Upgrading of calcareous phosphate ores by flotation: Effect of ore characteristics

Sedimentary phosphates contain-besides the phosphate minerals-, various associated gangue minerals such as: clays, silica, calcareous minerals (mainly calcite and dolomite), carbonaceous matter, iron oxides and/or pyrite. The common practiced flow-sheets for concentrating these types of phosphate ores consist of a combination of various mineral processing units such as: crushing and screening, attrition, washing, magnetic separation, and/or flotation. However, none of these combinations was successfully efficient to upgrade the calcareous ores because of the close similarity of the physical properties (density, particle size, particle shape, etc.) as well as the surface physico-chemical properties of the carbonate and phosphate minerals. For the last five decades extensive efforts have been spent to adopt flotation for separating carbonates from phosphate ores. These efforts include thermodynamic analysis, modification of the technique, controlling the pulp environment, and finding new reagents that can specifically differentiate between carbonates and phosphates.This paper reviews some of the published work on the separation of carbonates from phosphate ores by flotation and presents the flotation results of phosphate ore samples different in their physical properties and mineralogical composition. The results obtained reflect the effect of ore nature on the flotation performance and the reagents consumption.     

非开挖三维轨迹设计软件的应用与优化

文章对非开挖导向孔三维轨迹设计软件的功能和使用方法进行了介绍,对该系统近两年的工程应用进行了总结,并通过一个典型工程实例介绍了软件模拟施工环境和设计轨迹的过程。通过用户反馈信息的搜集,介绍了软件存在的部分问题及其改进方案,并对软件的进一步开发的思路进行了展望。     

Export upgrading and environmental performance: Evidence from China

This study argues that export upgrading can, but does not necessarily, lead to environmental improvement. A synergy between global and local linkage determines the likely disjuncture between export upgrading and environmental improvement. On the basis of the panel data covering 261 prefectural-level cities in China during 2003–2011, this study applies the decomposition of export sophistication to quantify diverse upgrading types. It also divides the sample cities into groups and uses the fixed-effect regression by groups to investigate the role of local linkages. Empirical findings indicate that environmental improvement associated with export upgrading in China has largely relied on changing product mix to avoid environmental costs, exhibiting a significant displacement effect. The role of efficiency promotion of production process is still insignificant. Local linkage may alter the environmental effects of export upgrading. Specialisation in polluting production can help cities to change product mix through the agglomeration of related firms. Stringent environmental regulation protects cities from the export–environment disjuncture through imposing additional costs. These findings suggest that the greening efforts of China should take one step further from export restructuring to efficiency promoting.     

Seismic upgrading of old masonry buildings by seismic isolation and CFRP laminates: a shaking-table study of reduced scale models

The efficiency of improving the seismic resistance of old masonry buildings by means of seismic isolation and confining the structure with CFRP laminate strips has been investigated. Five models of a simple two-story brick masonry building with wooden floors without wall ties have been tested on the shaking table. The control model has been built directly on the foundation slab. The second model has been separated from it by a damp-proof course in the form of a PVC sheet placed in the bed-joint between the second and the third course, whereas the third model has been isolated by rubber isolators placed between the foundation slab and structural walls. Models four and five have been confined with CFRP laminate strips, simulating the wall ties placed horizontally and vertically at floor levels and corners of the building, respectively. One of the CFRP strengthened models has been placed on seismic isolators. Tests have shown that a simple PVC sheet damp-proof course cannot be considered as seismic isolator unless adequately designed. Tests have also shown that the isolators alone did not prevent the separation of the walls. However, both models confined with CFRP strips exhibited significantly improved seismic behavior. The models did not collapse even when subjected to significantly stronger shaking table motion than that resisted by the control model without wall ties.     

城市污水处理厂升级改造工程设计与运行效果

为保护海洋环境,改善胶州湾的水污染现状,根据青岛市政府的要求对污水处理厂进行升级改造。主体生化工艺采用A2/O+移动床生物膜(MBBR)工艺,通过投加SPR-1生物填料,将好氧段改造为生物膜—活性污泥复合工艺。同时新建混凝、沉淀、过滤等深度处理设施。运行四年来,效果良好,抗冲击负荷能力强,可同时强化脱氮除磷,主要水质指标均稳定达到《城镇污水处理厂污染物排放标准》(GB18918-2002)一级A标准。实践证明,该工艺可大幅减少工程量,具有运行管理简便、处理效率稳定等特点,较好地解决了市政污水厂升级改造中的难题,可为其他污水厂的升级改造提供借鉴。同时,污染物年减排量明显提高,团岛海域水质环境质量将得到进一步改善。