Recovery of tantalum capacitors from waste printed circuit boards using a pneumatic separator

A large number of various types of electron devices including CPUs, chip resistors, and capacitors are mounted on the printed circuit boards of electronic devices such as personal computers. Anywhere from several to dozens of tantalum capacitors can be used on printed circuit boards. And these capacitors contain a considerable quantity of the expensive rare metal tantalum. An impact breaker can be used to detach almost all the electron devices in a liberated state from waste printed circuit boards. This study began by investigating the size and density distribution of the liberated electron devices. The results of this investigation showed that some kinds of electron devices including tantalum capacitors liberated from circuit boards had a narrow size distribution. Tantalum capacitors also had a particularly narrow density range unlike that of almost all other electron devices. Next, tantalum capacitors were recovered from the other electron devices using screens (standard sieves) and a column shaped pneumatic separator. The results of separation examinations of certain kinds of waste printed circuit boards have clearly shown that high grade tantalum capacitors can be recovered for every type of printed circuit board used in this study. More than 85 per cent of the grade of tantalum capacitors, more than 85 per cent of recovery and more than 70 per cent of Newton's separation efficiency can be obtained by this simple separation process.