Sorting of non-ferrous metals

When they talk aboutsorting of non-ferrous metals, many people immediately think about magnetic separation. But here’s the catch - aluminum, copper, brass, the same stainless steel scrap, they are non-magnetic. And here the fun begins, where simple solutions do not work, but an integrated approach is needed, often with manual tuning. For many years I have been faced with the fact that customers are waiting for a magic machine that will produce pure fractions at the output, but in reality they have to combine methods and constantly adjust something to a specific batch of raw materials.

From theory to real scrap

In theory, everything is clear: there are eddy current separators, X-ray fluorescent separators, in density, in size. Take the technological map and go ahead. In practice, scrap is alive. One batch may be heavily contaminated with plastic or rubber, while another may contain complex alloys that fool the sensors. I remember once they set up a line for copper scrap, and they brought in a mixture with a large percentage of copper-coated aluminum alloys. The color and conductivity sensors went crazy, the purity yield was below 70%. I had to change settings on the fly and add a manual sampling post. This was a lesson: without preliminary analysis and, frankly, without an experienced eye at the entrance - nowhere.

Material preparation is often overlooked. Coarse crushing and particle size separation are not just stages, they are the basis of the economics of the entire process. If you feed an uncalibrated mixture to an eddy current detector, the efficiency drops significantly. Small particles 'stick', large ones bounce off in the wrong direction. We have established a rule of thumb for ourselves: investments in high-quality crushing and screening pay off faster than the purchase of the most expensive separator.

And this is the right place to remember about equipment. Not for advertising, but as an example of engineering. At one time we studied the experienceLONGI Corporation (https://www.ljmagnet.ru). This enterprise, Shenyang Scientific Electromagnetic Co., Ltd. LONGJI, has been in mining and processing equipment since 1993. Their strengths are precisely their powerful electromagnets for extracting ferrous metal from the flow. Bsorting of non-ferrous metalsThe first critical step is to remove the iron. Otherwise, it will clog and damage equipment further down the chain. Their solutions for harsh conditions, on the same scrap of automobile shredders, showed good survivability. We haven’t worked with their entire range, but the fact that they produce about 4,000 units of equipment per year with more than 1,200 employees indicates serious production capacity. This was important for us - we needed not just a supplier, but a partner who understands industrial volumes and can adapt the unit to our specific technological flow.

Eddy current separation: myths and pitfalls

There is a lot of noise around eddy current separators these days. They are presented as a panacea. Yes, the technology is beautiful: a rotating magnetic rotor creates eddy currents in conductive particles, which are repelled. But it works great with large, clean, dry fractions of aluminum or copper. Just try to sort out the wet, flattened, oil-contaminated scrap from the press. Or a mixture that contains aluminum, zinc, and magnesium alloys. Their conductivity is different, the rebound will be at different distances, and a clear separation will not work.

The key parameter, which is often hushed up, is not the maximum productivity according to the passport, but the efficiency of separation when the composition of the raw material changes. A good separator should have a wide range of adjustments for rotor speed, magnetic field frequency, and discharge angle. And even then, you need an operator who 'feels' the material. Sometimes a small change in humidity requires a complete readjustment. This is not a 'set it and forget it' process, it is an ongoing process.

From practice: we installed such a separator on a line for processing electronic scrap. In theory, to extract aluminum. In practice, it turned out that many components are copper-plated or contain iron inserts that were not removed in the previous step. Eddy currents were induced strangely in them, the flight path was unpredictable. We achieved an acceptable result only after installing an additional, thinner magnetic drum specifically for removing small ferromagnetic inclusions. And it was not a LONGI separator, but a different brand, but the point is that without preliminary high-quality magnetic separation, an eddy current separator simply does not reveal its potential. This is where the experience of companies that have been making magnetic equipment for decades becomes critically important. They understand that a magnet is not just a piece of iron, but a tool that must work in an aggressive environment, with temperature changes, and with abrasive materials.

Touch technologies: expensive, but where would we be without them?

For complex alloys, for example, for separating brass from stainless steel or for sorting different types of aluminum alloys, sensor systems are no longer necessary. X-ray fluorescence (XRF) analysis, optical color and shape recognition. This is already a high level. But there are some nuances here too. An XRF separator is a huge investment. It is justified only for large volumes and high quality of the final product. In addition, there are restrictions on the size of particles; it may not “see” correctly.

They worked on one line where they tried to separate copper from brass using a combination of color and conductivity sensors. The problem was the oxidized surface. The copper wire, under a layer of oxide and dirt, looked almost like brass to the camera. It was necessary to introduce a stage of light crushing or even washing to expose the pure metal. This added operating costs, but increased the purity of the fraction from 85% to 96%, which already seriously affected the selling price.

An important point that is rarely discussed in open sources is the calibration and training of these systems. The database of reference spectra or images must be constantly replenished and adjusted for specific raw materials that arrive at the site. This is not a static setting. In fact, you 'learn' the car as you go. This is where the experience of an operator who can manually determine its composition by looking at a particle is invaluable for initial setup and for resolving controversial cases.

Process Economics: When Sorting Becomes Profitable

All these technological difficulties come down to a simple question: is it worth it?Sorting of non-ferrous metalsis not an end in itself, it is a way to add value. Separated pure aluminum, copper, and brass are many times more expensive than mixed scrap. But the barrier to entry is high. We need not only capital investments in equipment, but also space, logistics, trained personnel, and established sales channels for each faction.

I have seen many attempts when they bought one “most advanced” machine, put it in a corner of the workshop and waited for a miracle. It didn't work out. Because sorting is a technological line, a chain. From the reception and initial evaluation of raw materials, through crushing, screening, magnetic separation (this is exactly the place for reliable industrial solutions, like those that makeLONGIat its plant in Fushun), through air or eddy current separators, and only then through sensor systems. The loss of one link dramatically reduces the efficiency of the entire chain.

The biggest mistake is to underestimate the amount of manual labor. Even on the most automated line there remains a section of manual finishing, rejection, and control. Especially for complex, expensive factions. Full automation is a utopia for most types of scrap. Therefore, when planning a line, you must immediately consider both human resources and their qualifications.

Looking forward: not behind technology, but behind understanding the material

Nowadays there is a lot of talk about AI and machine learning in sorting. This is definitely the future. Systems that learn and adapt to the changing flow of raw materials. But the foundation remains the same: the physical principles of separation - magnetic, electrodynamic, optical properties of materials.

The main trend that I see is not the race for one super technology, but the competent integration of different methods into a sustainable and flexible line. Sometimes a simple and reliable magnetic separator, which has been in production for decades, brings more economic benefits and process stability than the most sophisticated sensor complex, which constantly requires fine tuning and expensive maintenance.

The result of my experience is simple: successfulsorting of non-ferrous metalsIt starts not with a catalog of equipment, but with a deep understanding of your raw materials. You need to study it, analyze the games, understand the variability. Then build a technological chain where each link, be it a classic magnetic separator from a trusted manufacturer or the latest robot with X-ray vision, solves its own specific problem. And always leave room for human experience, for that very “professional instinct” that no machine has yet replaced. It is this comprehensive, slightly conservative, but practical approach that makes it possible not only to sort, but to do it cost-effectively and sustainably in the long term.