Open Gradient Magnetic Separator for Removal of Heavy Metals from Waste Water Based on A Cryogen Free Superconducting 5 T Magnet

摘要

A robust, continuous process with in situ production of magnetizable agglomerates of heavy metal precipitates has been developed. The magnetic properties of the agglomerates result from enclosures of maghemite particles, on a nanometer scale. These flocs are removed in a magnetic barrier separator. A separator prototype has been built with a cryogen-free superconducting 5.5 T solenoid with an 80 mm warm bore. A cryocooler is used to cool the Nb_3Sn magnet to 8-9 K. The operating current of 120 A is fed through HTS current leads. The system can be operated in an automatic and unattended fashion. Some first results of copper removed from artificial waste water show that removal efficiencies of more than 95 percent can be achieved. Compared with other processes, such as the ferrite process, the iron percentage required in the flocs can be much lower.