Development of Recycling System for Rare Metals by High Performance Centrifugal Partition Chromatography

各种稀有金属已广泛用于制造电子设备和产品，例如电视机、个人电脑、二次电池。在这些金属中，镧和过渡金属如La、Y、Sm、Eu、Ni和Co是代表性的。这些稀有金属通常是从自然资源中生产的。这就是为什么我们应该从保护有价金属的角度出发，回收和开发使用后回收它们的工业技术。本研究项目对金属配合物的两相萃取平衡及其在高效离心分配色谱（HPCPC）分离金属中的应用进行了两年的基础研究，HPCPC方法原理上是基于多次萃取，因此对于从废料中分离密切相关的金属离子非常有用。 关于我们 离子相和移动的相来分离它们。选择了双-2-乙基己基次膦酸（BEHPA）和二-2-甲基壬基磷酸（DMNPA）分别作为镧和过渡金属的螯合剂。以0.16 M BEHPA/庚烷为固定相，以氯乙酸或三氯乙酸缓冲液为移动的流动相，研究了高效液相色谱法分离镧系金属。测定了轻、中等镧系金属的半萃取pH值（pH <1/2>），并根据pH值的差异评价了HPCPC分离的可行性。除Pr/Nd和Tb/Dy分离外，其余镧系金属离子均采用两步洗脱法实现了相互分离。影响HPCPC分离的主要因素是pH值和移动的流速。当水样中目标金属离子浓度较高时，需要增加BEHPA的浓度，DMNPA庚烷溶液作为固定相也可用于HPCPC分离过渡金属离子。Fe（III）萃取可以在非常低的pH值下进行，因此通过添加酒石酸盐来掩蔽。镍（II）和钴（II）被发现从其他过渡金属离子分离，通过这种HPCPC方法。这种技术将是相当有前途的回收钴和镍的电子零件的废料，因为它们的电池再利用。少

A variety of rare metals have widely been used for the manufacturing of electronic devices and products, e.g. television sets, personal computer, secondary batteries. Among the metals, such lanthanum and transition metals as La, Y, Sm, Eu, Ni and Co are representative ones. Such rare metals are generally produced from natural resources. This is the reason why we should recover and develop the industrial technique to recycle them after use, from the standpoint of conservation of valuable metals. In this research project, the fundamental studies on the two-phase extraction equilibrium of metal complexes and their applications to the metal separation by high performance centrifugal partition chromatography (HPCPC) have been undertaken for the last two years.The HPCPC method is in principle performed based on the multiple extraction, and therefore very useful for the separation of closely related metal ions from waste materials Metal ions of interest are partitioned repeatedly between stat … More ionary and mobile phases to separate them. Bis-2-ethylhexylphosphinic acid (BEHPA) and di-2-methylnonylhosphoric acid (DMNPA) were chosen as the chelating agents for the separation of lanthanum and transition metals, respectively. The mobile phase was made of chloroacetate or trichloroacetate buffer.The HPCPC separation of lanthanum metals was investigated using 0.16M BEHPA/heptane as a stationary phase. Half-extraction pH (pH_<1/2>) values were obtained for light and middle class lanthanum metals, and the differences in pH_<1/2> were evaluated for the feasibility of HPCPC separation. Except for Pr/Nd and Tb/Dy separation, the other lanthanum metal ions were separated mutually by the two-step elution method. The main factors governing HPCPC separation were found to be pH and flow rate of mobile phase used. Increased concentration of BEHPA is needed for aqueous samples containing higher concentrations of target metal ions.A DMNPA solution in heptane as the stationary phase was also used for the separation of transition metal ions by HPCPC. Fe(III) extraction can be carried out at very low pH values, and therefore was masked with addition of tartrate. Nickel(II) and cobalt(II) were found to separate from the other transition metal ions by this HPCPC method. This technique would be quite promising for the recovery of cobalt and nickel from waste materials of electrical parts, because of their reuse for batteries. Less