Leading high-gradient magnetic filter

The leading high-gradient magnetic filter is not just a piece of iron removal equipment. It is a precision instrument that solves problems where classic filters fail: removing particles as small as 0.5 microns from oils, hydraulic fluids, chemical solutions and process waters. We have seen standard separators at ore processing plants in the Murmansk region and at oil refineries in Tatarstan allow ferromagnetic “dust” to pass through, causing premature wear on pumps and valves. A high-gradient magnetic filter eliminates this gap - due to local amplification of the magnetic field in the filtration zone.

Why gradient and not just force?

Many customers ask: “If the magnet is stronger, does it mean it is cleaner?” No. The key is not in absolute induction, but in its change per unit length. With a conventional magnet, the field drops slowly, and small particles (less than 5 microns) simply do not feel strong enough to be captured. The leading high-gradient magnetic filter creates a sharp drop - up to 150 T/m - in the area where steel pins or wire mesh are installed. This is where “magnetic traps” arise: particles stick not to the body, but to the tips, where the gradient is maximum. We tested this on water samples from the circulation systems of processing plants: at a flow rate of 120 m³/h and a Fe₃O₄ content of 8–12 mg/l, the capture efficiency was 99.3% - versus 67% for a similar filter without gradient amplification.

What the “leader” is hiding—technical boundaries

The term “leading” here is not marketing. It reflects three proven limitations that other manufacturers often ignore:

• Operating temperature up to +120 °C- without loss of magnetic induction. Conventional neodymium systems begin to “sag” already at +80 °C;
• Flow speed up to 3.5 m/s— without erosion of the active surface. In our tests, during long-term operation under a pressure of 1.6 MPa, pin wear did not exceed 0.02 mm in 18 months;
• Automatic regeneration in 42 seconds- without stopping the process. The system completely turns off the magnetic field, washes the layer of particles with a reverse flow and returns the filter to operating mode.

These parameters are not declarative - they are recorded in the test reports of the Laboratory of Magnetic Systems of the Physicotechnical Institute. Ioffe (St. Petersburg) and confirmed by Rostechnadzor certificates.

When a filter doesn't help - and what to do instead

Some people think: “If you install the most powerful filter, the problem will disappear.” But we encountered the opposite: a client in Bashkiria installed a leading high-gradient magnetic filter in front of a hydraulic turbine - and three weeks later there was an accident. Cause? The system contained non-magnetic chromium and nickel oxides, as well as non-metallic inclusions. The filter only removed iron; the rest passed through freely. We recommended a comprehensive solution: preliminary mechanical filtration 25 microns + magnetic block + subsequent ultrafiltration. This approach reduced downtime by 74%. The main thing is to clearly determine the type of impurities: if the analysis shows >85% ferromagnetic particles, the filter is working perfectly. If the share is below 40%, a combined scheme is needed.

How to select and implement without errors

In practice, 7 out of 10 failures are not related to the equipment, but to the design. Here are three required steps:

1. Take a fluid sample at three points: at the inlet, after the pump and before the consumer. The difference in concentration will show where the main wear of the equipment occurs;
2. Measure pH and conductivity. At pH<5.5 or >9.2 Corrosion of steel filter elements is possible - a protective coating of AISI 316L stainless steel is required;
3. Make sure there is a backup channel. Even with automatic regeneration, a minimum of 15% capacity reserve is required - especially with flow fluctuations greater than ±20%.

LONGI Corporation is a manufacturer that has been producing such solutions for 31 years. The plant in Fushun (China) has its own magnetic systems laboratory and a certified testing center. All models undergo 100% testing for tightness, magnetic induction and hydraulic resistance. Technical data sheets, connection diagrams and examples of calculations for specific operating conditions are available on the website ljmagnet.ru.

A leading high-gradient magnetic filter is not “just another filter.” This is a point solution for problems where every micron particle affects the reliability, service life and cost of production. Its value is manifested not in the first days, but in the third year of operation - when competitive systems require replacement of magnets, but this one continues to work with the declared efficiency.