China Counterflow Type Magnetic Drum Separator

China counter-current type magnetic drum separator is not just equipment for removing ferromagnetic impurities. This is a precision tool where the direction of the material flow and the rotation of the drum work *against* each other - and it is this interaction that gives up to 98.7% cleaning efficiency at feed rates of up to 120 t/h. We tested this at three factories: in the Kemerovo region, in the Urals and in the Belgorod region. In each case there are different ores, different humidity, different levels of abrasiveness. But the result was the same: stable particle retention from 0.3 mm, zero loss of useful component, minimal wear of the shell.

Why does counterflow work where a conventional drum loses 15–22% of cleaning?

A regular magnetic drum - the material moves *in the same direction* as the drum rotates. The particles slide, touch the magnet briefly, and are often torn off by centrifugal force. The countercurrent type solves this problem fundamentally: the flow of bulk material is directed *toward* the rotation. The material is “captured” by the surface, slows down, is retained in the zone of maximum magnetic induction - and only then is dumped into the receiving tray.

In practice this means:

• The time of contact with the magnetic field increases by 2.3–2.8 times
• The critical size of captured particles is reduced from 1.2 mm to 0.25 mm
• Air consumption during pneumatic conveying does not affect efficiency - the system is resistant to pressure fluctuations
• The drum tilt angle is adjustable from 5° to 15° - there is an optimum for each material

We observed how one plant switched from a parallel to a counterflow separator - and reduced the amount of defects in the final product from 4.2% to 0.35% in three months. No replacement of crushers, no modernization of conveyors. Only due to precise magnetic separation.

Where they make mistakes when choosing - and how to avoid it

Some customers believe: “the higher the induction, the better.” This is a dangerous misconception. When induction exceeds 160 mT, “magnetic adhesion” begins in the loading zone: particles form agglomerates, clog cracks, and disrupt the uniformity of the layer. We have seen two cases where, due to overzealous magnet power, the separator worked for 11 days, and then required complete disassembly and cleaning every 48 hours.

The right approach is balance:

• For quartz sand, granulated slag, secondary raw materials: 110–130 mT
• For ferrous ores, blast furnace slag: 135–155 mT
• For fine coal lumps and phosphates: 95–115 mT + enhanced purge system

Another common mistake is ignoring the temperature regime. If the material arrives at temperatures above 65°C, standard neodymium magnets lose up to 30% of their strength after just 4 months. The solution is special grades of NdFeB with the addition of dysprosium and a heat-resistant design of the housing. We make such modifications according to specifications - but only after analyzing material samples and measuring the temperature at the supply point.

How to integrate a separator without stopping production

Installation takes from 2 to 5 working days, depending on the complexity of insertion into the existing conveyor. The main condition: the presence of a horizontal section of at least 2.5 m in length in front of the feed point. We do not use universal “flange adapters” - we make each set for a specific belt diameter, axis height and inclination angle.

Key parameters that we always clarify before design:

• Maximum performance in terms of weight and volume
• Average particle size and distribution (by sieve analysis)
• Moisture content and abrasive inclusions (according to laboratory data)
• Presence of vibration in the installation area (measured with an accelerometer)
• Available supply voltage and electrical panel protection class

At all facilities we carry out commissioning with measurement of residual magnetization in the purified product - the norm is no more than 30 g/t. If the indicator is higher, we adjust the position of the scraper, the rotation speed or the angle of inclination of the drum. We don’t leave until the result is recorded in the act.

China counter-current magnetic drum separator - a solution that grows with your production

This is not disposable equipment. LONJI drums last 8–12 years with 20 hours of daily use. The service life of the magnetic block is 10 years without loss of more than 5% of induction. All components are standardized: replacing bearings - 45 minutes, replacing a magnetic segment - 2 hours, without special tools.

Shenyang Longji Scientific Electromagnetic Company LLC has been creating such solutions since 1993. The Fushun plant produces 4,000 units of equipment per year. More than half of the engineers have specialized higher education - and they don’t just assemble separators. They model particle trajectories in ANSYS Maxwell, test new coatings for abrasion resistance, adapt designs to Russian climatic conditions and the requirements of TR TS 010/020.

China counter-flow type magnetic drum separator is not an imported replacement. This is a technology strategy. It reduces crusher repair costs, prevents failure of conveyor belts, and increases the value of the finished product. And it all starts with one right choice - not the most powerful, but the most accurate.