Improved 3D image segmentation for X-ray tomographic analysis of packed particle beds

Although High Resolution X-ray Micro Tomography (HRXMT) has been developed in the past years for the 3D analysis of multiphase mineral particles in packed particle beds, image analysis of fine and/or high-density/high atomic number particles has been limited by existing segmentation algorithms. In this regard, a feature-based segmentation algorithm has been developed and demonstrated to provide a more accurate image processing method for the analysis of such multiphase particle populations. Based on this improved segmentation algorithm, image analyses of packed particle bed samples were compared to segmentation by traditional 3D watershed segmentation. Also, calculation of particle number using optical microscopy, together with a digital camera, was accomplished to validate feature-based segmentation. Detailed procedures and results for sample preparation, image analysis and validation are presented and discussed.     

DEM modelling of non-spherical particle breakage and flow in an industrial scale cone crusher

Predictions of particle flow and compression breakage of non-round rock passing through an industrial scale cone crusher are presented. The DEM (Discrete Element Method) particle breakage model is generalised to allow non-round particles to be broken into non-round progeny. Particles are broken in this DEM model when the elastic energy of a contact is sufficiently high to initiate fracture. Progeny size distribution data from JKMRC Drop Weight Test (JKDWT) or JKMRC rotary breakage test (JKRBT) is used to generate the specific daughter fragments from each breakage event. This DEM model is able to predict the production of both coarser progeny which are resolved in the DEM model and finer progeny which are not. This allows the prediction of product down to very small sizes, limited only by the fineness of the fragments measured in the breakage characterisation. The predicted flow of material through the crusher, product size distribution and liner wear are discussed. The generalised breakage model demonstrated here is suitable for modelling all forms of crushers.     

Mathematical modeling of methane flow in coal beds

The paper offers to describe the free and occlude gas filtration and diffusion in a coal bed by a numerical model in the form of a system of heterogenous parabolic equations. The gas flow as a shock and depression wave has been considered, and the desorption isotherm conditions for these waves to arise in a coal bed are formulated. By analyzing experimental data on cavities generated by a sudden coal and gas outburst, the authors construct the numerical model describing gas and coal mix outflow in a mine. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 15–29, January–February, 2009.     

球形富氮炭材料的制备及其电化学性能

以吡咯为单体、FeCl3为氧化剂,通过低温水热法制备出球形聚吡咯(PPy),然后将PPy在N2保护下直接炭化获得球形富氮炭材料(SC).借助X射线衍射(XRD)、扫描电镜(SEM)、红外光谱(FT-IR)、元素分析及N2吸附-脱附对产物进行了表征.电化学测试结果显示,SC电极在6.0mol/L KOH的电解液中、-0.9～0.1V的电势范围内具有良好的电容行为,比电容高达235F/g.     

Liquid spread mechanisms in packed beds and heaps. The separation of length and time scales due to particle porosity

The distribution of liquid within a heap is a key factor in the system performance as it has a strong effect on the transport of both reagents and leached species and thus the leaching rate. How liquid spreads from drippers and the subsequent development of flow paths and any associated channelling is thus important. In this paper a pseudo 2-D column was used to investigate the horizontal spread of liquid in the vicinity of dripper in columns packed with both narrowly sized particles and more realistic particle size distributions. Both systems had distinct separation of the time scales at which different saturation features developed. There was an initial rapid formation of flow paths in the inter-particle spaces with only local wetting of the intra-particle spaces, though this was associated with little spread. Over a much longer time period there was extensive horizontal spread of the liquid within the ore particles, though this was associated with virtually no vertical flow. The externally held liquid (liquid content between the particles) showed strong channelling behaviour, especially in the realistically sized particles, despite the care that was taken to ensure uniform packing. This effect can be reduced by changing initial bed conditions and employing dense drip emitter locations, but it cannot be completely eliminated as particle level heterogeneities in heap leaching systems affect external flow paths creation. Hysteresis in the amount of liquid spread was also demonstrated, with the total spread depending not only on the current flow rate, but also on the flow history.     

移动床中热气体渗流传热与煤热解过程的数值计算

采用热气体对燃烧前的煤颗粒进行渗流炽热预处理,通过理论分析和计算的方法研究移动诃内热气体渗流加热对煤热解反应过程的影响,建立多孔介质渗流传热传质与煤质热解反应相互作用的物理数学模型,研究不同情况下床内颗粒料层中气固温度和煤热解挥发分析出浓度的分布规律,计算结果表明,移动床内煤的热解反应与渗流传热过程密切相关,增大入口渗流速度以及减少给料量,导致热渗透我域扩大,热作用区域内的煤层温度水平提高,热解反应区段向床方向偏移,在热解反应区域,孔隙率对流传质和煤热解过程中有很大的影响,研究结果,对于移动床煤热解反应装置的设计与运行具有一定的参考价值。     

2011-2016年中国对外贸易铜物质流分析

铜是我国最紧缺的大宗有色金属矿产,围绕铜开展国际贸易成为必然趋势。本文通过物质流分析法,基于海关含铜商品的科学分类,结合分层抽样法,厘定了中国含铜商品进出口贸易数据相关种类的含铜系数,系统分析了2011-2016年中国进出口含铜商品净进口量、分类占比情况以及中国铜对外贸易的空间格局。结果显示,2011-2016年铜净进口量不断增大;进口的含铜商品主要是铜矿砂及其精矿、精炼铜以及废杂铜,出口的含铜商品约73%是铜制品,其中占比最大的是电线电缆、家电、计算机以及发电机;中国进口的铜矿砂及其精矿、精炼铜以及废杂铜主要来源于铜矿资源丰富的国家,如：智利、美国等,而出口的铜制品却遍布全球;2011-2016年中国铜资源对外依存度保持高位,为65%-75%。     

钢铁产业链全球物质流网络分析

在经济全球化的背景下,一个国家的钢铁产业链并不是一个封闭的系统,其中的每一个环节都通过国际贸易进行内部系统与外部系统之间的物质交流,本文通过构建产业链关键环节的全球铁元素物质流复杂网络模型,分析了钢铁产业链不同环节的网络整体特征,以及国家的进出口总量和国家在网络中对资源流动的控制力。主要结论有:铁矿石环节的全球贸易物质量最大,网络密度最小,国家之间联系最不紧密,集团性最不明显,全球化程度最低,其贸易量主要集中于少数国家和少数贸易关系;钢铁制品环节的全球贸易网络规模最大,国家数和贸易关系数都最多,国家之间的贸易紧密度最高,全球化程度最高;废料环节的全球贸易网络分化最明显,表现出了较强的贸易集团性;中国在铁矿石、生铁、粗钢和废料环节的贸易网络中的控制力都较高,但在钢材和钢铁制品网络中的控制力不高。     

Strategies for restoring material flow in ore and waste pass systems

A major operational issue in underground mines is the interruption of material flow in ore pass and waste pass systems. Although the design of ore pass systems can be optimised to minimise the occurrence of flow problems, it is unlikely that these can be entirely avoided. This article reviews the methods employed in Canadian mines to restore flow due to the formation of hang-ups and blockages. A strategy is proposed to select the most appropriate technique based on type of hang-ups, blockages and their location within the ore pass or waste pass system.     

球向流场在被动法瓦斯压力测定中的时间及准确性优势研究

针对被动法煤层瓦斯压力测定过程中平衡时间和准确度问题进行分析研究,研究发现被动法瓦斯压力测定过程中只要存在气体交换面,即可测得瓦斯压力,同时通过建立模型进行计算发现钻孔成孔过程中,球向钻孔卸压半径远小于径向钻孔,故瓦斯损失较小,按照极限平衡理论,理论平衡时间较短,测定的压力值要略高即准确度较高。经数值模拟计算证明了上述计算的正确性,并且发现自由排放时间越长,球向钻孔占径向钻孔平衡时间的百分比越小,平衡时间优势越明显。经现场实践证明被动法瓦斯压力测定过程中球向钻孔在平衡时间和准确性上优势明显。     

煤矿物流系统电气与控制技术的设计及应用

本文介绍了我国煤炭行业物料搬运电气控制技术的现状,对全数字化控制的驱动器装置和控制监控系统技术及应用的有关问题进行了论述.     

复杂地质条件下过断层寻找断失盘矿层理论研究

原有的过断层寻找断失盘矿层理论的前提,是断层两盘产状不发生变化.但实际上,断层两盘产状经常发生变化.此时,根据原理论无法准确确定断失盘矿层位置.本文提出打破现有的过断层寻找断失盘矿层理论的假设前提,在断层两盘矿层产状发生变化或伴有显著牵引褶曲的复杂地质条件下,对过断层寻找断失盘矿层理论进行深化研究;并提出首先进行复杂地质条件下新地层断距及相关新断距的概念深化及数学模型的研究,在此基础上,进行复杂地质条件下矿层平巷、斜巷及伪倾斜巷道中,过断层寻找断失盘矿层的数学模型研究和巷道优化布置研究.     

废石尾砂胶结充填材料流动与强度性能的研究

为了解决极细全尾砂作为充填骨料制备充填料浆脱水困难、充填体强度偏低的问题,通过开展废石尾砂胶结充填试验,改善充填骨料粒级组成,研究废石掺量对充填料浆流动性能及充填体强度的影响规律。结果表明:相比较全尾砂胶结充填,掺入废石可以显著改善充填料浆的流动性能,提高充填料浆的输送浓度;在相同灰砂比和浓度情况下,废石尾砂胶结充填体强度高于全尾砂胶结充填体。因此,废石尾砂胶结充填体可以降低灰砂比,减少水泥用量,消纳地表废石。在云南金厂河矿山开展工业试验,确定了充填参数为浓度80%、灰砂比1∶8、废石掺量60%,原位取芯平均抗压强度为3.36MPa,满足采场充填体强度设计要求。     

穿层孔水压爆破法提高煤层透气性的研究

研究了峰峰矿务局牛儿庄矿开采2号大煤前、在野青底板巷道中向2号煤层打穿层钻孔进行水压爆破的工艺技术，分析了水压爆破致裂、传统水力压裂和传统爆破造缝各自的特点和水压爆破致裂煤体的机理，观测了爆破前、后钻孔瓦斯流量的变化和钻孔自然流量的衰减规律．试验结果表明，钻孔水压爆破可以有效地提高煤层的透气性，爆破前、后钻孔的自然流量提高3倍以上．     

5A30铝合金热变形的流变应力及材料常数

在Gleeble-1500热模拟试验机上,采用高温等温压缩试验,研究了5A30铝合金在300～500℃温度范围及应变速率在0.001～1s-1内压缩变形的流变应力变化规律,采用数学回归及最小偏差法求出了该合金的材料常数,建立了该合金流变应力与Zener-Hollomon参数的线性关系式.结果表明,该合金为正应变速率敏感材料,流变应力随变形温度升高而降低,随应变速率升高而增大;该合金的材料常数包括变形激活能Q为160.94kJ/mol,应力水平参数α为0.0184mm2/N,应力指数n为3.314,结构因子A为3.058×109s-1;合金流变应力模型可表达为σ=54.31ln{(Z/3.058×109)1/3.314+[(Z/3.058×109)2/3.314+1]1/2}.     

厚冲积层薄基岩采场围岩三维力学特征

采用相似条件采场类比、现场实测和数值分析综合研究方法,研究了厚冲积层薄基岩采场围岩三维力学特征,研究表明：厚冲积层薄基岩采场矿压显现与基采比密切相关,随着基采比增大,采场矿压趋于缓和。按基采比大小可将采场划分为“有板有壳”、“有板无壳”和“无板无壳”3种类型。“有板有壳”类型采场,应力壳为采场第1掩体,其下位的断裂带板（梁）结构为第2掩体,采场矿压显现缓和;“有板无壳”类型采场,断裂带板（梁）结构为采场惟一掩体,其上位无“应力壳”承载,板（梁）结构失稳后采场矿压显现剧烈;“无板无壳”类型采场,无板（梁）结构和“应力壳”的掩护,冲积层荷载直接传递在液压支架上,该类采场易发生压架事故。“无板无壳”类型采场的覆岩结构沿竖向划分为两带,即“垮落带”和“弯曲下沉带”。并对形成3种类型采场的力学机理进行分析。