金属矿山尾矿处理技术进展

介绍了国内外在尾矿高效浓缩、全尾矿充填采空区和膏体尾矿干式堆存方面的研究和应用进展;分析了这些尾矿处理新方法的特点;指出随着人们环保意识的增强,安全、高效和环境友好的尾矿处理方法将逐步取代传统的尾矿地表堆存方法。     

LAB-SCALE IMPULSE DRYING EXPERIMENTS WITH EXTENSION TO HIGHER IMPULSE

Impulse drying uses high temperature and high impulse in the press section of the paper machine. The technique can increase the water removal rate and thereby minimize the size of the dryer section or alternatively increase production capacity. Additionally, the technique improves paper properties compared to conventional wet pressing. This paper contains a discussion of the value associated with extending the press impulse in impulse drying. Experiments were conducted in a lab-scale press simulator. Experiments with 150 g/m² liner were conducted with four different press impulses, 160, 260, 360 and 450 kPa s. The impulse was varied by changing the dwell time between the pressurization and the depressurization phase. It was shown that increasing the nip length and press load beyond conventional shoe press limits gave noteworthy press dryness and sheet strength advantages. The impulse drying experiments were also compared with single and double-felted wet pressing experiments.     

LAB-SCALE IMPULSE DRYING EXPERIMENTS WITH EXTENSION TO HIGHER IMPULSE

Impulse drying uses high temperature and high impulse in the press section of the paper machine. The technique can increase the water removal rate and thereby minimize the size of the dryer section or alternatively increase production capacity. Additionally, the technique improves paper properties compared to conventional wet pressing. This paper contains a discussion of the value associated with extending the press impulse in impulse drying. Experiments were conducted in a lab-scale press simulator. Experiments with 150 g/m² liner were conducted with four different press impulses, 160, 260, 360 and 450 kPa s. The impulse was varied by changing the dwell time between the pressurization and the depressurization phase. It was shown that increasing the nip length and press load beyond conventional shoe press limits gave noteworthy press dryness and sheet strength advantages. The impulse drying experiments were also compared with single and double-felted wet pressing experiments.

     

超临界CO_2萃取干燥技术及其在低阶煤干燥中的研究进展

综述了超临界CO2萃取干燥技术的原理及工艺流程,简要评述了国外超临界CO2萃取干燥低阶煤的研究进展,与传统干燥技术相比,超临界CO2萃取干燥技术具有快速、高效、干燥应力小等优点。     

Advances and Challenges on Algae Harvesting and Drying

Biodiesel production from algae offers a promising prospect for practical applications among the still developing biofuel technologies. The fact that algae are capable of producing much more yield provides an edge over other types of biofuel. Though algal biofuel research is still developing and its practical application is yet to be ascertained, promising work on laboratory- and pilot-scale algae harvesting systems has been extensively reported. Because algae harvesting and drying are vital elements in biofuel production, recent advances on various algae harvesting, dewatering, and drying technologies are reviewed and discussed. Challenges and prospects of algae harvesting and drying are also outlined.     

Electrical field: A historical review of its application and contributions in wastewater sludge dewatering

Electric field-assisted dewatering, also called electro-dewatering, is a technology in which a conventional dewatering mechanism such a pressure dewatering is combined with electrokinetic effects to realize an improved liquid/solids separation, to increase the final dry solids content and to accelerate the dewatering process with low energy consumption compared to thermal drying. Electro-dewatering is not a new idea, but the practical industrial applications have been limited to niche areas in soil mechanics, civil engineering, and the ceramics industry. Recently, it has received great attention, specially, in the fields of fine-particle sludge, gelatinous sludge, sewage sludge, pharmaceutical industries, food waste and bull kelp, which could not be successfully dewatered with conventional mechanical methods. This review focuses on the scientific and practical aspects of the application of an electrical field in laboratory/industrial dewatering, and discusses this in relation to conventional dewatering techniques. A comprehensive bibliography of research in the electro-dewatering of wastewater sludges is included.As the fine-particle suspensions possess a surface charge, usually negative, they are surrounded by a layer with a higher density of positive charges, the electric double layer. When an electric field is applied, the usually negative charged particles move towards the electrode of the opposite charge. The water, commonly with cations, is driven towards the negative electrode. Electro-dewatering thus involves the well-known phenomena of electrophoresis, electro-osmosis, and electromigration. Following a detailed outline of the role of the electric double layer and electrokinetic phenomena, an analysis of the components of applied voltage and their significance is presented from an electrochemical viewpoint. The aim of this elementary analysis is to provide a fundamental understanding of the different process variables and configurations in order to identify potential improvements. Also discussed herein is the investigation of the electrical behaviour of a porous medium, with particular emphasis on porous medium conductivity determination.     

Sequential polymer dosing for effective dewatering of ATAD sludges

Dewatering problems associated with the sludge from autothermal thermophilic aerobic digestion (ATAD) of sludge, result in large chemical conditioning costs for effective dewatering. A variety of chemical conditioners were used to improve dewatering, but none of them were able to dewater the sludge as desired at acceptable conditioning doses. It was found that during the digestion process, chemical precipitation of divalent cations occurred. Some of the ATAD sludge colloids were found to have a positive zeta potential and these were thought to be the precipitated divalent cations. Sequential polymer dosing using either iron or cationic polymer, followed by anionic polymer, was found to improve dewatering. The use of anionic polymer is essential and allows the use of smaller amounts of iron or cationic polymer for effective dewatering. The use of the less expensive anionic polymer along with cationic polymers has the potential to make the use of the ATAD process more economical.     

液压油过滤脱水

本文研究了利用纤维材料的表面特性解决液压油的脱水问题的理论,并设计和制作 滤芯,实验效果良好。