Testing of a 5.5 T High-Gradient Superconducting Magnetic Separator

A 5.5 T central field high-gradient superconducting magnetic separator (HGMS) has been designed, fabricated, and tested at the Institute of High Energy Physics, Chinese Academy of Sciences. It has been developed for processing kaolin, to increase the brightness or whiteness whether it is for paper or ceramic applications. The HGMS system mainly consists of an NbTi superconducting magnet, a double-canister system, and a PLC (Process Logic Controller) control system. The solenoid magnet, with operating current of 148 A, has a clear bore of 300 mm. By using a G-M cryocooler (35 W/50 K, 1.5 W/4.2 K), the results of the experiment show that the HGMS system can be run in zero boil-off regimes without any additional cooling. A pressure control system for the helium vessel can accurately respond to variations of pressure above the pressure outside the vessel. The system will process kaolin slurry at typically 0.6～2.5 cm/s, resulting in a production rate of approximately 80～120 tones per day (dry basis). The operation is fully automatic, with a simple system for adjusting the process parameters. The HGMS magnet suffered no quench and operated stably during many experiments since January 2012. The details of the design, fabrication, and performance results of the HGMS are presented in this paper.