矿业科学学报

Geochemical characteristics and genesis of the Yanchang Formation terrestrial shale gas in the Yanchang exploration area

Xu Hongwei, Li Xianqing, Zhou Baogang, Yang Jie, Zhang Wei, Wang Zhe, Gao Wenjie

2017, 2(2): 99-108.

Abstract(784) PDF(295)

Abstract:
Through analyzing the gas composition and isotopes of carbon and hydrogen of the shale gas samples,the geochemical characteristics of the upper Triassic Yanchang Formation shale from the Yanchang exploration area in the southeastern Ordos basin were studied.The genesis and source of the Yanchang Formation shale gas in the Yanchang exploration area were also discussed.The results show that:①Shale gas of Yanchang Formation in the Yanchang exploration area mainly consist of hydrocarbon gases (87.89%~99.66%),with methane content less than 95% (60.44%~91.68%),high content of heavy hydrocarbon component,relatively lower dry coefficient（64.00%~93.43%）,and low non-hydrocarbon gases content (mainly N₂ and CO₂,0.68% and 1.36%,respectively ),belongs to typical wet gas.②The carbon isotope values of methane,ethane,propane and butane of Yanchang Formation shale gas in the Yanchang exploration area are mainly distributed in -53.4‰~-46.3 ‰,-39.7 ‰~-31.9 ‰,-34.3 ‰~-29.6 ‰ and -33.8 ‰~-25.0 ‰.The carbon isotope of Yanchang Formation shale gas in the Yanchang exploration area is mainly characterized by δ¹³C₁<δ¹³C₂ <δ¹³C₃ <δ¹³C₄.Only a small number of samples of the δ¹³C₃and δ¹³C₄are reversal.③Shale gas of Yanchang Formation in the Yanchang exploration area is dominated by thermogenic gas,mainly oil type gas formed by kerogen cracking that from the lowmature and mature stage of the partial sapropel type shale.

Research on roof fracture criterion and moving rule of gob-side entry in shallow seam

Zhang Guofeng, Miao Peipei, Wang Eryu, Chen Xin

2017, 2(2): 109-119.

Abstract(817) PDF(781)

Abstract:
Based on the characteristics that horizontal pressure between rocks is too small to form masonry beam after roof fracture in shallow-buried coal seam,the retaining gob-side entry fracture structure formed by falling down cutting roof.It was established that fracture mechanical model of lower slitting and upper bending cracks bilateral cantilever beam.The cutting-top working resistance was derived as the lateral basic roof fracture extends along the cracks of the cutting seam structure.The numerical model of surrounding rock structure under two fracture states of lateral basic roof was built.The movement and deformation law under two states of fracture structure indicated: When the cutting resistance is low,the roof breaks along the coal wall inside certain depth.The pour terraced cantilever beam of arc triangle direct roofs in emptied stope,can transfer large fracture dynamic load and overlying strata movement pressure along emptied roadway surrounding rock.With the unit cutting action of high shear resistance and cutting seam,the direct roof of caving zone and low basic roof were cut to slide along the cutting seam structure.It could reduce the structure length of transferring the overburden strata load from the side of arc triangle hanging deck,and optimize the roof bearing structure and surrounding rock stress,and also could reduce the additional load bore by the support body in the roadside by implementing active control of roof fracture state.At the same time,the hulking of waste rock could fill the empty area and make the overlying rock contact point move forward,and slow down the sinking and rotational deformation force of overlying rock.In the condition of the shallow seam and thin bedrock of Halagou mine,the observation of cutting large cross-section compounded roof experiment indicated that: advanced slitting on gob-side roadway can reduce support working resistance of lateral roof and immediate roof caving step distance.It could also reduce the roof fracture dynamic load caused by rock plate breakage.The actual cutting resistance dovetailed with the theoretical calculation results.

Numerical analysis of slope stability under the effect of rainfall infiltration

Zhang Na, Zhang Bo, Liu Longbiao, Sheng Hailong

2017, 2(2): 120-128.

Abstract(854) PDF(384)

Abstract:
Rainfall is one of the major causes for instability and failure of slopes,as a result,slope sliding and destruction are closely related to rainfall infiltration.This paper selected the eastern slope of the open pit on the west side of the Ⅶ orebody of the Tonglüshan Ancient Copper Mine site as the analysis object.Firstly,numerical calculation models were set up according to the engineering hydrogeological conditions and the occurrence of the investigated slope.Then,by using the SEEP/W module of the GEO-STUDIO software,the internal seepage characteristics of the slope under different rainfall intensities were simulated.Finally,combining with the SLOPE/W module,the coefficients of slope stability under various rainfall conditions were calculated.The results have shown that with the increase of rainfall intensity,the internal seepage field of the eastern slope of the open pit mine changed significantly,and the coefficient of slope stability was negatively correlated with the rainfall intensity.

Study on the water inrush evaluation and major contributing factors determination using vulnerable index method in a built-up coal mine

Du Weisheng, Jiang Yaodong, Jiao Zhenhua, Liu Huabo, Ren Zheng, Zheng Lijie

2017, 2(2): 129-136.

Abstract(676) PDF(363)

Abstract:
The hydrological data is always incomplete and inaccurate in built-up coal mines,which leads to many difficulties in water inrush forecasts.The AHP vulnerable index method was applied to analyze the water inrush risk because of its advantage in quantifying the influence of related factors.Six factors were selected as the major contributing factors in the evaluation model.The corresponding single factor thematic map was established through GIS and the weight of each factor was acquired through the established AHP model.By superposing the six factors,the entire floor was divided into four zones,which were vulnerable area,slight vulnerable area,slight safe area and safe area respectively.The past water inrush accident verified the forecast result.The sensitivity of the six factors was analyzed and the water-resisting layer played a significant role in controlling water inrush from floor.Several suggestions based on the prediction results were put forward: the west area should be mined firstly and the east area should be put focus prevention.The methodology has guiding significance on forecasting and controlling water inrush in built-up coal mines.

Conjecture about mechanism of butterfly-shape coal and gas outburst in excavation roadway

Ma Nianjie, Zhao Xidong, Zhao Zhiqiang, Guo Xiaofei, Liu Hongtao, Jia Housheng

2017, 2(2): 137-149.

Abstract(704) PDF(729)

Abstract:
Referring to roadway butterfly shape rock burst mechanism and nonlinear dynamic system theory,a conjecture about butterfly-shape coal and gas outburst mechanism in excavation roadway has been made,In this conjecture,the mechanical essence of coal and gas outburst in excavation roadway is that a certain degree of butterfly shape plastic zone increment appears in front of excavation face in an extremely short period of time,triggering in the quick release of surrounding rock elastic energy and gas energy,thus resulting in coal and gas outburst.From the aspects of consistency of plastic zone changing laws between butterfly rock burst and coal and gas outburst,the outburst energy source and the rationality of conjecture was verified,and the risk evaluation system of coal and gas outburst was established as well.Four necessary conditions of strength,stress,angle and triggering event for coal and gas outburst were put forward,besides,the sufficient conditions of coal and gas outburst were determined; Quantitative analysis and explanation(not qualitative)of the phenomenon,occurring condition and process of coal and gas outburst were studied for the first time.The research result has provided a new idea for the research work in the field of coal and gas outburst forecast,prediction and prevention in coal seam roadway.

Comparative study on the fire-extinguishing effectiveness of N₂ and CO₂ on coal flame combustion

Guo Zhiguo, Wu Bing

2017, 2(2): 150-157.

Abstract(741) PDF(270)

Abstract:
In order to master thoroughly the different fire-extinguishing effects of N₂ and CO₂ on coal flame combustion,the self-developed experiment device of coal flame combustion was used to conduct the fire-extinguishing experiment on coal flame combustion under the condition of importing same flux N₂ and CO₂gas fire-extinguishing agent for coal samples in Eight mine of Ping Dingshan coal mine,and the change laws of temperature of temperature field,index gas formation(O₂,CO and CH₄),heat release rate and flame image area obtained from the experimental stages of the coal flame combustion and smoldering extinguished were measured,The results show that:compared to the free combustion of coal,in coal flame combustion stage,flame out time,coal temperature rise rate,oxygen consumption,heat release rate as well as the speed of CO and CH₄ concentration decline in coal combustion with CO₂ much lower than that of coal combustion with N₂;meanwhile,the flame image area exponentially decline in coal combustion with CO₂,but the flame image area linearly decreases in coal combustion with N₂,In the coal smoldering extinguishes stage,the coal temperature,the speed of CO and CH₄concentration decline in the coal combustion with CO₂ much higher than that of coal combustion with N₂,but the oxygen consumption and heat release rate are lower,It follows that CO₂ has greater capacity of extinguishing coal combustion compared to N₂.

Characteristics of high level borehole deviation and its influence on extraction effect

Fu Shuai, Xie Beijing, Lü Pingyang, Wang Jiajian, Liu Wenbiao

2017, 2(2): 158-166.

Abstract(788) PDF(118)

Abstract:
In order to study the influence of high level borehole deviation on the extraction effect,borehole trajectory instrument was used to measure the borehole trajectory of high level borehole.Based on the deviation position,this paper divided the boreholes into four categories:upward deviation borehole,effective borehole,downward deviation borehole,and goaf deviation borehole.Then the extraction effect of each category was analyzed.Results show that high level boreholes have a serious deviation,the number of effective borehole is small,and goaf deviation borehole accounts for a significant proportion;fractures caused by mining activities are the main factor of borehole deviation;extraction effect drawings of these four categories boreholes have regularities and differences,which can provide the basis for optimal designs of high level borehole;gas drainage of effective boreholes is the highest and is 1.3 times higher than that of upward deviation boreholes,2.9 times higher than that of downward deviation boreholes,and 4 times higher than that of goaf deviation boreholes;the amount of gas drainage of goaf deviation boreholes is the lowest and meaningless.

Fault-tolerant localization method for underground mine based on wireless sensor network

Liu Xiaoyang, Liang Tao, Hu Qiaosen

2017, 2(2): 167-174.

Abstract(633) PDF(228)

Abstract:
This paper described a wireless-sensor-network based monitoring and positioning system for underground mine.This system regards the condition of ensuring the function of positioning as the basic requirements and uses reasonable fault-tolerant mechanism on the structure of the high degree of disaster.The paper proposed PIR or PIT interior point test method to determine the location area and miner relative position In the ranging phase,using simple and effective calculation method to update path fading model parameters and finally put forward weighted trilateral localization method based on RSSI ranging.The experimental simulation shows that this method effectively improves the personnel positioning accuracy,and proves that it has good fault tolerance.

Microstructure and properties of coal-fly-ash-based foam geopolymer

Wang Dongmin, Cui Yong, Li Duanle, Shao Ningning, Zhao Jihui, Rui Yafeng

2017, 2(2): 175-182.

Abstract(1106) PDF(100)

Abstract:
Large amount of circulating fluidized bed combustion fly ash (CFA) were generated in power plants.In this paper,foam geopolymer material was prepared using CFA,water glass (WG) and sodium hydroxide (NaOH) as raw material and hydrogen peroxide as foaming agent.By adopting (wt) 3%-8% hydrogen peroxide,the properties of foaming multiple,pore size distribution,apparent density,macro porosity and compressive strength were tested.The balance of foaming driving force and paste resistance and the influence of macro pore structure on compressive strength were studied.The results showed that the balance of the foaming driving force and paste resistance was content of H₂O₂ (wt) of 5%； and the foaming multiple,apparent density,macro porosity and compressive strength were 4.2,255 kg/m³,81.7% and 0.65 MPa respectively when the H₂O₂ foaming agent(wt) was 5%.The different pore size distribution had different degree of the decrease on compressive strength,the gray correlation degree between compressive strength of samples and pore diameter range of 10-20 μm was the greatest,that was,the range of pore size was 10-20 μm as the key factor,and the effect on compressive strength of samples was the largest.

Pore structure characteristics of filter cake in coal slurry water pressure filtration

Wang Donghui, Liu Wenli, Zhang Xueren, Chen Huan

2017, 2(2): 183-190.

Abstract(721) PDF(295)

Abstract:
The pore structure of filter cake is the key factor influencing coal slurry water filtering effect,but filter cake structure is easily damaged and coal particles and pores become indistinguishable during the coal slime filter cake measurement.In order to study the pore structure characteristics of filter cake in coal slurry water pressure filtration,this paper established a coal slime filter cake solidification device and method.Effect of -0.074 mm particles content and filtration pressure on coal slime filter cake pore structure were investigated using polarizing microscope.The results show that an increasing amount of -0.074 mm particles content results in smaller decreasing rate of pore diameter,pore area and porosity,narrower pore diameter distribution,and larger proportion of small pores in the constituents of porosity.It also leads to increasing fractal dimension of filter cake pore section edge,more zigzag pore section edge and more complicated pore structure.Increase in coal slime water filtration pressure prior compresses filter cake large pores.As the filtration pressure rises,filter cake pore compresses,porosity descends and fractal dimension of pore section edge ascends.In addition,it complicates the pore structure with more zigzag pore section edge and more irregular pore shape.

The characteristics and source apportionment of heavy metal pollution in the soil at a coal chemical industry area in northwest China

Zhang Kai, Yang Jiajun, Bai Lu, Qiang Changdi, Wang Sidi

2017, 2(2): 191-198.

Abstract(784) PDF(319)

Abstract:
This paper aims to investigate the heavy metal pollution in the soil at a large coal chemical industry area in northwest China,and perform the source apportionment of the pollution.Soil samples,raw coal and coal ash samples were taken from that area and were analysed with ICP-MS and cold atomic absorption method after digestion for determining 8 heavy metal elements including Cr,Cd,As,Pb,Ni,Se and Hg.Enrichment factor method,correlation coefficient analysis,cluster analysis and factor analysis method were used to evaluate the pollution and analyse the sources.Results indicated that the Cr,As,Se,Ag,and Cd were from the anthropogenic activity,and there were three main sources of pollution according to the data field model and the migration regularity of heavy metals in soil,coal and coal ash.Among the three pollution sources,coal gasification pollution was primarily loaded with Se,Cd,and Pb; slag field dust was mainly loaded with Cr,Hg and Ag; other external sources such as from traffic were mainly loaded with As,and Ni.The three sources contributed 32.01%,23.89% and 19.61% to the heavy metal pollution in the soil,respectively.

Study on the interface identification and management of engineering in underground coal mine

Zhang Zhiqiang, Zhu Wei, Seng Liyang, Wang Wei, Shangguan Danbin

2017, 2(2): 199-208.

Abstract(715) PDF(97)

Abstract:
Aiming at the coordination problems of under-well project management,the interface management theory was applied to the special coal mine under-well project management,and a set of interface management theory system and practice methods of coal mine under-well project were systematically put forward.On the basis of the construction of system framework of coal mine under-well project,the coal mine engineering interface was divided into the three types(target interface,process interface and organization interface),and according to the given interface analysis process,the three kinds of interface were identified and managed respectively,which can realize the effective control of interfaces,effective coordination of relations between elements,and change under-well project into ground project.The engineering interface management practice of Kailuan Group shows significant effect of interface management improving production efficiency.

2017 Vol. 2, No. 2