Coal is the world's most abundant energy source because of its abundance and relatively low cost. Due to the scarcity in the supply of high-grade coal, it is necessary to use low-grade coal for fulfilling energy d...Coal is the world's most abundant energy source because of its abundance and relatively low cost. Due to the scarcity in the supply of high-grade coal, it is necessary to use low-grade coal for fulfilling energy demands of modern civilization. However, due to its high ash and moisture content, low-grade coal exerts the substantial impact on their consumption like pyrolysis, liquefaction, gasification and combustion process. The present research aimed to develop the efficient technique for the production of clean coal by optimizing the operating parameters with the help of response surface methodology. The effect of three independent variables such as hydrofluoric acid(HF) concentration(10–20% by volume), temperature(60–100 °C), and time(90–180 min), for ash reduction from the low-grade coal was investigated. A quadratic model was proposed to correlate the independent variables for maximum ash reduction at the optimum process condition by using central composite design(CCD) method. The study reveals that HF concentration was the most effective parameter for ash reduction in comparison with time and temperature. It may be due to the higher F-statistics value for HF concentration, which effects to large extent of ash reduction. The characterization of coal was evaluated by Fourier transform infrared spectroscopy(FTIR) analysis and Field-emission scanning electron microscopy with energy-dispersive X-ray(FESEMEDX) analysis for confirmation of the ash reduction.展开更多
Dry separation of iron mineral from low-grade coal-series kaolin in Hubei Province of China was investigated. The structure and chemical composition of the kaolin ore were determined by X-ray diffraction(XRD) and X-ra...Dry separation of iron mineral from low-grade coal-series kaolin in Hubei Province of China was investigated. The structure and chemical composition of the kaolin ore were determined by X-ray diffraction(XRD) and X-ray Fluorescence(XRF) analyses. The narrow particle size range classification, dry magnetic separation and calcination were carried out to evaluate the particle size distribution, and the relation between the content of iron and the whiteness. Experimental results revealed that the highest content of iron(3.70%) in kaolin ore was in the particle size range from 60 to 74 μm, and pyrite was the main occurrence of iron in the kaolin ore. Dry magnetic separation showed that the removal rate of iron in kaolin ore could be increased obviously after calcination, and the rate of iron removal was 60% in the particle size range from 60 to 74 μm. As pyrite can be transformed into hematite through calcination, thermodynamic studies and XRD analysis showed that the maximum content of hematite was obtained at 900 ℃, which would be more beneficial to magnetic separation.展开更多
BACKGROUND Low-grade appendiceal neoplasms(LAMN)are characterized by low incidence and atypical clinical presentations,often leading to misdiagnosis as acute or chronic appendicitis before surgery.The primary diagnost...BACKGROUND Low-grade appendiceal neoplasms(LAMN)are characterized by low incidence and atypical clinical presentations,often leading to misdiagnosis as acute or chronic appendicitis before surgery.The primary diagnostic tool for LAMN is abdominal computed tomography(CT)imaging.Surgical resection remains the cornerstone of LAMN management,necessitating en bloc tumor excision to minimize the risk of iatrogenic rupture.Laparoscopy,known for its minimal invasiveness,reduced postoperative discomfort,and expedited recovery,is a safe and reliable approach for LAMN treatment.Despite the possibility of pseudomyxoma peritonei development,appendectomy and partial appendectomy generally result in negative tumor margins and favorable outcomes,which can be attributed to the disease’s slow growth and lower malignancy.CASE SUMMARY A 71-year-old male patient was admitted to our hospital with a pelvic spaceoccupying lesion detected 1 mo prior.Physical examination showed a soft abdomen without tenderness or rebound and no palpable masses.No shifting dullness was noted,and digital rectal examination revealed no palpable mass.Enteroscopy revealed a raised,smooth-surfaced mass measuring 3.0 cm in the cecum.Abdominal contrast-enhanced CT showed a markedly thickened and dilated appendix with visible cystic shadows.Laparoscopic surgery was performed and revealed a significantly dilated appendix,leading to laparoscopic resection of the appendix and part of the cecum.Post-surgical pathologic analysis confirmed LAMN.The patient received symptomatic and supportive post-operative care and was discharged on postoperative day 4 without complications such as abdominal bleeding,intestinal obstruction,or incision infection.No tumor recurrence was observed during a 7-mo follow-up period.CONCLUSION LAMN is a rare disease that lacks specific clinical manifestations.Abdominal CT plays a crucial role in diagnosing LAMN,and laparoscopic surgery is a safe and effective diagnostic and therapeutic approach.展开更多
BACKGROUND Low-grade myofibroblastic sarcoma(LGMS)is an extremely rare tumor characterized by the malignant proliferation of myofibroblasts.LGMS most commonly develops in adults,predominantly in males,in the head and ...BACKGROUND Low-grade myofibroblastic sarcoma(LGMS)is an extremely rare tumor characterized by the malignant proliferation of myofibroblasts.LGMS most commonly develops in adults,predominantly in males,in the head and neck region,oral cavity,especially on the tongue,mandible,and larynx.This article presents 2 cases of LGMS localized to the maxillary sinus and provides an overview of the available literature.CASE SUMMARY Two patients with LGMS located in the maxillary sinus underwent surgery at the Department of Head and Neck Surgery.Case 1:A 46-year-old patient was admitted to the clinic with suspected LGMS recurrence in the right maxillary sinus(rT4aN0M0),with symptoms of pain in the suborbital area,watering of the right eye,thick discharge from the right nostril,and augmented facial asymmetry.After open biopsy-confirmed LGMS,the patient underwent expanded maxillectomy of the right side with immediate palate reconstruction using a microvascular skin flap harvested surgically from the middle arm.The patient qualified for adjuvant radiotherapy for the postoperative bed,with an additional margin.Currently,the patient is under 1.5 years of observation with no evidence of disease.Case 2:A 45-year-old man was admitted to our clinic with facial asymmetry,strabismus,exophthalmos,and visual impairment in the right eye.Six months earlier,the patient had undergone partial jaw resection at another hospital for fibromatosis.A contrast-enhanced computed tomography scan revealed a tumor mass in the postoperative log after an earlier procedure.An open biopsy confirmed lowgrade fibrosarcoma(rT4aN0M0).The patient qualified for an extended total right maxillectomy with orbital excision and right hemimandibulectomy with immediate microvascular reconstruction using an anterolateral thigh flap.The patient subsequently underwent adjuvant radiotherapy to the postoperative area.After 9 months,recurrence occurred in the right mandibular arch below the irradiated area.The lesion infiltrated the base of the skull,which warranted the withdrawal of radiotherapy and salvage surgery.The patient qualified for palliative chemotherapy with a regimen of doxorubicin+dacarbazine+cyclophosphamide and palliative radiotherapy for bone metastases.The patient died 26 months after surgical treatment.The cases have been assessed and compared with cases in the literature.CONCLUSION No specific diagnostic criteria or treatment strategies have been developed for LGMS.The treatment used for LGMS is the same as that used for sinonasal cancer radical tumor excision;adjuvant radiotherapy or chemoradiotherapy should also be considered.They have low malignant potential but are highly invasive,tend to recur,and metastasize to distant sites.Patients should undergo regular follow-up examinations to detect recurrence or metastasis at an early stage.Patients should be treated and observed at the highest referral centers.展开更多
Based on the fluidized roasting reduction technology of low-grade pyrolusite coupling with pretreatment of stone coal, the manganese reduction efficiency was investigated and technical conditions were optimized. It is...Based on the fluidized roasting reduction technology of low-grade pyrolusite coupling with pretreatment of stone coal, the manganese reduction efficiency was investigated and technical conditions were optimized. It is found that the optimum manganese reduction efficiency can be up to 98.97% under the conditions that the mass ratio of stone coal to pyrolusite is 3:1, the roasting temperature of stone coal is 1000℃, the roasting temperature of pyrolusite is 800℃, and the roasting time is 2 h. Other low-grade pyrolusite ores in China from Guangxi, Hunan, and Guizhou Provinces were tested and all these minerals responded well, giving -99% manganese reduction efficiency. Meanwhile, the reduction kinetic model has been established. It is confirmed that the reduction process is controlled by the interface chemical reaction. The apparent activation energy is 36.397 kJ/mol.展开更多
Thermal energy is abundantly available in our daily life and industrial production,and especially,low-grade heat is often regarded as a byproduct.Collecting and utilizing this ignored energy by low-cost and simple tec...Thermal energy is abundantly available in our daily life and industrial production,and especially,low-grade heat is often regarded as a byproduct.Collecting and utilizing this ignored energy by low-cost and simple technologies may become a smart countermeasure to relieve the energy crisis.Here,a unique device has been demonstrated to achieve high value-added conversion of low-grade heat by introducing redox-active organic alizarin(AZ)onto N-doped hollow carbon nanofibers(N–HCNF)surface.As-prepared N–HCNF/AZ can deliver a high specific capacitance of 514.3 F g^(-1)(at 1 A g^(-1))and an outstanding rate capability of 60.3%even at 50 A g^(-1).Meanwhile,the assembled symmetric proton capacitor can deliver a high energy density of 28.0 Wh kg^(-1) at 350.0 W kg^(-1) and a maximum power density of 35.0 kW kg^(-1) at 17.0 Wh kg^(-1).Significantly,the thermally chargeable proton capacitors can attain a surprisingly high Seebeck coefficient of 15.3 mV K^(-1) and a power factor of 6.02µW g^(-1).Taking advantage of such high performance,a satisfying open-circuit voltage of 481.0 mV with a temperature difference of 54 K is achieved.This research provides new insights into construction of high value-added energy systems requiring high electrochemical performances.展开更多
BACKGROUND Low-grade myofibroblastic sarcoma(LGMS)is a rare spindle cell sarcoma espe-cially in the pancreas,with myofibroblastic differentiation.Hitherto,only a few cases have been reported.CASE SUMMARY Herein,we rep...BACKGROUND Low-grade myofibroblastic sarcoma(LGMS)is a rare spindle cell sarcoma espe-cially in the pancreas,with myofibroblastic differentiation.Hitherto,only a few cases have been reported.CASE SUMMARY Herein,we report a case involving the discovery of a pancreatic mass detected during a routine physical examination.Subsequent imaging and pathological tests of the patient led to the diagnosis of LGMS of the pancreas.Following surgical intervention,the patient experienced recurrence and metastasis.Conventional treatment is not effective for postoperative recurrent pancreatic LGMS with multiple metastases.After communicating with the patients and their families,informed consent was obtained for the treatment of anlotinib combined with pembrolizumab.Evaluation of imaging and clinical symptoms post-treatment revealed a relatively favorable response to the combination of anlotinib and pembrolizumab.CONCLUSION Based on the comprehensive literature review,our report aimed to provide evidence for a better understanding of the disease characteristics,diagnostic criteria,imaging findings,and identification of LGMS.And explore novel treatment strategies for this disease.展开更多
A new method for separating and recovering tin from a low-grade tin middling with high Si content and low Fe content by roasting with anthracite coal was researched by studying the reaction mechanism and performing an...A new method for separating and recovering tin from a low-grade tin middling with high Si content and low Fe content by roasting with anthracite coal was researched by studying the reaction mechanism and performing an industrial test,in which the Sn was sulfurized into SnS(g)and then collected using a dust collector.The Fe–Sn alloy may be formed at roasting temperatures above 950°C,and like the roasting temperature increases,the Sn content and Sn activity in this Fe–Sn alloy decrease.Also,more FeS can be formed at higher temperatures and then the formation of FeO–FeS with a low melting point is promoted,which results in more serious sintering of this low-grade tin middling.And from the thermodynamics and kinetics points of view,the volatilization of the Sn decreases at extremely high roasting temperatures.The results of the industrial test carried out in a coal-fired rotary kiln show that the Sn volatilization rate reaches 89.7%and the Sn is concentrated in the collected dust at a high level,indicating that the Sn can be effectively extracted and recovered from the low-grade tin middling with a high Si content and low Fe content through a reduction–sulfurization roasting process.展开更多
Coal gasification fine slag(FS)is a typical solid waste generated in coal gasification.Its current disposal methods of stockpil-ing and landfilling have caused serious soil and ecological hazards.Separation recovery a...Coal gasification fine slag(FS)is a typical solid waste generated in coal gasification.Its current disposal methods of stockpil-ing and landfilling have caused serious soil and ecological hazards.Separation recovery and the high-value utilization of residual carbon(RC)in FS are the keys to realizing the win-win situation of the coal chemical industry in terms of economic and environmental benefits.The structural properties,such as pore,surface functional group,and microcrystalline structures,of RC in FS(FS-RC)not only affect the flotation recovery efficiency of FS-RC but also form the basis for the high-value utilization of FS-RC.In this paper,the characteristics of FS-RC in terms of pore structure,surface functional groups,and microcrystalline structure are sorted out in accordance with gasification type and FS particle size.The reasons for the formation of the special structural properties of FS-RC are analyzed,and their influence on the flotation separation and high-value utilization of FS-RC is summarized.Separation methods based on the pore structural characterist-ics of FS-RC,such as ultrasonic pretreatment-pore-blocking flotation and pore breaking-flocculation flotation,are proposed to be the key development technologies for improving FS-RC recovery in the future.The design of low-cost,low-dose collectors containing polar bonds based on the surface and microcrystalline structures of FS-RC is proposed to be an important breakthrough point for strengthening the flotation efficiency of FS-RC in the future.The high-value utilization of FS should be based on the physicochemical structural proper-ties of FS-RC and should focus on the environmental impact of hazardous elements and the recyclability of chemical waste liquid to es-tablish an environmentally friendly utilization method.This review is of great theoretical importance for the comprehensive understand-ing of the unique structural properties of FS-RC,the breakthrough of the technological bottleneck in the efficient flotation separation of FS,and the expansion of the field of the high value-added utilization of FS-RC.展开更多
A hydrotalcite(layered double hydroxide, LDH) inhibitor which is suitable for the whole process of coal spontaneous combustion and a LDH inhibitor containing rare earth lanthanum elements were prepared. The inhibition...A hydrotalcite(layered double hydroxide, LDH) inhibitor which is suitable for the whole process of coal spontaneous combustion and a LDH inhibitor containing rare earth lanthanum elements were prepared. The inhibition effect and mechanism were analyzed by scanning electron microscopy(SEM),X-ray diffraction(XRD), thermal performance analysis, in-situ diffuse reflectance infrared spectroscopy and temperature-programmed experiment. The results have shown that the inhibitor containing lanthanum can play a good inhibitory role in every stage of coal oxidation. During the slow oxidation of coal samples, the inhibitor containing lanthanum ions can slow down the oxidation process of coal and increase the initial temperature of coal spontaneous combustion. At the same time, because the hydroxyl groups in LDHs are connected with-COO-groups on the coal surface through hydrogen bonds, the stability of coal is improved. With the increase of temperature, LDHs can remove interlayer water molecules and reduce the surface temperature of coal. CO release rate of coal samples decreases significantly after adding inhibitor containing lanthanum element, and the maximum inhibition rate of the inhibitor is 58.1%.展开更多
Coal pyrolysis is a fundamental reaction in the thermal processing and utilization of coal.Investigating the behavior and kinetics of coal pyrolysis is crucial for optimizing,designing,and developing a composite riser...Coal pyrolysis is a fundamental reaction in the thermal processing and utilization of coal.Investigating the behavior and kinetics of coal pyrolysis is crucial for optimizing,designing,and developing a composite riser for the staged pyrolysis gasification process of pulverized coal.In this study,the non-isothermal pyrolysis behavior and kinetics of coal were examined at different heating rates(30,50,100,300,500,700,and 900℃/min)using thermogravimetry(TG)coupled with Fourier-transform infrared spectroscopy.Analysis of the TG/derivative TG(TG/DTG)curves indicated that coal pyrolysis mainly occurred between 300℃ and 700℃.Higher heating rates led to more volatiles being released from the coal,and a higher temperature was required to achieve rapid pyrolysis.Kinetic analysis showed that both the model-free methods(Friedman,Flynn-Wall-Ozawa,and Kissinger-Akahira-Sunose)and the model-based method(Coats-Redfern)effectively describe the coal pyrolysis process.The change in the Ea values between the two kinetic models was consistent throughout the pyrolysis process,and the most probable mechanism was the F2 model(secondary chemical reaction).In addition,the heating rate did not change the overall reaction order of the pyrolysis process;however,a higher heating rate resulted in a decrease in the Ea value during the initial pyrolysis stage.展开更多
Hydroconversion of coal tar to produce aromatic hydrocarbons(BTX)represents a crucial strategy for the highvalue hierarchical utilization of coal.This study focused on the hydrocracking of hydrorefined products derive...Hydroconversion of coal tar to produce aromatic hydrocarbons(BTX)represents a crucial strategy for the highvalue hierarchical utilization of coal.This study focused on the hydrocracking of hydrorefined products derived from coal tar to enhance the production of benzene,toluene,and xylene(BTX).Various reaction conditions,including reaction temperature,hydrogen pressure,space velocity,and hydrogen-to-oil volume ratio,were systematically explored to optimize BTX yields while also considering the process’s economic feasibility.The results indicate that increasing the reaction temperature from 360℃ to 390℃ significantly favors the production of BTX,with yields increasing from 21.42%to 41.14%.Similarly,an increase in hydrogen pressure from 4 MPa to 6 MPa boosts BTX production,with yields rising from 36.31%to 41.14%.Reducing the space velocity from 2 h^(-1) to 0.5 h^(-1) also favors the BTX production process,with yields increasing from 37.96%to 45.13%.Furthermore,raising the hydrogen-to-oil volume ratio from 750 to 1500 improves BTX yields from 41.61%to 45.44%.Through economic analysis,the optimal conditions for BTX production were identified as a reaction temperature of 390℃,hydrogen pressure of 5-6 MPa,space velocity of 1 h^(-1),and hydrogen-to-oil volume ratio of 1000,achieving a BTX yield of 43.73%.This investigation highlights the importance of a holistic evaluation of hydrocracking conditions to optimize BTX production.Furthermore,the findings offer valuable insights for the design and operation of industrial hydrocracking processes aimed at efficiently converting coal tar-derived hydrorefined feedstock into BTX.展开更多
Long-term permeability experiments have indicated that sorption-induced swelling can switch from internal to bulk depending on the evolutive sorption status.However,this sorption swelling switch mechanism has not been...Long-term permeability experiments have indicated that sorption-induced swelling can switch from internal to bulk depending on the evolutive sorption status.However,this sorption swelling switch mechanism has not been considered in current analytical permeability models.This study introduces a normalized sorption non-equilibrium index(SNEI)to characterize the sorption status,quantify the dynamical variations of matrix swelling accumulation and internal swelling partition,and formulate the sorption swelling switch model.The incorporation of this index into the extended total effective stress concept leads to an analytical transient coal permeability model.Model results show that the sorption swelling switch itself results in the permeability switch under stress-constrained conditions,while the confined bulk swelling suppresses the permeability recovery to the continuous reduction under displacement-constrained conditions.Model verifications show that current experimental observations correspond to the early stages of the transient process,and they could be extended to the whole process with these models.This study demonstrates the importance of the sorption swelling switch in determining permeability evolution using simple boundary conditions.It provides new insights into experimentally revealing the sorption swelling switch in the future,and underscores the requirement of a rigorous model for complex coupled processes in large-scale coal seams.展开更多
Discoveries of many coal seams at depths by drilling carried by Geological Survey of Pakistan in Sor Range and Harnai Gochina, extended the coal seams at depth which is challenge for mine owners to exploit feasibly. B...Discoveries of many coal seams at depths by drilling carried by Geological Survey of Pakistan in Sor Range and Harnai Gochina, extended the coal seams at depth which is challenge for mine owners to exploit feasibly. Bed to bed gypsum samplings (and their chemical analyses) of huge gypsum deposits from Sulaiman foldbelt is a base for industrialist and also planers to develop cement and gypsum industries to increase export and foreign exchange for the development of area and Pakistan. Low and high grade sedimentary iron deposits, silica sand and uranium host rocks and their extensions in Sulaiman and Kirthar foldbelts are presented. Anomalies of a few base metals arise as a result of geochemical exploration carried at part of Loralai District of Balochistan. Theropod dinosaurs were frequent in India, while Poripuchian titanosaurs (Sauropoda, Dinosauria) were frequent in Pakistan. Besides some ichnotaxa, many bone taxa such as 1 titanosauriform, 14 titanosaurian sauropod (including one new titanosaur), and 3 theropod dinosaurs are established from Pakistan. Among these 12 titanosaur species and 3 theropod species are named in about 10 km<sup>2</sup> area of Vitakri dome and 2 titanosaur species are named in about a few hundred square meter area of Mari Bohri (Kachi Bohri) which is about 10 km westward from Vitakri dome. Pakistan is a unique country which discoverd 14 diversified titanosaurs in a short area and also in a short period (67 - 66 million years ago/Ma). About 400 bones found from a few meter thick upper part of upper shale horizon of latest Maastrichtian Vitakri Formation which is base for titanosaur taxa. Cranial material is in low fraction (but include significant diverse snouts), caudal vertebrae are prominent, the cervicals, dorsals and sacrals have significant numbers, forelimb and hind limb bones have balanced fraction. Humeri, femora and tibiae are most common. To know the position of Pakistani titanosaurs among titanosaurs and sauropods, there is a need to extend list of characters for phylogenetic analyses. This broad feature list should include main characters of titanosaurs from Pakistan and also from global world.展开更多
Injecting carbon dioxide(CO_(2))into coal seams may unlock substantial carbon sequestration potential.Since the coal acts like a carbon filter,it can preferentially absorb significant amounts of CO_(2).To explore this...Injecting carbon dioxide(CO_(2))into coal seams may unlock substantial carbon sequestration potential.Since the coal acts like a carbon filter,it can preferentially absorb significant amounts of CO_(2).To explore this further,desorption of the adsorbed gas due to pressure drop is investigated in this paper,to achieve an improved understanding of the long-term fate of injected CO_(2) during post-injection period.This paper presents a dual porosity model coupling gas flow,adsorption and geomechanics for studying coupled processes and effectiveness of CO_(2) sequestration in coals.A new adsorption?desorption model derived based on thermodynamics is incorporated,particularly,the desorption hysteresis is considered.The reliability of the proposed adsorption-desorption isotherm is examined via validation tests.It is indicated that occurrence of desorption hysteresis is attributed to the adsorption-induced pore deformation.After injection ceases,the injected gas continues to propagate further from the injection well,while the pressure in the vicinity of the injection well experiences a significant drop.Although the adsorbed gas near the well also decreases,this decrease is less compared to that in pressure because of desorption hysteresis.The unceasing spread of CO_(2) and drops of pressure and adsorbed gas depend on the degree of desorption hysteresis and heterogeneity of coals,which should be considered when designing CO_(2) sequestration into coal seams.展开更多
The quality upgrading and deashing of inferior coal by chemical method still faces great challenges.The dangers of strong acid,strong alkali,waste water and exhaust gas as well as high cost limit its industrial produc...The quality upgrading and deashing of inferior coal by chemical method still faces great challenges.The dangers of strong acid,strong alkali,waste water and exhaust gas as well as high cost limit its industrial production.This paper systematically investigates the ash reduction and desilicification of two typical inferior coal utilizing ammonium fluoride roasting method.Under the optimal conditions,for fat coal and gas coal,the deashing rates are 69.02%and 54.13%,and the desilicification rates are 92.64%and 90.27%,respectively.The molar dosage of ammonium fluoride remains consistent for both coals;however,the gas coal,characterized by a lower ash and silica content(less than half that of the fat coal),achieves optimum deashing effect at a reduced time and temperature.The majority of silicon in coal transforms into gaseous ammonium fluorosilicate,subsequently preparing nanoscale amorphous silica with a purity of 99.90%through ammonia precipitation.Most of the fluorine in deashed coal are assigned in inorganic minerals,suggesting the possibility of further fluorine and ash removal via flotation.This research provides a green and facile route to deash inferior coal and produce nano-scale white carbon black simultaneously.展开更多
Phase change materials (PCMs) can be incorporated with low-cost minerals to synthesize composites for thermal energy storage in building applications.Stone coal (SC) after vanadium extraction treatment shows potential...Phase change materials (PCMs) can be incorporated with low-cost minerals to synthesize composites for thermal energy storage in building applications.Stone coal (SC) after vanadium extraction treatment shows potential for secondary utilization in composite preparation.We prepared SC-based composite PCMs with SC as a matrix,stearic acid (SA) as a PCM,and expanded graphite (EG) as an additive.The combined roasting and acid leaching treatment of raw SC was conducted to understand the effect of vanadium extraction on promoting loading capacity.Results showed that the combined treatment of roasting at 900℃ and leaching increased the SC loading of the composite by 6.2%by improving the specific surface area.The loading capacity and thermal conductivity of the composite obviously increased by 127%and 48.19%,respectively,due to the contribution of 3wt% EG.These data were supported by the high load of 66.69%and thermal conductivity of 0.59 W·m^(-1)·K-1of the designed composite.The obtained composite exhibited a phase change temperature of 52.17℃,melting latent heat of 121.5 J·g^(-1),and good chemical compatibility.The SC-based composite has prospects in building applications exploiting the secondary utilization of minerals.展开更多
Understanding the variations in microscopic pore-fracture structures(MPFS) during coal creep under pore pressure and stress coupling is crucial for coal mining and effective gas treatment. In this manuscript, a triaxi...Understanding the variations in microscopic pore-fracture structures(MPFS) during coal creep under pore pressure and stress coupling is crucial for coal mining and effective gas treatment. In this manuscript, a triaxial creep test on deep coal at various pore pressures using a test system that combines in-situ mechanical loading with real-time nuclear magnetic resonance(NMR) detection was conducted.Full-scale quantitative characterization, online real-time detection, and visualization of MPFS during coal creep influenced by pore pressure and stress coupling were performed using NMR and NMR imaging(NMRI) techniques. The results revealed that seepage pores and microfractures(SPM) undergo the most significant changes during coal creep, with creep failure gradually expanding from dense primary pore fractures. Pore pressure presence promotes MPFS development primarily by inhibiting SPM compression and encouraging adsorption pores(AP) to evolve into SPM. Coal enters the accelerated creep stage earlier at lower stress levels, resulting in more pronounced creep deformation. The connection between the micro and macro values was established, demonstrating that increased porosity at different pore pressures leads to a negative exponential decay of the viscosity coefficient. The Newton dashpot in the ideal viscoplastic body and the Burgers model was improved using NMR experimental results, and a creep model that considers pore pressure and stress coupling using variable-order fractional operators was developed. The model’s reasonableness was confirmed using creep experimental data. The damagestate adjustment factors ω and β were identified through a parameter sensitivity analysis to characterize the effect of pore pressure and stress coupling on the creep damage characteristics(size and degree of difficulty) of coal.展开更多
Coal gasification fly ash(CGFA)is an industrial solid waste from the coal circulating fluidized bed(CFB)gasification process,and it needs to be effectively disposed to achieve sustainable development of the environmen...Coal gasification fly ash(CGFA)is an industrial solid waste from the coal circulating fluidized bed(CFB)gasification process,and it needs to be effectively disposed to achieve sustainable development of the environment.To realize the application of CGFA as a precursor of porous carbon materials,the physicochemical properties of three kinds of CGFA from industrial CFB gasifiers are analyzed.Then,the activation potential of CGFA is acquired via steam activation experiments in a tube furnace reactor.Finally,the fluidization activation technology of CGFA is practiced in a bench-scale CFB test rig,and its advantages are highlighted.The results show that CGFA is characterized by a high carbon content in the range of 54.06%–74.09%,an ultrafine particle size(d50:16.3–26.1 μm),and a relatively developed pore structure(specific surface area SSA:139.29–551.97 m^(2)·g^(-1)).The proportion of micropores in CGFA increases gradually with the coal rank.Steam activation experiments show that the pore development of CGFA mainly includes three stages:initial pore development,dynamic equilibrium between micropores and mesopores and pore collapse.The SSA of lignite fly ash(LFA),subbituminous fly ash(SBFA)and anthracite fly ash(AFA)is maximally increased by 105%,13%and 72%after steam activation;the order of the largest carbon reaction rate and decomposition ratio of steam among the three kinds of CGFA is SBFA>LFA>AFA.As the ratio of oxygen to carbon during the fluidization activation of LFA is from 0.09 to 0.19,the carbon conversion ratio increases from 14.4%to 26.8%and the cold gas efficiency increases from 6.8%to 10.2%.The SSA of LFA increases by up to 53.9%during the fluidization activation process,which is mainly due to the mesoporous development.Relative to steam activation in a tube furnace reactor,fluidization activation takes an extremely short time(seconds)to achieve the same activation effect.It is expected to further improve the activation effect of LFA by regulating the carbon conversion ratio range of 27%–35%to create pores in the initial development stage.展开更多
文摘Coal is the world's most abundant energy source because of its abundance and relatively low cost. Due to the scarcity in the supply of high-grade coal, it is necessary to use low-grade coal for fulfilling energy demands of modern civilization. However, due to its high ash and moisture content, low-grade coal exerts the substantial impact on their consumption like pyrolysis, liquefaction, gasification and combustion process. The present research aimed to develop the efficient technique for the production of clean coal by optimizing the operating parameters with the help of response surface methodology. The effect of three independent variables such as hydrofluoric acid(HF) concentration(10–20% by volume), temperature(60–100 °C), and time(90–180 min), for ash reduction from the low-grade coal was investigated. A quadratic model was proposed to correlate the independent variables for maximum ash reduction at the optimum process condition by using central composite design(CCD) method. The study reveals that HF concentration was the most effective parameter for ash reduction in comparison with time and temperature. It may be due to the higher F-statistics value for HF concentration, which effects to large extent of ash reduction. The characterization of coal was evaluated by Fourier transform infrared spectroscopy(FTIR) analysis and Field-emission scanning electron microscopy with energy-dispersive X-ray(FESEMEDX) analysis for confirmation of the ash reduction.
基金Funded by the Academician Workstation of Yichang Hui Long Science and Technology Co.Ltd.Association of Science and Technology of Hubei Province(No.[2013]104-22)
文摘Dry separation of iron mineral from low-grade coal-series kaolin in Hubei Province of China was investigated. The structure and chemical composition of the kaolin ore were determined by X-ray diffraction(XRD) and X-ray Fluorescence(XRF) analyses. The narrow particle size range classification, dry magnetic separation and calcination were carried out to evaluate the particle size distribution, and the relation between the content of iron and the whiteness. Experimental results revealed that the highest content of iron(3.70%) in kaolin ore was in the particle size range from 60 to 74 μm, and pyrite was the main occurrence of iron in the kaolin ore. Dry magnetic separation showed that the removal rate of iron in kaolin ore could be increased obviously after calcination, and the rate of iron removal was 60% in the particle size range from 60 to 74 μm. As pyrite can be transformed into hematite through calcination, thermodynamic studies and XRD analysis showed that the maximum content of hematite was obtained at 900 ℃, which would be more beneficial to magnetic separation.
基金Scientific Research Fund of National Health Commission of China,Key Health Science and Technology Program of Zhejiang Province,No.WKJ-ZJ-2201Key Project of Social Welfare Program of Zhejiang Science and Technology Department,“Lingyan”Program,No.2022C03099and Clinical Research Fund Project of Zhejiang Medical Association,No.2021ZYC-A173.
文摘BACKGROUND Low-grade appendiceal neoplasms(LAMN)are characterized by low incidence and atypical clinical presentations,often leading to misdiagnosis as acute or chronic appendicitis before surgery.The primary diagnostic tool for LAMN is abdominal computed tomography(CT)imaging.Surgical resection remains the cornerstone of LAMN management,necessitating en bloc tumor excision to minimize the risk of iatrogenic rupture.Laparoscopy,known for its minimal invasiveness,reduced postoperative discomfort,and expedited recovery,is a safe and reliable approach for LAMN treatment.Despite the possibility of pseudomyxoma peritonei development,appendectomy and partial appendectomy generally result in negative tumor margins and favorable outcomes,which can be attributed to the disease’s slow growth and lower malignancy.CASE SUMMARY A 71-year-old male patient was admitted to our hospital with a pelvic spaceoccupying lesion detected 1 mo prior.Physical examination showed a soft abdomen without tenderness or rebound and no palpable masses.No shifting dullness was noted,and digital rectal examination revealed no palpable mass.Enteroscopy revealed a raised,smooth-surfaced mass measuring 3.0 cm in the cecum.Abdominal contrast-enhanced CT showed a markedly thickened and dilated appendix with visible cystic shadows.Laparoscopic surgery was performed and revealed a significantly dilated appendix,leading to laparoscopic resection of the appendix and part of the cecum.Post-surgical pathologic analysis confirmed LAMN.The patient received symptomatic and supportive post-operative care and was discharged on postoperative day 4 without complications such as abdominal bleeding,intestinal obstruction,or incision infection.No tumor recurrence was observed during a 7-mo follow-up period.CONCLUSION LAMN is a rare disease that lacks specific clinical manifestations.Abdominal CT plays a crucial role in diagnosing LAMN,and laparoscopic surgery is a safe and effective diagnostic and therapeutic approach.
文摘BACKGROUND Low-grade myofibroblastic sarcoma(LGMS)is an extremely rare tumor characterized by the malignant proliferation of myofibroblasts.LGMS most commonly develops in adults,predominantly in males,in the head and neck region,oral cavity,especially on the tongue,mandible,and larynx.This article presents 2 cases of LGMS localized to the maxillary sinus and provides an overview of the available literature.CASE SUMMARY Two patients with LGMS located in the maxillary sinus underwent surgery at the Department of Head and Neck Surgery.Case 1:A 46-year-old patient was admitted to the clinic with suspected LGMS recurrence in the right maxillary sinus(rT4aN0M0),with symptoms of pain in the suborbital area,watering of the right eye,thick discharge from the right nostril,and augmented facial asymmetry.After open biopsy-confirmed LGMS,the patient underwent expanded maxillectomy of the right side with immediate palate reconstruction using a microvascular skin flap harvested surgically from the middle arm.The patient qualified for adjuvant radiotherapy for the postoperative bed,with an additional margin.Currently,the patient is under 1.5 years of observation with no evidence of disease.Case 2:A 45-year-old man was admitted to our clinic with facial asymmetry,strabismus,exophthalmos,and visual impairment in the right eye.Six months earlier,the patient had undergone partial jaw resection at another hospital for fibromatosis.A contrast-enhanced computed tomography scan revealed a tumor mass in the postoperative log after an earlier procedure.An open biopsy confirmed lowgrade fibrosarcoma(rT4aN0M0).The patient qualified for an extended total right maxillectomy with orbital excision and right hemimandibulectomy with immediate microvascular reconstruction using an anterolateral thigh flap.The patient subsequently underwent adjuvant radiotherapy to the postoperative area.After 9 months,recurrence occurred in the right mandibular arch below the irradiated area.The lesion infiltrated the base of the skull,which warranted the withdrawal of radiotherapy and salvage surgery.The patient qualified for palliative chemotherapy with a regimen of doxorubicin+dacarbazine+cyclophosphamide and palliative radiotherapy for bone metastases.The patient died 26 months after surgical treatment.The cases have been assessed and compared with cases in the literature.CONCLUSION No specific diagnostic criteria or treatment strategies have been developed for LGMS.The treatment used for LGMS is the same as that used for sinonasal cancer radical tumor excision;adjuvant radiotherapy or chemoradiotherapy should also be considered.They have low malignant potential but are highly invasive,tend to recur,and metastasize to distant sites.Patients should undergo regular follow-up examinations to detect recurrence or metastasis at an early stage.Patients should be treated and observed at the highest referral centers.
基金financially supported by the National Natural Science Foundation of China (Nos. 21176026 and 21176242)the National High Technology Research and Development Program of China (No. 2012AA062401)+2 种基金the National Key Technology R&D Program of China (Nos.2012BAB07B05 and 2012BAB14B05)China Ocean Mineral resources R&D Association (No. DY125-15-T-08)the Fundamental Reserarch Funds for the Central Universities of China (No. FRT-TP-09-002B)
文摘Based on the fluidized roasting reduction technology of low-grade pyrolusite coupling with pretreatment of stone coal, the manganese reduction efficiency was investigated and technical conditions were optimized. It is found that the optimum manganese reduction efficiency can be up to 98.97% under the conditions that the mass ratio of stone coal to pyrolusite is 3:1, the roasting temperature of stone coal is 1000℃, the roasting temperature of pyrolusite is 800℃, and the roasting time is 2 h. Other low-grade pyrolusite ores in China from Guangxi, Hunan, and Guizhou Provinces were tested and all these minerals responded well, giving -99% manganese reduction efficiency. Meanwhile, the reduction kinetic model has been established. It is confirmed that the reduction process is controlled by the interface chemical reaction. The apparent activation energy is 36.397 kJ/mol.
基金This work was supported by the National Natural Science Foundation of China(U1802256,21773118)Leading Edge Technology of Jiangsu Province(BK20202008)+1 种基金Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX21_0204)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Thermal energy is abundantly available in our daily life and industrial production,and especially,low-grade heat is often regarded as a byproduct.Collecting and utilizing this ignored energy by low-cost and simple technologies may become a smart countermeasure to relieve the energy crisis.Here,a unique device has been demonstrated to achieve high value-added conversion of low-grade heat by introducing redox-active organic alizarin(AZ)onto N-doped hollow carbon nanofibers(N–HCNF)surface.As-prepared N–HCNF/AZ can deliver a high specific capacitance of 514.3 F g^(-1)(at 1 A g^(-1))and an outstanding rate capability of 60.3%even at 50 A g^(-1).Meanwhile,the assembled symmetric proton capacitor can deliver a high energy density of 28.0 Wh kg^(-1) at 350.0 W kg^(-1) and a maximum power density of 35.0 kW kg^(-1) at 17.0 Wh kg^(-1).Significantly,the thermally chargeable proton capacitors can attain a surprisingly high Seebeck coefficient of 15.3 mV K^(-1) and a power factor of 6.02µW g^(-1).Taking advantage of such high performance,a satisfying open-circuit voltage of 481.0 mV with a temperature difference of 54 K is achieved.This research provides new insights into construction of high value-added energy systems requiring high electrochemical performances.
文摘BACKGROUND Low-grade myofibroblastic sarcoma(LGMS)is a rare spindle cell sarcoma espe-cially in the pancreas,with myofibroblastic differentiation.Hitherto,only a few cases have been reported.CASE SUMMARY Herein,we report a case involving the discovery of a pancreatic mass detected during a routine physical examination.Subsequent imaging and pathological tests of the patient led to the diagnosis of LGMS of the pancreas.Following surgical intervention,the patient experienced recurrence and metastasis.Conventional treatment is not effective for postoperative recurrent pancreatic LGMS with multiple metastases.After communicating with the patients and their families,informed consent was obtained for the treatment of anlotinib combined with pembrolizumab.Evaluation of imaging and clinical symptoms post-treatment revealed a relatively favorable response to the combination of anlotinib and pembrolizumab.CONCLUSION Based on the comprehensive literature review,our report aimed to provide evidence for a better understanding of the disease characteristics,diagnostic criteria,imaging findings,and identification of LGMS.And explore novel treatment strategies for this disease.
基金This work was financially supported by the National Science Fund for General Projects of China(No.51874153).
文摘A new method for separating and recovering tin from a low-grade tin middling with high Si content and low Fe content by roasting with anthracite coal was researched by studying the reaction mechanism and performing an industrial test,in which the Sn was sulfurized into SnS(g)and then collected using a dust collector.The Fe–Sn alloy may be formed at roasting temperatures above 950°C,and like the roasting temperature increases,the Sn content and Sn activity in this Fe–Sn alloy decrease.Also,more FeS can be formed at higher temperatures and then the formation of FeO–FeS with a low melting point is promoted,which results in more serious sintering of this low-grade tin middling.And from the thermodynamics and kinetics points of view,the volatilization of the Sn decreases at extremely high roasting temperatures.The results of the industrial test carried out in a coal-fired rotary kiln show that the Sn volatilization rate reaches 89.7%and the Sn is concentrated in the collected dust at a high level,indicating that the Sn can be effectively extracted and recovered from the low-grade tin middling with a high Si content and low Fe content through a reduction–sulfurization roasting process.
基金the National Natural Science Foundation of China(No.52374279)the Natural Science Foundation of Shaanxi Province(No.2023-YBGY-055).
文摘Coal gasification fine slag(FS)is a typical solid waste generated in coal gasification.Its current disposal methods of stockpil-ing and landfilling have caused serious soil and ecological hazards.Separation recovery and the high-value utilization of residual carbon(RC)in FS are the keys to realizing the win-win situation of the coal chemical industry in terms of economic and environmental benefits.The structural properties,such as pore,surface functional group,and microcrystalline structures,of RC in FS(FS-RC)not only affect the flotation recovery efficiency of FS-RC but also form the basis for the high-value utilization of FS-RC.In this paper,the characteristics of FS-RC in terms of pore structure,surface functional groups,and microcrystalline structure are sorted out in accordance with gasification type and FS particle size.The reasons for the formation of the special structural properties of FS-RC are analyzed,and their influence on the flotation separation and high-value utilization of FS-RC is summarized.Separation methods based on the pore structural characterist-ics of FS-RC,such as ultrasonic pretreatment-pore-blocking flotation and pore breaking-flocculation flotation,are proposed to be the key development technologies for improving FS-RC recovery in the future.The design of low-cost,low-dose collectors containing polar bonds based on the surface and microcrystalline structures of FS-RC is proposed to be an important breakthrough point for strengthening the flotation efficiency of FS-RC in the future.The high-value utilization of FS should be based on the physicochemical structural proper-ties of FS-RC and should focus on the environmental impact of hazardous elements and the recyclability of chemical waste liquid to es-tablish an environmentally friendly utilization method.This review is of great theoretical importance for the comprehensive understand-ing of the unique structural properties of FS-RC,the breakthrough of the technological bottleneck in the efficient flotation separation of FS,and the expansion of the field of the high value-added utilization of FS-RC.
基金Funded by National Natural Science Foundation of China (No.52074218)。
文摘A hydrotalcite(layered double hydroxide, LDH) inhibitor which is suitable for the whole process of coal spontaneous combustion and a LDH inhibitor containing rare earth lanthanum elements were prepared. The inhibition effect and mechanism were analyzed by scanning electron microscopy(SEM),X-ray diffraction(XRD), thermal performance analysis, in-situ diffuse reflectance infrared spectroscopy and temperature-programmed experiment. The results have shown that the inhibitor containing lanthanum can play a good inhibitory role in every stage of coal oxidation. During the slow oxidation of coal samples, the inhibitor containing lanthanum ions can slow down the oxidation process of coal and increase the initial temperature of coal spontaneous combustion. At the same time, because the hydroxyl groups in LDHs are connected with-COO-groups on the coal surface through hydrogen bonds, the stability of coal is improved. With the increase of temperature, LDHs can remove interlayer water molecules and reduce the surface temperature of coal. CO release rate of coal samples decreases significantly after adding inhibitor containing lanthanum element, and the maximum inhibition rate of the inhibitor is 58.1%.
基金the financial support from the National Natural Science Foundation of China(Grant No.21576293 and 21576294)。
文摘Coal pyrolysis is a fundamental reaction in the thermal processing and utilization of coal.Investigating the behavior and kinetics of coal pyrolysis is crucial for optimizing,designing,and developing a composite riser for the staged pyrolysis gasification process of pulverized coal.In this study,the non-isothermal pyrolysis behavior and kinetics of coal were examined at different heating rates(30,50,100,300,500,700,and 900℃/min)using thermogravimetry(TG)coupled with Fourier-transform infrared spectroscopy.Analysis of the TG/derivative TG(TG/DTG)curves indicated that coal pyrolysis mainly occurred between 300℃ and 700℃.Higher heating rates led to more volatiles being released from the coal,and a higher temperature was required to achieve rapid pyrolysis.Kinetic analysis showed that both the model-free methods(Friedman,Flynn-Wall-Ozawa,and Kissinger-Akahira-Sunose)and the model-based method(Coats-Redfern)effectively describe the coal pyrolysis process.The change in the Ea values between the two kinetic models was consistent throughout the pyrolysis process,and the most probable mechanism was the F2 model(secondary chemical reaction).In addition,the heating rate did not change the overall reaction order of the pyrolysis process;however,a higher heating rate resulted in a decrease in the Ea value during the initial pyrolysis stage.
文摘Hydroconversion of coal tar to produce aromatic hydrocarbons(BTX)represents a crucial strategy for the highvalue hierarchical utilization of coal.This study focused on the hydrocracking of hydrorefined products derived from coal tar to enhance the production of benzene,toluene,and xylene(BTX).Various reaction conditions,including reaction temperature,hydrogen pressure,space velocity,and hydrogen-to-oil volume ratio,were systematically explored to optimize BTX yields while also considering the process’s economic feasibility.The results indicate that increasing the reaction temperature from 360℃ to 390℃ significantly favors the production of BTX,with yields increasing from 21.42%to 41.14%.Similarly,an increase in hydrogen pressure from 4 MPa to 6 MPa boosts BTX production,with yields rising from 36.31%to 41.14%.Reducing the space velocity from 2 h^(-1) to 0.5 h^(-1) also favors the BTX production process,with yields increasing from 37.96%to 45.13%.Furthermore,raising the hydrogen-to-oil volume ratio from 750 to 1500 improves BTX yields from 41.61%to 45.44%.Through economic analysis,the optimal conditions for BTX production were identified as a reaction temperature of 390℃,hydrogen pressure of 5-6 MPa,space velocity of 1 h^(-1),and hydrogen-to-oil volume ratio of 1000,achieving a BTX yield of 43.73%.This investigation highlights the importance of a holistic evaluation of hydrocracking conditions to optimize BTX production.Furthermore,the findings offer valuable insights for the design and operation of industrial hydrocracking processes aimed at efficiently converting coal tar-derived hydrorefined feedstock into BTX.
基金supported by the Australian Research Council(Grant No.DP200101293)the National Natural Science Foundation of China(Grant No.42202286)the Zhejiang Collaborative Innovation Center for Prevention and Control of Mountain Geological Hazards(Grant No.PCMGH-2017-Z-02).
文摘Long-term permeability experiments have indicated that sorption-induced swelling can switch from internal to bulk depending on the evolutive sorption status.However,this sorption swelling switch mechanism has not been considered in current analytical permeability models.This study introduces a normalized sorption non-equilibrium index(SNEI)to characterize the sorption status,quantify the dynamical variations of matrix swelling accumulation and internal swelling partition,and formulate the sorption swelling switch model.The incorporation of this index into the extended total effective stress concept leads to an analytical transient coal permeability model.Model results show that the sorption swelling switch itself results in the permeability switch under stress-constrained conditions,while the confined bulk swelling suppresses the permeability recovery to the continuous reduction under displacement-constrained conditions.Model verifications show that current experimental observations correspond to the early stages of the transient process,and they could be extended to the whole process with these models.This study demonstrates the importance of the sorption swelling switch in determining permeability evolution using simple boundary conditions.It provides new insights into experimentally revealing the sorption swelling switch in the future,and underscores the requirement of a rigorous model for complex coupled processes in large-scale coal seams.
文摘Discoveries of many coal seams at depths by drilling carried by Geological Survey of Pakistan in Sor Range and Harnai Gochina, extended the coal seams at depth which is challenge for mine owners to exploit feasibly. Bed to bed gypsum samplings (and their chemical analyses) of huge gypsum deposits from Sulaiman foldbelt is a base for industrialist and also planers to develop cement and gypsum industries to increase export and foreign exchange for the development of area and Pakistan. Low and high grade sedimentary iron deposits, silica sand and uranium host rocks and their extensions in Sulaiman and Kirthar foldbelts are presented. Anomalies of a few base metals arise as a result of geochemical exploration carried at part of Loralai District of Balochistan. Theropod dinosaurs were frequent in India, while Poripuchian titanosaurs (Sauropoda, Dinosauria) were frequent in Pakistan. Besides some ichnotaxa, many bone taxa such as 1 titanosauriform, 14 titanosaurian sauropod (including one new titanosaur), and 3 theropod dinosaurs are established from Pakistan. Among these 12 titanosaur species and 3 theropod species are named in about 10 km<sup>2</sup> area of Vitakri dome and 2 titanosaur species are named in about a few hundred square meter area of Mari Bohri (Kachi Bohri) which is about 10 km westward from Vitakri dome. Pakistan is a unique country which discoverd 14 diversified titanosaurs in a short area and also in a short period (67 - 66 million years ago/Ma). About 400 bones found from a few meter thick upper part of upper shale horizon of latest Maastrichtian Vitakri Formation which is base for titanosaur taxa. Cranial material is in low fraction (but include significant diverse snouts), caudal vertebrae are prominent, the cervicals, dorsals and sacrals have significant numbers, forelimb and hind limb bones have balanced fraction. Humeri, femora and tibiae are most common. To know the position of Pakistani titanosaurs among titanosaurs and sauropods, there is a need to extend list of characters for phylogenetic analyses. This broad feature list should include main characters of titanosaurs from Pakistan and also from global world.
基金The research was conducted as part of the“Establishing a Research Observatory to Unlock European Coal Seams for CO_(2) Storage(ROCCS)”project(Grant No.899336)The work of the second author is also sponsored by Shanghai Pujiang Program(Grant No.23PJ1412600)。
文摘Injecting carbon dioxide(CO_(2))into coal seams may unlock substantial carbon sequestration potential.Since the coal acts like a carbon filter,it can preferentially absorb significant amounts of CO_(2).To explore this further,desorption of the adsorbed gas due to pressure drop is investigated in this paper,to achieve an improved understanding of the long-term fate of injected CO_(2) during post-injection period.This paper presents a dual porosity model coupling gas flow,adsorption and geomechanics for studying coupled processes and effectiveness of CO_(2) sequestration in coals.A new adsorption?desorption model derived based on thermodynamics is incorporated,particularly,the desorption hysteresis is considered.The reliability of the proposed adsorption-desorption isotherm is examined via validation tests.It is indicated that occurrence of desorption hysteresis is attributed to the adsorption-induced pore deformation.After injection ceases,the injected gas continues to propagate further from the injection well,while the pressure in the vicinity of the injection well experiences a significant drop.Although the adsorbed gas near the well also decreases,this decrease is less compared to that in pressure because of desorption hysteresis.The unceasing spread of CO_(2) and drops of pressure and adsorbed gas depend on the degree of desorption hysteresis and heterogeneity of coals,which should be considered when designing CO_(2) sequestration into coal seams.
文摘The quality upgrading and deashing of inferior coal by chemical method still faces great challenges.The dangers of strong acid,strong alkali,waste water and exhaust gas as well as high cost limit its industrial production.This paper systematically investigates the ash reduction and desilicification of two typical inferior coal utilizing ammonium fluoride roasting method.Under the optimal conditions,for fat coal and gas coal,the deashing rates are 69.02%and 54.13%,and the desilicification rates are 92.64%and 90.27%,respectively.The molar dosage of ammonium fluoride remains consistent for both coals;however,the gas coal,characterized by a lower ash and silica content(less than half that of the fat coal),achieves optimum deashing effect at a reduced time and temperature.The majority of silicon in coal transforms into gaseous ammonium fluorosilicate,subsequently preparing nanoscale amorphous silica with a purity of 99.90%through ammonia precipitation.Most of the fluorine in deashed coal are assigned in inorganic minerals,suggesting the possibility of further fluorine and ash removal via flotation.This research provides a green and facile route to deash inferior coal and produce nano-scale white carbon black simultaneously.
基金financially supported by the National Natural Science Foundation of China, China (Nos. 52274252 and 51874047)the Special Fund for the Construction of Innovative Provinces in Hunan Province, China (No. 2020RC3038)the Changsha City Fund for Distinguished and Innovative Young Scholars, China (No. kq1802007)。
文摘Phase change materials (PCMs) can be incorporated with low-cost minerals to synthesize composites for thermal energy storage in building applications.Stone coal (SC) after vanadium extraction treatment shows potential for secondary utilization in composite preparation.We prepared SC-based composite PCMs with SC as a matrix,stearic acid (SA) as a PCM,and expanded graphite (EG) as an additive.The combined roasting and acid leaching treatment of raw SC was conducted to understand the effect of vanadium extraction on promoting loading capacity.Results showed that the combined treatment of roasting at 900℃ and leaching increased the SC loading of the composite by 6.2%by improving the specific surface area.The loading capacity and thermal conductivity of the composite obviously increased by 127%and 48.19%,respectively,due to the contribution of 3wt% EG.These data were supported by the high load of 66.69%and thermal conductivity of 0.59 W·m^(-1)·K-1of the designed composite.The obtained composite exhibited a phase change temperature of 52.17℃,melting latent heat of 121.5 J·g^(-1),and good chemical compatibility.The SC-based composite has prospects in building applications exploiting the secondary utilization of minerals.
基金supported by the National Natural Science Foundation of China(Nos.52121003,51827901 and 52204110)China Postdoctoral Science Foundation(No.2022M722346)+1 种基金the 111 Project(No.B14006)the Yueqi Outstanding Scholar Program of CUMTB(No.2017A03).
文摘Understanding the variations in microscopic pore-fracture structures(MPFS) during coal creep under pore pressure and stress coupling is crucial for coal mining and effective gas treatment. In this manuscript, a triaxial creep test on deep coal at various pore pressures using a test system that combines in-situ mechanical loading with real-time nuclear magnetic resonance(NMR) detection was conducted.Full-scale quantitative characterization, online real-time detection, and visualization of MPFS during coal creep influenced by pore pressure and stress coupling were performed using NMR and NMR imaging(NMRI) techniques. The results revealed that seepage pores and microfractures(SPM) undergo the most significant changes during coal creep, with creep failure gradually expanding from dense primary pore fractures. Pore pressure presence promotes MPFS development primarily by inhibiting SPM compression and encouraging adsorption pores(AP) to evolve into SPM. Coal enters the accelerated creep stage earlier at lower stress levels, resulting in more pronounced creep deformation. The connection between the micro and macro values was established, demonstrating that increased porosity at different pore pressures leads to a negative exponential decay of the viscosity coefficient. The Newton dashpot in the ideal viscoplastic body and the Burgers model was improved using NMR experimental results, and a creep model that considers pore pressure and stress coupling using variable-order fractional operators was developed. The model’s reasonableness was confirmed using creep experimental data. The damagestate adjustment factors ω and β were identified through a parameter sensitivity analysis to characterize the effect of pore pressure and stress coupling on the creep damage characteristics(size and degree of difficulty) of coal.
基金financially supported by the Special Research Assistant Fund Project of Chinese Academy of Sciences.
文摘Coal gasification fly ash(CGFA)is an industrial solid waste from the coal circulating fluidized bed(CFB)gasification process,and it needs to be effectively disposed to achieve sustainable development of the environment.To realize the application of CGFA as a precursor of porous carbon materials,the physicochemical properties of three kinds of CGFA from industrial CFB gasifiers are analyzed.Then,the activation potential of CGFA is acquired via steam activation experiments in a tube furnace reactor.Finally,the fluidization activation technology of CGFA is practiced in a bench-scale CFB test rig,and its advantages are highlighted.The results show that CGFA is characterized by a high carbon content in the range of 54.06%–74.09%,an ultrafine particle size(d50:16.3–26.1 μm),and a relatively developed pore structure(specific surface area SSA:139.29–551.97 m^(2)·g^(-1)).The proportion of micropores in CGFA increases gradually with the coal rank.Steam activation experiments show that the pore development of CGFA mainly includes three stages:initial pore development,dynamic equilibrium between micropores and mesopores and pore collapse.The SSA of lignite fly ash(LFA),subbituminous fly ash(SBFA)and anthracite fly ash(AFA)is maximally increased by 105%,13%and 72%after steam activation;the order of the largest carbon reaction rate and decomposition ratio of steam among the three kinds of CGFA is SBFA>LFA>AFA.As the ratio of oxygen to carbon during the fluidization activation of LFA is from 0.09 to 0.19,the carbon conversion ratio increases from 14.4%to 26.8%and the cold gas efficiency increases from 6.8%to 10.2%.The SSA of LFA increases by up to 53.9%during the fluidization activation process,which is mainly due to the mesoporous development.Relative to steam activation in a tube furnace reactor,fluidization activation takes an extremely short time(seconds)to achieve the same activation effect.It is expected to further improve the activation effect of LFA by regulating the carbon conversion ratio range of 27%–35%to create pores in the initial development stage.