The invention discloses a preselecting method of low-grade magnetic
iron ore, comprising the steps of crushing the raw ore of the magnetic
iron ore by coarse crushing, intermediate crushing and fine crushing operations, conveying to subject to ultra-fine crushing operation, and then crushing by a high-pressure
roller mill, scattering the crushed product by a wet cylindrical
sieve, conveying the ore on the cylindrical
sieve to the vibrating
sieve by a belt to perform wet
gradation, conveying the ore on the vibrating sieve to a dry
magnetic separator by the belt to discard the waste, returning the
ore concentrate of the dry
magnetic separator to the high-pressure
roller mill to crush the
ore concentrate again, perform
magnetic separation and discarding
tailings of the
ore concentrate below the vibrating sieve and the ore concentrate below the cylindrical sieve in a wet coarse grain intermediate-
field intensity magnetic separator, and selecting the coarse ore concentrate of the intermediate-
field intensity magnetic separator by a
grinding separation technology. The invention has the advantages that the invention selects quantities of qualified mine
tailings by wet
magnetic separation before
grinding ore, reduces ore
grinding work, reduces ore grinding
energy consumption and has high
system processing capacity; the invention can be widely used in magnetic ore dressing
plant, and in particular suitable for treatment of preselecting low-grade magnetic
iron ore with the iron grade lower than or equal to 22%.