基于顶板断裂分析的综采大断面回撤通道协同控制技术

为了解决大断面回撤通道传统支护工艺准备时间长、成本高等问题,基于顶板断裂位置分析,提出一种切顶卸压联合“桁架-锚索-支架”的回撤通道协同控制技术。研究表明：工作面基本顶断裂位置对回撤通道围岩受力具有重要影响,基本顶超前断裂,顶板断裂线位于回撤通道煤柱上方时,回撤通道支护最为困难。据此,首先采用水力压裂技术超前预裂工作面基本顶,限定顶板断裂线远离回撤通道,降低覆岩大结构影响,解除回撤通道的区域应力环境;其次,采取“桁架-锚索-支架”组合支护形式,保障回撤通道围岩小结构的稳定。该技术在葫芦素煤矿21103工作面回撤通道进行了工业性试验,相较常规支护技术,回撤通道协同控制技术成本低、支护效率高,巷道围岩变形量小,保障了工作面的快速回撤。     

大采高工作面末采期间快速贯通技术研究

为实现大采高工作面末采期间回撤通道快速顺利贯通,以万利一矿42301大采高工作面为工程背景,在末采期间采取矿压观测和顶板控制的措施,保证回撤通道贯通期间避开周期来压。在此基础上对挂网工艺进行优化,缩短了挂网时间,为回撤通道安全快速贯通提供了技术保障。实践结果表明:工作面回撤通道贯通时间大幅减少,整个贯通过程仅用了32 h;采用现场多频次测量顶底板高程的方法,保证贯通期间工作面顶底板平整,使高差从2 700 mm减小到200 mm以内,回撤通道贯通质量高,仅局部20台支架底板存在小于200 mm的台阶高差;采用矿压监测手段和顶板控制措施,保证工作面末采期间未受到矿压影响,回撤通道安全顺利贯通。     

顶板断裂来压力学模型及其在综放工作面末采阶段的应用

针对综放工作面末采阶段支架回撤过程中容易出现压架的问题,建立了顶板断裂来压力学模型,并根据顶板断裂前后的平衡方程推导出顶板在不同断裂形式下支护体、煤体内应力增量平均值的统一表达式。以神东矿区多通道快速回撤技术模式为研究对象,根据顶板断裂面与主回撤通道的位置关系分两种情况进行了力学分析,结果表明:工作面回撤停采的合理位置应能够使主回撤通道处于顶板断裂面以外;回撤期间利用停采让压原理调节周期来压步距,采取在主撤巷道内加强支护、控制贯通前后工作面高差等措施,能有效保证综放工作面末采阶段的安全高效回撤。     

基于能量计算的预掘回撤通道顶板下沉量分析

采用预掘回撤通道技术的综采工作面在末采阶段易发生顶板大变形而引发压架事故。本文基于工作面贯通后的3种基本顶破坏形式,建立了不同的回撤通道顶板力学模型,通过分析顶板变形过程中的能量释放与做功过程,求得不同基本顶破坏形式下的回撤通道直接顶下沉量。结合张家峁煤矿N14201工作面回撤通道顶板大变形案例,分析了不同顶板力学模型的影响因素,发现基本顶破断位置、关键块及其上覆岩层厚度、关键块回转角和支护强度对回撤通道顶板下沉量影响显著,确定了张家峁煤矿N14201工作面发生压架事故的原因,即基本顶在保护煤柱上方4～6 m范围内破断以及上部3^-1煤层开采导致主关键层破断失稳。     

特殊条件下大采高工作面回撤通道稳定性控制研究

为了实现特殊条件下大采高工作面设备快速安全回撤,以赵庄矿5310工作面回撤通道为工程背景,综合采用现场调研、数值模拟、理论分析等方法,研究了基本顶不同断裂位置和周期来压步距对回撤通道的影响,进而确定合理的回撤通道位置;根据回撤通道赋存特征和围岩条件,坚持"顶帮协同控制"的原则,在提高支架初撑力的基础上,顶板采用全锚索支护、煤帮为锚网索联合支护。现场监测表明,该支护方案能够实现工作面设备顺利回撤,可为类似条件下工作面回撤通道的稳定性控制提供借鉴和参考。     

回撤通道直接顶下沉量计算及其影响因素分析

回撤通道的直接顶下沉量对设备回撤具有重要影响,本文基于基本顶断裂位置,建立了工作面贯通后回撤通道直接顶挠度力学模型,将支承应力表达式简化为与其拟合的x的n次抛物线函数,断裂位置不同,n的取值不同,推导出了回撤通道顶板中心线处直接顶下沉量表达式。312工作面基本顶断裂位置d约12 m,此时n取4,求得直接顶下沉量约为105 mm。在理论计算的基础上,对直接顶下沉量影响因素进行了分析,结果表明:直接顶下沉量随着基本顶断裂位置、煤层埋深、应力集中系数及回撤通道跨度的增大而增加,随着直接顶厚度及弹性模量的增大而减小,其余因素影响较弱。在保证设备回撤空间的条件下,尽可能减小回撤通道跨度,控制直接顶下沉量。     

超大采高综采工作面回撤通道支护技术研究

为实现榆神矿区8.2 m超大采高工作面大型设备安全高效回撤,以金鸡滩煤矿12^-2108工作面回撤通道为工程背景,采用理论计算、数值模拟和现场矿压实测的方法,研究工作面末采阶段基本顶周期来压规律与顶板断裂位置,得出末采阶段基本顶周期来压步距19.3 m,工作面推进距主回撤通道7.9 m时受动压影响剧烈,在贯通前2 m处来压结束,运用停采等压技术证明工作面与回撤通道贯通时无须等压,同时确定基本顶下一次周期来压断裂位置位于主、辅回撤通道中间煤柱约4.8 m处,工作面最终实现了无来压贯通。基于采场矿压规律研究,回撤通道创新性地提出采用恒阻大变形锚索+钢带十字链接按A,B、C三个不同应力分区支护整体受力的新设计方法,通过现场实测应用得出：C区域的锚索伸长量大于B和A区域,越靠近工作面侧锚索下沉量越大,位于回撤通道中部（C区）靠近回采侧恒阻锚索最大延伸量达到180 mm,而垛式支架撤出后大断面巷道一侧邻空成悬臂梁,此时恒阻大变形锚索完全受力,回撤通道顶板整体向采空区倾斜的现象,证明支架撤出过程中恒阻锚索能够保持顶板临时稳定性,保证了顶板没有出现冒顶现象,底板、抹角、帮角基本没...     

基于实测应力的回撤通道顶板断裂位置确定方法

为确定综采工作面在末采阶段顶板断裂位置对回撤通道的影响程度,根据工作面贯通后顶板的不同断裂形式,基于弹性力学理论建立回撤通道顶板结构力学模型,对顶板断裂位置与贯通后回撤通道保护煤柱侧帮部应力关系进行了分析,得到了不同顶板断裂位置下回撤通道煤柱帮竖向应力计算公式。最后,根据红柳林煤矿综采工作面回撤通道保护煤柱应力测试结果,对15205和15206工作面回撤通道的顶板断裂位置进行了判断。     

大采高工作面末采期间矿压显现规律研究

预掘双通道综采设备回撤工艺作为榆神矿区主要综采设备回撤工艺,实现了综采设备的安全、高效回撤。但是目前大采高综采工作面末采期间回撤通道矿压显现规律能够参考的工业试验数据有限。因此,以红柳林煤矿15205综采工作面6.3 m大采高设备为研究背景,监测工作面回撤通道垛式支架压力、顶板下沉量以及围岩离层数据,发现在综采工作面末采阶段,垛式支架能够对顶板起到明显的支护效果,主回撤通道内片帮分布规律与顶板下沉规律基本一致,并且工作面分别在距离回撤通道42 m、14 m、9 m以及6.5 m时出现明显矿压显现变化。     

综采工作面末采及回撤矿压显现规律与顶板控制技术

神东矿区综采末采使用辅巷多通道回撤技术,通过对末采阶段和支架回撤阶段矿压显现规律的研究,提出了末采等压的顶板控制技术。以补连塔煤矿22303综采工作面为例,研究得出:在综采工作面末采贯通前需通过计算留预留一定尺寸的等压煤柱进行停采让压,当工作面来压后基本顶回转断裂,形成稳定砌体梁结构,在贯通时主回撤通道将不会来压,能够保证支架的安全回撤;当让压后工作面仍不来压,则工作面在回撤时将处于来压状态,需要加强回撤通道的支护强度,防止压架事故发生。     

Current situation and future trend of China rare earth luminescent material industry

<正>Rare earth luminescent material is one of the most important application sectors of rare earths.China enjoys the exceptional advantage to develop rare earth luminescent material for its abundant rare earth resources.After several decades'endeavor,China's rare earth luminescent material industry,headed by rare earth phosphor for lamp and LED and high efficient rare earth energy-saving light source,has been gradually developed into a scale industry.China has become a major production base of rare earth phosphor for lamps and rare earth     

China rare earth market review

正June 1~10,2014Rare earth market remained weak.Quoted price of rare earth products was similar to that in May.There was no sign of recovery in downstream market.The market of NdFeB magnetic materials and phosphor was depressed.Catalyst,polishing powder and ceramic industries remained inactive.Demand from downstream industry was soft.Consumers purchased on their needs.Suppliers had strong intention to sell.Prices of rare earth products     

Annual Report analysis of Chinese rare earth-related listed companies in 2013

<正>Chinese rare earth-related listed companies have published their 2013 annual reports.It can be understood from their reports that production and operation activities of Chinese rare earth-related companies were still heavily affected by macro economy and industrial policies.They basically followed the steps of national economy.In 2013,world economy recovered slowly but the economy     

Market opportunities and challenges for rare earth polishing powder

正1.Status of rare earth polishing powder Rare earth polishing powder with high content of cerium oxide began to replace iron oxide for glass polishing and became one of the key materials in glass polishing process since 1940.Compared with traditional iron oxide,rare earth polishing powder has many advantages,such as fast polishing rate,high polishing quality and long service life.It can achieve good surface quality and improve operation conditions.For example,in lens polishing,the polishing work that cerium     

Baotou Research Institute of Rare Earths developed a new RE alloy preparation technology

正Pyrometallurgy Laboratory of Baotou Research Institute of Rare Earths had independently developed a new preparation technology of rare earth alloy for NdFeB.The alloy can remarkably enhance the coercivity of NdFeB magnet but also evidently reduce the production cost of the magnet.The new master alloy was prepared in the kA pilot-scale electrolytic cell by the independent technology.The rare earth master alloy can be used as the raw material for NdFeB.Compared     

China rare earth market review

正November 21~30,2014Due to weak demand from downstream industries,transactions of rare earth in Chinese domestic market were inactive.It was difficult to sell any rare earth products except for dysprosium oxide and terbium oxide.Suppliers lost confidence in recent market.Demand for rare earth products was soft.Consumers continued to take a wait-and-see attitude.Rare earth export market remained slow.     

Galaxy Magnets achieved the net profit of 34.02 million yuan in the first six months of 2014

正Galaxy Magnet announced its financial results for the first half of 2014 on August 14.For the first six months ended on 30 June 2014,Galaxy Magnet achieved operation income of RMB 182.3 million,up8.40% over the same period of 2013,and the net profit attributable to the shareholders of the listed company of 34.02 million yuan,increasing 35.49% over the same period of last year.Stable performance increase was led by development of new customers and application market of magnets.     

Rare Earth Application in Steel in China

<正>China has rich rare earth resources.Output of rare earth and steel in China ranks the top first in the world.However,there is still certain distance between the steel produced in China and developed countries from the point of varieties and quality.China still has to import some types of steel.Improving the quality should be emphasiZed in future development of steel industry in China.Rare earth can be used to upgrade traditional steel     

Current situation and future trend of China rare earth luminescent materialindustry(continued)

<正>Developing ecological lighting source The world is facing the big problem of energy shortage today and the contradiction between economy development and environmental protection is worsened.Therefore,people are more likely to choose an ecological light source that is more energy efficient and environmental friendly.The choice provides great opportunity for the development of rare earth optical material industry in China.The concept of green lighting positions rare earth luminescent material as a leading player in illumination market.The light source of both rare earth luminescent lamp and LED lamp is ecological and energy saving.This is why     

稀散金属产业的观察与思考

分析了近年来国内外稀散金属产业的生产、应用、资源与市场状况.铟锡氧化物靶材、砷化镓晶片、锗红外材料、铼高温合金和硒在电解锰及玻璃的应用等已成为稀散金属的主要应用领域.稀散金属的产量快速增长达到历史高位而导致了市场的失衡.以GaInP_2/GaAs/Ge,CIGS和CdTe为代表的非硅系太阳能电池是稀散金属的新兴应用领域,将给稀散金属带来日益增长的需求.