浅埋煤层沙土质冲沟坡体下开采矿压显现特征

为了分析在冲沟坡体下浅埋煤层开采工作面矿压显现特征,基于冲沟发育的矿区浅埋煤层地质条件,以工作面背沟开采为主要方式,采用物理模拟和理论分析的方法,研究了浅埋煤层冲沟采动坡体活动特征.结果表明:冲沟坡体下开采时,基本顶初次破断具有不对称性;冲沟采动坡体被地表超前裂隙切割成多边块状,并在两侧坡体的夹挤摩擦作用下缓慢回转下沉;相同地质条件下,坡角越大,采动坡体对工作面矿压显现影响越大.同时,建立了在冲沟坡体下采场基本顶初次破断的力学模型,分析认为在冲沟发育浅埋煤层条件下,基本顶初次破断时开切眼侧与推进侧岩块长度比值为1～1.33.     

薄基岩下浅埋煤层开采地表沉陷预测方法

综合分析榆神府矿区薄基岩下浅埋煤层综采工作面上覆基岩的断裂下沉机理,以及基岩控制层破断与工作面周期来压及地表沉陷之间的动态关系。根据基岩控制层破断下沉的分布函数,利用随机介质理论导出此类条件下地表沉陷的预计模型,并提出参数的确定方法。该模型直接建立起工作面周期来压步距与地表移动分布的数学关系,适用于榆神府矿区薄基岩下浅埋煤层开采的地表沉陷预计。     

采场覆岩破坏规律研究

为了研究采场覆岩破坏规律,以平朔井工三矿39107工作面地质情况及开采条件为基础,依据相似定律制作相似模型,得出地表最大垮落位置在距开切眼100 m处,达到充分采动等,岩层下沉量最大值8.2 m,开切眼位置处地表下沉量约为3.6 m;岩层最大垮落位置在距开切眼105 m处,地表沉陷值最大值7m左右,开切眼位置处地表发生台阶式下沉,下沉量2～3 m,地表沉陷后形成的地表裂隙宽度为0.1～1.2 m;开挖处应力值降低,工作面前方由于超前支承压力的作用应力值升高,超前支承压力峰值距工作面在8～12 m之间,平均10 m;超前影响范围为14～17 m,平均15.5 m;工作面垮落带高度为32～40 m,裂隙带发育较高,最终裂隙导通地表,使地表形成了台阶下沉;工作面直接顶初次来压为16 m,基本顶初次来压为40 m,基本顶周期来压为12～18 m,平均为15 m.     

大倾角厚煤层综采工作面覆岩移动与矿压显现规律研究

以南山煤矿小沟分矿B8煤层综采工作面为研究对象,采用相似材料模拟试验及现场观测的方法,对大倾角厚煤层综采工作面的覆岩移动与矿压显现规律进行研究,结果表明：采场基本顶中会形成“厂”形移动拱结构,其随煤层的开采逐渐向上覆岩层扩展,直至地表;周期来压表现出工作面中下部来压周期长、来压步距大,而上部来压周期偏短、来压步距偏小的特征,工作面初次来压步距约为40.0 m,周期来压步距为8.3～20.7 m;垮落带高度为41.0 m,断裂带高度为69.0 m,弯曲下沉带高度为46.0 m。     

基于相似模拟实验覆岩移动规律研究

以石圪台矿地质资料为背景,基于材料配比实验制作物理模型,模拟2-2煤层开采中上覆岩层及地表的移动规律。研究结果表明:地表纵向最大下沉量3.6 m;竖直方向下沉量关于下沉中心位置左右对称;顶板初次来压步距约32.0 m,周期来压步距约10.5 m。     

浅埋煤层坚硬顶板深孔预裂爆破技术研究

为了解决神木地区何家塔矿5~(-2)浅埋煤层开采过程中,顶板悬露时间长,不易垮落的问题,以实际地质资料为依据,采用相似模拟实验模拟该煤层开采过程中煤层上覆围岩下沉变化得出:开挖过程中基本顶初次来压步距大,可达70 m左右。结合该矿地质情况提出了深孔爆破弱化顶板的方案,并且确定爆破各项参数。实验工作面的应用结果表明,采用预裂爆破后基本顶来压步距缩小到48 m位置,顶板冒放性能得到良好的改善,保证了矿井安全高效生产。     

浅埋煤层重复采动下覆岩运动及裂隙演化规律分析

为了更深入的解析浅埋煤层在重复采动下的覆岩运动规律,通过使用UDEC数值模拟方法,对山西某煤矿1#、2#煤层进行模拟开采,最终得出浅埋煤层重复采动下覆岩运动及裂隙演化规律,并通过二维物理相似模拟实验来验证,结果表明:1#煤层开采后,工作面初次来压步距为30 m,大约每开挖10 m形成一次周期来压,周期来压步距约为10 ...     

伊犁矿区浅埋深“三软”厚煤层首采工作面矿压规律研究

为了掌握新疆伊犁矿区浅埋深厚煤层开采矿压特点,利用支架压力监测、地表岩移观测和煤体超前应力监测等实测手段,对新疆伊犁四矿首采21103工作面在浅埋深薄基岩“三软”厚煤层条件下的矿压规律进行分析。结果表明：工作面基本顶初次来压步距约21m,周期来压步距平均11m,动载系数平均1.22～1.25,工作面矿压显现整体不强烈,现有ZFY13000/24/42型放顶煤支架适应性良好|工作面超前支承压力分布具有应力集中系数低、超前影响范围小等特征,对回采巷道影响不显著|研究结论为类似条件工作面安全高效回采提供有益借鉴。     

浅埋煤层顶板分级及灾变预防

对南梁煤矿浅埋单体长壁工作面的顶板进行了分级,分析了目前工作面的支护状况,提出了通过强制放顶,将顶板初次来压步距及初次来压和周期来压的台阶下沉控制在允许范围内的预防大面积垮落灾变的措施,为预防开采过程中发生大面积来压和实现浅埋煤层单体工作面连续推进具有重要意义。     

伊犁矿区浅埋深“三软”厚煤层首采工作面矿压规律研究

为了掌握新疆伊犁矿区浅埋深厚煤层开采矿压特点,利用支架压力监测、地表岩移观测和煤体超前应力监测等实测手段,对新疆伊犁四矿首采21103工作面在浅埋深薄基岩“三软”厚煤层条件下的矿压规律进行分析。结果表明：工作面基本顶初次来压步距约21m,周期来压步距平均11m,动载系数平均1.22～1.25,工作面矿压显现整体不强烈,现有ZFY13000/24/42型放顶煤支架适应性良好|工作面超前支承压力分布具有应力集中系数低、超前影响范围小等特征,对回采巷道影响不显著|研究结论为类似条件工作面安全高效回采提供有益借鉴。     

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