Whether the feed particle size of the permanent magnet dry roller magnetic
separator in quartz sand dry iron removal is within the equipment design range
directly determines the iron removal effect. Many customers have found that the
iron content in finished products fluctuates between high and low, and they have
been investigating and troubleshooting. The problem lies in the fluctuation of
grinding or grading processes, which leads to the particle size of materials
entering the magnetic separator exceeding the equipment's processing
capacity.
The feed particles are too coarse, and magnetic impurities are trapped inside
the particles, making it difficult for the magnetic force to reach them. The
magnetic field depth of the dry roller magnetic separator is limited, and it is
usually suitable for fine powder materials below -2mm. When a large amount of
coarse particles larger than 2mm are mixed into the feed, these particles
quickly roll over the surface of the magnetic roller, and the internal or
associated magnetic minerals are discharged with the sand before they can be
adsorbed. Even more troublesome is that coarse particles will bounce on the
surface of the magnetic roller, knocking down the already adsorbed fine iron
powder and further deteriorating the iron removal effect. The solution is to
check the grinding or grading process at the front end of the magnetic separator
to ensure that the feed fineness is stable within the equipment design range. If
there is a large fluctuation in the particle size of the front-end grinding
material, a high-frequency vibrating screen can be added in front of the
magnetic separator for inspection.
The feeding particle size is too fine, which can also affect the iron removal
effect. When the proportion of -200 mesh fine powder in the material exceeds
80%, the fine powder is prone to agglomerate or adhere on the surface of the
magnetic roller, forming a layer of material shell, shielding the magnetic field
lines, and reducing the adsorption capacity. At the same time, the flowability
of the fine powder is poor, and it is unevenly distributed on the surface of the
magnetic roller. In some areas, the material layer is too thick, and in some
areas, there is even no material coverage. In this situation, a dispersing
device can be installed in front of the magnetic separator to re disperse the
agglomerated material, or the feeding speed can be appropriately reduced to
allow the fine powder to have enough time to stay in the magnetic field
zone.
Uneven particle size distribution inevitably leads to fluctuations in iron
removal efficiency. When coarse particles and fine powder are mixed in the same
batch of materials, the coarse particles bounce on the surface of the magnetic
roller, and the fine powder adheres to the surface of the magnetic roller. The
two motion states interfere with each other, and the sorting process is
extremely unstable. It is recommended to set up a grading device in front of the
magnetic separator to divide the material into two sections according to
particle size, and enter the magnetic separator with different parameters for
processing - for coarse particles, use higher magnetic roller speed and larger
material layer thickness, and for fine particles, use lower speed and thinner
material layer. Although this increases equipment investment, the iron removal
efficiency and stability will be significantly improved.
During daily inspections, samples are taken once per shift to test the
particle size of the magnetic separator feed. A standard sieve is used to
quickly screen and confirm whether the -2mm ratio is stable within the required
range of the equipment. When the particle size exceeds the standard, first check
the front-end grinding or grading equipment, and then adjust the parameters of
the magnetic separator. Shanlu Heavy Industry has accumulated many years of
experience in the field of dry magnetic separation of quartz sand, and can
provide magnetic separator selection and matching classification schemes based
on customer material particle size distribution. Encountering problems during
equipment operation, welcome to contact the technical team of Shandong Heavy
Industry for communication: Manager Zhang 13583776655 (same as WeChat).