magnetic grain separator

When you hear “magnetic grain separator,” many people think of just a magnetic strip over a belt. In fact, this is a whole system, and if you approach it carelessly, you can not so much clear the grain as create new problems. They often think that the main thing is the strength of the magnet, but they forget about the uniformity of the field, the extraction of captured metal, and resistance to abrasive. And in vain.

The main mistake: chasing ?power?

At the beginning of my work, I also fell for this bait. The customer demands: “Give me the most powerful magnet!” They installed a separator with neodymium magnets of monstrous strength. And six months later - a call: “Your equipment is breaking down, the grain is not being cleared from the magnet, you almost have to tear it off with a crowbar?” The problem was not with the magnet, but with the design. A strong field is good, but if a metal particle sticks tightly and cannot be removed quickly and effortlessly, then the whole process stops. I had to redo it.

Here it is important to understand the difference between magnetic induction and field gradient. For small, weakly magnetic inclusions (scale, worn particles), it is often not the absolute strength that is more important, but the field configuration that creates a high gradient. This is what is “addictive”? particle. I am now looking at some models, for example, fromLONGI Corporation- in their passportmagnetic grain separatorBoth the induction and the coverage area are always shown on a separate line, indicating the gradient. This already speaks of a serious approach.

By the way, about LONJI. On their websitehttps://www.ljmagnet.ruYou can find not just pictures, but rather detailed diagrams of the cleaning zones. Company,?Shenyang Scientific Electromagnetic Co., Ltd. LONGJI?, has been operating since 1993, and you can feel it. They're not the type to just put magnets in a case. Their production base in Fushun, with an area of ​​about 140,000 m2 and their own engineers, allows them to work out such nuances.

Construction: Where the Devil Lies

So, we've sorted out the magnets. But the body, tray, self-cleaning system - this is where failures most often occur. I remember an incident at one elevator: they installed a separator with excellent magnetic blocks, but the body was made of ordinary steel, not stainless steel. Humidity, dust, condensation - after a year corrosion began. Rust itself has become a source of pollution. Irony.

Therefore, now I always look at three things: the material of execution (for food grain, stainless steel is required in the contact area), the tightness of the components (so that grain dust does not clog the mechanisms) and the type of cleaning. Cleaning can be manual, semi-automatic and automatic. For large flows, of course, only automatic with electric drive. But there is a catch here: if the drive is weak or the trajectory of the cleaning element is not optimal, then some of the metal will remain on the surface.

At the same LONGI, in some models, a system of “traveling magnetic field” is implemented. for self-cleaning. In essence, the magnetic system is not static, but moves, dropping attracted particles into a separate bunker. An elegant solution, but requires precise tuning and quality components. Not every manufacturer will be able to do this consistently. But if the company produces about 4,000 units of various equipment per year, then, probably, their technological discipline is in order.

Line integration: don't create a bottleneck

The most common headache in practice is not the separator itself, but its integration into an existing production line. You arrive at the site, and there: “Put it here?” And ?here? — the angle of incidence of the grain on the belt is 45 degrees, the flow speed is higher than the rated value, and there is also vibration from neighboring equipment. In such conditions even the bestmagnetic separatorwill work at half capacity.

The grain should be distributed over the working surface in an even thin layer. If the layer is thick, the metal particle in the middle may simply not be felt. magnetic field. Therefore, preliminary devices for uniform flow distribution - feeders, dividers - are required. They are often ignored and saved.

Another point is the installation point. It is better to install after primary cleaning (stone pickers, triers), but before delicate operations such as peeling or crushing. To catch metal that might have gotten in from wear and tear on previous equipment. But sometimes, for especially important parties, they place it at the exit, as a finishing barrier. This is a matter of cleanliness requirements and the economics of the process.

What do we catch and what do we lose?

Everyone is talking about ferromagnetic metals (iron, steel). Everyone catches them. But there are also weakly magnetic ones - for example, some types of stainless steel, scale hardened during wear. It’s more difficult to catch them; you need those same high-gradient systems. And there are also non-magnetic metals - copper, aluminum, lead. A magnetic separator will not save you from them. This is about the issue of comprehensive protection. Sometimes clients are surprised: “Why did they find aluminum shavings after your separator?” We have to explain the basics.

Therefore, a competent technological map includes not one, but several types of separation: magnetic, pneumatic, sieve.Magnetic grain separator- This is a critical, but not the only link in the security chain.

I had a bad experience when they tried to solve all problems using a super-strong magnet, neglecting air separation. As a result, the metal was caught, but light impurities (films, dust) remained and spoiled the batch during storage. Lesson learned: equipment must work within the system.

Service and “little things” that make all the difference

Any equipment, even the most reliable, requires attention. For magnetic separators, this is, first of all, regular checking of magnetic properties. Over time, especially with temperature changes or mechanical shocks, the magnet may lose strength. Once every six months or a year it is worth measuring the induction with a Teslameter. It takes 10 minutes, but prevents major losses.

The second “trifle” - this is cleaning. Not only automatic, but also general. Grain dust is an excellent abrasive and insulator. If it covers the magnetic plate with a thick layer, the efficiency will decrease. The instructions often say “wipe with a dry cloth”. In fact, in a workshop environment, this turns into a weekly procedure that someone has to do and monitor something.

When choosing a supplier, I now always look not only at the technical characteristics, but also at the availability of spare parts, the availability of diagrams, and the clarity of the instructions. If the company is like the sameLONGI, has a solid history (operating since 1993), a large staff of engineers (more than 1200 people, of which over 60% have higher education), then, as a rule, their documentation and support are in order. This is not a guarantee, but a serious indicator. It's easier to work with someone who produces key components themselves, rather than just being an assembler.

Instead of a conclusion: thinking out loud

So, back to the beginning.Magnetic grain separator- this is not a piece of hardware with a magnet. This is a calculation device that must correspond to a specific flow, specific tasks and be part of a well-thought-out system. His choice is not a search for the cheapest or the most powerful? option in the catalog. It is a balance between magnetic efficiency, structural reliability, serviceability and ultimately overall production economics. Often the 10-15% saved at the purchase stage is then many times offset by losses from downtime, repairs or, God forbid, a rejected batch of grain. Experience, including bitter ones, suggests that it is better not to experiment here, but to rely on proven solutions and those who stand behind them.