Performance of dry-separation processes in the recovery of cenospheres from fly ash and their implementation in a recovery unit     

H.T.B.M. Petrus  Tsuyoshi Hirajima  Yuji Oosako  Moriyasu Nonaka  Keiko Sasaki  Takashi Ando 《International Journal of Mineral Processing》2011,98(1-2):15-23

Cenospheres recovery is one of the coal fly ash beneficiations, providing economic as well as environmental benefits. Current techniques, such as lagoon or other wet-separation processes, consume large amounts of water and add to water pollution due to leaching of toxic materials from fly ash. The other possible disadvantage is the need for a wide operational area, which is unsuitable for densely populated countries. As wet-separation processes have some disadvantages, an improved and/or sustainable alternative recovery technique is required. An air classifier is one of the alternative techniques. In this study, two types of air classifiers, namely a closed-type pneumatic separator and a micron separator, have been investigated. In terms of separation efficiency, it was found that the micron separator has the potential to be applied in cenospheres recovery from coal fly ash, giving a Newton's efficiency of 0.44, as compared to a value of about 0.26 for the closed-type pneumatic separator. The cenospheres recoveries of both pieces of equipment at their optimum Newton's efficiencies were similar at over 60 wt.%. The separation performance was further assessed from the particle distributions of the overflow and underflow products obtained from both pieces of equipment, as well as from SEM images. It was found that the lower Newton's efficiency of the closed-type pneumatic separator was due to the re-concentration of fine particles in the underflow product at air-flow rates higher than 2.2 m/s (the underflow product yield was about 55 wt.%).In order to further confirm the applicability of this technique, the micron separator, which had provided higher separation efficiency and cenospheres recovery, was deployed in a cenospheres recovery unit prior to the use of a wet-separation process (float and sink tank). About 80% of the cenospheres was recovered, with an 87.8% reduction in the total mass of fly ash to be separated in the float and sink tank. Consequently, much less water was needed for the process of cenospheres recovery. Moreover, it was also confirmed that the micron separator could yield higher quality fly ashes, that is, fly ash types I and II, from lower feed quality of fly ash type IV, which is the lowest category in commercial classification of fly ash according to JIS A6201.  相似文献   

In situ observation of a garnet/perovskite transition in CaGeO<Subscript>3</Subscript>     

Shigeaki Ono  Takumi Kikegawa  Yuji Higo 《Physics and Chemistry of Minerals》2011,38(9):735-740

We used an in situ measurement method to investigate the phase transition of CaGeO₃ polymorphs under high pressures and temperatures. A multi-anvil high-pressure apparatus combined with intense synchrotron X-ray radiation was used. The transition boundary between a garnet and a perovskite phase at T = 900–1,650 K and P = 3–8 GPa was determined as occurring at P (GPa) = 9.0−0.0023 × T (K). The transition pressure determined in our study is in general agreement with that observed in previous high-pressure experiments. The slope, dP/dT, of the transition determined in our study is consistent with that calculated from calorimetry data.  相似文献   

西藏班戈县东嘎花岗岩体特征及锡找矿前景分析     

申文环  王玉吉  田秀荣  彭明章  赵丽娜 《中国煤炭地质》2013,(12):83-86

东嘎花岗岩体位于冈底斯一念青唐古拉板片北缘、班公错一怒江结合带中段班戈一崩错板片。岩体时代为燕山晚期,属印度一欧亚板块碰撞造山构造环境。岩石属富钠、硅铝过饱和类型,该岩体位于斑戈一嘉黎一波密一察隅锡成矿远景带内,岩浆分异程度高,具有S型花岗岩体的典型特征,与滇西、川西含锡花岗岩体特征相似,成矿条件有利。区域化探资料显示锡异常明显,异常为Sn、Rb、Y、u、Nb、Ag、w、Th、Pb等多元素组合。sn元素的强度高、规模大。据区域地质、岩石化学及地球化学特征及区域成矿资料,东嘎花岗岩体具有良好的锡成矿前景。  相似文献   

Urban mapping,accuracy, & image classification: A comparison of multiple approaches in Tsukuba City,Japan     

Rajesh Bahadur Thapa  Yuji Murayama 《Applied geography (Sevenoaks, England)》2009,29(1):135-144

The rapid growth of urban space and its environmental challenges require precise mapping techniques to represent complex earth surface features more accurately. In this study, we examined four mapping approaches (unsupervised, supervised, fuzzy supervised and GIS post-processing) using Advanced Land Observing Satellite images to predict urban land use and land cover of Tsukuba city in Japan. Intensive fieldwork was conducted to collect ground truth data. A random stratified sampling method was chosen to generate geographic reference data for each map to assess the accuracy. The accuracies of the maps were measured, producing error matrices and Kappa indices. The GIS post-processing approach proposed in this research improved the mapping results, showing the highest overall accuracy of 89.33% as compared to other approaches. The fuzzy supervised approach yielded a better accuracy (87.67%) than the supervised and unsupervised approaches. The fuzzy supervised approach effectively dealt with the heterogeneous surface features in residential areas. This paper presents the strengths of the mapping approaches and the potentials of the sensor for mapping urban areas, which may help urban planners monitor and interpret complex urban characteristics.  相似文献   

中巴地球资源卫星在辽东区域环境监测中的应用评价研究   总被引：8，自引：0，他引：8  

刘玉机  胡远满  布仁仓  韩玺山 《测绘科学》2000,25(2):30-32

对中巴资源一号卫星 CCD传感器接收的辽宁省营口幅数据 ,从几何精度、空间分辨率、数据噪声等方面 ,进行了图像数据质量评价 ,认为从总体上讲 ,达到了设计要求 ,具有广阔的应用前景 ,同时指出 ,CCD传感器在稳定性和同一性方面尚需改进  相似文献   

基于用岛类型和方式的舟山市无居民海岛分类保护应用研究          下载免费PDF全文

李爱国  邬梁超  王平波  应诗瑶  金瑜嘉  叶云  廖维敏 《海洋开发与管理》2022,39(8):85-90

无居民海岛是舟山市经济、社会和生态发展的重要资源支撑。为促进舟山市无居民海岛的精细化管理和可持续发展,文章分析舟山市无居民海岛开发利用和保护存在的问题,提出无居民海岛分类保护原则,基于国家权益类、自然保护区类、海洋特别保护区类、其他重要保护类、限制开发类和保留类的单岛功能定位分别制定管理方案,基于旅游娱乐用岛等9种用岛...  相似文献   

Long-Term Variations of Potential Temperature and Dissolved Oxygen of the Japan Sea Proper Water   总被引：4，自引：0，他引：4  

Hideto Minami  Yuji Kano  Kan Ogawa 《Journal of Oceanography》1999,55(2):197-205

Observed potential temperatures and concentrations of dissolved oxygen are analyzed to elucidate their variations during the period from 1958 to 1996 at Stn. P (37°43′ N, 134°43′ E) and from 1965 to 1996 at Stn. H (40°30′ N, 137°40′ E) in the Japan Sea. At Stn. P, increases of the potential temperature for the period are found below 800 m depth with the largest value of 0.16 ± 0.09°C per century at 800 m depth. At Stn. H, the potential temperature increased below 500 m depth. The increase rate has the largest value of 0.50 ± 0.18°C per century at 500 m depth and it is 0.30 ± 0.09°C per century at 800 m depth. The concentrations of dissolved oxygen increased around 800 m depth at Stn. P. At Stn. H, they increased above 800 m depth. On the other hand, they decreased below 1200 m depth at both stations. The layer of the dissolved oxygen minimum has deepened in these decades. These features appearing in the distributions of temperature and dissolved oxygen are successively simulated by a vertical one-dimensional advection-diffusion model including consumption of dissolved oxygen and termination of the deep water supply. These results suggest that the supply of the Japan Sea Proper Water into the deep layer, which is cold and rich in dissolved oxygen, has been decreasing for the last four decades. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Mechanical properties and stress–dilatancy relationships of unsaturated soil under various cyclic loading conditions     

Tun Tun  Win  Sato  Tomotaka  Saito  Hirotaka  Kohgo  Yuji 《Acta Geotechnica》2020,15(7):1799-1813

Acta Geotechnica - Most studies investigating the effect of cyclic loading on soil properties have been conducted for saturated soils. Embankments such as fill dams, roads and railways are usually...  相似文献   

台风过境期间辽河口滨海湿地水动力特征的数值模拟研究          下载免费PDF全文

王煜嘉  孙振宇  赵学凯  赵梓宇  弓耘  许慧  张明亮 《应用海洋学学报》2024,43(1):020-032

本研究基于FVCOM环流模型,耦合ECMWF背景风场和Jelesnianski台风经验模型形成合成风场,对9711台风“温妮”过境辽河口区域的水动力进行模拟研究。模型通过在动量方程、湍流方程中加入附加源项来表达盐沼植被对水动力的阻碍作用。使用研究区域实测的潮位、流速、流向等数据对水动力模型进行验证,模拟结果与实测数据吻合较好。结果表明：潮滩盐沼植被对台风过境期间的潮位变化无明显影响,但对流速具有显著的衰减作用,且芦苇对潮流的衰减作用大于盐地碱蓬植被,芦苇区的速度最大衰减率达81.43%。此外,台风路径变化对辽河口湿地海域的增减水及流速影响较大,台风强度越强,局部区域造成的风暴潮增水和流速也相应越大。  相似文献   

基于遥感的江苏省区域建设用海集约利用现状评价          下载免费PDF全文

王玉洁  汤茹男  蔡雯沁  张慧铭  潘铄宇  张东 《海洋开发与管理》2019,36(11):15-22

区域建设用海是海域使用的一种重要方式。文章以土地与海域集约利用评价为参照,从"投入—产出"的角度出发构建了区域建设用海集约利用评价指标体系,利用遥感解译方法从2017年高分影像中提取并计算了江苏省12个区域建设用海的主要评价指标值,应用TOPSIS模型评价了江苏省沿海已建项目的集约用海现状。研究表明:①江苏省区域建设用海开发利用程度较低,53.2%的土地处于未利用状态,农渔业为面积占比最小的用地类型,江苏省对第二、第三产业的发展更为重视。②已有的开发活动中,人工设施面积较小,建筑与道路等面积占比远小于生态面积,区域生态健康状况良好。③根据指标计算,江苏省区域建设用海集约利用评价得分集中在0.4～0.6,集约利用程度整体较低,不同项目集约化利用程度差异较小,主要原因在于项目投资强度两极分化,道路等基础设施不够完善等。④从不同用海类型来看,交通运输用海集约利用程度最高,其用海结构布局最适宜,效率最高。文章所建指标具有指向性,应用TOPSIS模型进行无须赋予权重,因此更能客观真实地反映江苏省区域建设用海的集约利用情况。  相似文献