某铅锌矿采空区处理与矿柱爆破的协同技术

采空区安全隐患处理问题是空场法开采矿山的共性问题,并且在采空区治理中一般会伴随遗留矿柱的回采.为进一步研究采空区处理与矿柱爆破的彼此协同技术,以某铅锌矿945 m中段以上采空区处理与遗留矿柱回采为例,通过调研矿山开采现状,制定并优选了采空区顶板强制崩落技术方案.爆破实施结果表明:矿柱爆破破顶技术方案整体上是可行的,爆破...     

某铅锌矿采空区处理与矿柱爆破的协同技术

采空区安全隐患处理问题是空场法开采矿山的共性问题,并且在采空区治理中一般会伴随遗留矿柱的回采。为进一步研究采空区处理与矿柱爆破的彼此协同技术,以某铅锌矿945 m中段以上采空区处理与遗留矿柱回采为例,通过调研矿山开采现状,制定并优选了采空区顶板强制崩落技术方案。爆破实施结果表明:矿柱爆破破顶技术方案整体上是可行的,爆破达到了开"天窗"的效果,消除了采空区顶板垮落的地压风险;破顶区域炮孔堵塞带来的装药长度不足问题,通过调整起爆顺序,即由原来的分段爆破改成集中同段爆破,增大爆轰能量进行解决,最终实现了地表成功破顶。研究中涉及的相关爆破技术可为其他类似开采条件的矿山提供有益参考,丰富了采空区处理与矿柱爆破回采协同技术在类似矿体开采的现实价值。     

采煤工作面的支护参数及质量标准探讨

回采工作面顶板控制设计的内容主要包括:选择采场支护形式、选择采空区顶板的处理办法、决定控顶距离、选择支护形式、制定工作面日常顶板管理方案等。因此,主要对采煤工作面支护方式选择、支护参数确定以及相关质量标准做探讨。     

浅析煤矿综采面采空区悬顶处理技术

针对神东矿区高瓦斯矿井属于复合型顶板的综采面瓦斯治理的实际情况,为防止采空区大面积悬顶突然垮落造成瓦斯事故,提出了以退锚索、高压预裂、码放黄土袋、断网为主的采空区悬顶处理技术,防止采空区大面积悬顶突然垮落造,从而保证了高产高效顺利进行,为今后类似条件工作面悬顶问题的处理与解决,提供有益的参考。     

浅析采煤工作面的支护参数及质量标准

回采工作面顶板控制设计的内容主要包括：选择采场支护形式、选择采空区顶板的处理办法、决定控顶距离、选择支护形式、制定工作面日常顶板管理方案等。这些顶板管理的方法在实践中得到了充分的验证，并且从实践中得到了许多宝贵的经验。本文主要对采煤工作面支护方式选择、支护参数确定以及相关质量标准做了探讨。     

东坡煤矿聚能穴爆破侧向切顶技术浅析

东坡煤矿2109试验工作面位于采区西翼的中部，受到2107采空区的采动影响，上顺槽动压显现强烈，巷道维护难度很大。根据该采区的采掘规划，后续工作面仍将面临动压巷道的支护难题。动压巷道矿压显现强烈与相邻采空区的顶板运移过程密切相关，且该影响过程将贯穿于巷道的服务期间。综合考虑支护成本与巷道支护效果，建议采用聚能穴爆破侧向切顶工艺，即上一个工作面回采期间，在与下一个工作面相邻的巷道内采用人工爆破，及时切落顶板，以消除对接续工作面的动压影响。     

针对孤岛综放面煤层自燃防治方案研究

综放开采煤层都是特厚煤层,平巷沿底板掘进,留有顶煤。由于受采动影响,使得顶煤破碎离层;有些煤层煤质松软,掘进时,时常冒落形成空洞区;有的上分层已采,下分层采用综采放顶煤技术,由于煤层起伏变化,中间煤层破碎等原因,使综放平巷与顶采空区连通;无煤柱开采留小煤皮的沿空巷道与临近层采空区连通。由于上述种种因素,使综放无煤柱开采平巷自然火灾增多,且火源沿巷道顶板及沿空侧（或顶部）采空区发展迅速。     

再生破碎复合顶板综采工作面快速推进工艺技术研究

通过对再生破碎顶板综采工作面顶板控制技术、设备配套选型、采煤工作面回采工艺优化、采煤工作面防片帮漏顶技术的实施、瓦斯治理措施落实、劳动组织优化以及生产过程中人机系统的科学合理配合与实施,使再生破碎复合顶板综采工作面在回采过程中实现了安全高效快速推进。     

断层破碎带化学注浆加固技术

东北大巷煤柱地区巷道在过断层破碎带时,顶板破碎严重,空顶大,通过采取化学注浆技术对巷道经行加固,改变了巷道围岩的力学性质,为巷道的安全快速掘进提供了有力条件。     

煤矿硬岩复杂构造带放顶煤工作面开采技术研究

基于云冈矿复杂地质条件和变形破坏特点,为了更好的解决深部矿井坚硬顶板下围岩破碎巷道支护困难的问题,结合可采范围,提出了将放顶煤工作面五巷布置改为四巷布置,少掘一条放顶工艺巷和一条初放小切巷。这样即可以有效的避开复杂地质构造带对其巷道围岩的影响,又减少成本,缩短掘进及回采时间,采用中长钻孔爆破顶煤及顶板,确保顶煤回收率及顶板全部垮落,保证了矿井安全高效生产。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...