优质页岩陶粒滤料的制备与基本性能研究

以天然页岩为原料,分别采用破碎法和成球法制成滤料生料,经焙烧,膨胀,制备了陶粒滤料.对这2种方法制备的陶粒滤料的孔隙率、孔径和酸碱可溶率等指标进行了分析比较.结果表明,2种方法均可制备出性能优异的陶粒滤料.陶粒滤料的制备方法对其性能影响不大,而焙烧程序对陶粒滤料的性能有较大影响.实际生产时,可根据页岩特性、生产成本等确定陶粒滤料的制备方法.     

不同孔隙率对采空区自燃的影响规律研究

为探究煤矿采空区在不同孔隙率条件下对煤自燃环境的影响,基于多孔介质渗流特性的相关理论,以煤矿综采工作面为原型建立了U型通风采空区三维模型和渗流数学模型,利用Fluent软件对采空区以不同的孔隙率大小和分布方式进行数值模拟计算,从而得到采空区的漏风和氧气浓度的分布状态,以及氧化带的位置变化情况,进而研究不同孔隙率对采空区煤自燃环境的影响规律。研究表明:采空区漏风主要源于工作面下隅角处,进入采空区的漏风量大小与采空区的孔隙率有关。孔隙率越大,靠近工作面的漏风流速越大,氧气浓度越高,而深入采空区,孔隙率大小对采空区漏风影响越小,氧化带随着孔隙率的增大不断向采空区深部移入;孔隙率分布方式对采空区漏风速度的影响较大,且距离工作面越近影响越大,采空区深部则差别不大。     

Quantification of changes in zero valent iron morphology using X-ray computed tomography

Morphological changes within the porous architecture of laboratory scale zero valent iron （ZVI） permeable reactive barriers （PRBs）, after exposure to different groundwater conditions, have been quantified experimentally for different ZVI/sand ratios （10%, 50% and 100%, W/W） with the aim of inferring porosity changes in field barriers. Column studies were conducted to simulate interaction with different water chemistries, a synthetic groundwater, acidic drainage and deionised （DI） water as control. Morphological changes, in terms of pore size and distribution, were measured using X-ray computed tomography （CT）. CT image analysis revealed significant morphological changes in columns treated with different water chemistries. For example, 100% ZVI （W/W） columns had a higher frequency of small pores （0.6 mm） was observed in ZVI grains reacted with typical groundwater, resulting in a porosity of 27%, compared to 32% when exposed to DI water. In comparison, ZVI grains treated with the acidic drainage had higher porosity （44%） and larger average pore size （2.8 mm）. 10% ZVI PRB barrier material had the highest mean porosity （56%） after exposure to any water chemistry whilst 100% ZVI （W/W） columns always had the lowest （34%） with the 50% ZVI （W/W） in between （40%）. These results agree with previously published PRB field data and simultaneously conducted geochemical monitoring and mass balance calculation, indicating that both the geochemical and hydraulic environment of the PRB play an important role in determining barrier lifespan. This study suggests that X-ray CT image analysis is a powerful tool for studying the detailed inter pores between ZVI grains within PRBs.     

填埋场排水层结构对其渗透性能的影响

垃圾填埋场存在着因渗滤液收集和排水系统渗透性能减弱而失效的问题,威胁着填埋场的安全稳定及其周边地质环境。因此,研究填埋场排水层结构及其渗透性演变规律对垃圾填埋场的正常运营及其对周边环境的影响评价具有重要现实意义。以相似理论为基础,采用现场垃圾渗滤液作为渗流流体,对比分析了2种结构排水层、3个渗流段的排水孔隙度和渗透性的演变规律。研究结果表明:渗滤液在单粒组结构排水层渗流时,第3渗流段渗透性的变化滞后于第2渗流段及第1渗流段;砂砾粒径较渗流深度对排水孔隙度的影响作用更大;砂砾粒径越大,排水层淤堵的发生时间越晚;在排水层中间段设置粒径较大的砂砾层,可以减缓排水层渗透性的降低速率。     

沿海农田林网建设关键技术的经济学择优

对江苏沿海地区农田林网的经营类型、造林树种、林带配置进行了技术经济学分析和多目标灰色局势决策择优。结果表明：农田林网经营类型宜选择复合经营的果材兼用型林网。造林树种可选择速生丰产的杨树等用材树种和经济效益高的桃树等果树。林网配置在海堤河岸上选择用材树种,营造基干林带,筑起大网格框架；在道路沟渠上立体配置林果树种,营造主林带和副林带,构建中网格；在脱盐排水沟上添加果树辅助林带,建立小网格,形成多树种多林种合作、大中小网格配套、多道防线联防、多效益多产品产出的复合配置模式。     

滨海沙滩造林种果后土壤理化性质的变化

在滨海沙滩营造木麻黄防护林，林带老化后进行更新，部分林地改种潮州柑或芒果而成为果园，并于其间套种农作物或牧卓；结果表明，人为耕作活动对土壤的热化起到了明显的促进作用．在造林种果的同时，大量肥料的施入及优质客土改良了土壤，使＞１．０ｍｍ的砂粒比例明显减少，＜０．０１ｍｍ的粉粘粒及土壤养分含量明显增加，其中沙草地、防护林及果园，０—４０ｃｍ土壤粉粘粒含量分别为５６．４ｇ／ｋｇ、５９．６ｇ／ｋｇ和１０８．９ｇ／ｋｇ，土壤有机质为０．７１ｇ／ｋｇ、２．０２ｇ／ｋｇ和４．１１ｇ／ｋｇ；土壤氮素含量随有机质提高而提高，柑园速效磷和钾含量是沙草地的３７倍和３．５倍，然而防护林的种植对土壤速效磷和钾的影响却不明显；由于雨水淋洗，土壤盐分减少；又由于酸性化学肥料的大量施入，土壤ｐＨ值由８．３下降为５．３．果园的营建，明显改善了土壤的肥力状况及其保水保肥性能，提高了沙滩地的利用价值及生态经济效益．     

改性活性炭在环境保护中的应用

活性炭是一种应用广泛的吸附催化剂 ,其性能取决于它的孔隙结构和表面化学性质。为了提高其吸附效率和改善其吸附选择性及其催化性能 ,往往需要对活性炭的孔隙结构进行调整以及改变其表面化学性质。综述了活性炭的改性方法及其特点、改性活性炭在环境保护中的应用及其再生等方面的研究概况     

An analytical model for the interpretation of pulse injection experiments performed for testing the spatial variability of clay formations

This paper presents an analytical model to describe pulse injection experiments. This model solves the advection-diffusion equation while taking into account back diffusion from the clay core to the inlet and from the outlet to the clay core. In most analytical models, back diffusion is neglected. For sufficiently high Péclet numbers, this is a good approximation. However, in experiments where the Péclet number is low, back diffusion is important and must be taken into account. An additional advantage of the present model is that both concentration and flux are conserved at the inlet and at the outlet of the clay core. This model is used to fit pulse injection experiments with iodide and tritiated water (HTO) in clay cores. The (new) model is required for fitting the experimental results since in clay layers advection is very slow leading to a low Péclet number. The experiments are performed on clay cores taken from different depths from the Boom Clay and the Ypres Clay layer under the site of the nuclear power plant of Doel (Belgium). The quality of all fits is excellent and the obtained parameter values are coherent. For HTO, the fitted value for the diffusion accessible porosity is consistent with measurements of the water content in Ypres Clay cores. In both types of clays, the apparent diffusion coefficient at zero flow is between 10(-10) and 2 x 10(-10) m(2)/s for iodide and between 2 x 10(-10) and 3 x 10(-10) m(2)/s for HTO. The dispersion length is in the order of 10(-3) m. The average value for the diffusion accessible porosity is between 0.35 and 0.4 for HTO and between 0.2 and 0.25 for iodide.     

纳米材料污染物在土体中运移的研究进展

纳米材料以污染物形式进入土体,并对土体环境产生影响。从理论与实验两个方面对国外相关研究进行了综述分析。理论方面主要参照胶体运移机理对纳米材料在土体中运移过程进行初步解释。实验方面,多以柱淋洗实验模拟纳米材料在孔隙介质中运移过程,并着重探究了影响纳米材料运移性能的主要因素。最后,基于现有研究的成果与不足,提出了相应的研究展望。     

不同瓦斯压力和孔隙率的原煤电阻率和渗透率变化规律研究

为了解不同瓦斯压力和孔隙率下原煤的电阻率和渗透率变化及电阻率和渗透率的响应规律,以淮南矿区谢一矿51采区C15煤层煤体为研究对象,研究不同瓦斯压力和孔隙率下煤样三轴压缩全过程的电阻率与渗透率的变化规律。研究结果表明:孔隙率相同时,最小电阻率和最小渗透率随着瓦斯压力的增大先增加后减小,瓦斯压力在4 MPa时,最小渗透率基本为0;瓦斯压力相同时,最小电阻率和最小渗透率随着孔隙率的增大而增大;全应力应变过程电阻率和渗透率满足随应变的增大先减小后增大的规律,不同加载阶段电阻率变化和渗透率变化规律保持一致,渗透率变化幅度比-应变曲线拐点滞后于电阻率变化幅度比-应变曲线;可利用电阻率变化规律反映应力变化以及渗透率变化情况。