Possible methods of recycling NdFeB-type sintered magnets using the HD/degassing process

With the rapid growth in the use of NdFeB-type magnets and with the growing environmental need to conserve both energy and raw materials, the recycling of these magnets is becoming an ever important issue. In this paper it is demonstrated that hydrogen could play a vital role in this process. Fully dense sintered NdFeB-type magnets have been subjected to the hydrogen decrepitation (HD) process. The resultant powder has been subsequently processed in one of two ways in order to produce permanent magnets. Firstly, the powder was subjected to a vacuum degassing treatment over a range of temperatures up to 1000 °C in order to produce powder that would be suitable for the production of anisotropic bonded or hot pressed magnets. Secondly, the HD-powder has been used to produce fully dense sintered magnets; in which case optimisation of the milling time, sintering temperature and time was carried out. The optimum degassing temperature for coercive powder was found to be 700 °C, giving powder with a remanence (Br) of 1350 mT (±50 mT) and an intrinsic coercivity (Hcj) of 750 kA m⁻¹ (±50 kA m⁻¹). The best sintered magnet was produced by very lightly milling the powder (30 min, roller ball mill), aligning, pressing and vacuum sintering at 1080 °C for 1 h. The magnetic properties of this magnet were: (BH)_max = 290 kJ m⁻³ (±5 kJ m⁻³), Br = 1240 mT (±50 mT) and Hcj = 830 kA m⁻¹ (±50 kA m⁻¹); representing decreases of 15%, 10% and 20%, respectively, from the properties of the initial magnet.     

Solids flow characteristics in loop-seal of a circulating fluidized bed

The hydrodynamics of solids (FCC) recycle in a loop-seal (0.08 m) at the bottom of the downcomer (0.08 m-I.D.x4.0 m-high) in a circulating fluidized bed (0.1 m-I.D.x 5.3 m-high) have been determined. Solid flow rate through the loop-seal increases linearly with increasing aeration rate. At the same aeration rate, the maximum solid flow rate can be obtained at a loop-seal height-to-diameter ratio of 2.5. The effects of solid inventory, solid circulation rate and gas velocity on pressure balance around the CFB have been determined. At a given gas velocity and solid circulation rate, pressure drops across the downcomer and loop-seal increase linearly with increasing solids inventory in the bed. At a constant solid inventory, pressure drops across the riser and the downcomer increase with increasing solid circulation rate but decrease with increasing gas velocity in the riser. The obtained solid flow rate has been correlated with pressure drop across the loop-seal.     

AKD生产中三乙胺的回收和利用

从副产物三乙胺盐酸盐中回收三安对降低ＡＫＤ生产成本至关重要。采用了物理和化学相结合的方法使回收三乙胺的含水量低于０．１％,满足了ＡＫＤ生产的要求。     

以循环碱液替代石灰乳提镓

提出并以实验证实了一种镓、铝分离的新方案—以循环碱液替代石灰乳浸出镓精矿副产碳酸铝,可降低提镓成本,增强在世界市场的竞争力．     

绿色住区可持续发展机制研究：从控制论角度探讨延安枣园村规划设计

绿色住区以生态（ 自然和人文） 系统的良性循环为基本原则,运用生态系统的生物共生和物质多级传递、循环再生原理,结合控制论的实践方法和多学科的现代科技成就,根据当地环境和资源状况,以绿色建筑技术为支撑,以动态调节为特点,将会形成高效和谐、自养自净、无废无污、生活舒适、文脉延续的人类理想居住模式     

美国废旧轮胎的回收利用

介绍了当今美国及加拿大在回收处理废旧轮胎方面的最新信息。说明了美国南北几个不同的州处理和利用旧轮胎作电厂和水泥厂燃料的情况,以及利用粉末橡胶改性沥青的方法和意义。简要介绍了硫化橡胶脱硫的新方法。对我国发展汽车工业所产生的副产物－废旧轮胎的合理利用、保护环境、寻找新的可利用的能源有一定的借鉴价值。     

装备再制造工程与失效分析

装备再制造工程是以实现废旧装备性能跨越式提升为目的的系统工程,基于循环经济4R准则即减量化（Reduce）、再利用（Reuse）、再制造（Remanufacturing）和再循环（Recycle）的装备再制造工程是建设节约型社会的重要手段,具有重要的社会经济意义。装备再制造工程与失效分析关系密切,失效分析是装备再制造工程的基础和前提,装备再制造工程是失效分析的结果与发展。结合失效分析和再制造工程实例,阐述了失效分析和再制造工程的相互关系及其在工程中的联合作用。     

Comparison of Economics of Various Ozone Generation Systems

The specific production costs of ozone are presented for a capacity range of 1 to 1,000 kg/h ozone for various plant configurations and air or oxygen as feed gas, and for air preparation, liquid oxygen delivered to site, oxygen produced on–site and/or oxygen recycle systems. The influence of operating parameters such as ozone concentration or on–stream time are studied. Ozone is often considered to be “expensive”. It is difficult to pinpoint the rationale behind this statement. It could be caused by the difficulty to compare a chemical (ozone) which is produced on–site and requires a plant investment, with chemicals (such as chlorine) which are bought as such and delivered to the plant. It is certainly influenced by the fact that the economy of utilizing ozone s i not easily quantified. This paper presents an attempt to quantify the economics of ozone production for a wide range of production capacities, ranging from 1 to 1,000 kg/h. Different operating conditions are compared as well as different plant concepts. In order t o assure a meaningful comparison, certain parameters are common for all cases.     

矿产资源领域走循环经济之路探索

循环经济的本质是强调减少资源消耗，走内涵发展道路，不断提高资源利用效率，提高经济增长的质量和效益。本文从循环经济的理念出发，针对我国目前矿产资源现状及所面临的问题，提出了在矿产资源领域发展循环经济的几点建议。     

影响循环氢压缩机长周期运行因素分析

通过对影响循环氢压缩机联锁停车因素进行分析,采取相应措施,加强设备、仪表的操作、维护 和检修,实现了机组长周期运行。