Scheelite ores which are often found in tungsten deposits such as skarn occasionally include other valuable sulfide minerals. The similarity between scheelite and pyrrhotite in their densities makes gravity separation more difficult and decreases the grade of scheelite concentrate.
Generally, if scheelite ores contain a great amount of pyrrhotite, pyrrhotite is first removed by magnetic separation and then, scheelites are separated by gravity separation before being sent to the consumers respectively. On the other hand, if there is a small amount of pyrrhotite in scheelite ores, pyrrhotite is separated by gravity-magnetic separation and thrown away. The magnetic separation process involves the addition of scheelites to the magnetic flocculation, leading to the loss of scheelites.
Ryom Chol Ung, a researcher at the Faculty of Mining Engineering, has proposed a method whereby the magnetic field upwardly pulls magnetic mineral particles so that heavy valuable minerals such as scheelite are concentrated while heavy gangue minerals such as pyrrotite are floated by the magnetic force and removed directly from the table. In addition, he has simulated the gravity concentration of scheelite on the table and the removal of pyrrhotite floated by the magnet force using CFD and made a comparison through experiments.
The experimental result shows that the grade and separation efficiency are 28.4% and 76.5% on the conventional table, and 65.3% and 80.1% on the magnet bar-fixed table, respectively, which means separation efficiency of the proposed method is higher.
You can find the details in his paper “Simulation of pyrrhotite removal from scheelite ore by magnetic force in table concentration” in “Journal of Mining and Environment” (EI).
© 2021 Kim Chaek University of Technology