suspended magnetic separator

When you hear “suspended magnetic separator,” many, especially beginners, imagine just a magnetic plate hanging over a conveyor. Like, hang it up - and that’s it, let the metal catch it. In fact, if you approach it this way, you can easily miss half of the useful iron, or even damage the conveyor belt. I went through this myself when the first such system was installed at one of the processing plants near Chelyabinsk ten years ago. Then we thought - what’s so complicated about it? It turned out that the distance from the working surface to the belt, the angle of installation, even the speed of the flow - all these are not just 'technical parameters', but factors that either give a pure product or constant complaints from enrichers.

Design: where the main pitfalls lie

The main mistake is to assume that all suspended separators are approximately the same. In terms of design, yes, the principle is the same: a magnetic system in the housing, a suspended frame, and sometimes self-cleaning. But here are the details... Let's take, for example, the magnetic system itself. Previously, ferrite magnets were often installed - cheap, but for difficult conditions, where a large piece can fly and the flow is dense, their strength is no longer enough. Nowadays it's mostly neodymium, of course. But here there is a nuance: neodymium-iron-boron is a common name, and the quality of the alloy, the protective coating against corrosion - this depends on the manufacturer. I have seen cases where, in wet production, after six months the active zone began to “bloom” and the field strength dropped.

The body is also history. It must be durable to protect the magnet from impacts, and not too massive so as not to complicate installation and adjustment. Cast steel - reliable, but a bit heavy. Welded from sheets - it’s easier, but you need to monitor the quality of the seams so that it doesn’t deteriorate over time. We once installed a separator at one of our facilities near Krasnoyarsk, where the housing was, let’s say, not the most successful design. After a couple of years of work in the vibration zone from the crusher, microcracks appeared on the frame. Not critical, but had to be strengthened.

And a self-cleaning mechanism. It would seem a brilliant solution - no need to stop the line for cleaning. But it is justified only with a constant, fairly intense flow of extracted metal. If metal is found rarely, but in large pieces, this system may not work as it should, and “chew” the piece. We had to offer customers a combined option: manual cleaning plus the ability to install self-cleaning later if the operating mode changes.

Installation and configuration: theory vs. practice

The optimal suspension height is always written in the passport. Let's say 300 mm for a certain fraction. But on site it turns out that the conveyor is “walking” due to the load, and the material does not always flow in a perfectly even layer. Therefore, the rule is simple: we install it, do a test run with control (pre-selected) metal inclusions and adjust the height in real time. Sometimes it is better to lower it by 20-30 mm, even if this slightly reduces the current performance, but is guaranteed to remove all dangerous inclusions. This is especially important on lines in front of crushers.

The installation angle relative to the flow is a separate issue. Standard - perpendicular. But if the flow is very fast, it sometimes makes sense to rotate the separator a little to increase the time the magnetic field is exposed to the particle. This is not a panacea, and it needs to be considered for each case, but this technique has come to the rescue several times during the sorting of solid waste, where the belt moves quickly, and aluminum cans and small ferromagnetic scrap come across.

There is nothing to say about fastenings. It would seem like a small thing. But if the suspension is made on ordinary chains, without locking mechanisms, then over time the separator can swing due to vibration, changing the gap. It is now considered good practice to use rigid traverses with adjusting screws. At the samesuspended magnetic separatorfromLONGI Corporation, which we installed at the enrichment plant, was just such a system. It’s convenient that you can accurately set the position even after installation, without resorting to a crane.

Case: when expectations did not coincide with reality

I had an interesting, although not entirely successful, experience at a glass factory. The task is to extract small ferromagnetic particles from broken glass on the return conveyor. They installed a powerfulsuspended magnetic separator. Logically, everything should work. But the efficiency turned out to be lower than expected. They began to figure it out. It turned out that cullet, especially when wet, creates a rather dense, sticky layer on the tape. The magnetic field weakened, not breaking through this mass to small chips. It was necessary to additionally install a device for loosening the layer in front of the separator. Conclusion: the separator cannot be considered as a completely independent solution. He is part of the system. It is necessary to analyze the entire technological cycle before and after it.

Another point about the same project is the material of the separator body facing the material. It was smooth. And cullet, you know, is an abrasive material. After several months of continuous use, noticeable abrasions appeared. Not completely, of course, but the appearance has become unaesthetic. Now I always draw the attention of clients to this point: for abrasive environments it is better to order models with a reinforced protective plate or a special wear-resistant coating.

Manufacturer's choice: not only price, but also 'iron' logistics

The market is now saturated. You can buy a Russian assembly, and a Chinese one, and a European one. Prices vary greatly. When we considered options for a large mining and processing plant, including looking awayLONGI. What attracted me was that the company was not just a trading company, but a manufacturing one.'Shenyang Scientific Electromagnetic Co., Ltd. LONGJI', created back in 1993, has its own full cycle - from development to testing. This is important because you can request changes to the design for specific tasks, rather than just choosing from a catalog. An area of ​​140,000 m2 and more than 1,200 employees, the majority of whom are process engineers, speak of serious scale. The annual capacity of 4,000 units of equipment is also impressive - this means there is experience in mass production and, as a result, proven quality control technology.

But for us, it was not only the plant that was key. On-site technical support and availability of spare parts were important. European brands often lose here in terms of delivery times for components. And in the case of a breakdown, each line stop means huge losses. Therefore, in the end, the choice often comes down to a balance: advanced technology, affordable price and prompt service availability. Sometimes reliability and maintainability outweigh the small difference in magnetic field strength indicated in the data sheet.

Looking forward: what else can be improved

Nowadays there is a lot of talk about 'smart' systems. And in the areasuspended magnetic separatorsthis is also relevant. The simplest step is sensors for monitoring the gap and temperature of the magnetic system. Overheating is the main enemy of permanent magnets. If the standard package included a sensor with data output to the remote control, this would prevent system degradation. Some advanced manufacturers are already starting to offer this.

Another direction is adaptability. A separator that can itself slightly adjust the height depending on the load on the conveyor (say, through a laser layer thickness scanner) is no longer a fantasy, but a matter of the coming years. Especially for industries with raw materials that are unstable in composition and volume.

Overall,suspended magnetic separator- is far from a primitive device. This is a precision instrument, the effectiveness of which is 30% determined by the quality of manufacturing, and 70% by competent implementation in the technological chain. Errors at the selection and installation stage are very expensive to correct later. Therefore, my main advice is: do not skimp on engineering. It’s better to invite a specialist to look at your line in person than to spend months sorting out problems with under-separated product or unscheduled stops.