煤压实工艺在改善焦炭致密性的影响与实践

近年来,高炉对焦炭质量要求越来越高,提高焦炭冷热态强度即焦炭致密性愈发重要。首先研究影响焦炭质量的因素:配合煤的堆密度,论述提高配合煤堆密度的现有方法应用及缺点。介绍煤压实工艺,详细了解煤压实工艺在改善焦炭强度中的作用。通过对比试验验证煤压实对焦炭质量的影响,确定了最佳煤压实工艺并设计实际生产试验方案。通过实际生产试验,介绍了配合煤运转流程、压实机布置方案及试验结果、环境除尘方案及效果。介绍了生产过程中的参数检测和控制,并对生产效果进行了验证。基于此,分析试验技术经济,得出煤压实工艺在提高焦炭质量方面有极大推广价值。煤压实工艺能够提高焦炭致密性,满足高炉生产需要。同时,通过在焦炉中煤压实工艺的践,验证了煤压实工艺对提高焦炭冷热态强度的作用。

1470kN 双辊配煤压实机的研制与半工业性试验

本文借鉴国外先进煤压实技术,结合鞍钢高炉用焦及化工总厂五送煤生产配煤实际,对配煤压实机的研究、组装、调试和半工业性试验,做了必要的理论分析论述。

提高入炉煤堆密度技术在炼焦生产中的应用与发展

阐述了原料预处理及炼焦工艺对焦炭质量提升的作用,介绍了入炉煤堆密度对提升焦炭质量的作用及机理,说明了入炉煤水分、入炉煤细度、物理压实等因素对入炉煤堆密度及焦炭质量的影响,指出了入炉煤堆密度对提高焦炭质量的实际价值,顶装煤压实工艺对提高焦炭质量提升是一个积极有益的技术方向。

Acoustic emission generated during the gas sorption-desorption process in coal

An experimental system for monitoring the acoustic signals generated in coal during gas sorption and/or desorption was designed and the acoustic signals were observed under different gas pressures. The experimental results show that signals generated by the coal during gas adsorption are attenuated over time. Also, the signals are not continuous but are impulsive. The intensity of the signals generated during gas desorption is far smaller than that observed during adsorption. The signal seen during desorption remains essentially stable. Cycles of sorption and desorption cause acoustic emission signals that exhibit a memory effect, which depends upon the maximum gas pressure the sample was exposed to in earlier cycles. Lower pressures in subsequent cycles, compared to the maximum adsorption pressure in previous cycles, cause both the energy and impulse frequency to be lower than previously. On the contrary, a gas adsorption pressure that exceeds the maximum pressure seen by the sample during earlier cycles causes both the energy and impulse frequency to be high.

Experimental research on overlying strata movement and fracture evolution in pillarless stress-relief mining

In multiple seams mining, the seam with relatively low gas content （protective seam） is often extracted prior to mining its overlying and/or underlying seams of high gas content and low permeability to minimize the risk of high gas emission and outbursts of coal and gas. A key to success with this mining sequence is to gain a detailed understanding of the movement and fracture evolution of the overlying and underlying strata after the protective seam in extracted. In Zhuji mine, the No. 11-2 seam is extracted as a protective seam with the pillarless mining method by retaining goal-side roadways prior to its overlying No. 13-1 seam. An investigation has been undertaken in the panel 1111 （1） of Zhuji mine to physically simulate the movement and fracture evolution of the overlying strata alter the No. 1 I-2 seam is extracted. In the physical simulation, the displacement, strain, and deformation and failure process of the model for simulation were acquired with various means such as grating displacement meter, strain gauges, and digital photography. The simulation result shows that： （1） Initial caving interval of the immediate roof was 21.6 m, the first weighting interval was 23.5-37.3 m with the average interval of 33.5 m, and the periodic weighting interval of the main roof was in a range of 8.2-20.55 m and averaged at 15.2 m. （2） The maximum height of the caving zone after the extraction of No. 11-2 seam was 8.0 m, which was 4 times of the seam mining height and the internal strata of the caving zone collapsed irregularly. The mining-induced fractures developed 8-30 m above the mined No. 11-2 seam, which was 7.525 times of the seam mining height, the fracture zone was about 65° upward from the seam open-off cut toward the goaf, the height of longitudinal joint growth was 4-20 times of the mining seam height, and the height of lateral joint growth was 20-25 times of the mining seam height. （3） The ＂arch-in-arch＂ mechanical structure of the internal goaf was bounded by an expansion angle of broken strata in the lateral direction of the retained goaf-side roadway. The spatial and temporal evolution regularities of over- burden＇s displacement field and stress field, dynamic development process and distribution of fracture field were analyzed. Based on the simulation results, it is recommended that several goaf drainage methods, i.e. gas drainage with buried pipes in goaf, surface goaf gas drainage, and cross-measure boreholes, should be implemented to ensure the safe mining of the panel 1111 （1）.

Longhole waterjet rotary cutting for in-seam cross panel methane drainage

In order to improve the efficiency of gas drainage before and during longwall extraction,a waterjet rotary cutting system has been developed for in-seam cross panel methane drainage.The purpose of the water rotary cutting system developed was to create artificial fractures along the gas drainage boreholes.During the design of the system,it was perceived that the nozzle geometry is one of the key factors,affecting cutting capacity.Therefore,we studied the structural and geometric parameters of the nozzle and optimized its performance during laboratory tests and numerical simulation.Underground trials conducted in a coal mine,indicate that production of gas drainage before and after cutting significantly increased by up to three times.The advantages of waterjet assisted gas drainage method has been identified as:1) increasing gas drainage efficiency,2) a possible development of a gas drainage fractured network within coal seams associated with panel extraction,and 3) reducing the risk of exceeding gas limits during longwalling.

Experiment and Numerical Simulation on Axial Compressive Performance of Autoclaved Fly Ash Solid Brick Masonry Columns

To study the influence of slenderness on the axial compressive performance of autoclaved fly ash solid brick masonry columns, compression experiments were conducted on 12 samples of autoclaved fly ash solid brick masonry column and 4 samples of fired clay brick masonry column. The damage patterns and compressive performance were compared and analyzed. The experimental results indicate that the compressive bearing capacity decreases as slenderness increases from 3 to 18, and the compressive bearing capacity of the autoclaved fly ash solid brick masonry columns is lower than that of the fired clay brick masonry columns. The formulae for the axial compressive bearing capacity of autoclaved fly ash solid brick masonry columns were derived based on the experiments. The nonlinear FEA program ANSYS was adopted to simulate the behaviors of masonry columns. By comparing the simulation results and experimental results, it is shown that the simulation results agree well with the experimental ones. The rationality and applicability of the simulation results were verified.

Dynamic action simulation system and preliminary experiments of coal seams and gas

In order to study the dynamic action and physical effects of coal seams and gas, a simulation system for this dynamic action was developed and a physical model built in our laboratory. Using this newly built model, the volume of coal outbursts and the temperature during the outburst process were studied. The results show that： l） for coal seams with similar structure and com- ponents, two factors, i.e., gas pressure and ground stress affect the volume of coal outbursts, with gas pressure being the more im- portant of the two and 2） the changes in coal temperature, both its increase and decrease, are affected by ground stress and gas pressure, it is a process of change. Preliminary tests show that the system can simulate the dynamic interaction of coal and gas, which is helpful for studying the dynamic mechanism of solid-gas coupling of gas and coal.

Technology of back stoping from level floors in gateway and pillar mining areas of extra-thick seams

According to the special requirements of secondary mining of resources in gateway-and-pillar goal in extra-thick seams of Shanxi, this paper presents a technical proposal of back stoping from level floors. Numerical simulation and theoretical analysis are ccsed to investigate the compaction characteristics of cavities under stress as well as an appropriate mining height of the primary-mining layer based on dif- ferent mining widths and pillar widths. For Yangjian coal mine, the mining thickness of the first seam during back stoping from level floor is determined to be 3 m, which meets the relevant requirements. Gateway-and-pillar goaf of a single layer has a range of influence of 9 m vertically. If gateway-and-pillar goaf occurs both in 9-1 and 9-5 layers, the range is extended to within 11.2 m. When the mining width of a gateway is less than 2 m or larger than 5 m, the gateway-and-pillar goal in the upper layer of the primary-mining seam can be filled in and compacted after stoping. When the working face is 2 m away from the gateway and pillar before entering into it and after passing through it, the coal body under the gateway and pillar is subjected to relatively high stress. During mining of the upper layer, moreover, the working face should interlock the goaf in primary-mining layer for 20 m.

Application of crosswell seismic technique in detecting the gob area of coal mines

To date, significant exploitations of the coal mines have left a considerable number of undetermined empty spaces, also known as the gob areas, behind. The existence of these areas could make the overlaying terrane lose the gravity support. The inhomogeneous sinkage of the overlaying terrane could destroy the buildings constructed on it dramatically, which has currently been a classical geological disaster. In the current study, the crosswell seismic mechanism was addressed and applied to detect the gob area distribution and, espcially, to measure the compaction extent of the gob areas. The results clearly show that the crosswell seismic technique is a very powerful method to discover the distribution and compation degree of the gob areas. More importantly, the current findings provided a novel way for evaluating the compaction extent of the gob areas.

Determining areas in an inclined coal seam floor prone to water-inrush by micro-seismic monitoring

The failure depth of the coal seam floor is one important consideration that must be kept in mind when mining is carried out above a confined aquifer.Determining the floor failure depth is the essential precondition for predicting the water-resisting ability of the floor.We have used a high-precision microseismic monitoring technique to overcome the limited amount of data available from field measurements. The failure depth of a coal seam floor,especially an inclined coal seam floor,may be more accurately estimated by monitoring the continuous,dynamic failure of the floor.The monitoring results indicate the failure depth of the coal seam floor near the workface conveyance roadway（the lower crossheading） is deeper and that the failure range is wider here compared to the coal seam floor near the return airway（the upper crossheading）.The results of micro-seismic monitoring show that the dangerous area for water-inrush from the coal seam floor may be identified.This provides an important field measurement that helps ensure safe and highly efficient mining of the inclined coal seam above the confined aquifer at the Taoyuan Coal Mine.

Technique and experiment of active direct gas pressure measurement in coal roadway

An active measurement method and its principle was introduced consideringthe low success rate,special difficulty,and long measurement time of the direct gas pressuremeasurement currently used in coal roadways.The technology of drilling,boreholesealing depth,borehole sealing length,sealing control of the measuring process,compensatorycomputation of gas loss quantity and other key techniques were discussed.Finally,based on the latest instrument the authors developed,a series of experiments of directgas pressure measurement in the coal roadways of the Jincheng and Tongchuanmine district,were carried out.The experimental results show that active gas pressuremeasurement technique has advantages as follows:(1) the application scope of direct gaspressure measurement technique is wide and it does not have the restriction of coalhardness,coal seam fissure and other conditions;(2) the measured results are credible,which can be tested by the same gas pressure value acquired from a different borehole inthe same place;(3) the measurement process is convenient and quick,it takes about 2 to3 days to acquire the gas pressure value in a coal seam.

Shock tube study of kerosene ignition delay at high pressures

Ignition delay times of China No.3 aviation kerosene were measured behind reflected shock waves using a heated high-pressure shock tube.Experimental conditions covered a wider temperature range of 820-1500 K,at pressures of 5.5,11 and 22 atm,equivalence ratios of 0.5,1.0 and 1.5,and oxygen concentration of 20%.Adsorption of kerosene on the shock tube wall was taken into account.Ignition delay times were determined from the onset of the excited radical OH emission in conjunction with the pressure profiles.The experimental results of ignition delay time were correlated with the equations:11 0.22 1.09 2 3.2 10 [Keros ene ] [O2] exp(69941 RT) and 7 0.88 0.23 4.72 10 P exp(62092 RT).The current measurements provide the ignition delay behavior of China No.3 aviation kerosene at high pressures and air-like O2 concentration.