矿业科学学报

Accumulation conditions of shale gas in transitional marine-continental coal measures of the Carboniferous-Permian in Henan Province

Shao Longyi, Zhang Liang, Zhang Jingkai, Wang Dewei, Shi Biao, Fu Yafei, Xu Lianli, Song Jianjun

2016, 1(3): 209-221.

Abstract(860) PDF(157)

Abstract:
The Carboniferous-Permian strata in Henan Province are a set of coal-bearing series of transitional marine-continental facies,of which the mudstones have potentials for shale gas exploration.The mudstones are characterized by a variable thickness of the individual effective mudstone layer and a huge accumulative thickness.In this paper,we utilized the outcrop and borehole core data and investigated the accumulation conditions and the reservoir characteristics of the shale gas in the Carboniferous and Permian coal-bearing strata of Henan Province.The total organic carbon (TOC),organic matter types,thermal evolution degree,contents of brittle minerals and clay minerals,and pore morphological types of the mudstones were determined by the TOC analyzer,microscopic identification of kerogen,reflectance measurement of vitrinite,X-ray diffraction (XRD),low temperature nitrogen gas adsorption,respectively.The results showed that the abundance of organic matters of the mudstones was relatively high,with the TOC contents in the mudstones of the Taiyuan,Shanxi and Xiashihezi Formations being 0.95%～8.04%,0.78%～9.41% and 0.2%～2.13%,respectively.The types of organic matter were dominated by type Ⅲ,followed by type Ⅱ₂.The thermal evolution degree ranged from mature to over-mature stage which was favorable for the formation of dry gas.The maturity of the mudstones had a zoned distribution,with the highest maturity being distributed along the Jiaozuo-Zhoukou belt and the lower maturity being distributed towards the south and north from this belt.The XRD analysis showed that the clay minerals of the mudstones could account for 62.0% while the brittle minerals only accounted for 34.1%,indicating that the mudstones had a higher gas adsorption capacity but were difficult for hydraulic fracturing.The clay minerals were mainly composed of 57.1% of illite/smectite mixed layer and 23.5% of kaolinite,which were beneficial to the formation of pore space.The porosity of the mudstones ranged from 1.0% to 4.5%,and the permeability varied between 0.003 and 0.032 mD.The experiment of low temperature nitrogen gas adsorption revealed that the morphological types of the pores included the parallel plate-slit pores and the inclined plate-slit pores.The meso-pores provided the vast majority of specific surface area and total pore volume.The gas contents could reach 1.0～3.0 m³/t which is suitable for the condition of shale gas reservoir.It was concluded that the siliciclastic member in the middle Taiyuan Formation (H₁) and the basal part of the Shanxi Formation (H₂) have a higher hydrocarbon potential.The major favorable exploration areas are those having a good preservation condition or a less serious influence from the regional thermal events.

Experimental study on failure law of cracking and disintegration of rock mass in large-scale slope

Tao Zhigang, Pang Shihui, Zhang Bo, Zhu Yalong

2016, 1(3): 222-227.

Abstract(697) PDF(283)

Abstract:
The process of instability and failure of slope rock mass include cracking,through,disintegration,slipping.But capturing the variation and characteristics of surface deformation and deep sliding surface mechanical in each session is the key to explore the landslide monitoring and early warning guidelines.In this paper,“Constant Resistance Large Deformation Cable (NPR) deep sliding force automatic monitoring system and surface displacement monitoring system”has been applied in Nanfen open-pit iron mine stope footwall to carry out field physical simulation experiment of landslide induced by artificial excavation.It aims to explore the disintegration of slope rock mass crack damage and the variation and time effects of deep sliding force before and after the landslide.The results show that due to the effect of artificial excavation disturbance,the time of slope rock mass surface cracks is lagging behind the deep sliding force mutation time; that is,when the sliding force fell sharply after 4 h,the slope surface rock mass initial cracking was 6 mm(length 200 cm ); when the sliding force fell sharply after 96 h,the surface rock mass crack width was 74 mm(length 1306 cm ); when the sliding force fell sharply after 168 h,the sliding slope collapsed completely.It proved that the duration of this type of slope from the deep mechanical imbalance to the failure of slope surface disintegration is at least 7 days,and also the results provide a scientific basis for the establishment of monitoring and early warning rule of sliding force in this region.

The water absorption test of rock in the rainy and humid environment

Zhang Fang, Liu Wenfang, Han Zongfang, Zheng Shanlin, Wang Shupeng, Lin Yajun

2016, 1(3): 228-235.

Abstract(844) PDF(334)

Abstract:
The water absorption characteristics of rocks are closely related to the temperature and humidity of environment.The rainfall type slopes with rock as the main material are always formed in a certain temperature and humidity environment.It is one-side to study the sliding disaster mechanism of rock water absorption solely.By using the intelligent testing system for vapor water absorption of soft rock and simulating rainfall temperature and humid environment to study the relationship between rock water absorption and three factors such as lithology,rain delay and temperature,it is concluded that the lithological composition is different and the hydraulic response characteristics of the rainfall type rock slope are also different.It indicates that in the rainfall＇s temperature and humidity(20℃,100%),dry conglomerate＇s water absorption is biggest,and sandstone is second while epidotic amphibolite is minimal.The conglomerate has strong rain infiltration capacity,and sandstone＇s curve slope is negative when the water absorption reaches peak.It shows that absorption rule changes from absorption to ponding.Epidotic amphibolite soon present “condensation” phenomenon,and its infiltration capacity is very weak.The research reveals that rock slope whose main component is conglomerate has strong ability of rain infiltration.During heavy rainfall,the effect of seepage and underground runoff is the main factor.It is necessary to consider the coupling effect of seepage and runoff.Rock slope whose main component is epidotic amphibolite has strong ability of drainage.During heavy rainfall,the effect of surface runoff and underground runoff is the main factor,so it is necessary to considers groundwater seepage force as the main factor.

Catastrophic analysis of roof cut-off disasters in proximity to coal seam beneath a room mining goaf

Zhang Lingfan, Chen Zhonghui, Li Bo, Guo He, Chai Mao

2016, 1(3): 236-242.

Abstract(770) PDF(310)

Abstract:
Aiming at the support crushing disasters in proximity to coal seam beneath a room mining goaf caused by the different pressure time of the roof above pillars and the immediate roof,according to the nonlinear variation of the pillars’ instability failure under the influence of the overlying load,a system mechanics model composed of roof-pillars-gangue was established.In addition,by using the cusp catastrophe theory,the instability mechanisms of the system under the linear loads were studied,the necessary sufficient condition for instability failure of the system and the formula of the jump value and the releasing energy of displacement of pillars were gained,and the main factors for instability failure of the system were analyzed.The results show that the unstable failure of pillars leads to the support crushing disasters.By using the energy method,the attacking dynamic factor and the working resistance of support were calculated.The rationality of the theoretical derivation has been verified by an engineering example.

Experimental study of the effect of tackifier on the water-based foam performance

Chen Peng, Huang Kai, Sun Yongduo

2016, 1(3): 243-248.

Abstract(699) PDF(293)

Abstract:
In order to investigate the influence of the tackifier on the water-based foam performance,the sodium carboxymethyl cellulose is selected to analyze the relationship between the surface tension and viscosity of the foam solution.The results show that the solution viscosity increases slowly with the increase of the tackifier concentration when its concentration is less than 4g/L.Subsequently,the viscosity presents a rapid increase.The surface tension decreases rapidly with the increase of the tackifier concentration when it is less than 2g/L,then keeps stable.The foam life is measured by an improved pressure method,and the Ar-t equations for different concentrations of the sodium carboxymethyl cellulose are obtained using the fitting method.The gravity drainage coefficient and diffusion drainage coefficient,which are characterized by the decay process of foam,are used to obtain the quantitative data of the foam stability.It is found that the foam stability increases with the increase of the tackifier concentration,while the solution foaming ability decreases with its concentration.The decay process of the foam produced by the viscous bubble solution is mainly affected by the diffusion drainage.

Application of visible post-processing method of FLAC^3Dmodel node displacement in surface subsidence

Wang Zhiqiang, Guo Lei, Su Zehua, Wang Jianming, Xu Jie

2016, 1(3): 249-255.

Abstract(1129) PDF(731)

Abstract:
To solve the problem of loss of node information employing plane squeeze method if surface subsidence of FLAC^3D model is relatively large,the node numbering method is proposed for studying surface subsidence visible post-processing.The major steps of this method are to extract numbers of nodes before subsidence of the model,then extract displacements of nodes via these numbers after subsidence,and finally obtain subsidence data.The result demonstrates that node numbering method has a broader scope of application and a larger number of subsidence nodes are compared with plane squeeze method.

Study on synthesizing mullite with bauxite tailing

Liu Dongfang, Liu Wenkai, Xue Baoda, Zhang Zhihao, Huang Liangliang, Ma Xiangdong

2016, 1(3): 256-260.

Abstract(675) PDF(282)

Abstract:
To enhance the efficient utilization of bauxite tailings,the mullite was synthesized by bauxite tailings in molybdenum wire furnace at 1550 ℃ and 1650 ℃ for 4h.The sintered samples were analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM) and energy dispersive spectrometry(EDS).The content of mullite was determined by TOPAS.The results indicated that the mullite was in high purity and well growth.The mullite was long column in morphology,alternating each other.As the temperature increased,the crystal profile of mullite was much more clear and the content of mullite increased slightly.

Research on ultra-high-speed interruption safety technology for mine low-voltage power system based on DSP

Gao Yan, Guo Lin, Gao Feng, Wang Yanwen

2016, 1(3): 261-268.

Abstract(643) PDF(296)

Abstract:
The electric arc or spark originating from the low voltage cable fault is the major source of the coal mine gas explosion accident.In order to limit the energy detonating gas which is caused by the fault,the topology of neutral solid state circuit breaker is put forward in this paper in which IGBTs work is the main components of this device.Directed against the mine low-voltage power system,selective and ultra-high-speed single-phase electric leakage protection based on pattern recognition method and ultra-high-speed short circuit protection based on current rate of change are proposed to meet the requirements of full fault time,in which the fault duration should be shortened to no more than 3ms.Results of the experiments show its satisfactory performance.

Influences of sodium hexametaphosphate on interactions of coal and clay particles in flotation

Xu Dongfang, Zhu Shuquan, Zhu Zhibo, Cui Haoran

2016, 1(3): 269-276.

Abstract(1042) PDF(472)

Abstract:
The influences of sodium hexametaphosphate on interfacial properties of fine minerals in coal flotation were investigated by many tests,including flotation,Zeta potential measurement,adsorptive capacity and theoretical calculations of extended DLVO.The flotation results showed that high content of kaolinite is unfavorable for coal flotation.An addition of 20% kaolinite decreased the coal recovery by 18.70%.At low concentration,sodium hexametaphosphate depressed the flotation of kaolinite,whereas it had little effect on coal flotation.At high concentration,sodium hexametaphosphate lost the selective inhibition ability.With 1000g/t sodium hexametaphosphate,the Zeta potentials of coal and kaolinite particles were shifted from -25mV,-39mV to -32mV and -57mV,respectively.As a result,the electrostatic repulsion between coal particles and kaolinite particle were enhanced.In addition,by adsorbing on the surface of kaolinite,sodium hexametaphosphate increased the steric hindrance repulsion and strengthened the dimensional stabilization effect when particles approached to each other.

Effect and mechanism of semi-coke powder on concentration and dehydration of excess sludge

Zhang Liping, Wang Wenxiao, Xiang Jun, Chen Tingting, Li Qiang, Yuan Yuefu

2016, 1(3): 277-283.

Abstract(719) PDF(257)

Abstract:
Objective The semi-coke powder was selected from a factory producing semi-coke with high volatile bituminous coal under medium-low temperature carbonization and pyrolysis.The semi-coke powder was used to conditioning the excess sludge from waste water treatment plant.Based on the physicochemical properties analysis of semi-coke powder,raw sludge and treated sludge by semi-coke powder,concentrating,filtering and dewatering property of sludge was researched through experiments.Meanwhile,the mechanism of conditioning sludge with semi-coke was analyzed by Zeta potential,microscope,infrared spectrum and scanning electron microscope.The experimental results showed: when semi-coke dosage was 250%,the specific resistance of filtration decreased significantly from 3.22×10¹³m/kg (raw sludge) to 4.33×10¹¹m/kg,the water content of sludge after concentration was reduced from 98.6% to 91.2%,the settling velocity of sludge obviously accelerated from 3.0mL/min to 34.3mL/min,the water content of filter cake was low down from 87.8% to 63.6%,and the low calorific value of sludge increased from 10.68MJ/kg to 21.77MJ/kg.The mechanism of semi-coke powder conditioning sewage sludge were adsorption and flocculation abilities to improve the settling performance,skeleton construction forming rigid frame structure with many channels and intervals which could prevent sludge cake compression and maintain high permeability during air-pump filtration,weakening the hydrophilicity and increasing the hydrophobicity of sludge.

Effect of oxygen-containing functional groups on the attachment probability of low rank coals in coal flotation

Geng Jianchun, Liu Wenli

2016, 1(3): 284-290.

Abstract(1151) PDF(736)

Abstract:
In order to improve the hydrophobicity and flotability of low rank coals and realize the efficient flotation of low rank coals,the Pingshuo long-flame coal and Shengli brown coal were surface modified with three types of surfactants which are CTAB,SDS and Span-80.The oxygen-containing functional groups in each modified coal were detected through ion exchange method,and the attachment probability of them were measured as well.The modifying rule of surfactants on low rank coals were analyzed and the mechanism was also discussed.It was found that the content of oxygen-containing functional groups was the most important factor that affected the hydrophobicity and flotability of low rank coals.The modification of low rank coals with surfactants could mask part of the oxygen-containing functional groups and improve the hydrophobicity of low rank coals as well as its attachment probability on bubbles.Hydrogen bonding is the main factor that make surfactants attach on the coal surface.The functional groups on the polar end of the surfactants and the strength of the hydrogen bond between them and the oxygen-containing functional groups on the coal surface play a decisive role in the surface modification.

Analysis of economic and environmental benefits of clean coal technology in the perspective of the pollution control

Yang Yang, Qi Jiao, Zhang Ran

2016, 1(3): 291-298.

Abstract(782) PDF(133)

Abstract:
At present,a variety of traditional energy is being used in China,such as coal,oil,natural gas,and coal is one of the main energy in China.However,the extensive use of coal causes increasingly serious environmental problems.In this paper,we analyze the economic and environmental benefits of clean coal technology with system dynamics theory by introducing new factors,such as “the pollution gas governance input”,“the supply reduction benefits”,“the power supply coal saving benefit”.We establish the benefits of clean coal technology with USC technology and IGCC technology as the representative of the estimation model,respectively by calculating the ordinary thermal power technology and two kinds of clean coal technology.According to the analyses,we find that USC technology and IGCC technology have significant environmental and social benefits.At the same time,we find that the use of USC technology and IGCC technology can reduce pollution of gas investment and the government’s spending on environmental governance,from a long-term point of view with considerable economic benefits.

2016 Vol. 1, No. 3