Surface chemical analysis in coal preparation research: complementary information from XPS and ToF-SIMS     

A. N. Buckley  R. N. Lamb 《International Journal of Coal Geology》1996,32(1-4)

The application of X-ray photoelectron spectroscopy (XPS) to coal surface characterisation for preparation research is described. Progress towards the acquisition of complementary surface chemical information by time-of-flight secondary ion mass spectrometry (ToF-SIMS) is also discussed. Surface-based beneficiation techniques such as flotation are assuming greater importance as the proportion of fines in raw coal increases due to the proliferation of high capacity mining methods. A necessary condition for the floatability of a coal particle is adequate hydrophobicity, and the degree of hydrophobicity of the flotation concentrate is one factor influencing the ease with which its dewatering can be affected. The hydrophobicity of a coal is very difficult to measure directly because of microporosity, and it is often necessary to deduce the degree of hydrophobicity from a knowledge of the surface chemistry. XPS is able to provide sufficient analytical data to allow relative levels of hydrophobicity to be estimated. In principle, ToF-SIMS should be able to supply additional information enabling refinement of such estimates; however, there are insufficient data at present to allow the ionic fragments detected to be related to specific functional groups at the coal surface.  相似文献   

Characterisation of brown coal humic acids and modified humic acids using pyrolysis gcms and other techniques     

W. R. Jackson  G. D. Bongers  P. J. Redlich  G. Favas  Y. Fei  A. F. Patti  R. B. Johns 《International Journal of Coal Geology》1996,32(1-4)

It has been proposed that Victorian brown coal can be considered as a two-component structure — a lignocellulosic “host”, containing various amounts of weakly bound or entrapped “guest” material together with very small amounts of inorganic and/or mineral matter. The latter predominantly consists of wax esters and/or terpenoid material. In this paper we describe attempts to gain structural information regarding the more complex, “host” component of the coal. Our initial model compound has been humic acid that can be readily obtained from the coal by alkaline extraction. It has been found that “pure” humic acid, free from material associated with the “guest” components of the coal, can be obtained by a highly selective, low-yielding alkaline extraction. This humic acid has been studied by nmr spectroscopy and pyrolysis gas chromatography-mass spectroscopy (py-gc/ms). The products arising from py-gc/ms have been compared with those obtained from similar pyrolysis of whole coals. Alkylation of humic acids using alkyl halides in the presence of base has been successfully carried out and reactivity of the resulting materials compared with those of the parent coal and humic acid.  相似文献   

三江盆地七星河区成因地层分析   总被引：1，自引：0，他引：1  

邹艳荣  蔡玉兰 《煤田地质与勘探》1996,24(1):1-4

区内存在５种等时性地层界面，据此将含煤岩系划分为６个成因单元，１０个亚单元。沉积环境经历了５个演化阶段，其中扇三角洲废弃阶段为最有利的聚煤时期。聚煤的有利部位位于废弃的扇三角洲体之上。  相似文献   

水压与钻孔联合爆破拆除大型地面煤仓          下载免费PDF全文

李玉民  赵锦桥  孙文进 《探矿工程》1996,(6):47-48

分析了水压与钻孔联合爆破的特点，给出了设计方法及参数，实践表明，在坚固筒体内构筑物拆除中应用该技术可取得安全，快速解体破碎和定向倾倒的良好效果。  相似文献   

淮南谢—矿煤的组成对甲烷吸附性的影响     

姚多喜 《中国煤田地质》1996,(Z1)

从淮南谢—矿五层煤（Ｃ＿（１３）、Ｂ＿（１１ｂ）、Ｂ＿（１０）、Ｂ＿（４ｂ）和Ａ＿３）中精选出镜煤、壳质暗煤、惰性暗煤及构造煤，采用重量法，分别测定它们的甲烷吸附量，从而研究不同成分组成的煤其甲烷吸附性能。  相似文献   

井筒及围岩应力,应变观测方法研究     

苏仲杰  隋惠全 《岩土力学》1997,18(3):82-87

采用最新研制的岩体应力、应变匹配传感器对西安立井煤柱开采引起的井筒附加应力特别是对井筒穿过断层附近产生的附加应力进行了较系统的观测，并对观测结果进行了分析和总结。  相似文献   

抚顺盆地超厚煤层的沉积条件分析   总被引：11，自引：0，他引：11  

吴冲龙  王海清 《煤田地质与勘探》1997,25(2):1-6

根据抚顺盆地早第三纪超厚煤层中异常丰富的成因标志，论证了一种与河流、风暴作用有关的陆相超厚煤层形成新机制－湖成异地－微异地混合堆积机制。在这一新机制中，由风暴上升流（也许还有地震）触发的水下重力流及风暴回流，既驱动湖滨泥炭沼泽和三角洲上的有机碎屑及无机碎屑进入湖泊中心区，又造成泥炭碎屑在较深水环境的再次堆积，从而使其中无机碎屑与泥炭碎屑有效地分离。  相似文献   

新疆伊犁盆地侏罗纪煤岩特征及煤相   总被引：2，自引：1，他引：2  

张井  王士俊 《煤田地质与勘探》1997,25(3):21-26

应用煤岩学方法，探讨了新疆伊犁盆地侏罗纪煤的煤岩特征及煤相划分，将煤相划分为９种类型即干燥森林沼泽相，潮湿森林沼泽相，草木混生型沼泽相或芦苇沼炭沼泽相。通过煤相分析，为伊犁盆地成煤环境的研究提供了佐证。  相似文献   

Flexible spectral methods for the generation of random fields with power-law semivariograms     

Johannes Bruining  Diederik van Batenburg  Larry W. Lake  An Ping Yang 《Mathematical Geology》1997,29(6):823-848

Random field generators serve as a tool to model heterogeneous media for applications in hydrocarbon recovery and groundwater flow. Random fields with a power-law variogram structure, also termed fractional Brownian motion (fBm) fields, are of interest to study scale dependent heterogeneity effects on one-phase and two-phase flow. We show that such fields generated by the spectral method and the Inverse Fast Fourier Transform (IFFT) have an incorrect variogram structure and variance. To illustrate this we derive the prefactor of the fBm spectral density function, which is required to generate the fBm fields. We propose a new method to generate fBm fields that introduces weighting functions into the spectral method. It leads to a flexible and efficient algorithm. The flexibility permits an optimal choice of summation points (that is points in frequency space at which the weighting function is calculated) specific for the autocovariance structure of the field. As an illustration of the method, comparisons between estimated and expected statistics of fields with an exponential variogram and of fBm fields are presented. For power-law semivariograms, the proposed spectral method with a cylindrical distribution of the summation points gives optimal results.  相似文献   

Influence of gas production induced volumetric strain on permeability of coal   总被引：10，自引：0，他引：10  

Satya Harpalani  Guoliang Chen 《Geotechnical and Geological Engineering》1997,15(4):303-325

Summary The gas permeability of a coalbed, unlike that of conventional gas reservoirs, is influenced during gas production not only by the simultaneous changes in effective stress and gas slippage, but also by the volumetric strain of the coal matrix that is associated with gas desorption. A technique for conducting laboratory experiments to separate these effects and estimate their individual contribution is presented in this paper. The results show that for a pressure decrease from 6.2 to 0.7 MPa, the total permeability of the coal sample increased by more than 17 times. A factor of 12 is due to the volumetric strain effect, and a factor of 5 due to the gas slippage effect. Changes in permeability and porosity with gas depletion were also estimated using the measured volumetric strain and the matchstick reservoir model geometry for flow of gas in coalbeds. The resulting variations were compared with results obtained experimentally. Furthermore, the results show that when gas pressure is above 1.7 MPa, the effect of volumetric strain due to matrix shrinkage dominates. As gas pressure falls below 1.7 MPa, both the gas slippage and matrix shrinkage effects play important roles in influencing the permeability. Finally, the change in permeability associated with matrix shrinkage was found to be linearly proportional to the volumetric strain. Since volumetric strain is linearly proportional to the amount of gas desorbed, the change in permeability is a linear function of the amount of desorbing gas.  相似文献