某深埋长隧地应力演化及围岩应力位移模拟研究

结合西部地区某深埋长大公路隧道信息化施工 ,对深埋长隧地应力演化及围岩应力位移进行了弹塑性有限元数值模拟研究。研究结果表明 ,隧道轴线现代地应力状况与隧道埋深、地层岩性及构造发育程度有关 ,最大地应力为40 0MPa左右 ;隧道周边围岩应力在曲边墙底部最大 ,约 3 8 0MPa ,隧道开挖引起的围岩应力影响范围约 2 5 0m ;隧道水平收敛和拱顶下沉位移与隧道埋深近于成直线关系。这些研究结果为深埋长隧信息化设计和施工以及围岩稳定性分析提供了科学依据。     

矿产品供需关系经济分析

矿产品供需关系决定矿产品价格的市场走向，运用供需二维图解可以预测矿产品供需动态，给出精确的供需二维图要注意资源增加与减少、代用材料和新产品开发等因素，指出精心积累矿产品供需资料，仔细观察供需关系，可以预测矿产品价格和市场走向。     

Design of backfilled thin-seam coal pillars using earth pressure theory

In underground coal mining any increase in coal recovery rate is dependent on a decrease in pillar size. Backfilling is one way of reducing the required size of pillars and hence the volume of coal left underground. Therefore any comparisons made between a self-supported mine layout and backfill supported mine layout are based directly on pillar design. The most effective way to examine the effect of backfill on pillar support, and subsequently the rate of recovery, would be to incorporate the mechanisms of backfill support directly into the current design procedure for coal pillars. This paper presents a review of the mechanics of backfill support, a method of estimating the magnitude of that support based on earth pressure theory, and an example that incorporates backfill support into current coal pillar design.     

Oxidation of As-bearing gold ore—a comparison of batch and column experiments

This study deals with the experimental determination of the rate of weathering and As release from Au-bearing sulfide ores of the Mokrsko-West deposit (Czech Republic). The elevated As contents in the ore and the possible As mobilisation must be taken into account due to the close proximity of the deposit to the Vltava River, a source of drinking water for Prague. Crushed and homogenized ore material was divided into four grain-size fractions showing uniform chemical and mineralogical composition and subjected to batch and column leaching experiments. The most important reactions controlling metal leaching include (i) oxidation of sulfides, (ii) carbonate equilibrium and (iii) precipitation of hydrated ferric oxides (HFO). Hydrated ferric oxides were found to be important sorbents of mobilized As. The highest concentration of As in the leachates was obtained from the 64–1000 μm fraction. The oxidation rate in the agitated batch experiment calculated on the basis of sulfate concentrations is an order of magnitude higher (3.8×10⁻⁹ to 4.4×10⁻⁸ mol SO₄²⁻ h⁻¹ g⁻¹) than in the static column experiment (9.6×10⁻¹⁰ to 7.4×10⁻⁹ mol SO₄²⁻ h⁻¹ g⁻¹). The higher oxidation rate of batch experiments is explained by abrasion of oxidation products (mainly HFO) and by further exposition of reaction surfaces of the sulfide grains.     

Effective resource estimates for primary diamond deposits from the EKATI Diamond Mine™, Canada

Primary economic diamond deposit modelling has rarely been documented in the public domain. This paper presents information collected from significantly diamondiferous kimberlite pipes located near Lac de Gras in the Arctic region of Canada's Northwest Territories. The resource estimation process is widely accepted as a cyclical iteration of data collection and evaluation processes. A resource database is typically assembled from a large inventory of exploration data. These data must be methodically quality checked before accepting the information for interpretive analysis. The foundation of a mineral resource model is based on clear understanding of the geology model along with subsidiary grade, volume, and density models. Defining these models is an iterative process of statistical analyses and interpretation. As a deposit progresses along a path towards development, reducing risk to acceptable levels is critical for identifying and realizing its maximum value.     

Mapping the Bonanza: Geographies of Mining Investment in an Era of Neoliberal Reform*

Geographic analyses of how national policies of economic liberalization influence global patterns of economic activity often draw their conclusions from studies of the paradigmatic sectors of manufacturing and, to a lesser extent, services. There is, by contrast, relatively little work examining how neoliberal policy reforms in the developing world may be driving changes in the geography of primary sector (i.e., extractive) activities at the global scale. This article presents and analyzes new data on direct investment in the international mining industry. It reports methods and results from a research project to systematically map and evaluate changes in the commodity mix and geographical spread of mining‐related investment in the world economy since 1990. It confirms and quantifies what was hitherto anecdotal evidence of a geographic shift in investment during the 1990s away from mature targets toward a small number of “rising stars” in the developing world, following the adoption in many countries of neoliberal economic policies from the mid‐1980s onward. However, the findings challenge conventional interpretations of this shift as an investment “bonanza” in the periphery and highlight how recent investment trends are highly specific in geographical scope, concentrated within a few commodities, and how the allocation of investment between established and emerging targets is variable over both time and space.     

Primary component analysis method and reduction of seismicity parameters

Introduction Data mining (SHAO and YU, 2003) is a new kind of technique developed with database and artificial intelligence in recent years, which processes the data in the database to abstract the im- plied and pre-unknown, but potentially useful information and knowledge from large amounts of incomplete, noisy, blurring and stochastic data. For data mining, data purging is an important link beforehand that includes eliminating noise, making up lost domain, and deleting ineffective data, as…     

Experimental study on reduction of U (Ⅵ) by an anaerobic bacterium, Shewanella putrefaciens: Application to sandstone-hosted interlayer oxidation-zone type uranium deposits, China

An experimental study on reduction of U (Ⅵ) by anaerobic bacteria, Shewane//a putrefaciens, is first reported here in China. The experimental conditions were: 35℃ and pH =7.0-7.4, corresponding to a physicochemical environments in which the sandstone-hosted interlayer oxidation-zone type uranium deposit formed in Northwest China's Xinjiang. Bacteria adopted in the present experiment, Shewanella putrefaciens, occur extensively in natural environment. Our study shows that nano-crystal precipitates of uraninite quickly occurred on the surface of the cells within one week. It was found that the pitchblende was characterized by a random arrangement of uraninite nanocrystals (2-4 nm) in it, significantly different from natural pitchblende in which uraninite nanocrystals are arranged in order. Finally, a possible mechanism of uranium biomineralization by microorganisms in the deposits is discussed. Our investigation may supply a technical train of thoughts for bioremediation of nuclear-contaminated water environments and for underground dissolving extraction of the sandstone-hosted uranium ores.     

东北地区矿业开发态势与矿山环境地质问题综合研究

在论述东北地区矿业开发态势的同时,阐述了区内能源矿产、金属矿产及非金属矿产开采引发的主要环境地质问题,针对区内复杂的矿山环境地质问题现状,提出了开展东北地区矿山环境地质综合研究问题的工作思路.     

Biomineralization of Uranium: A Simulated Experiment and Its Significance

A simulated experimental reduction of U^v1 and the synthesis of uraninite by a sulfate-reducing bacteria,Desulfovibrio desulfuricans DSM 642, are first reported. The simulated physicochemical experimental conditions were:35℃, pH=7.0-7.4, corresponding to the environments of formation of the sandstone-hosted interlayer oxidation-zone type uranium deposits in Xinjiang, NW China. Uraninite was formed on the surface of the host bacteria after a one-week‘s incubation. Therefore, sulfate-reducing bacteria, which existed extensively in Jurassic sandstone-producing environments,might have participated in the biomineralization of this uranium deposit. There is an important difference in the orderdisorder of the crystalline structure between the uraninite produced by Desulfovibrio desulfuricans and naturally occurring uraninite. Long time and slow precipitation and growth of uraninite in the geological environment might have resulted in larger uraninite crystals, with uraninite nanocrystals arranged in order, whereas the experimentally produced uraninite is composed of unordered uraninite nanocrystals which, in contrast, result from the short time span of formation and rapid precipitation and growth of uraninite. The discovery has important implications for understanding genetic significance in mineralogy, and also indicates that in-situ bioremediation of U-contaminated environments and use of biotechnology in the treatment of radioactive liquid waste is being contemplated.