矿业科学学报

Basic characteristics of coalfield tectonic framework in China

Cao Daiyong, Ning Shuzheng, Guo Aijun, Li Huantong, Chen Limin, Liu Kang, Tan Jieqing, Zheng Zhihong

2016, 1(1): 1-08.

Abstract(1137) PDF(613)

Abstract:
The occurrence of coal-bearing strata in China is characterized by the variety of coal-bearing basins,the remarkable spatial and temporal differences of late tectonic deformations.The main controlling factors,which determine the tectonic framework of coalfields,include geodynamic environment,tectonic evolution,deep structures,tectonic stress,and lithologic combination features of coal measures.The continent of China has experienced multi-stage tectonic movements since the late Paleozoic,and due to the spatio-temporal heterogeneity of continental tectonic evolution and the complexity of basement properties,the coalfield structures present complex and ordered patterns.The coalfield tectonic framework of China can be divided into two major coalfield regions,three coal deformation zones,and five coal occurrence structural areas.Taking coal occurrence structural sub-areas as basic units,the tectonic characteristics of five coal occurrence structural areas in China were summarized in this paper.

Assessment and control of water inrush in the 10th coal seam floor in the Ganhe Mine，Huobao Corporation

Li Shenju, Cui Fangpeng, Wu Qiang, Li Xianzhi, Li Peng, Su Benzhen

2016, 1(1): 9-15.

Abstract(825) PDF(362)

Abstract:
The Vulnerability Method was applied to evaluate and forecast the water inrush in the 10th coal seam floor in the Ganhe Mine,Huobao Corporation,with aim to control its threat to underground mining.The results show that the probability of water inrush in the 10th coal seam floor from Ordovician limestone aquifer is generally high.First of all,the southeast part of the mine area is the relative safe site.The central-north mine area is the relative vulnerable site.The fault areas in north part and the other part of the mine area are the most vulnerable sites to form water inrush.The hydro geological condition revealed by the drilling engineering is the same as that of the evaluation result and the validity of the evaluation is proved Finally,some countermeasures for controlling the coal seam floor water inrush were proposed.

The mechanism of directional fracture controlled blasting and its application

Song Junsheng, Wang Yanbing, Gao Xiangtao, Yang Guoliang, Yue Zhongwen

2016, 1(1): 16-28.

Abstract(1052) PDF(225)

Abstract:
Synthetically using methods including high speed laser tattoo shadow, super dynamic strain testing technology, digital laser dynamic caustics experimental system, this paper studies the cutting seam cartridge explosion wave propagation mechanism, multi-angle observation of the detonation wave propagation process, clearly observed explosion stress wave and explosive gas separating phenomenon.Air interval cutting seam cartridge blasting cement mortar model testing was carried out.The spatial distribution law of stress was summarized.The cutting seam cartridge decoupling blasting explosive raw crack dynamic fracture effect was analyzed.The different charge structures influence on critical raw crack extension was compared.The best decoupling coefficient is 1.67 with directional fracture controlled blasting effect was determined.It studied double hole grooving method, initiation at the same time, through the crack between the two hole and the hole of the lateral dynamic behavior of crack propagation.Finally the cutting seam cartridge directional fracture controlled blasting technology was applied in shaft and tunnel blasting construction.The directional fracture of cutting seam cartridge blasting effect was verified.This research will provide experimental basis and theoretical guidance for engineering practice.

Ground pressure features of roadway under close range goaf in the Xinyu Mine

Shan Renliang, Huang Bo, Song Yongwei, Wu Huimin, Fu Xiaolin

2016, 1(1): 29-37.

Abstract(775) PDF(330)

Abstract:
To study the ground pressure features of roadway under close range goaf,deformation laws of surrounding rock during mining are analyzed by deformation monitoring.Variations of vertical stress in surrounding rock during mining are obtained by numerical simulation.The results show that the convergence between roof and floor can be 2.02-3.09 times that between two side walls.The intense influence area is 10 m front of working face,where deformation velocity can become fast.The two side walls are influenced more significant in this area.Vertical stress in surrounding rock closed to coal pillar increases when adjacent to the working face.It can be found that the existence of goaf make curves no longer obey exponential function to the base.Working face under goaf has incomplete roof.So effects of abutment pressure decrease.The influence scope of abutment pressure is only 5-10 m,which reduces obviously compared to common roadway.The formation of side abutment pressure in upper coal pillars make a roadway under goaf has a larger deformation,and side walls supports are easy to damage because of a compressive expansion in surrounding rock.Roof sinking caused by the damage of support in side walls,and the seepage from goaf will aggravate the heave of Al mudstones floor.

Research on technology of improving top-coal recovery in longwall top-coal caving mining based on BBR system

Wang Jiachen, Zhang Jinwang, Chen Yi

2016, 1(1): 38-48.

Abstract(895) PDF(179)

Abstract:
The optimization of drawing parameters is one of the major ways to improve top-coal recovery in longwall top-coal caving mining.Based on the BBR system,the drawing mechanism of loosen top-coal in mutil-openings and partially reverse drawing techniques were analyzed by loose top-coal drawing experiments and distinct element numerical calculations.The results show that the top-coal recovery ratio in mutil-openings condition is larger than that in single-opening condition.The increased volume comes from the middle and upper parts of the top-coal above the central face.With the increasing of opening length,the volume of drawing body increases linearly and the rock mixed position in drawing body moves to directly above the opening;the shape of the boundary of the top coal appears the bulging characteristic toward the goaf gradually.The partially reverse drawing technique increases the top-coal recovery ratio in the lower end of the face by 13.98% compared to normal drawing technique.The shape of the boundary of the top-coal near the junction of reversed segment and normal segment is beneficial to the development of drawing body,which decreases the residual coal in the goaf.With increasing reversed segment’s length,the growth rate of the drawing volume in reversed segment decreases after an initial increasing phase.The top-coal recovery ratios in both the middle and the lower parts of the face are increased by using the partially reverse drawing technique with double-openings.

Study on gas flow pressure caused airflow disorder in parallel downward ventilated roadways

Wang Kai, Wu Zeqi, Zhou Aitao, Feng Shuo

2016, 1(1): 49-57.

Abstract(942) PDF(427)

Abstract:
The high-concentration of methane accumulating in a tilted roadway could produce gas flow pressure.This gas flow pressure can induce airflow disorder in the tilted roadway and its lateral roadways.In this paper,an experimental system was constructed for representing parallel downward ventilation roadways.With this system,a series of experiments were conducted to study the gas flow pressureinduced airflow disorder in coal mine roadways.The tilted roadway was saturated with 100% concentration methane while the lateral roadway was saturated with air for all experiments.The resistance coefficient of the tilted roadway and the lateral roadway were changed in different experiments.The experimental results indicate that the gas flow pressure could cause complex airflow changes in parallel downward ventilation roadways and lead to methane and airflow reciprocation in the roadways.A vibration model was developed based on a simplification of the experimental system.The vibration model can explain the effects of windage on the damping force of the vibration.Both the experiment and model results indicate that the windage increase of the tilted roadway or the lateral roadway can weaken the airflow vibration.Analysis of the methane movement in the experimental system indicates that for the tilted roadway and the lateral roadway an windage increase in one roadway is helpful for the airflow stability but harmful for its own gas discharge.If gas accumulation appears in an in situ downward ventilation roadway,the windage of the lateral roadway should be increased without delay to keep the system airflow stable and to discharge the accumulated methane as soon as possible.

Experimental and numerical study on bud shaped composite sealing ring of hydraulic support

Zhang Xi, Wang Gang, He Ming, Yu Miao

2016, 1(1): 58-66.

Abstract(896) PDF(161)

Abstract:
Based on the analysis for bud shaped composite sealing ring of hydraulic support, nonlinear problems and contact problems of finite element analysis, this paper expounds the material properties of the rubber, polyurethane, basic theory and constitutive model of rubber elastomer, and characterizes the material properties of rubber and polyurethane with Mooney-Rivlin model of different constants.Through uniaxial tension and compression tests of rubber and polyurethane, the parameters of Mooney-Rivlin model of two kinds of materials are obtained.According to the experimental parameters, the finite element analysis is made on the bud shaped composite ring, which is found to be suitable for the dynamic seal.As the loading increases, the sealing effect decreases.The research has reference significance to the design of the seal.

Walking mechanism design and analysis on obstacle crossing for inspection robot in thin coal seam face

Shang Deyong, Fan Xun, Zhao Jianwei

2016, 1(1): 67-73.

Abstract(728) PDF(461)

Abstract:
Because the thin coal seam working face is narrow and complicated,a compact crawler robot with four rockers is designed,which has high capability of obstacle-crossing. According to the robot centroid position,the obstacle-crossing maximum heights of the robot with rockers and the robot without rockers are both optimized. The obstacle-crossing maximum height of the robot with rockers is 232.91 mm,which can meet the design requirements. The obstacle-crossing processes are virtually simulated in ADAMS,and the change rule of the drive motor output torque is analyzed for reasonable motor selection. Finally,the experimental walking mechanism prototype is tested for obstacle-crossing. The results have shown that this structure robot has high obstaclecrossing capability and high adaptability,which can meet the special requirements of the thin coal seam working face.

Corrosive protection mechanism of Zinc-rich coatings and application in coal mining equipment

Chen Huahui, Pan Junyan, Ma Feng, Xie Bo, Jin Fengtian

2016, 1(1): 74-81.

Abstract(839) PDF(80)

Abstract:
Corrosive protection performance of self made inorganic Zinc rich primer coating (KD) and different corrosion protection coating systems [KD+intermediate+finish paint (KDZY),commercial primer+intermediate+finish paint (ZYQT),KD+water based intermediate+finish paint (KDSX) and KD+commercial finish paint (KDSM)] were tested and analyzed by salt spray,immersion,electrochemical tests and field experiment.The results show that the self-made inorganic Zinc-rich primer coating KD presents excellent corrosive protection in the salt spray test.Its corrosive protection mechanisms include cathodic protection,physical shielding and self-healing function.The KDZY and KDSX coating systems based on KD primer also have good corrosive protection in the salt spray test.The ZYQT and KDZY coating systems have good protection for Cl^- penetrating due to high resistor and better insulation.The ZYQT coating system manifests good corrosion protection in coal mining environment.All coating systems show poor water immersion resistance,so the coating systems are not suitable for a long time application in water immersion condition.

A study of low volatile coal water slurry-preparation and combustion

Huang Bo, Xie Weiwei, Zhu Shuquan, Chu Tiancheng, Wang Yajia

2016, 1(1): 82-88.

Abstract(889) PDF(696)

Abstract:
This exploratory work focused on the preparation of coal water slurry from low volatile coal and its combustion characteristics. Sample of raw coal and coal slime (Tunliu&Changcun, Luan Ltd, Shanxi, CN) were ground and prepared into highconcentration coal water slurry (CWS), which could be up to 72% and the apparent viscosity was less than 1 200 mPa·s, showing a good slurryability of the sample. Then thermo gravimetric analysis (TGA) and combustion test were conducted and the result showed that sample from Changcun had a comparatively higher ignition temperature, while a lower combined combustion characteristic index compared to the high volatile CWS. Under the same heating rate, a higher activation energy was required for low volatile CWS, while its ash deposition rate was well below that of high volatile CWS. When combusted continuously in a 10t/h industry boiler under the condition of national emission standards, the Changcun CWS was well distributed in the furnace with a uniform temperature, a bright, stable and sparkless flame, and the burn-out rate was high with a combustion thermal efficiency of 86.93%.

Pyrite tailings flotation based on collaboration of flotation machine and flotation column

Huang Gen, Xu Hongxiang, Zhang Shuguang

2016, 1(1): 89-95.

Abstract(690) PDF(319)

Abstract:
Flotation tests were conducted by using a sample of pyrite flotation tailings from a mine concentrate plant located in Yunfu，Guangdong province of China.The results show that the coarse and fine particles were effectively recovered based on the collaboration of flotation machine and flotation column to take advantages of the two flotation devices.The analysis of size and sulfur content distribution showed that sulfur mainly existed in +74 μm and -10 μm size fractions.Using flotation machine，under a closed-circuit of two stage roughing two stage scavenging and two stage cleaning after regrinding of primary concentrate，concentrates containing sulfur of 33.42% with recovery of 63.82% were obtained when the flotation feeding sulfur was 6.91%.Under the same flotation reagents dosage，concentrates containing sulfur of 32.68% with recovery of 70.84% were obtained by collaboration of flotation machine and flotation column.Compared with flotation machine，the collaboration of flotation machine and flotation column was more efficiency.The recovery of -54 μm significantly increased.Especially for the -20 μm size fraction，the recovery increased by almost 10 percentage points.

Experimental study on properties of cement mixed with ultrafine circulating fluidized bed fly ash

Ren Caifu, Wang Dongmin, Zheng Dapeng, Li Duanle, Wang Yiren

2016, 1(1): 96-102.

Abstract(936) PDF(442)

Abstract:
The effect of ultrafine circulating fluidized bed fly ash (UCFA) on physical and mechanical properties of cement containing different contents of circulating fluidized bed fly ash (CFA) is studied,through rheological property and mortar strength of fresh cement paste test and combined with MIP and SEM microscopic test method,etc.The results show that cement single-mixed CFA has a larger water demand and poor fluidity,and its strength decreases significantly.Compared with cement single-mixed CFA,the cement of which CFA is partially replaced with 5% (optimum content) UCFA has a corresponding less water demand,greater fluidity ,smaller yield stress(τ₀) and plastic viscosity(η) of cement paste,and the workability of paste is improved obviously.Strength of cement containing 30% fly ash increases by 6% at 3 days,when strength of cement containing 60% fly ash increases by 5% at 28 days,reaching 32.5 cement grade requirements.The incorporation of UCFA can promote cement containing CFA to generate more ettringite and C-S-H gel and optimize pore structure of hardened cement paste,and thus improve strength of cement.

2016 Vol. 1, No. 1