Leading demagnetizer for magnetic separators

The leading demagnetizer for magnetic separators is not just an additional module. This is a critical element of the technological chain, on which the purity of the final product, the service life of the equipment and the stability of the entire line directly depend. We saw how at one plant in the Kemerovo region, after installing a demagnetizer, the accident rate of conveyor belts decreased by 42% in three months. Cause? Elimination of residual magnetization of ferromagnetic particles that previously “stuck” to the rollers and caused uneven wear.

Why standard separators are often insufficient

Magnetic separators effectively remove large ferromagnetic materials - nuts, bolts, wire scraps. But they do not solve the problem of weakly magnetized particles: iron oxides, dusty inclusions, microscopic steel fragments. These particles pass through the separator field or remain on its surface and then re-enter the material flow. The result is a decrease in product quality, clogging of crushers, and premature failure of sieves and filters.

The demagnetizer eliminates precisely this “invisible threat.” It doesn't attract - it demagnetizes. Its task: to reset the residual induction to a level below 0.5 mT. Only at this value do particles stop behaving like magnets and lose their ability to aggregate and adhere.

In practice, we encounter three typical mistakes when choosing:

• Installing a demagnetizer with insufficient power - the particles are only partially demagnetized and are reactivated by mechanical action;
• Incorrect location relative to the separator - if the distance exceeds 150 mm, efficiency drops by 30–50%;
• Ignoring flow speed - when exceeding 2.5 m/s, even high-frequency models do not have time to complete the full demagnetization cycle.

How does a leading demagnetizer for magnetic separators work?

The key feature is the two-stage pulse mode. First, the device creates a strong alternating field (up to 300 kA/m), which “looses” the magnetic domains in the particles. Then - a smooth decrease in amplitude to zero according to an exponential law. It is this decline, and not the pulse itself, that ensures the complete disappearance of residual magnetization.

We work with models designed for a supply voltage of 380 V ±10%, frequency 50 Hz, operating temperature from −25 to +60 °C. The case is made of AISI 304 stainless steel with IP65 - withstands dust, moisture, shocks during loading. Installation takes no more than 4 hours: mounting on the separator frame, connecting to the power bus and synchronizing with the conveyor controller via the RS-485 digital interface.

Mean time between failures is 42,000 hours. For comparison: for budget analogues this figure rarely exceeds 18,000 hours. The difference is explained not only by the quality of the coils (cast copper wire with double enamel insulation), but also by the thermal control algorithm: temperature sensors are built directly into the winding, and not into the housing.

Proven solutions from LONGI Corporation

Shenyang Longji Scientific Electromagnetic Co., Ltd. has been developing demagnetizers since 1993. Over 30 years, the company has created 17 generations of devices adapted to the conditions of Russian enterprises - from coal mines in the Far East to cement plants in the Volga region.

Today, the leading demagnetizer for magnetic separators in the LONGI line is the modelLJ-DMX-2200. Its differences:

• Throughput up to 1200 t/h with a belt width of 2200 mm;
• Automatic adaptation of the demagnetization frequency in the range of 50–200 Hz to the current transportation speed;
• Built-in diagnostic system: LED indicators indicate overheating, open circuit, voltage mismatch;
• 36 month warranty - unlimited operating hours.

More than 60% of customers implement LJ-DMX-2200 in combination with LONGI separators of the LJ-MSF series. This combination provides maximum synchronization: the demagnetizer is activated exactly 1.8 seconds after the material passes through the separation zone - the optimal interval for a complete field reset.

What to check before buying

Don't go for the highest power. First answer three questions:

1. What type of material?LJ-DMX-mm is suitable for coal and ore). For fine mineral powders - only LJ-DMX-2200 with enhanced vibration protection.
2. What is the belt speed?At 1.2–1.8 m/s the basic version is sufficient. At 2.2–2.8 m/s, a modification with extended pulse time is needed.
3. Is there access to the service?On the websiteljmagnet.ruAll drawings, instruction manuals and video instructions for replacing modules have been published. Service centers operate in 12 regions of the Russian Federation - the average time for a specialist to visit is 36 hours.

The leading demagnetizer for magnetic separators is not a consumable, but an investment in predictability. It transforms cleaning from a routine operation into a controlled process step. One that can be measured: in percentage reduction in defects, in thousands of rubles in savings on repairs, in days of uninterrupted operation.