采矿回采中大块的预防与处理

本文通过分析金川龙首矿下向六角形进路胶结充填采矿法回采过程中，大块的产生原因及危害，提出预防大块产生的措施，并且论述了大块的处理方法。     

矿房挤压爆破对岩石块度影响的研究与实践

矿房采矿应用中深孔爆破回采时,经常出现矿石大块,加大二次破碎工作量,为出矿增加难度。为了解决这一难题,经过反复实验,采用部分挤压爆破,在爆破震动的允许范围内,确定最优的爆破参数,在减少大块率方面取到预期效果。本文是基于生产实践总结出对于本矿山条件下的矿房回采产生大块处理方法的经验,为以后工作提供了借鉴。     

分段空场法在大红山铁矿的优化调整与应用

大红山铁矿I号铜矿带浅部I1矿体持续生产盘区采用分段空场采矿法进行回采,在前期回采爆破回采过程中,存在大块多、块度大及废石混入率大等现象,导致眉线口卡块频繁、铲运大块及二次解块工作量大,生产效率较低,同时增加出矿安全风险。本次结合矿体实际情况,通过优化采切工程布置及中深孔凿岩参数,有效解决了前期回采中存在的问题,并为后期生产回采提供有利经验。     

中深孔爆破落矿中降低大块率的途径

应用中深孔进行爆破落矿，普遍存在大块问题。针对陕西太白黄金矿业有限责任公司阶段矿房采矿法回采的实际情况，通过分析、研究、试验，找出大块产生的根本原因，总结出降低中深孔爆破中大块率的有效途径。     

深部金属矿山卸压开采中矿体安全回采方案研究

传统矿体安全回采方案,卸压巷道垂直偏移量较大,为此,提出深部金属矿山卸压开采中矿体安全回采方案。确定采场结构参数、凿岩爆破参数、预留矿体层厚度、抵抗线等矿体回采参数,选择合理的掏槽方式,将矿体顶部作为充填体,布置掏槽炮孔,选取孔内微差起爆方式、孔底起爆顺序,避免矿石大块的崩落。进行对比实验,结果表明,设计方案相比传统方案,减少了卸压巷道的垂直偏移量,保证了卸压巷道的稳定性,使矿体回采更加安全稳固。     

坑下破碎矿仓设计中几个问题的商榷

前言近年来由于采矿技术的不断发展,国内外许多坑下金属和非金属矿山相继采用了深孔大量崩矿法,因此大块量增多,二次破碎量增大,为了提高劳动生产率减轻笨重的体力劳动,国内外许多坑下矿山特别是用箕斗或带式运输机的矿山都设置了地下破碎,设置地下破碎优点很多:1、可使回采的矿石块度加大,并可提高回采     

香炉山钨矿中深孔爆破参数优化研究

针对香炉山钨矿西部矿段采用预切顶中深孔房柱法进行采场回采,对采场切割槽及矿房崩矿进行了爆破参数优化,应用正交试验法对排距、孔底距等影响爆破效果的主要参数进行优选,确定了合理的中深孔凿岩爆破参数,降低了爆破大块率,提高了采装运效率,降低了矿石成本,使矿山获得显著的经济效益。     

黑山铁矿无底柱分段崩落法开采工艺优化

针对黑山铁矿露天转地下无底柱分段崩落法开采中存在矿石损失贫化率大,与大块矿产出率高等问题,进行了系统优化研究。通过回采工艺优化,将原“等间距”进路菱形布置方式改为“半矿半岩”与近矿围岩结合的布置方式,确定了最优崩矿排距值,有效降低了矿石损失贫化率;通过中深孔布孔方式优化,提出了进路中深孔采用“三凿岩中心”、切割井采用“双凿岩中心”取代原“单凿岩中心”的优化方法,有效降低了大块矿产出率,并保护了眉线,节约中深孔凿岩成本约47万元/年,经济效益显著。     

水平扇形中深孔崩落法在矿山爆破中的应用

矿山的开采技术决定了矿山的生产力,不同的矿山情况、不同的阶段,需要采用不同的开采方法,水平扇形中深孔爆破法是一种综合型爆破法,其同时不仅融合了多种开采爆破技术,其所采用最小抵抗线这种方法能很好的控制大块率,减少二次破碎的工作量,也能在回采过程中更好的保障开采工作的安全,十分适用于高品位矿石的收尾回采工作。在呼伦贝尔山金矿业有限公司22#矿井900m中段205采场中,一直采用传统的顶柱保留式采矿法,这样一来顶柱中的矿石以及夹层、顶层等保护层的矿石遗留无法采出,损失较大,本次研究我们尝试设计水平扇形中深孔崩落采矿法,以期通过这种爆破方法来对余留的顶柱、夹层、顶层等进行回采,从而提高采场的出矿量,提高企业的生产效益。     

桦树沟铜矿中深孔落矿中存在的问题及对策研究

桦树沟铜矿床铜矿体呈隐伏、半隐伏状态赋存于铁矿体下部,构成上铁下铜格局。主要矿石类型有含铁碧玉岩型和蚀变千枚岩型,区内岩石普遍发生浅变质作用,主要表现为重结晶作用。桦树沟铜矿在2850m水平以下均采用中深孔落矿,在中深孔落矿的过程中存在着大块多、矿石贫化大以及一部分矿石难以用中深孔回采等问题。     

节理岩体矿岩块度三维模拟研究

为实现矿岩块度预测的三维可视化模拟，根据岩体内节理面倾向、倾角和节理间距等几何参数的分布规律，采用Boost Random库实现节理面Monte Carlo随机模拟，从而建立原始块度预测的节理素描文件，然后引入崩落块度修正系数计算崩落块度预测的节理素描文件。根据节理素描文件数据计算三维节理面网络，逐个取出节理面平面，对模拟范围的长方体模型进行切割，建立块度三维模型。利用块度三维模型分别计算块体的容积系数和共线性值，对块体进行形状分类。结合VTK库和HOOPS 3D实现上述算法，以普朗铜矿自然崩落法为例对首采区原始块度进行预测：块体体积的四分位点分别为0.164，0.403，0.853 m3，块体等效尺寸在0.5～3.0 m区间时块体占较大的体积百分比；同时，根据块体等效尺寸分布曲线得到放矿口的尺寸应大于5 m×5 m。研究结果表明：该方法能够根据现场节理面调查结果模拟岩体内节理分布，进而利用矿岩块度三维模型实现矿岩块度的预测和统计分析，为自然崩落法开采研究提供了重要依据。     

Occurrence of deoxyribonucleic acid fragmentation during prolactin-induced structural luteolysis in cycling rats

We determined whether fragmentation of genomic DNA, one of the hallmarks of apoptosis, occurs during structural luteolysis in cycling rats. Corpora lutea (CL) were collected from rats at each estrous cycle stage (1800 h), and fragmented DNA was extracted. Only CL from rats at the proestrous stage showed distinct DNA fragmentation. To determine the period of occurrence of DNA fragmentation, CL were collected at several points between 1200 h on the day of proestrus and 0600 h on the day of estrus. Distinct DNA fragmentation was observed from 1800 h (proestrus) to 2400 h (proestrus), and the extent was significantly lower at 0600 h (estrus). It is known that prolactin (PRL) induces structural luteolysis in rats. To examine the role of PRL in luteal DNA fragmentation, 2-bromo-alpha-ergocryptine (BE) was used to suppress the PRL surge on the day of proestrus. CL collected at 1800 h from BE-treated rats did not show distinct DNA fragmentation, and PRL injection offset the effect of BE. Histochemical analysis with a 3'-end labeling technique confirmed the occurrence of DNA fragmentation in luteal tissue. These results suggest that apoptotic cell death occurs during PRL-induced structural luteolysis.     

Structural analysis of xyloglucan oligosaccharides by the post-source decay fragmentation method of MALDI-TOF mass spectrometry: influence of the degree of substitution by branched galactose, xylose, and fucose on the fragment ion intensities

Highly branched xyloglucan oligosaccharides were analyzed by the post-source decay (PSD) fragmentation method of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). The ratio of [M-Xyl]+ and [M-Gal]+ fragment ion intensities could be used to characterize the degree of Gal substitution at the non-reducing end, because the number of possible chemical species was directly related to their relative ion intensity. The intensity of the [M-Fuc]+ ion was predominantly strong in the fragment spectrum of fucosyl oligosaccharides as the first fragmentation, indicating the fucosyl linkage to be much weaker than the other glycosidic linkages in the MALDI-PSD fragmentation. Setting fragment ion [M-Fuc]+ to the pseudo precursor ion [MF]+, the second fragmentation ions were produced from [MF]+ in the drift region in PSD fragmentation of fucosyl oligosaccharides.     

高线碳化钨辊环碎裂分析及控制

对高速线材轧机精轧机组中使用的碳化钨辊环进行了受力分析。指出了轧制应力、热应力及装配应力在辊环断裂过程中的作用。认为辊环的质量控制关键在于辊环的合理使用上,主要从轧辊的冷却、修磨、合理轧制、合理选用这几方面来解决辊环的碎裂问题。     

Dynamic Fragmentation of an Ultrahigh-Strength Concrete during Edge-On Impact Tests

To understand and model damage generated during impact by a penetrator of ultrahigh strength concrete targets, edge-on impact tests are performed with Ductal concrete, which is unreinforced or reinforced with short fibers. Two edge-on impact configurations are designed with a dynamic confinement system. The first configuration uses aluminum projectiles and allows us to study the dynamic fragmentation that spreads out within the tile without any confined damage close to the impact point. The fragmentation process is composed of numerous oriented millimetric cracks. In the second configuration, steel projectiles are used with a higher impact velocity. Damaged zones are visualized by using an ultrahigh speed camera and a sarcophagus configuration designed to prevent the fragments from moving. Postmortem studies of impacted tiles enabled us to observe an intense fragmentation of the targets and confined damage close to the impact point when steel projectiles were used. Simulations are performed with an anisotropic damage model coupled with a concrete plasticity model. Orientation and crack density are compared with postmortem observations.     

张坝沟石灰石矿改进穿孔爆破工作的分析研究

张坝沟石灰石矿长期采用传统光面爆破技术来减小爆破震动及后冲对永久边坡的危害。但是传统光面爆破存在大量的缺陷，需要找到一种更优越的光面爆破方法来保证永久边坡的稳定性。文中较详细地介绍了爆轰波在爆破破岩中的作用，根据其破岩机理提出了几种新的更优越的光面爆破方法。     

Olfactory function in monozygotic twins discordant for schizophrenia

Microtubule disassembly is commonly believed to be a process of endwise tubulin dimer release. The present study demonstrates by video interference contrast microscopy that Escherichia coli lipopolysaccharide (LPS) caused microtubule disassembly in vitro by both endwise shortening and fragmentation. In contrast, the microtubules were only shortened from their ends in the presence of DNA, used as another example of a macromolecular microtubule effector. LPS-caused microtubule fragmentation was confirmed by transmission electron microscopy. Because of its ability to induce both fragmentation and endwise shortening, LPS, which is involved in sepsis pathogenesis, has to be regarded as a highly active microtubule-destabilizing agent.     

Analysis of antiretroviral nucleosides by electrospray ionization mass spectrometry and collision induced dissociation

Antiretroviral nucleoside drugs used against the human immunodeficiency virus (HIV) infection have been analyzed using negative ion electrospray ionization (ESI) mass spectrometry and collision-induced dissociation (CID-MS/MS). Mass fragmentation of azidothymidine (AZT), didanosine (ddI), dideoxycytidine (ddC) and dideoxythiacytidine (3TC) were obtained at different cone voltages and collision energies. Fragmentation of purines and pyrimidines occurred by different pathways. For purines (ddI), the fragmentation was similar to those found in endogenous nucleosides; mainly the pseudo molecular ion is present (M-H)- and a cleavage through the glycosidic bond forming (B)- was observed. For pyrimidines (AZT, ddC, 3TC), the fragmentation pathways were different from endogenous nucleosides; for AZT, the fragmentation occurred primarily through the elimination of the azido group in the 3'-position (M-H2-N3)-, whereas ddC and 3TC presented more complex fragmentation patterns. For ddC, fragmentation appeared to be dominated by a retro Diels-Alder mechanism (M-CONH)-. For 3TC, the sulfur atom in the sugar moiety provided greater stability to the charge, producing fragments where the charge resided initially in the dideoxyribose (M-C2O2H6)-.     

Simple parametrization of fragment reduced widths in heavy ion collisions

A systematic analysis of the observed reduced widths obtained in relativistic heavy ion fragmentation reactions is used to develop a phenomenological parametrization of these data. The parametrization is simple, accurate, and completely general in applicability.     

Models for the length distributions of actin filaments: II. Polymerization and fragmentation by gelsolin acting together

In a previous paper, we studied elementary models for polymerization, depolymerization, and fragmentation of actin filaments (Edelstein-Keshet and Ermentrout, 1988, Bull. Math. Biol. 60, 449-475). When these processes act together, more complicated dynamics occur. We concentrate on a particular case study, using the actin-fragmenting protein gelsolin. A set of biological parameter values (drawn from the experimental literature) is used in computer simulations of the kinetics of gelsolin-mediated actin filament fragmentation.