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How to Detect a Drop in Magnetic Field Strength of a Plate Magnetic Separator?
release time:
2026-10-13
In the wet iron removal process for quartz sand, a plate magnetic separator relies on magnetic plates to attract iron impurities. After two or three years of operation, many customers find that the iron removal effect is
In the wet iron removal process for quartz sand, the plate magnetic separator relies on magnetic plates to attract iron impurities. After two or three years of operation, many customers find that the iron removal effect is far worse than before, and the iron content in the concentrate gradually exceeds the standard. When measured with a gaussmeter, the magnetic field strength on the surface of the magnetic plate is significantly lower than when the machine was new. Demagnetization of magnetic plates is an unavoidable issue for permanent magnet equipment, but the rate of demagnetization varies. The key lies in whether several pitfalls have been encountered in daily use.
When magnetic plates are exposed to high temperatures for extended periods, the demagnetization rate accelerates noticeably. Although NdFeB magnetic material has strong magnetic force, its temperature resistance is limited. Once the operating temperature exceeds 80°C, the magnetic domain structure gradually becomes unstable, and the magnetic force permanently decays. If a plate magnetic separator is installed near a dryer or hot air duct, the magnetic plates are exposed to heat radiation for extended periods, and the demagnetization rate will be several times faster than under normal operating conditions. It is recommended to install a heat insulation board between the magnetic separator and the heat source, or adjust the equipment layout to increase the distance. The cooling water temperature should also not be too high; in summer, the inlet water temperature should preferably be kept below 25°C.
If iron sludge adsorbed on the surface of magnetic plates is not cleaned for extended periods, the magnetic field is shielded while demagnetization is also accelerated. Some customers think that magnetic plates being fully covered with iron powder does not affect use, since it will fall off once the power is cut. In reality, the adsorbed ferromagnetic material forms a magnetic short circuit, and the magnetic field lines close within the iron sludge layer. The magnetic plates themselves are in an "overloaded" state. Over time, the magnetic domain orientation gradually shifts, and the magnetic field strength naturally decreases. Rinsing the magnetic plates once per shift to keep the surface clean is more effective than any maintenance.
Strongly magnetic large iron pieces mixed into the feed can also cause localized demagnetization upon impact with the magnetic plates. After large iron pieces such as broken steel bars and bolts are attracted by the magnetic plates, they repeatedly impact the surface of the magnetic plates under the scouring of the slurry. The magnetic domain structure at the impact points is destroyed, forming localized weak magnetic zones. Installing a grid or permanent magnet iron remover before the plate magnetic separator to intercept large iron pieces in advance can effectively protect the magnetic plates.
During routine maintenance, use a gaussmeter to inspect the magnetic field distribution on the surface of the magnetic plates once a quarter. If a certain area is found to be significantly lower, and it is confirmed to be demagnetization rather than iron sludge coverage, the only option is to replace that magnetic plate. Shanlu Heavy Industry has served in the field of quartz sand magnetic separation equipment for many years and can recommend magnetic materials with higher temperature resistance grades based on on-site operating conditions. If you encounter problems during equipment operation, you are welcome to contact the Shanlu Heavy Industry technical team for communication: Manager Zhang 13583776655 (same on WeChat).
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