Abstract: The contrast tests on magnetite powder for coal preparation of Tunlan coal preparation plant by adopting the cyclone and the cyclone gravity column with different cone angle are carried out. The test results show that with the cone angle of the water cyclone bottom in singlecone structure increasing, total iron grade of the coarse underflow products is increased, and its SiO₂ content is decreased. For the coarse magnetite powder, the effect of iron increase and silicon reduction by the cyclone gravity column in complex structure is better than that by water medium cyclone at single cone angle of 120°.

Key words: Cone angle, Cyclone gravity column, Magnetite, Iron improvement and silicon reduction