Development of high-power microwave mechanical integrated continuous mining device

This article introduces a high-power microwave mechanical integrated continuous mining device,which can achieve synchronous cutting of hard rocks by microwave and machinery.The device includes a cutting system,a rotary translation system,a loading system,a high-power microwave system,and a control and monitoring system.The technology of“master-slave follow-up”disc cutter alternating side cutting of rock was proposed,which could improve the effectiveness of rock breaking.The integrated structure of a microwave-cut system was then proposed,and synchronous motion of the microwave-cut system and adjustment of the loading system could be realized.The automatic adjustment technology of the microwave working distance was developed to dynamically control the optimal microwave working distance.The basic functions of the equipment were verified by tests.By comparing the two types of disk cutters,it is found that the master-slave follow-up disk cutter can improve significantly the dust removal effect and rock breaking efficiency in rock breaking process versus the conventional large disc cutter.Cutting tests of slate with or without microwave were conducted using a master-slave follow-up disk cutter.The results show that the cutting patterns of slates change from intermittent chunks(without microwave irradiation)to persistent debris(with microwave irradiation),and the cutting speed is significantly improved(170%).The development of the device provides a scientific basis for changing the conventional mining technology of metal mines and realizing the mechanical continuous mining in hard metal mines.

Mechanical response of roof rock mass unloading during continuous mining process in underground mine

Taking the test stopes during continuous mining induced roof caving of Tongkeng ore-body No.92 as example, the calculation flow of unloading analysis was established. According to the unloading region division method of the affected zone theory, and the deterioration laws of mechanics parameters of unloading rock mass, the continuous mining process in underground mine was analyzed by the software MIDAS/GTS, the mechanical response of roof rock mass unloading was studied, and the differences were analyzed with the conventional simulation. The result shows that the maximum tensile stress, subsidence displacement and equivalent plastic strain of roof rock mass are 1.5 MPa, 20 cm and 1.5% in the unloading analysis, while 1.0 MPa, 13 cm and 0.9% in the conventional analysis. The values of unloading analysis, which are also closer to the actual situation, are greater than those of conventional analysis; the maximum step in continuous mining is 48 m, which shows that the induced treatment of the roof should be carried out after 2 mining steps

Non-explosive mining and waste utilization for achieving green mining in underground hard rock mine in China

Innovations of mining technologies were proposed by beneficial utilizations of unfavorable factors such as high geostress,high geotemperature and high mining depth to achieve green mining as mining depth increases inevitably.Cuttability of deep hard rock was investigated by experimental and regressed analyses to find the reasonable stress adjustment method to improve non-explosive mechanized fragmentation for hard ore-rock.A non-explosive mechanized and intellectualized mining method was proposed to continuously and precisely exploit phosphate underground,which promoted the high-recovery,low-waste and high-efficiency exploitation of phosphate with recovery rate over 90%,dilution rate near 5%and cutting efficiency about 107.7 t/h.A circular economy model and the backfill system were proposed to conduct resource utilizations of solid waste,by which the utilization amount of waste increased year after year.In 2018,the utilization amounts of phosphogypsum,yellow phosphorus slag and waste rock increased to 1853.6×10^3 t/a,291.1×10^3 t/a and 1493.8×10^3 t/a,respectively.

Feasibility Study on Continuous Mining Method in Deep Position of Jinchuan Nickel Mine, China

Jinchuan nickel mine is the largest nickel mine in China. Cut-and-fill mining method with high density cementing materials is used in the mine. The original mining design divided the mining operation into two steps. The first step stopped the mining rooms and the second step stopped the pillars. Because the two-step method made big trouble for finally mining pillars and strongly limited the mining speed and production, it was successfully changed to a continuous cut-and-fill method without pillars. However, the mining operation in the mine has been down to 800 m and the mining condition is getting worse and more complicated. Through systematical field investigations and 3-D FEM analysis, it is proved that the mining method without pillars is feasible for mining deeper orebodies in Jinchuan nickel mine.

A model to determine hole spacing in the rock fracture process by non-explosive expansion material

The application of the non-explosive expansion material （NEEM） is widely used as the controlled fracture method in quarry min- ing, especially in hard rocks. The pressure of NEEM is an important parameter in causing rock fracture. An empirical model based on hole spacing was developed to determine the pressure of NEEM in the rock fracture process. Primarily, the empirical model was developed by the mathematical method, utilizing dimensional analysis. Then, the Phase2 code, which is based on the finite element method, was utilized to predict crack growth in rocks. The results of numerical analysis show slight deviations from the empirical model. Hence, the polynomial re- gression analysis was used to modify the model. Finally, the modified model shows a good agreement with the results gained from numerical modeling.

CFD modeling of methane distribution at a continuous miner face with various curtain setback distances

Knowledge of the airflow patterns and methane distributions at a continuous miner face under different ventilation conditions can minimize the risks of explosion and injury to miners by accurately forecasting potentially hazardous face methane levels. This study focused on validating a series of computational fluid dynamics(CFD) models using full-scale ventilation gallery data that assessed how curtain setback distance impacted airflow patterns and methane distributions at an empty mining face(no continuous miner present). Three CFD models of face ventilation with 4.6, 7.6 and 10.7 m(15, 25, and 35 ft) blowing curtain setback distances were constructed and validated with experimental data collected in a full-scale ventilation test facility. Good agreement was obtained between the CFD simulation results and this data.Detailed airflow and methane distribution information are provided. Elevated methane zones at the working faces were identified with the three curtain setback distances. Visualization of the setback distance impact on the face methane distribution was performed by utilizing the post-processing capability of the CFD software.

Similar material simulation of time series system for induced caving of roof in continuous mining under backfill

With the help of similar material simulation test,time series system for induced caving of roof in continuous mining under complex backfill in ore body No.92 of Tongkeng Tin Mine was studied. According to the similarity theory,a two-dimensional similar simulation test-bed was constructed. The stress and displacement that change along with the advance of mining were acquired and analyzed automatically by data system. The processes of continuous mining of ore-block in 5 intervals and artificial induced caving of roof were simulated. The results of the test show that ore body remained as safety roof in thickness of 15 m guarantees the safe advance of stoping work face. Caving of safety roof puts in practice at the first two mining intervals when the third interval of continuous mining is finished,and one interval as the safety distance should be kept all the time between stopping and caving. While mining in the last interval,pre-slotting should be implemented first of all,and the roof of the last two mining intervals is caved simultaneously. Only this kind of time series system can be an efficient and safe way for induced caving of roof in continuous mining.

Energy method and numerical simulation of critical backfillheight in non-pillar continuous mining

Non-pillar continuous mining(NPCM) is regarded as a high-efficient, high-level and one-step mining technology, which can be divided into two substopes. Back fill stability status in substope I, which directly influence the loss rate and dilution rate, etc, will determine whether the experimental research is successful or not. By employing energy method of limit analysis and finite element numerical simulation method, the critical backfill height was determined under the prerequisite condition of its stability, which put forward theoretical basis for reasonable and correct selection of backfill’s parameters. The result showed that the first backfill could not keep stable for NPCM, while the other was able to.

Classification of conditions for short-wall continuous mechanical mining in shallowly buried coal seam with thin bedrock

The room and pillar method is usually used to extract coal from shallowly buried seams with thin bedrock. This results in a very low production efficiency and in a low degree of extraction. In recent years short-wall continuous mechanical mining has been extensively used in many situations except shallowly buried coal seams with thin bedrock. The principles governing movement of the overlying strata above the 2-2 coal seam were deduced from in-situ experience, laboratory data, calculations and computer simulations. The thicknesses of the bedrock in the Shendong Coal Field where the coal is shallowly buried are classified into 5 types: <10 m, 10–15 m, 15–25 m, 25–35 m and >35 m, which was done using fuzzy clustering results. A series of reasonable, relative parameters in each category have been calculated and analyzed. One proposed way to perform short-wall continuous mechanical mining in shallowly buried coal seams is given. This is significant for coal mines with similar geological conditions.

High Efficiency Dust Scrubbers for Continuous Miner in Underground Mines

Based on the experimental data by a full scale test model and the relevant existing achievements, four new concepts of group dust scrubbers were designed in the paper. The new dust scrubbers consist of two to four common dust separators in series: wet fan, wet Venturi and foam filter bed. Wetting and foaming agents are used to increase the efficiency of dust separation. High efficiency is not required for each part of the group dust scrubbers, but the whole system has a high working reliability. All parts of the group dust scrubbers have the most suitable separating efficiency for different size and concentration of dust particles in airflow, according to their technical features. Four group dust scrubbers have a high efficiency from 94.4% to 99.7% for separating respirable dust at a rational cost.

Correlation between longitudinal crack occurrence and mold heat transfer in continuous casting based on process data mining

The correlation between the longitudinal crack occurrence and integrated heat transfer of the mold with data mining methods was investigated.Firstly,three kinds of support vector machine models based on principal component analysis with different input features were established to explore the effect of integrated heat transfer on the accuracy of the prediction model for the longitudinal crack.The results show that the accuracy was improved while features including mean and standard deviation of integrated heat transfer were added.Then,the difference in integrated heat transfer between defect and normal samples under the same process parameters was quantitatively compared.Compared with normal samples,the temperature difference of cooling water for defect samples decreased by 0.65%,and the temperature difference fluctuation increased by 31.1%.Finally,the literature data were used to provide support for the quantitative correlation according to defect formation mechanism.A new criterion for the prediction of longitudinal crack and a discovering method for correlation between product quality and process parameters in the manufacturing industry have been provided.

Investigation of a non-explosive directional roof cutting technology for self-formed roadway

Traditional explosives have characteristics of high risk,large vibration,and poor directional fracturing.Consequently,an instantaneous expander with a single crack surface(IESCS),which is a novel nonexplosive directional rock-breaking technique,has been developed.The directional roof-cutting mechanism of the IESCS method,driven by high-pressure gas,was theoretically analyzed.Laboratory experiments and numerical simulations proved the directional slitting effect of the IESCS method to be excellent.Compared with shaped-charge blasting,the charge of IESCS was reduced by 8.9%,but the crack rate increased by 9%in field tests.After IESCS pre-splitting,the roof directionally collapsed along the cutting line,and the gangue filled the goaf.Moreover,the directional roof cutting by the IESCS could decrease roadway stress.The average pressure of hydraulic supports on the cutting side of the roof was 31%lower than that on the non-cutting side of the roof after pre-splitting.After the self-formed roadway constructed by the IESCS was stabilized,the final relative displacement of the roof and floor was 157.3 mm,meeting the required standard of the next working face.Thus,the IESCS was effectively applied to directional roof pre-splitting.The results demonstrate the promising potential of IESCS in the mining and geotechnical fields.

面间煤柱与顺槽“掘-充-留”一体化科学问题与技术

我国将煤炭作为兜底保障能源的局面短期内无法改变,仍将长时间面临煤炭资源保护与煤基固废利用率低的难题。通过创新采掘方法,同时实现提高煤炭资源回采率、规模化处置煤基固废,为煤炭行业绿色可持续发展提供了新途径。在深入调研煤炭资源开采技术发展现状的基础上,提出了煤矿“掘-充-留”掘进新工法。从大断面巷道快速掘进、连续高效充填和巷道安全留设3个方面,通过理论分析、数值模拟等手段,系统论述了“掘-充-留”工法的科学问题和关键技术,研究结果表明:①针对大断面巷道快速掘进、掘进工作面围岩稳定性控制等工程难题,凝练了煤岩特性与掘进机截割参数匹配机制、覆岩载荷空间传递机制与围岩变形机理、锚杆/索-顶板相互作用关系及支护机制3个科学难题,构建了以掘进区地质环境超前实时感知、落-装-运煤多工序智能协同作业、钻锚支架随掘随支围岩时效控制和大断面巷道防漏风及通风优化为核心的技术体系;②从大断面巷道承载体系及时构建及其承载性能调控两个方面凝练了连续高效充填的科学问题,包括充填体-煤层-锚杆/索协同承载机制、多元固废基充填材料水化固结机制,明晰充填体物理力学特性时空演化规律,建立了充填空间安全高效搭建、充填材料工作性能调控、充填材料流动-固结感知为核心的连续高效充填关键技术体系,相关理论与技术的突破可以为充填材料的原材料优选及配比设计、添加剂开发/选型及工作性能调控、掘进速率及充填步距优化设计、充填体固结监测等提供基础理论依据;③基于巷道安全留设及全生命周期内围岩易断裂、易片帮和易损伤等关键难题,阐述了巷道围岩应力场时空分布特征、巷道变形与损伤演化机制、巷道围岩工程质量监测与稳定性调控理论3个科学问题,形成了以巷道围岩稳定性智能预警、巷道围岩变形控制为核心的关键技术体系。开展煤矿“掘-充-留”工法的科学研究与工程示范,实现固废规模化处置-面间煤柱高效回收-顺槽快速掘进的协同,可以推动煤炭行业绿色低碳转型发展。

深埋藏锌多金属矿床开拓方案的选择

随着中国社会的不断进步和发展,对资源的开发与利用更加的科学化、合理化、智能化和绿色化。我国目前依然处于工业化和城镇化的发展阶段,对金属资源有一定的需求。对于埋藏较深的锌多金属矿床的开发与利用显得尤为重要,合理的开拓方案更是重中之重,开拓方案的选择涉及到基建期工程量、矿山建设投资及矿山投产的时间。综合矿体的赋存条件、基建投资、经济效益等多方面因素,对该矿两个矿区同时建设或接续开采、对一矿是否分期开采进行了充分的论证与分析,为同类矿山提供参考。

煤矿连采连充胶结充填体监测技术研究

为了对煤矿连采连充开采胶结充填体状态进行监测,基于连采连充工艺特点和充填体特性,提出了充填体状态监测的5项基本内容,主要包括液位监测、受力监测、强度监测、温度监测和应力监测,研究了各项监测内容的监测技术和监测方案。结果表明,液位监测采用浮标式液位监测技术适应性较好;受力监测采用挡墙压力计进行监测,量程约为150 kPa;强度监测通过实验室测试充填体的强度,并展望了原位强度测试技术;温度监测采用温度传感器来实现;应力监测采用千帕级和兆帕级双通道应力计进行监测。

连采连充膏体充填工艺系统设计与应用

针对查庄煤矿工业广场下压煤开采问题,设计了连采连充膏体充填工艺系统,给出了参与灰浆制作与矸石破碎处理设备的各项参数,在保证膏体质量的基础上实现了绿色充填。采用充填工业泵对膏体进行泵送,充填巷道上端口采用喷射机进行上三角密封,从而保证了接顶率。在进行采动影响分析时发现,膏体充填后顶板最大离层量为20.5 mm,地表最大下沉量为27 mm,地表建筑在I级建筑物损坏等级之内,证明了方案的可行性,有效解决了该矿“三下”压煤开采问题。

面向图数据的量子行走模型及算法研究进展

作为量子计算的通用计算模型,量子行走广泛应用于安全通信、快速搜索、相似性计算以及图挖掘等领域。现阶段研究者对量子行走的设计思路、未来发展以及模型与算法间的相互关系关注甚少,忽略了量子行走的量子特性在图计算等应用中的理论优势。聚焦面向图数据的量子行走模型及算法,首先,分析量子行走的核心设计策略及其理论优势,归纳相关算法核心算符的构造形式与空间维度特征,厘清模型与算法间的逻辑联系;其次,依据离散时间和连续时间的分类,梳理不同图数据上量子行走模型的研究进展及设计难点,总结量子行走从规则图向不规则图上扩展的演化趋势;进一步,围绕图相似性计算、空间搜索以及图挖掘三项应用系统地介绍量子行走算法的研究进展,分析相关算法的技术特征、优势及不足;最后,从效率优化、精度提升、幺正约束以及图重构等角度,对面向图数据的量子行走模型与算法未来发展方向进行了展望。

连采连充工作面挡墙支架的研制

针对现用的连采连充工作面挡墙结构一致性差、经济性差、自动化程度低的问题,研制了一种新型可移动模块化挡墙支架。基于巷道布置与充填方案,确定挡墙支架的关键尺寸与机械结构,力学校验通过后试制样机,并开展地面模拟试验,新型挡墙性能表现优良。该挡墙方案自动化程度高,支护性能优,经济性更好,是更加可靠的连采连充挡墙方案,有广泛应用的潜力。

基于主动学习和持续学习的同义词挖掘模型

要提升同义词挖掘的效果通常需要现成的相关领域同义词库的支持。由于相关领域同义词库极其稀缺,给模型优化带来了阻碍。针对缺少相关领域同义词库而导致模型在相关领域的同义词挖掘效果难以持续提升的问题,提出了基于主动学习和持续学习的同义词挖掘模型(SYN-AC)。首先,基于主动学习的方法获取专家标记数据,设计了一个新的损失函数并利用标记后的数据去微调模型;其次,为了减少时间和空间消耗,采用了持续学习的方法,使模型在只使用当前组标记的数据进行训练的情况下,也能不断提高同义词挖掘效果,而不需要每次都使用所有标记数据对模型重新微调。使用了3个数据集模拟专家标记的过程,实验结果表明,在其中2个数据集上比效果最好的BERT(Bidirectional Encoder Representations from Transformers)模型F1值分别提升了9.34个百分点和2.75个百分点。验证了SYN-AC能够有效提高同义词挖掘的效果。

缓倾斜煤层群开采辅助运输系统改造及开拓优化设计

针对缓倾斜煤层群开发过程中由于辅助提升及运输系统复杂引起的一系列问题,提出以无轨化辅助运输系统为改造目标,以新建缓坡斜井为改造方式,对沙吉海一号矿井进行辅助提升及运输系统改造。结合井筒布置情况,对矿井进行开拓优化设计,采用缓坡斜井兼做采区辅助运输上山的方式开发煤层群,减少采区个数,延长各采区服务年限,有利于缓解矿井采掘接续紧张的局面。对于新疆地区煤层群开发,沙吉海一号矿井开拓优化思路有一定的借鉴意义。