废旧锂离子电池负极材料回收再生利用研究进展

随着锂离子电池的广泛应用，大量的废旧锂离子电池产量逐年增加，由于负极材料容量较低(≈175 mAh·g^-1)以及需要较高的工作电势，硅负极材料仍然处于研究阶段，所以对大量的退役锂离子电池石墨负极进行高效回收直接再生具有重要的现实意义。为此，本文介绍近年来废旧锂离子电池石墨负极材料回收利用研究现状，分析废旧石墨负极常用回收利用方法优缺点，主要包括火法回收、湿法回收和材料再生等方案，并对废旧锂离子电池石墨负极材料的高效、绿色回收利用进行了展望。     

废旧氢镍电池回收处理技术研究进展

目前废旧氢镍电池的回收处理是能源材料再利用的重要内容之一.本文对氢镍电池的化学组成、工作原理以及废旧氢镍电池的回收处理方法进行了评述,阐述了废旧氢镍电池处理技术的研究现状.废旧氢镍电池的主要回收处理方法是采用火法冶金、湿法冶金、正负极分开处理三种回收处理技术,本文同时介绍了一种新的废旧氢镍电池回收处理技术,并就当前废旧氢镍电池回收处理研究中存在的问题提出了相关建议.     

废旧动力磷酸铁锂电池资源化回收技术研究进展

对当前国内外废旧磷酸铁锂电池的回收技术进行了较为全面的阐述,其中包括常采用的干法回收技术、湿法回收技术以及生物浸出回收技术,并根据各方法的优缺点进行了分析比较,同时对废旧磷酸铁锂电池的回收技术发展作了初步的展望。     

废旧钴基合金材料的资源综合利用

叙述了从废旧钴基合金回收有价元素的意义以及废旧钴基合金的元素组成情况.介绍了目前从废旧钴基合金回收稀土、钴的工艺,并对其进行了评述.针对具体问题,提出了用过硫酸钠氧化使钴、铁与稀土分离,然后溶解钴、铁沉淀,利用二者沉淀条件的不同分离钴、铁的工艺路线,最终实现对稀土和钴的回收,且稀土的收率为96.86%,钴的收率为94.29%.     

论废旧电子线路板的资源化回收利用

电子工业迅猛发展,如何有效回收利用废旧电子线路板已成为一个新课题。文章就电子线路板回收的意义、现状及方法进行了探讨,以期废旧电子线路板资源化回收利用能步入良性发展轨道。     

废旧稀土金属钕铁硼回收技术研究现状与展望

稀土是重要的战略资源,也是世界强国资源争夺的核心。磁性材料尤其钕铁硼永磁体在生产制备和使役过程中产生大量废料,我国废旧钕铁硼产量逐年增多,形成了稀土“城市矿山”。研究废旧钕铁硼的回收利用技术,对我国稀土绿色和可持续发展具有重要意义。本文总结了国内外废旧稀土金属钕铁硼各种回收方法,综述了近年来稀土磁性废料回收技术研究进展,并面向保护环境和节约资源及低成本的发展趋势,对废旧稀土金属回收技术进行了展望。     

废旧锂离子电池中有价金属的回收技术进展

随着锂离子电池在电动汽车和储能领域的大量使用,废旧锂离子电池所面临的环境和资源问题日益突出。为了更好地资源利用和环境保护,世界各国对废旧锂离子电池中有价金属的回收和利用,及无危害处理相当重视。文中综述了国内外对废旧锂离子电池回收技术的研究现状,比较了不同回收途径的优缺点,讨论了回收技术的发展方向。本文中归纳的废旧锂离子电池回收方法,在目前回收领域中得到了广泛地研究,并且起到了显著效果,但是大多集中在对锂、钴、镍、锰、铜、铝等有价金属的回收利用上,对废旧锂离子电池中的导电碳、石墨以及电解质的回收和处理方面的研究较少,对工艺过程中产生的污染和安全性问题也缺乏系统的研究。另外,随着锂离子电池生产技术的发展,新的电极材料将会出现并取代过渡金属氧化物,比如单质硫、导电聚合物等;同时也需要相应的电解液与之匹配,如新型的有机电解液、聚合物电解质等,这将向废旧锂离子电池回收技术提出了新的要求。今后废旧锂离子电池资源化回收技术的研究方向是降低成本,减少污染和实现回收物质的多元化以及提高回收率。     

发达国家废旧铅酸蓄电池回收业现状

废旧铅酸蓄电池具有较高的回收利用价值,但处理不当容易造成严重的环境污染。国外发达国家的回收体系、政策法规以及回收技术等值得我们学习和借鉴。废旧铅酸蓄电池,因其具有较高的回收利用价值而成为循环经济的热点。然而,如果废旧铅酸蓄电池处理、处置不当,很容易造成严重的环境污染,并威胁到人类健康。因此,废旧铅酸蓄电池又被国际公认为危险废弃物。     

硬质合金回收研究进展及发展趋势

硬质合金的使用量逐年快速增长,生产上废弃的硬质合金渐渐受到重视.改进废旧硬质合金的二次回收工艺,对资源的保护和可持续发展的意义重大.回收硬质合金的研究主要围绕节能环保、工艺简洁、回收效率和回收质量等方面展开.文中综述了国内外关于回收废旧硬质合金碳化钨和钴的研究目的,主要方法及其基本原理、应用工艺条件和综合回收效果.指出物理处理和化学处理冶金方法相结合、机械破碎和高温热处理相结合的方法对废旧硬质合金具有很好的综合回收效果,是当前研究的主要方向.最后对硬质合金回收的未来发展进行展望.     

铼的回收技术研究进展

综述了从矿石、冶炼废液、废催化剂、废旧合金物料中回收铼的主要工艺技术,并对其关键技术进行了分析。结果表明,从矿石及冶炼废液中回收铼的技术相对较为成熟;高效、清洁的离子交换树脂、萃取剂的开发将会是铼冶金领域的重大革新。从废催化剂、废旧合金等铼的二次资源中回收铼的研究较少,尚需开发适合于规模化、工业化应用的回收技术,这是今后铼回收方面的重要研究课题。     

冷热双混辊压法高炉熔渣破碎试验

围绕高炉熔渣余热回收设计开发了冷热双混辊压法高炉熔渣破碎装置,并以水淬高炉渣作为冷却介质,开展了高炉熔渣辊压破碎试验。试验研究了电机转速R、辊间距离L、冷却介质漏斗高度H等装置运行参数对处理后炉渣的厚度、温度以及玻璃化率的影响,获得最佳参数,为高炉熔渣余热回收及工业试验奠定基础。结果表明,在电机转速为9 r/min、辊间距离为2 mm、水淬渣漏斗高度为4 mm时,处理后的高炉渣呈现为厚度最小为1.26 mm的薄片。此时,炉渣温度为442 ℃,玻璃体化率达89.8%,可在保证高炉渣后续利用的同时,最大程度地提高余热回收温度。     

Strengthening of Masonry Arches with Fiber-Reinforced Polymer Strips

This paper deals with masonry arches and vaults strengthened with surface fiber-reinforced polymer (FRP) reinforcement in the form of strips bonded at the extrados and/or intrados, considering strip arrangements that prevent hinged mode failure, so the possible failure modes are: (1) crushing, (2) sliding, (3) debonding, and (4) FRP rupture. Mathematical models are presented for predicting the ultimate load associated with each of such failure modes. This study has shown that the reinforced arch is particularly susceptible to failure by crushing, as a result of an ultimate compressive force being collected by a small fraction of the cross section. Failure by debonding at the intrados may also be an issue, especially in the case of weak masonry blocks or multiring brickwork arches. Failure by sliding has to be considered if the reinforcement is at the extrados and loading is considerably nonsymmetric.     

Numerical Cracking and Debonding Analysis of RC Beams Reinforced with FRP Sheet

Bonding a fiber reinforced polymer (FRP) sheet to the tension-side surface of reinforced concrete (RC) structures is often performed to upgrade the flexural capacity and stiffness. Except for upper concrete crushing, FRP sheet reinforcing RC structure may fail in sheet rupture, sheet peeloff failure due to opening of a critical diagonal crack, or concrete cover delamination failure from the sheet end. Accompanying the occurrence of these failure modes, reinforcing effects of the FRP sheet will be lost and load-carrying capacity of the RC structures will be decreased suddenly. This study is devoted to developing a numerical analysis method by using a three-dimensional elasto-plastic finite element method to simulate the load-carrying capacity of RC beams failed in the FRP sheet peeloff mode. Here, the discrete crack approach was employed to consider geometrical discontinuities such as opening of cracks, slipping of rebar, and debonding of the FRP sheet. Comparisons between analytical and experimental results confirm that the proposed numerical analysis method is appropriate for estimating the load-carrying capacity and failure behavior of RC beams flexurally reinforced with a FRP sheet.     

Maximum Shear Strength of RC Beams Retrofitted in Shear with FRP Composites

In reinforced concrete (RC) beams strengthened in shear with fiber-reinforced polymer (FRP), crushing of the web can be a potential mode of failure. The guidelines provided by codes and standards for the design of structures strengthened with externally bonded FRP recommend limiting the maximum shear strength to avoid such an undesirable failure scenario. However, these limitation provisions are not based on specific research studies performed on beams strengthened in shear with FRP. Rather, they simply duplicate provisions used in conventional concrete codes and standards. The main objective of this research study is to assess the suitability of the limits specified by the guidelines, and propose, if necessary, an alternative equation as an upper limit for shear strength against web crushing failure in such structures. To this end, an analytical approach was developed based on the static theorem of the theory of plasticity. The predictions of the equations resulting from this approach were compared with those obtained from tests reported in the literature and with those predicted by ACI Committee 440-02, Canadian Standard S6-06, and the European recommendations fib TG 9.3. The study shows that the current ACI Committee 440-02 and Canadian Standards provisions are overly conservative and therefore need to be reviewed.     

Strengthening of Masonry Walls against Out-of-Plane Loads Using Fiber-Reinforced Polymer Reinforcement

Thirty masonry walls strengthened using three different fiber-reinforced polymer (FRP) systems, with three anchorage methods, were fabricated and tested under a concentrated load over a 100 mm square area or a patch load over a 500 mm square area. The test results indicated a significant increase in the out-of-plane wall strength over the unstrengthened wall. While failure occurred in the unstrengthened wall by bending, four different modes of failure, that is, punching shear through the bricks, debonding of FRP reinforcement from the masonry substrate, crushing of brick in compression, and tensile rupture of the FRP reinforcement, were observed in the strengthened walls, depending on the types and configurations of FRP and anchorage systems. With appropriate surface preparation and anchorage systems, premature failure due to FRP debonding is prevented. Based on the principles of strain compatibility and force equilibrium, simple analytical models are presented to predict the ultimate load-carrying capacity of the strengthened walls. The test results compared well with the analytical predictions.     

Quasi-Balanced Failure Approach for Evaluating Moment Capacity of FRP Underreinforced Concrete Beams

Failure of concrete beam sections underreinforced with fiber-reinforced polymer (FRP) is initiated by FRP rupture before concrete crushing. In such a case, the typical rectangular stress block based on the balanced failure mechanism may not apply. In the present study, rigorous sectional analyses are performed implementing existing concrete stress-strain models for a wide range of values of design parameters. Based on the results of the numerical analyses, the variation of parameters of equivalent stress block of concrete was investigated, and an alternative, yet simple, design method for evaluating moment-carrying capacity of FRP underreinforced concrete beam using quasi-balanced failure approach was developed. The proposed design method was verified by comparing the predicted moment-carrying capacity with existing test results.     

建筑垃圾制备膏体充填材料骨料级配优化

建筑垃圾用作井下充填材料,不仅可以消除其大量堆放造成的环境危害,而且可以解决矿山采空区充填材料不足的问题,有效维护采场安全。采用土工试验的方法,测试了建筑垃圾的基本物理性质。针对建筑垃圾一次破碎中间粒径缺失问题,提出了新的破碎工艺,即将一次破碎后粗骨料的1/3二次破碎至15 mm以下后回混,能够得到级配良好的骨料。根据膏体材料强度及流动性能要求,选用建筑垃圾制备骨料,普通水泥作为胶凝材料,粉煤灰作为添加料,制备合格的膏体材料,开展单轴抗压试验和坍落度试验。结果表明：使用建筑垃圾制备骨料时,控制粉煤灰掺量为15%、水泥掺量为10%、含水率在27%~28%之间,膏体材料的坍落度为21.5~24.0 cm,得到的充填体3 d单轴抗压强度为1.23 MPa、28 d单轴抗压强度为3.55 MPa,能够满足膏体材料对强度和流动性能的要求。     

冷热双混辊压法高炉熔渣破碎试验

围绕高炉熔渣余热回收设计开发了冷热双混辊压法高炉熔渣破碎装置,并以水淬高炉渣作为冷却介质,开展了高炉熔渣辊压破碎试验。试验研究了电机转速R、辊间距离L、冷却介质漏斗高度H等装置运行参数对处理后炉渣的厚度、温度以及玻璃化率的影响,获得最佳参数,为高炉熔渣余热回收及工业试验奠定基础。结果表明,在电机转速为9 r/min、辊间距离为2 mm、水淬渣漏斗高度为4 mm时,处理后的高炉渣呈现为厚度最小为1.26 mm的薄片。此时,炉渣温度为442 ℃,玻璃体化率达89.8%,可在保证高炉渣后续利用的同时,最大程度地提高余热回收温度。     

Combined Shear and Flexural Behavior of Hybrid FRP-Concrete Beams Previously Subjected to Cyclic Loading

Concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) were initially proposed for bridge substructures in corrosive environments in the early 1990s. Systematic studies have since demonstrated the feasibility and merits of CFFTs with or without internal mild steel reinforcement. However, the experimental database in this field is still quite limited. This paper enhances the test database through a series of monotonic bending tests on one control RC specimen and five CFFT specimens previously subjected to reverse cyclic loading. Although the control RC specimen suffered shear-flexural cracks, specimens with carbon fibers experienced flexural failure by longitudinal splitting of the FRP tube in tension and its crumpling in compression. Specimens with glass or hybrid (glass/carbon) fibers, on the other hand, all failed by local buckling of FRP with either burst crushing or crumpling cracks. The specimen with hybrid fibers had higher normalized initial stiffness primarily because of its higher FRP/concrete stiffness ratio. The tests showed that the ductility of CFFT increases with FRP rupture strain. Further synthesis of flexural strength with FRP and mild steel reinforcement indexes reveals the existence of an optimized overall reinforcement index to achieve a design moment without overconfining concrete. Finally, the study confirms that shear failure is not critical for CFFT specimens at short shear span-to-depth ratios, even with internal mild steel reinforcement, as long as the FRP architecture is designed properly.     

Fatigue Performance of RC Beams Strengthened in Shear with CFRP Fabrics

In recent years, a tremendous effort has been directed toward understanding and promoting the use of externally bonded fiber-reinforced polymer (FRP) composites to strengthen concrete structures. Despite this research effort, studies on the behavior of beams strengthened with FRP under fatigue loading are relatively few, especially with regard to its shear-strengthening aspect. This study aims to examine the fatigue performance of RC beams strengthened in shear using carbon FRP (CFRP) sheets. It involves six laboratory tests performed on full-size T-beams, where the following parameters are investigated: (1) the FRP ratio and (2) the internal transverse-steel reinforcement ratio. The major finding of this study is that specimens strengthened with one layer of CFRP survived 5 million cycles, some of them with no apparent signs of damage, demonstrating thereby the effectiveness of FRP strengthening systems on extending the fatigue life of structures. Specimens strengthened with two layers of CFRP failed in fatigue well below 5 million cycles. The failure mode observed for these specimens was a combination of crushing of the concrete struts, local debonding of CFRP, and yielding of steel stirrups. This failure may be attributed to the higher load amplitude and also to the greater stiffness of the FRP which may have changed the stress distribution among the different components coming into play. Finally, comparison between the performance of specimens with transverse steel and without seems to indicate that the addition of transverse steel extends the fatigue life of RC beams.