheng Coal with a High Ash Fusion Temperature

Nowadays, entrained flow bed gasification technology is the foundation of the modern coal chemical industry, while its liquid slag discharge process generally requires the flow temperature (FT) of ...

Effects of biomass blending, ashing temperature and potassium addition on ash sintering behaviour during co-firing of pine sawdust with a Chinese anthracite

When biomass and coal are co-combusted, the ash sintering behaviour cannot be directly predicted on the basis of the properties of individual fuel ash. Knowledge of the ash sintering behaviour can help understanding the subsequent ash fouling and slagging. Herein, the ash sintering characteristics during co-combustion of Jincheng coal (JC) and pine sawdust (PS), together with the effects of biomass blending ratio, ashing temperature and K2CO3 catalyst addition were investigated in depth. The results indicated that for a given JC/PS blend, the ash slagging degree expressed by different decision indices was different, but the tendency was consistent. No obvious fusion phenomenon was observed among the individual particles from the blends without K2CO3 addition. Both types of the particles from individual fuel could be separately identified with obvious difference from their respective particles. When K2CO3 was added to the blends, the ash surface structure varied from unmelted to slightly adhesion. The formation of potassium silicates made great contributions to slagging. The molten and solidified zone on the agglomerate surface featured high contents of K, Si, O and Al, and the coating on the melting surface was composed of the mixture of K-bearing aluminosilicates, potassium chloride and smaller amounts of Ca-bearing aluminosilicates.

Ash fusion temperature regulation mechanism of Xiangyang coal by coal blending

The modifications in the low ash fusion temperature (AFT) of Xiangyang coal (XY) were investigated by blending it with three high AFT coals [Jincheng coal (JC), Sunjiahao coal (SJH), and Shajuzi coal (SJZ)], respectively. These three coals all improved XY AFT effectively. With the JC mass ratio varying from 0 to 50%, the AFT of XY/JC gradually increased. The AFT of XY/SJH increased significantly (0–30%), slowly (30–40%), and rapidly (40–50%) with increasing SJH content. For SJZ, the AFT of XY/SJZ increased quickly (0–30%) and very slowly (30–50%). For XY entrained-flow gasification, the appropriate blending ratios of JC, SJH, and SJZ were 40–50%, 30–40%, and 20–40%, respectively. X-ray diffraction, scanning electron microscopy, and FactSage thermodynamic calculation were applied to investigate the effects of mineral transformation on AFT. Quartz (SiO2), anorthite (CaAl2Si2O8), diopside (CaMgSi2O6), and hedenbergite (CaFeSi2O6) were detected in XY ash at 1100 °C. As the mass ratios of high AFT coals increased, the obvious increase in anorthite content led to the rise in the AFT of XY/JC; mullite (Al6Si2O13); and corundum (Al2O3) with a high melt point formed in ashes causing the increase in the AFTs of XY/SJH and XY/SJZ, respectively.

Regulation of ash fusibility for high ash-fusion-temperature (AFT) coal by industrial sludge addition

The effects of an industrial sludge (IS) on three high ash-fusion-temperature (AFT) coals (Jincheng coal (JC), Fuxing coal (FX) and Jiaozuo coal (JZ)) were investigated by an AFT detector, X-ray diffraction (XRD) analyzer, and thermo-physical modeling software. The results showed that IS could reduce the AFTs of three high AFT coals. The effect of IS on the AFTs of JC and JZ coals was clearly different from its effect on FX coal. When adding 18% IS ash to three coal ashes, the flow temperatures (FTs) of JC-IS and JZ-IS mixtures were reduced to below 1380 °C, which met the requirement of entrained-flow bed gasification, and the FT of FX-IS mixture was still higher than 1380 °C. After adding iron-rich IS ash (Fe2O3 > 41%) into three coal ashes, under reducing atmosphere, the Fe3+ was converted into Fe2+, the interactions of Fe2+ and Al2O3 led to the formation of a large amount of low melting-point (MP) hercynite (FeAl2O4). And some CaO could easily react with Al2O3 and SiO2 in the mixed ashes to produce anorthite (CaAl2Si2O8), restraining the formation of high MP mullite, which decreased the AFTs of these three mixtures. At 1100 °C, no mullite was detected in JC-IS and JZ-IS mixed ashes, and some mullite still existed in FX-IS mixed ash when the IS ash mass ratio even reached 30%, which might be the main reason for the decrease in the AFTs of JC and JZ was different from that of FX.

A Roadheader-Assisted Coal Cutter Based on Tensile Failure Mechanism of Coal

This paper proposes a new roadheader-assisted coal cutter (RACC) based on the tensile failure mechanism of coal. An innovative mining method, called the cutting inside and spalling outside mining (CISOM) method, is developed based on this new RACC. The mechanical model is established, and the working mechanism of the new CISOM method is illustrated using a column model and a beam model. The mechanical models reveal that the tensile stress causes greater deflection than compressive stress. The deflection and mining width demonstrates a quadratic relationship. To understand the stratum behaviors and improve mining efficiency, the stability of a working face owned by Jincheng Coal Mining Group in Shanxi is analyzed using UDEC numerical simulation. Numerical results indicate that the optimal values of the parameter are 0.8 m width for the inside cutting and 0.4 m width for the outside spalling at #1305 working face. The newly developed RACC was successfully applied at #1305 working face. The field results showed that the recovery rate of CISOM method is over 90%; i.e., it is improved by 20% in comparison with the traditional method.

Effect of extracellular signal-regulated kinas 1/2 expression and HPV16 infection and their interaction in progression of cervical cancerization

Objective: To investigate the effect of ERK1/2 protein expression and HPV16 infection, as well as their interaction in the cervical carcinogenesis. Methods: A total of 176 patients, including 34 cases with normal cervix (NC), 26 cases with cervical intraepithelial neoplasm Ⅰ (CIN Ⅰ), 57 cases with cervical intraepithelial neoplasm Ⅱ/Ⅲ (CIN Ⅱ/Ⅲ) and 59 cases with cervical squamous cell carcinoma (SCC), were enrolled from Shanxi Tumor Hospital, Shanxi Maternal and Child Health Center, Jincheng Coal General Hospital from September 2013 to March 2014. The information about their demographic characteristics and risk factors associated with cervical cancer was collected with structural questionnaire, and cervical tissue samples were collected from each subject. HPV16 infection was detected by PCR, and phosphorylation of ERK1/2 (p-ERK1/2) protein expression levels were detected by immunohistochemistry. Meanwhile, cervical cancer cell lines Siha (HPV16 positive) and C33A (HPV negative) were treated with ERK inhibitor U0126 in vitro. Cell proliferation was determined by living cell count, cell cycle and apoptosis was detected by flow cytometry. Results: The HPV16 infection rate (trend χ(2)=17.99, P<0.001) and p-ERK1/2 protein high expression (trend χ(2)=10.58, P=0.001) increased gradually along with the severity of cervix lesions. There was an additive interaction between HPV16 infection and p-ERK protein expression in the CIN Ⅰ, CIN Ⅱ/Ⅲ and SCC groups. Cell experiments showed that after ERK inhibition, the proliferation of the two cells were reduced (Siha: t=6.863, P<0.001; C33A: t=7.092, P<0.001) and the apoptosis were increased (Siha: t=-5.201, P=0.006; C33A: t=-4.335, P=0.005). After ERK inhibition, the cell proliferation index of Siha (HPV16 positive) was higher than that of C33A (HPV16 negative) (t =7.066, P<0.001), but the apoptosis rate of Siha was lower than that of C33A (t=-2.431, P=0.057). Conclusions: HPV16 infection and the high expression of p-ERK1/2 could increase the risk of cervical cancer. And there might be synergistic actions between the two factors in the progression of cervical cancer. The effect of ERK1/2 activation to HPV16 infection cells might be more significant in the process of cervical cancer cell proliferation and apoptosis.

Comparison of the catalytic effects of eight industrial wastes rich in Na, Fe, Ca and Al on anthracite coal combustion

The catalytic effects of eight industrial wastes rich in Na, Fe, Ca and Al on Jincheng anthracite coal combustion were compared. The thermogravimetric experiments showed that Na-rich brine sludge (BS) and salt sludge (SS) exhibited better catalytic effects on coal combustion than Fe-rich iron mud (IM) and steel residue (SR). However, IM and SR exhibited better catalytic effects than Ca-rich white lime mud (WLM) and calcium carbide residue (CCR). Among the eight industrial wastes, Al-rich alumina residue (AR) and aluminium slag (AS) demonstrated the worst catalytic effects. BS, which contains more Na (mainly in the form of NaCl, which was equivalent to Na2O with a content of 13.14%) than SS (mainly in the form of NaCl and Na3Mg(CO3)2Cl, which were equivalent to Na2O with a content of 7.64%) does, reduced the ignition temperature of Jincheng coal from 582°C to 561°C because of the promoted transfer of oxygen to the carbon surface through the cyclic oxidation and reduction reactions between Na2O and Na2O2. IM, which contains more Fe (mainly in the form of γ-Fe2O3, which was equivalent to Fe2O3 with a content of 92.22%) than SR (mainly in the form of Fe2SiO4 and α-Fe, which were equivalent to Fe2O3 with a content of 8.29%) does, reduced the ignition temperature of Jincheng coal to 569°C as a consequence of the enhanced transfer of oxygen to the carbon surface through the cyclic oxidation and reduction reactions between FeO and Fe2O3.

Effect of ash preparation method on the sintering characteristics of ashes from combustion of coal and biomass blends

Sintering behaviour of ashes from combustion of coal and biomass blends was experimentally investigated with a focus on the effect of ash preparation method. Blends of a Chinese anthracite, Jincheng coal, and two biomass materials, a wheat straw and a pine sawdust, respectively, were subjected to three different ash preparation procedures, namely, a low temperature oxygen plasma ashing device operating at ca 150°C, combustion in a Muffle furnace at 815°C and in a drop tube furnace at 1500°C. The resulting ash samples were then subjected to the sintering temperature measurement using a pressure-drop sintering device, morphological and mineralogical characterisation using scanning electron microscope (SEM) fitted with X-ray energy dispersive spectroscopy (EDS) and X-ray diffractometry analyser (XRD), respectively. For the same coal and biomass blends but different ash preparation methods, the sintering temperatures were always the lowest for the ash samples from the plasma ashing device and the highest from drop tube furnace. SEM imaging showed that the texture of ash samples from the plasma ashing device was irregular, loose and more fibrous, indicating little interactions among the different mineral and inorganic constituents in the individual fuels. The muffle furnace and drop tube furnace ashes were denser and more uniform in shape as the mineral matter and inorganics became fused together. In addition, the drop tube furnace ashes were mostly in spherical-shape, indicating ash melting had occurred during combustion. The XRD analysis revealed that different minerals were present in the ash samples due to different ash preparation temperatures, with high temperature minerals present in the drop tube furnace ash. Biomass addition in the blends lowered the sintering temperature of corresponding ash; the higher the proportion of biomass in the blend, the lower the ash sintering temperature regardless the ashing method. At the same biomass addition ratio, the ash sintering temperature of the blend with the wheat straw addition was lower than that with the pine sawdust addition, because the wheat straw had a higher K and Cl content but lower Ca than the pine sawdust. The EDS and XRD analyses confirmed that the ashes of coal/wheat straw blends contained more K-bearing minerals, while the ashes of the coal/pine sawdust contained more Ca and K-bearing minerals. Both Ca and K-bearing minerals reacted with other minerals in the ash to form low temperature eutectics, leading to the reduction of sintering temperatures of the coal and biomass blends. However, the melting points of the K-containing minerals are higher than the Ca-containing minerals, therefore, the sintering temperatures of ash with the wheat straw addition were lower than those with the pine sawdust addition.

Recent developments in coal mine methane extraction and utilization in China: A review

Over past decades, China has changed the manner in which coal mine methane (CMM) was treated: from mitigating its dangers as a mining hazard to developing its potential as an unconventional gas resource. CMM is rich in China coal seams. These coal seams normally have three distinct characteristics: high pressure, strong adsorption and low permeability. These characteristics require novel extraction and utilization technologies. This paper presented a comprehensive review of how these technologies evolve with time from underground extraction to surface drainage to combined surface-underground approach. Major conclusions include: (1) CMM is mainly drained through underground extraction technologies. In order to improve the drainage efficiency, these technologies usually combine with mining-induced stress relief or other active stimulation techniques and modern borehole sealing techniques; (2) Several innovative surface CMM extraction technologies have been proved as effective for Chinese CMM formation conditions, such as gob surface well extraction, stress-relieved seams surface well extraction, multi-branch horizontal directional surface well extraction, and multipurpose surface well extraction; (3) A combined surface-underground approach has been applied to Huainan and Jincheng coal mines. These applications represent the new development trend of CMM extraction and control in China; and (4) Apart from the CMM extraction technologies, utilization technologies also achieved significant progresses in China. The electricity generation and safe transportation technologies of low-concentration gas have also been developed to improve the gas utilization rate and guarantee the safe long distance and large flow transportation of low-concentration gas in China. The implementation of CMM extraction and utilization technologies has led to a large increase of coal production, gas extraction and utilization, and a significant reduction of fatality.

Influence of biomass addition on Jincheng coal ash fusion temperatures

The ash fusion temperatures (AFTs) of Jincheng (JC) coal, two kinds of biomass (cotton stalk (CS) and sargassum natans (SA)) and various coal–biomass mixtures were investigated in this study. Fluid temperatures (FT) were found 1531°C, 1534°C and 1428°C for JC, CS and SA ash respectively, which were higher than the normal operating temperature of entrained bed gasifier. However, the FTs of JC and CS mixture ash were lower than that of either single JC or CS ash, which showed a minimum value of 1292°C with 80% CS, and the FTs of JC and SA mixture ash showed the similar trend with a minimum value of 1258°C when SA proportion was 40%. At high temperature, refractory minerals were presented in three respective ashes, which were mullite of JC ash, lime and periclase of CS ash, merwinite and akermanite of SA ash. And they could support the ash skeleton structure. Interaction between coal and biomass ash occurred during blending ash melting process, which formed co-eutectic and decreased the AFTs. The relationship between the ash fusion temperatures and the ash chemical composition was also discussed.

The Effect of Sodium Dodecyl Sulphate (SDS) on Wettability of Different Coals

Three coals (Jincheng coal, Hancheng coal and Shan-bei coal) varying widely in coal type have been treated with anionic surfactant Sodium Dodecyl Sulphate (SDS). The effect of SDS on wettability of coals was explored by contact angles and zeta potentials characterisation techniques. Results obtained show that the addition of SDS can obviously improve the wettability of coals, and as the coal rank decreases, the wettability increases under investigation. Moreover, the wettability obviously increases with the significant decrease of particle size. The zeta potential for each coal, in the absence of surfactant, is negative, and the potential becomes more negative with the addition of SDS. Meanwhile, the FTIR spectrogram was used to test the changes of-COOH and-OH to analyze the reason for change of wettability, the results show that the wettability changes may be attributed to that the negative active ions of SDS are adsorbed on the coal surface, resulting in the increase of hydrophilic groups of the coal surface.

Bone mineral density changes in coal workers' pneumoconiosis in Two and Triple stages with increasing ages

To observe the bone mineral density changes in coal workers' pneumoconiosis in Two and Triple stages with increasing ages. Chose 70 cases of coal workers pneumoconiosis in Two and Triple stages in Jincheng Coal Mining Group, all of workers were male, of 55-years old-80 years old, an average of 67 years old. 10 years of ages to grouping, whole body bone mineral densities were measured by body dual-energy X-ray absorptiometry. We analyzed the BMD changes bone loss, osteoporosis occurrence. Chest bone, pelvis, spine bone mineral densities of coal workers pneumoconiosis in Two and Triple stages were significantly decreased. We found that the rate of Pelvic BMD decline of coal workers' pneumoconiosis patients in Two stage was significantly faster after 65 years of age. In Different age groups of coal workers' pneumoconiosis patients in Two and Triple stages, incidence of bone loss and osteoporosis were significantly increased. With the age increasing, Coal workers' pneumoconiosis in Two and Triple stages significantly accelerated the speed of the rate of BMD decline. This phenomenon was most obvious in the chest bone, pelvis, and spine.

Bone mineral density changes in coal workers' pneumoconiosis

To observe the bone mineral density changes of coal workers' pneumoconiosis. We chose 150 cases of One-Triple coal workers pneumoconiosis in Jincheng Coal Mining Group, all of workers were male, of 55-years old-80 years old, an average of 67 years old. 10 years of age to grouping, Whole body bone mineral density and T value were measured by body dual-energy X-ray absorptiometry. We analyzed the BMD changes bone loss, osteoporosis occurrence. The BMD of six parts were not declined obviously in One stage of coal workers' pneumoconiosis; the BMD of Chest bone, pelvis and spine were declined obviously in two stage of coal workers' pneumoconiosis; the BMD of six parts were declined obviously in Triple stage of coal workers' pneumoconiosis; The occurrence rate of bone loss was significantly higher in Two and Triple coal workers pneumoconiosis. The occurrence rate of osteoporosis was significantly higher in Triple coal workers pneumoconiosis. With the increase in the severity of coal workers' pneumoconiosis, the BMD of six parts were declined, The occurrence rate of bone loss osteoporosis was significantly higher.

Effect of temperature and pressure on the mineralogical and fusion characteristics of Jincheng coal ash in simulated combustion and gasification environments

The effects of the pressure and temperature on the fusibility of coal ash during combustion and gasification were investigated. Experimentation was conducted using a high pressure thermogravimetric analyzer (HPTGA) apparatus. In order to observe the conversion of minerals with changing temperature and pressure in different atmospheres, the resulting ash samples were analyzed using an X-ray diffractometry (XRD) analyzer. In addition, the quantitative XRD analyses of ash samples and a field emission scanning electron microscope (FSEM), together with X-ray energy dispersive spectroscopy (EDS) were employed to verify the detailed mechanisms of ash fusion. The results indicated that temperature and type of atmosphere had a dominant effect on the ash fusion characteristics while the effect of pressure was somewhat more complicated, depending on the temperature and atmosphere being experienced by the ash. The high-temperature minerals such as mullite were formed with increasing temperature under both combustion and gasification atmospheres. However, in gasification atmosphere, there were more fluxing minerals and feldspar minerals present, such as muscovite, anhydrite and K-feldspar, decreasing the fusion temperature. The effect of pressure on the ash fusibility showed different behavior at different temperatures. At 900°C, the decompositions of low-temperature minerals, such as muscovite, anhydrite and oldhamite, were suppressed with increasing pressure, resulting in a decrease in the fusion temperatures. On the other hand, at 1000°C, the low-temperature minerals transformed into high-temperature minerals such as mullite and sanidine with rising pressure. However, the presence of fluxing minerals and the melting of iron-containing minerals resulted in the lowering of the fusion temperatures.

Influence of ash composition on the sintering behavior during pressurized combustion and gasification process

To determine the ash characteristics during fluidized bed combustion and gasification purposes, the investigation of the impacts of chemical composition of Jincheng coal ash on the sintering temperature was conducted. A series of experiments on the sintering behavior at 0.5 MPa was performed using the pressurized pressure-drop technique in the combustion and gasification atmospheres. Meanwhile, the mineral transformations of sintered ash pellets were observed using X-ray diffractometer (XRD) analyzer to better understand the experimental results. In addition, quantitative XRD and field emission scanning electron microscope/energy dispersive X-ray spectrometer (FE-SEM/EDS) analyses of ash samples were used for clarifying the detailed ash melting mechanism. These results show that the addition of Fe2O3 can obviously reduce the sintering temperatures under gasification atmospheres, and only affect a little the sintering temperature under combustion atmosphere. This may be due to the presence of iron-bearing minerals, which will react with other ash compositions to produce low-melting-point eutectics. The FE-SEM/EDS analyses of ash samples with Fe2O3 additive show consistent results with the XRD measurements. The CaO and Na2O can reduce the sintering temperatures under both the combustion and gasification atmospheres. This can be also contributed to the formation of low-melting-point eutectics, decreasing the sintering temperature. Moreover, the fluxing minerals, such as magnetite, anhydrite, muscovite, albite and nepheline, contribute mostly to the reduction of the sintering temperature while the feldspar minerals, such as anorthite, gehlenite and sanidine, can react with other minerals to produce low-melting-point eutectics, and thereby reduce the sintering temperatures.