SIEMENS

Electronic products are veritable treasure troves. In 2010, 7.7 million smartphones were sold in Germany alone. These phones contained a total of 230 kilograms of gold, over 2.3 tons of silver, and 85 kilograms of palladium – all hidden in items such as electrical contacts and solder on printed circuit boards. Kilo for kilo, that boils down to a higher percentage of precious metals than is available in the world’s best mines. After the usual service life of three to four years, these mobile phones could therefore yield significant value. The concept of recovering precious materials from household and industrial waste is known as “urban mining.” But before closed-cycle waste management is established for all valuable raw materials, there are a number of obstacles to overcome.

For example, an individual cell phone contains less than 0.4 grams of precious metals. When the phone goes through a shredder, these materials are mixed with others, often making it difficult to separate them. If the effort of collecting, separating, and processing is to be profitable, other materials, such as copper, must also be recovered.

That’s why Professor Stefan Gäth of the Frauenhofer Project Group for Materials Recycling and Resource Strategies in Alzenau and Hanau, Germany, advocates intelligent recycling. “Instead of diluting the concentration of specific materials with a shredder, we could, for example, deliberately remove the vibration alarm in order to recover the tungsten it contains,” he suggests. “If the composition of an individual cell phone is known, such processes can be automated. We are therefore creating a database with that information right now.”

Another difficulty is the logistical effort required for recovery. Old cell phones are collected at a rate of only five percent per year. Very often these devices sit in a drawer for years or end up in the trash. Similarly, in Germany 80 percent of deregistered cars are exported, and after several more years of service they are usually scrapped without any appreciable recycling. By comparison, the removal of raw materials from natural deposits is much simpler in terms of logistics.

But demand for raw materials is increasing enormously and for some of them, such as the rare earth metals and tungsten, niobium, and gallium, availability may soon reach critical levels. China, for example, has a virtual monopoly when it comes to extracting rare earths. Only small deposits of many metals have been found and most of these deposits are located in politically unstable countries. All of these factors are driving the development of recycling and the expansion of closed-cycle waste management. Recycling lowers dependence on imports and reduces waste. However, it should not be confused with “downcycling” – a process that only produces material of lower quality, such as a park bench made of plastic waste.

Recycling systems have long been established for glass, paper, and many metals. For some metals such as copper and iron, the amount of recycled material in new products is over 50 percent worldwide.

Recycling works well for machines and structures with large steel or aluminum parts, but Dr. Ulrich Bast, a materials expert at Siemens Corporate Technology (CT), says, “Our waste is becoming more complex. Many products, such as cars, aircraft, cell phones, and LEDs, increasingly contain a mix of highly specialized materials. Electronic modules and lightweight products that use steel, alloys, and composite materials contain many valuable components such as gold, platinum, palladium, copper, rare earth metals, glass fibers, and plastic, but these are often tightly bound together. This makes recycling more difficult. Easy dismantling later on should therefore be a key design goal.” To date, according to Frost&Sullivan, worldwide recycling rates for electronics and electrical appliances have been around 19 percent.

Dr. Jens-Oliver Müller, project leader for Recycling at CT, and his research team in Munich are addressing this situation in Project MORE (Motor Recycling), which is supported by the Federal Ministry of Education and Research. For example,the team is developing methods for recovering the permanent magnets from various systems. There hasn’t been a satisfactory recycling solution for these magnets up to now. Compact and lightweight synchronous motors for electric cars and generators for wind power plants use powerful neodymium-iron-boron magnets containing up to 30 percent of neodymium and smaller amounts of dysprosium, praseo?dymium, and other rare earth metals.

Getting More out of Magnets. “In addition to recycling materials, it is also important to extend the life of products by repairing, reusing, refurbishing, and upgrading them,” says Müller. “In MORE we are exploring a variety of approaches to recycling. For example, we are doing research to find out how approximately one kilogram of heavy magnets or other components of old motors from electric cars can be recovered, repaired, and reused. However, this requires a motor design that stays the same for a number of years. We are also testing to see how well a magnetic material can be reused if the presorted material is cleaned, ground, melted, and sintered into a new magnet. At the same time we are also doing research on the recycling of raw materials. Through the recovery of raw materials it is possible not only to produce magnets of all shapes and sizes but also to reset their magnetic properties.”

If recycling is to become a serious source of raw materials, the processes involved will have to become significantly more efficient. In cooperation with the Institute for Factory Automation and Production Systems at the Friedrich-Alexander-Universität in Erlangen-Nürnberg, Siemens is investigating concepts for automating the disassembly of electric motors. Another important partner of the MORE project is the German recycling company Umicore AG & Co. KG, which boasts Europe’s highest level of expertise in recovering metals using thermal processes. Frank Treffer, a project director at Umicore, sees a lot of potential in this area. “Large amounts of valuable materials are widely distributed in waste – for example, the bits of silver in each of thousands of RFID labels,” he says. “Fundamentally, modern recycling technologies make it possible to recover these materials. But often there’s still a major gap in terms of logistics.”

A Solvent that Saves Carbon Fibers. Siemens researchers are also actively involved in another future field. Corporate Technologies expert Dr. Heinrich Zeininger is working on recycling carbon fibers from fiber-reinforced composite materials. This lightweight construction material combines the high rigidity of carbon fibers with the moldability of a plastic matrix. It is used in aircraft, spacecraft, and automobile construction. Carbon fibers are expensive and require a lot of energy to manufacture. Additionally, plastic fibers are carbonized, meaning that they are converted into carbon at high temperatures. The length of these fibers and the form of the woven material produced from them is always exactly suited to the requirements of the component being manufactured.

Until now, the only available recycling method was pyrolysis, which means burning away the plastic – a process that tends to damage fibers, causing them to became matted and tangled. At that point they can only be cut into small pieces and used to produce, for example, conducting polymers. But that’s a dead end in terms of the materials cycle. In view of this, CT scientists have now developed a “solvolytic” recycling method that has been registered for a patent. This method uses a solvent to remove the plastic.

As a result of this process, carbon fibers are left intact at their full length, woven materials keep their shape, and even their surfaces remain undamaged, ensuring good adhesion to plastic. The reuse of these fibers requires significantly less energy than would be needed to carbonize them at 2,000 °C.

Zeininger developed this process as part of the Bavarian Cluster Initiative MAI Carbon, which is supported by the Federal Ministry of Education and Research. “Because of their special properties, carbon fiber-reinforced materials will be used more and more by Siemens, for example in motors and rotor blades,” he explains. “Our process is useful because a recycling concept is always a necessary part of the development of new products. The next challenge will be to integrate the recovered carbon fibers into new products, even when the geometry of the new component differs from that of the original component.” When it comes to product life cycles, Siemens Healthcare Sector is also concerned with protecting the environment and using resources efficiently. To that end, a multi-step take-back concept has been developed. Used devices, such as X-ray machines, will be remanufactured into “refurbished systems.” Individual components will be reused or used as replacement parts, and valuable materials, such as the heavy metal molybdenum that is recovered from X-ray emitters, will be reused.

When it comes to product life cycles, Siemens Healthcare Sector is also concerned with protecting the environment and using resources efficiently. To that end, a multi-step take-back concept has been developed. Used devices, such as X-ray machines, will be remanufactured into “refurbished systems.” Individual components will be reused or used as replacement parts, and valuable materials, such as the heavy metal molybdenum that is recovered from X-ray emitters, will be reused.

Design-to-recycling is another promising approach. This involves designing products in such a way as to maximize ease of disassembly and separation of materials. In this setup, non-recyclable materials are removed before old components are reprocessed. For example, the aluminum frames of Siemens subway trains are held together by easily removed hexagonal bolts. The trains also contain a large amount of recycled metals, and their insulating boards are installed only between the shell and the paneling. The cork tiles for reducing impact noise in floors are covered with aluminum foil and rubber. These material layers can simply be stripped off when the trains are disassembled.

Given the variety of extractable valuable resources at current prices and the energy requirements for their removal, it will become increasingly important to create closed-material cycles in the future. “One way that Siemens can help to increase recycling around the world would be to expand product services,” says Müller. “In cases where fees are charged for disposal, customers will be particularly interested in having recycling included in the service package for Siemens products.”