Geochemical Characteristics of REE in Jurassic Coal of Yan＇ an Formation from Dongsheng Coalfield

Concentrations of rare earth clcments (REE) in Jurasaaic coal of YanAn Formation from Dongsheng coalfield located in the northeast of Ordos basin were determined by instrumental neutron activation analysis (INAA). Curves of distribution pattern of REE were drawn, and many geochemical parameters were calculated. The result shows that 1) The contents of REE in Jurassic coal with low ash and sulfur are lower than those of Carboniferous and Pemlian coal from the Basin of North China; 2) Inside the Dongsheng coalfield, coal from the north has higher contents of REE than that form the south because the north is near the area of source rock which is thc main supplier of REE, while the south is far away from the area of source rocks; 3) Although Jurassie coal in Dongsheng is the low-ash coal with less than 10%, the contents of REE are still proportional to ash yield of ash and SiO2 contents. 4) Ahhough the jurassic coal in Dongshcng were detposited in oxidative continental environment of river-lake, Eu depletion of REE in coal commonly exists, and positive abnomity of Ce dose not exist. This reflects the REE distribution pattern of REE in source rock of continental area; and 5) Compared with other rocks, coal shows extremely complexity of distribution pattern of RFE,which is the result of continuous alteration and redistribution of matter in coal occurred in open basin system.     

STUDY ON REGULATIONS OF.SULFUR OCCURRENCE AND PYRITE MAGNETISM OF LATE PERMIAN COALS IN SOUTHWEST CHINA

The Permian coal In southwest China contains highest sulfur among the Chinese coal. Compositional variations of sulfur in coal are mainly controlled by paiaogeographicai environments during peat accumulation. High organic sulfur coal is formed in peat swamp developing in tidal flat of limited carbonate platform, and it is provided with especial petrological and geochemical characteristics, and its organosuLfur-containing compounds are mainly thiophene series. The macroscopical and microscopical shapes or types of pyrites in Late Permian coal are diversified. Bituminous coal and anthracite are diamagnetic, but the pyrites are paramagnetic. The magnetic susceptibility of the pyrites is depended on the content of paramagnatic elements associated with pyrites.     

Activity and Structure of Calcined Coal Gangue

Coal gangue was activated by means of calcination in seven temperature ranges. Systematic research was made about activation mechanism and structural evolution. Glycerin-ethanol method, SEM, M1P and XRD were used to determine the variation of structure and activation of coal gangue during the calcination. The experimental results show that because of heat treatment in the range of calcination temperature, mineral composition and microstructure of coal gangue are changed. In addition, its activity is improved evidently. The amount of lime absorbed by the sample calcined at 700 ℃ is 2-4 times that by uncalcined coal gangue in the course of hydration. When NaOH is added to coal gangue-lime system, hydration reaction of the system is sped up and the microstructure of hydrating samples of coal gangue is improved.     

Analysis and Research of Factors Affecting Coal Mining with Plough

Coal mining with ploughs is an ideal coal mining technology for thin and thinner coal seams.The cxistenec conditions of coal scams are different for cach other,which affeets coal mining with ploughs to different dcgrees,and the application results are also different.The authors analyzc the affeeting factors by means of mathcmatical methods.The research is useful to the application of ploughs.     

Coal and gas outburst dynamic system

Coal and gas outburst is an extremely complex dynamic disaster in coal mine production process which will damage casualties and equipment facilities, and disorder the ventilation system by suddenly ejecting a great amount of coal and gas into roadway or working face. This paper analyzed the interaction among the three essential elements of coal and gas outburst dynamic system. A stress-seepage-damage coupling model was established which can be used to simulate the evolution of the dynamical system, and then the size scale of coal and gas outburst dynamical system was investigated. Results show that the dynamical system is consisted of three essential elements, coal-gas medium(material basis), geology dynamic environment(internal motivation) and mining disturbance(external motivation). On the case of C13 coal seam in Panyi Mine, the dynamical system exists in the range of 8–12 m in front of advancing face. The size scale will be larger where there are large geologic structures. This research plays an important guiding role for developing measures of coal and gas outburst prediction and prevention.     

Neoproterozoic stratigraphic correlation of Subei-Huainan in China

Subei-Huainan in the southeastern margin of the North China platform is a key area of convergence of China’s north-south stratigraphic correlation of Neoproterozoic.Due to the lack of fossils,the Neoproterozoic stratigraphic correlation is still a difficulty in this area.The division of Neoproterozoic strata and the establishment of the correlation framework of the stratigraphic sequences have been done through recognizing the regularity of meter-scale cycles by measuring the outcrop of Neoproterozoic strata and using the Fischer diagram and the sea-level curve of transgressive-regressive by the maximum flooding sedimentary and molar teeth carbonate sedimentary.The maximum flooding sedimentary which becomes cycle sequence comparison of sign is isochronous in the same basin and is a key of cycle sequence comparison although paleogeographic environment and sedimentary sequence may be different in the sedimentary strata of the same geologic time.Molars carbonates,having specific geological distrution time and depositional environment and mainly developing in the ramp environment of the platform edge in the 1500-650 Ma,are the new symbol of the stratigraphic correlation in the Neoproterozoic.Because of the missing of the fossil record,the maximum flooding and the molar-teeth carbonate sedimentary,as the new research ideas,are used in stratigraphic division and correlation.     

Research on Kaolinite in Coal Measures of West Beijing by Mossbauer Spectroscopy

The spatial occurrence of iron in kaolinite of coal measures west of Beijing was studied by using the Mossbauer spectroscopy technique and a step-by-step method of fitting. The results show that there are three kinds of spatial occurrence in kaolinites： tetra-coordination Fe（3＋） in Si-O tetrahedrons, sexa-coordination Fe（3＋） in A1--O octahedrons and sexa-coordination Fe（2＋） in A1-O octahedrons, respectively occupying 51.72 %, 37.25 % and 11.03 %, Neither foreign matter of magnetic Fe mineral nor superparamagnetic goethite exists in kaolin concentrates. Fe in kaolin concentrates cannot be removed by conventional methods, which is significant for both theoretical research on kaolinite minerology and practical use of the kaolinites of coal measures west of Beijing.The research also illustrates that the Mossbauer spectroscopy is an effective method in studying the micro-superfine Fe in kaolin.     

On the Range of the Common Cycle Time in a Road Network

In a coordinated road network, the optimal common cycle time is determined by evaluating the performance of the network in the given range of cycles. Normally, this range is determined by users’ experience. And a large range of common cycle time, e.g. \[0,0\] is chosen, which requires long computation time. This study considers that the optimal common cycle time ranges between the minimal and maximal value of intersections’ individual optimal cycle time. It is proved mathematically from the convexity condition, that the delay of the network and each individual intersection are convex functions of the cycle time according to Webster delay model. Finally, 2 000 random cases for the network composed of two intersections and of eight intersections are created to underline the proposed conclusions. The results of all cases confirm the validity, and show up to 90% improvement in computation time to compare with experience range. The signal optimization tool, Synchro, is also used to validate the conclusion by 50 random cases. The results confirm reliability further.     

Subsidence History of the Eastern Depression in the North Yellow Sea Basin

Using a back-stripping method, our paper simulated the subsidence history of the eastern depression in the North Yellow Sea Basin. The subsidence history curve pattern and the subsidence chorisogram during every subsiding period were exposed. Combining with the regional geologic background and the distribution features of the subsiding centers in every period, a contrasting study of the pattern and the classical subsidence history curves shows the subsidence history is made up of Mesozoic （J3-K1） and Cenozoic （E2-Q） subsiding cycles. The two subsiding cycles are separated by the late Cretaceous and Paleocene （K2-E1） uplift denudation. Both subsiding cycles have the characteristics of an extension basin. The rapid subsidence during the late Jurassic and Eocene is equivalent to the initial subsiding phases in both cycles.. The slow subsidence of both, the early Cretaceous and Neogene, can be regarded as thermal subsidence phases.     

Chemical looping combustion of coal in interconnected fluidized beds

Chemical looping combustion is the indirect combustion by use of oxygen carrier. It can be used for CO2 capture in power generating processes. In this paper, chemical looping combustion of coal in interconnected fluidized beds with inherent separation of CO2 is proposed. It consists of a high velocity fluidized bed as an air reactor in which oxygen carrier is oxidized, a cyclone, and a bubbling fluidized bed as a fuel reactor in which oxygen carrier is reduced by direct and indirect reactions with coal. The air reactor is connected to the fuel reactor through the cyclone. To raise the high carbon conversion efficiency and separate oxygen carrier particle from ash, coal slurry instead of coal particle is introduced into the bottom of the bubbling fluidized bed. Coal gasification and the reduction of oxygen carrier with the water gas take place simultaneously in the fuel reactor. The flue gas from the fuel reactor is CO2 and water. Almost pure CO2 could be obtained after the con- densation of water. The reduced oxygen carrier is then returned back to the air reactor, where it is oxidized with air. Thermodyanmics analysis indicates that NiO/Ni oxygen carrier is the optimal one for chemical looping combustion of coal. Simulation of the processes for chemical looping combustion of coal, including coal gasification and reduction of oxygen carrier, is carried out with Aspen Plus software. The effects of air reactor temperature, fuel reactor temperature, and ratio of water to coal on the composition of fuel gas, recirculation of oxygen carrier par- ticles, etc., are discussed. Some useful results are achieved. The suitable tem- perature of air reactor should be between 1050―1150℃and the optimal temperature of the fuel reactor be between 900―950℃.     

MESOZOIC-CENOZOIC INVERSION OFTHE TURPAN-HAMI BASIN, NORTHWEST CHINA

The Turpan-Hami basin, rich in coal and petroleum, is a superimposedbasin of three types basins in different tectonic environments. This coal, oil and gasbasin has undergone a complex tectonic-sedimentary evolution, in which two important stages were the negative inversion from a foredeep to a extensional basin duringEarly Mesozoic and the positive inversion to a thrust foreland basin in Late MesozoicEarly Cenozoic. The early normal faults residues are recognized with the addition oftectonic-sedimentary analysis to confirm the basin extension during Jurassic time andits tectonic inversion subsequently.     

Electrochemical Intercalation of Lithium into Raw and Mild Oxide-treated Carbon Nanotubes Prepared by CVD

The raw carbon nanotubes ( CNTs ) prepared by chemical vapor deposition ( CVD ) were used in electrochemical lithiation. To remove the impurity the mild oxidation was done on the samples. The electrochemical characteristics of the two samples are investigated by the galvanostatic charge-dischorge measurements and cyclic voltammetry. The structural and interfacial changes of the CNTs electrode were analyzed by XRD and FTIR. The samples show a reversibility of lithium intercalation and de-intercalation. The reversible capacities of the first five cycles are larger than 300 mAh/ g and the irreversible capacity of the first cycle was much larger than that mentioned in literatures. There is no identical change in the structure during the charge and discharge. The reactions at the interface between electrode and the electrolyte are similar to those of other carbonaceous materials.     

Application of 3D Visual Techniques in Daliuta Coal Mine

3D visualization is one of major problems in ＂Digital Mine＂ theory and its technological research field. Through the observation of 3D geological models, spatial structural information, connected with the information of production management hidden in geological data, could be detected. In order to meet the requirement of more efficient coal exploration, a case study of geological characters of the Daliuta Coal Mine is presented in which 3D visual models of the ground surface and geologic bodies are established on the basis of data models and data structures of 3D geology modeling. The main conclusions of this study are as follows： （1） Through analysis and organization of spatial discrete data, the drillhole database is designed with the data of the Daliuta mine; the connections amomg drillhole data are realized and displayed in a 3D environment. （2） Combining real data of the Daliuta mine, drillhole visualization is realized in a 3D environment by using the CoalMiner system. （3） The ground surface modeling of the Daliuta coal mine adopted a surface-data model and a TIN data structure. （4） 3D models of coal seams and rock formations of the Daliuta mine are established, which provide a method for the simulation of complex surfaces of geologic bodies. In the end, the models are applied to the Daliuta coal mine and the result shows that better geological effects are obtained.     

Constitutive model for methane desorption and diffusion based on pore structure differences between soft and hard coal

This paper aims to improve the accuracy and applicability of gas diffusion mathematical models from coal particles. Firstly, a new constitutive model for gas diffusion from coal particles with tri-disperse pore structure is constructed by considering the difference in characteristics between soft coal and hard coal.The analytical solution is then derived, that is, the quantitative relationship between gas diffusion rate(Qt/Q_∞) and diffusion time(t), The pore structure parameters of soft coal and hard coal from Juji coal mine are determined. Gas diffusion rules are numerically calculated and investigated by physical simulation methods. Lastly, the applicability of this model is verified. The results show that the homogeneous model only applies to the gas diffusion process of hard coal during the initial 10 min. The calculation results from this model and the physical experimental results of soft coal and hard coal are nearly identical during the initial 30 min.     

T-Q diagram analyses and entransy optimization of the organic flash cycle(OFC)

The electrical power generation from low temperature heat source attracts more and more attentions but the temperature mismatching between the heat sources and working medium in the organic Rankine cycle(ORC)becomes an issue.The organic flash cycle(OFC)is an effective solution to this issue.In this paper,the OFC is analyzed by the concept of entransy loss and the T-Q(temperature-heat flow rate)diagram for the heat-work conversion.The equations for cycles of the basic OFC and the OFC whose heat source is the exhaust gas of the turbine in a Brayton cycle(the combined cycle)are derived theoretically and the results indicate that larger entransy loss rate leads to larger output power with prescribed inlet parameters of the hot stream in the discussed cases,which is displayed by the T-Qdiagram intuitively.Two numerical examples demonstrate that the optimal mass flow rate of the working medium for the maximum entransy loss rate is the same as that for the maximum output power.The T-Qdiagram analyses is in accordance with the numerical results.The concept of entransy loss can be used as the criteria for the OFC optimization.     

Response characteristics of gas pressure under simultaneous static and dynamic load: Implication for coal and gas outburst mechanism

Coal and gas outbursts are dynamic disasters in which a large mass of gas and coal suddenly emerges in a mining space within a split second. The interaction between the gas pressure and stress environment is one of the key factors that induce coal and gas outbursts. In this study, first, the coupling relationship between the gas pressure in the coal body ahead of the working face and the dynamic load was investigated using experimental observations, numerical simulations, and mine-site investiga...     

Mechanical genesis of Henan（China） Yima thrust nappe structure

Considering the serious coal and rock dynamic disasters around the main slip plane called F16 in the coal mining area） of Henan Yima（China） thrust nappe structure,the mechanical genesis of the Yima thrust nappe structure was studied comprehensively using geomechanics,fault mechanics,elastic mechanics,and Coulomb＇s law of friction.First,using the centrifugal inertia force of Earth＇s rotation as a source,a mechanical model of N-S compression superimposed with W-E reverse torsion was established to explain the formation of the early Yima coal basin and Jurassic Yima Group coal measures.Second,an equation for the ultimate stress in the forming stage of F16 was derived using the plastic slip-line field theory and the parabolic Mohr failure criterion.Moreover,the distribution of ultimate stress and the geometric characteristics of the fault profile were obtained using the field model parameters.Finally,the stress field of F16 and the mechanical genesis of the large-scale reverse thrust sheet were discussed based on elastic mechanics theory and Coulomb＇s law of friction.The results show that the tectonic framework of the early Yima coal basin and the formation pattern of Jurassic Yima Group coal measures given by the model are consistent with the in-situ explorations.The geometric characteristics of the fault profile obtained by numerical calculation can better reflect the shape of F16 in its forming stage,and the mechanical genesis of the large-scale reverse thrust sheet also concurred with the field situations.Thus,this work can provide a foundation for further studies on the genesis of the thrust nappe structure,the mechanism of rock bursts induced by F16,and the characteristics of the residual stress field in the Yima mining area.     

CONTROL OF GAS EMISSION AT COAL FACE IN CHINA

All the underground coal mines in China are gassy mines. The gas emission at coal face increasingly grows with the increase of working depth and coal output,for example,the gas emission at a full mechanized coal face of mine No.2 at Yongquan with a daily output of 2,000t/d is up to 66--72m^3/min. Special gas emission phenomena such as gas blowout, gas and coal outburst etc. have occurred at some faces, which threatens the safe production of face, obstructs the growth of productivity and limits the full play of mechanized equipment. In this paper, gas at face is divided, according to its origin, into three constituents, namely, coming from the coal wall, mined coal and goaf; and a formula for calculation is given. Also, the characteristics of the variation of gas emission at coal face, and thesinfluence of mining sequence of a group of seams and supplied air quantity on the gas emission are discussed. Furthermore, based on the regularity of gas emission st coal face from the above three sources, and on the experiences of years, three principles on controlling gas emission at coal face are presented, that are managing the gas on classification basis, harnessing each source separately and comprehensive prevention and control. Finally, technical measures for prevention and treatment of the accumulation of gas in the upper corner of face, at the working place of coal-winning machine and in the bottom trough of conveyor are introduced.     

Intelligent and ecological coal mining as well as clean utilization technology in China: Review and prospects

Coal is an essential fossil fuel in China; however, coal mining and its utilization are being under the increasing pressure from ecological and environmental protection. Therefore, the consulting project "Technical Revolution in Ecological and Efficient Coal Mining and Utilization Intelligence and Diverse Coordination of Coal-based Energy System," initiated by Chinese Academy of Engineering, puts forward three stages(3.0, 4.0 and 5.0) of China's coal industry development strategy. Aimed at "reduced staff,ultra-low ecological damage, and emission level near to natural gas," breakthroughs should be achieved in the following three key technologies during the China Coal Industry 3.0 stage(2016–2025): including intelligent coal mining, ecological mining, ultra-low emission and environmental protection. This paper focuses on the development trends of the China Coal Industry 3.0 and its support for China Coal Industry 4.0 and 5.0 is analyzed and prospected as well, which may offer technical assistance and strategy orientation for realizing the transformation from traditional coal energy to clean energy.     

Control over Surrounding Rocks Deformation of Soft Floor and Whole-Coal Gateways with Trapezoidal Supports

In Gengcun Colliery, Yima Coal Group Co. Ltd.the characteristics of the gateways of thick coal seam and the coal seam is with fully mechanized sublevel caving mining are that the thickness of roof coal seam of gateways is larger, their surrounding rocks are the whole-coal mass and the coal seam is prone to Spontaneous Combustion. With the natural equilibrium arch theory, the reasonable adjacent distance of No. 11 mine-type metal supports was calculated in trapezoidal gateways based on these characteristics. Then, in-situ supporting experiments were carried out. There sults indicate that under the action of virgin rock stress, the width of broken rocks zone of surrounding rocks is 1.7-2.0m in return heading and 1.1-1.3 m in going headway. And their surrounding rocks belong to the Ⅳ-type soften rock and the Ⅲ-type common surrounding rock respectively. Therefore, under the movable abutment pressure, the gateways deformation is serious. It is suggested that the designed gateways have to use pre-broadened cross section to suit their deformation. At the same time, the accumulated water on gateway floor must be drained in time. These measures weretaken in the 1302 and 1304 coal faces in Gengcun Colliery, and the satisfactory results have been obtained.