大采高综采工作面末采阶段来压规律与顶板控制技术

为研究大采高综采面末采阶段矿压显现规律,保证设备快速回撤,以察哈素煤矿3101首采面末采阶段开采实践为工程背景,采用理论分析和现场实测相结合的方法,研究工作面推进速度对来压特征影响,确定合理等压位置并提出末采支护方案。结果表明:工作面加速推进可使来压步距和来压持续长度明显增加;利用停采等压技术可有效控制来压位置;合理留设等压间隔煤柱,可保证挂网和贯通回撤阶段顶板压力显现较缓和;采用补强支护和相关顶板控制技术可保证回撤通道的稳定性。     

水力压裂对末采矿压显现规律的影响研究

为研究水力压裂对工作面末采矿压显现规律的影响,以隆德煤矿213综采工作面为背景,采用FLAC^3D建立其末采数值模型,考虑水力压裂前后岩体的力学变化特征,对比分析了有无水力压裂对末采悬顶长度以及矿压的影响,在此基础上设计了213综采工作面水力压裂方案,实测了工作面矿压以及回撤巷道变形。数值计算结果表明,无水力压裂条件下,213综采工作面顶板岩体在末采贯通阶段周期来压步距约为10～15 m,采空区上方岩体悬顶长度约为13 m;而水力压裂条件下周期来压步距则减小为5～10 m,悬顶长度减少为5 m。现场开展末采水力压裂施工后,工作面剩余可采长度为4～6 m发生周期来压,卸压区平均支架工作阻力减小9.7%;回撤巷道顶底板移近速度在工作面剩余可采长度低于26 m时由缓慢变形阶段的2.5～5.7 mm/d增加至快速变形阶段的13.0～66.9 mm/d。水力压裂在末采阶段的实施,有效控制了工作面的悬顶长度,成功实现了工作面的安全开采,切实保证了末采撤架工作的顺利完成。     

超长大采高综采工作面末采回撤调压关键技术研究

针对超长大采高综采工作面末采阶段的矿压调控问题,采用理论分析、数值模拟和现场试验的方法,通过研究小保当煤矿112201工作面末采贯通阶段的围岩应力分布规律以及矿压显现特征,确定相应的矿压调节技术方案,有效调控末采阶段工作面的周期来压步距,维护了顶板岩层稳定性,实现了工作面柔性塑料网(宽15m×长360m)的顺利铺设。研究表明：工作面末采期间回撤通道的围岩应力将由回采帮向煤柱帮转移,加强回撤通道围岩支护强度,可保证回撤通道稳定性|通过调整工作面回采速度,改变周期来压位置和减小来压持续长度,可实现工作面的顺利挂网与贯通,对类似工作面设备的顺利回撤具有借鉴意义。     

浅埋中厚煤层超长工作面末采矿压规律研究

为探究浅埋条件下中厚煤层超长工作面进入末采阶段时的矿压显现规律,以锦界煤矿31114综采工作面为研究对象,通过分析相似工作面矿压数据得出:浅埋中厚煤层地质条件下,工作面周期来压步距与工作面长度近似成反比,来压强度随工作面长度增加而增加,但增幅不大;理论推测31114工作面末采时工作面来压步距为9.58m,最大来压强度约...     

综采工作面末采回撤期间矿压显现规律研究

为了确保综采工作面在末采期间支架顺利回撤,基于东曲煤矿工作面的开采技术条件,通过现场矿压观测和分析,研究了综采工作面采场以及巷道在末采期间的矿压显现规律。研究表明:工作面在末采阶段,工作面来压步距增大,但来压强度仍未超过液压支架的最大承受能力,工作面内液压支架初撑力较小,因此造成煤壁多次出现片帮等现象。工作面在距离回撤巷道约20 m时,回撤巷道围岩变形量突增,但巷道内单体支柱未出现折断现象,因此巷道具有一定稳定性。     

7.0m大采高工作面覆岩破断及矿压显现规律研究

为解决神东矿区7.0 m大采高综采工作面的安全高效开采问题,采用现场实测、理论分析和物理模拟的手段,对19个特大采高工作面的矿压规律和关键技术进行研究。研究结果表明:特大采高工作面矿压显现较普通采高工作面更加强烈;由于特大采高工作面采高明显增大,覆岩第一亚关键层易进入垮落带,难以形成"砌体梁"结构,而呈"悬臂梁"结构周期性破断,形成工作面的周期来压,其持续长度与支架控顶距接近,较关键层"砌体梁"结构来压持续长度明显偏大;并且随着埋深的增大,高位关键层的破断对特大采高工作面矿压显现的影响也逐渐加大,多关键层的同步破断显然会传递更大的覆岩载荷,进而加剧了工作面矿压显现。针对特大采高工作面的矿压显现特征与特殊的覆岩破断规律,建立了支架合理工作阻力的确定方法,研发了特大采高工作面开采设备,开发了大断面巷道支护技术、强制放顶技术和末采快速贯通技术,实现了特大采高工作面的安全高效开采。     

大采高综采工作面矿压显现规律研究

为研究大采高综采工作面的矿压显现规律,以山西某矿3301大采高综采工作面为研究背景,对该工作面的周期来压步距与初次来压步距进行数值模拟和现场实测,结果表明:运用数值模拟和现场实测得出的该工作面的初次来压步距约为45 m,周期来压步距约为23 m,周期来压步距约为初次来压步距的1/2,数值模拟计算结果与现场实测结果一致,数值模拟计算方法可有效应用于大采高综采工作面周期来压步距与初次来压步距的计算中。     

综采工作面末采阶段来压规律与顶板控制技术

为分析综采工作面末采阶段矿压的情况,使得设施可以及时回撤,用理论分析和实际相联系的方式,探究工作面进度对来压特点的影响,明确适当等压位置。工作面推进的加快可直接影响来压步距,并且来压的时间长度也显著的增加。使用停采等压技术能够高效的控制来压位置,使用补强支护和顶板控制方式能够确保回撤退道的稳固性。     

浅埋近距离煤层工作面末采阶段等压原理与应用

为研究浅埋近距离煤层工作面末采阶段等压原理,以高家梁煤矿20314工作面末采阶段为工程背景,首先利用关键层位置判别法确定2-2上煤层间距5 m处的细粒砂岩为亚关键层,间距32 m处的粗粒砂岩为主关键层;通过覆岩岩层离层量Sn判断了上覆岩层破断层位,然后,分析工作面末采阶段不采取停采等压和采取等压技术2种情况下工作面贯通后上覆岩运动规律,并通过理论计算确定工作面距回撤通道6.6 m处为最佳停采等压位置,并在20314工作面末采阶段进行现场试验,回撤工作安全顺利完成。     

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     

Market and recycling of NiMH battery

<正>Market status and future trend of NiMH battery1.Global market of small NiMH battery Global market size of small NiMH batteries declined year on year since 2011.The trend will continue to 2018,at the rate of 5%to 10%annually.Demand for small NiMH batteries will be stable gradually.Many electrical apparatuses are powered by the built-in lithium battery today,which is the main reason for the shrunk market of small NiMH batteries.But,for some products,small NiMH     

China rare earth market review

正September 1-10,2014 Affected by the National Day holiday,rare earth transaction was stagnant and the market showed a weak steady state.As there was no good news for downstream market,some products with flat demand would likely rally slightly for some time to     

2014 second batch of rare earth quota released

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矿用防爆轴流对旋主要通风机叶片ANSYS模态分析及应用

高效节能矿用防爆对旋主要通风机的叶片是主要通风机运行的关键部件,叶片在运行时不断受到气流的作用力,从而使叶片产生振动,当叶片振动的频率与叶片的固有频率接近时,容易产生共振从而导致叶片的断裂。一旦叶片断裂时,对主要通风机的安全运行产生致命的影响,从而导致矿山、化工等企业发生重大事故,将会产生不可估量的损失。基于有限元分析软件ANSYS,对高效节能矿用防爆轴流对旋主要通风机叶片进行模态分析及产生对应的六阶模态频率,对主要通风机叶片的运行频率、固有频率及产生的共振问题进行了原理分析,并且解决了叶片频率共振的问题,从而为主要通风机叶片结构设计提供理论依据,并对主要通风机叶片的安全运行提供保障。     

2013 NdFeB export analysis

<正>China totally exported nearly 24,000 tonsof NdFeB products during 201 3,including 18,825 tons of permanent magnet,valued USD 1.34 billion at an average price of 71.4 USD/kg;3,277 tons of NdFeB magnetic powder,valued USD 1 01 million at an average price of 30.9 USD/kg;1,334 tons of strip casting ribbon,with total export value of USD 74million at an average price of 55.3 USD/kg;and 586