Environmentally Compatible Disposal
Propellants in spray cans are highly flammable and the pressure filling means that the cans represent a problem during waste incineration. This is why few firms specializing in this flow of waste have established themselves on the market. One of these companies in Neunkirchen in Saarland has now fundamentally modernized its spray can processing, installing the QZ 1200 Querstromzerspaner of the German plant engineering and construction firm MeWa Recycling Maschinen und Anlagenbau GmbH.
In Germany, the ozone-damaging propellant CFC in the manufacture of spray cans was stopped in the 1990s. Nowadays, the industry uses other mixtures in hair sprays, deodorants, paint sprays and other atomisers. These usually consist of propane, butane or dimethyl ether.
However, even with these substances the disposal is anything but free of problems. The propellants used are highly flammable, and the pressure filling means that the cans form a highly explosive mixture during shredding. For this reason, above all spray cans that are still filled represent a considerable danger in waste incineration systems. Consequently, a small circle of disposal companies have specialised in these specific waste fractions in Germany.
One of these sophisticated plants is operated by Seiba Entsorgungstechnik GmbH in their branch in Neunkirchen. The company has been specializing in the recycling of spray cans since as long ago as 1988. The plant has now been fully modernized. Where rotor shears used to shred the aerosol cans, the QZ 1200 Querstromzerspaner from MeWa now operates according to a completely new concept. At the same time as replacing the shredding unit, the entire waste gas plant was adapted to the state of the art.
Seiba obtains some of the material from disposal companies all over Germany as well as from France and the Benelux states. The remaining quantities are partially filled cans from the manufacturing industry.
The industry makes the aerosol cans either from tin or aluminum. Alongside the filled propellant gases and the cosmetics, paints or lacquers, the containers still have small proportions of plastics, which are primarily fitted in the valve devices.
After more than 20 years, it was above all the low wear and significantly higher throughputs compared to rotor blades that moved the disposal company to replace the obsolete rotor shears with the QZ from MeWa, including new explosion and gas protection facilities. Everywhere there are different metal-plastic composites to separate, the patented machine shows its great versatility. Instead of cutting, the MeWa Querstromzerspaner with its chain principle separates the cans into their individual component parts in seconds. Any residual liquids are immediately extracted from the machine and drained off. The hollow bodies made of tin or aluminum are separated from the plastic components by the loads applied in the barrel of the QZ.
The exposed metals and plastics are cleaned in a water bath and separated into the three fractions aluminum, ferrous metals and plastic by means of a magnet and an NE cutter. The extracted recycled resources are passed on by the plant to recycling firms in the region.
The Querstromzerspaner convinces in this process not only with the low wear to its chain but also due to the generally low maintenance overhead and a significantly higher throughput than rotor shears.
A number of safety levels ensure a disposal process in the plant that is environmentally compatible. In order to ensure the customer has the highest possible recycling safety, Seiba Entsorgungstechnik GmbH has installed video surveillance for the processes.
First of all, the pressurized gas packages are picked up by scanners at the initial check. An employee then picks out extraneous materials, the material flow is metered via vibrating channels and integrated scales and sent across a conveyor belt to the QZ. A sluice system ensures that no gases can escape from the Querstromzerspaner into the hall. To prevent gas explosions, the oxygen concentration in the barrel is monitored electronically and nitrogen is sprayed in at regular intervals.
The propellant gases that are released are separated together with the inert gas via the condensation and used thermally. The entire process and hall air is routed via a waste gas cleaning stage with downstream filter. It goes without saying that the plant is approved in line with Federal Immission Protection Laws and has been inspected/approved with respect to safety by TÜV Süd (German Technical Inspection Association).
In this special application, the MeWa Querstromzerspaner shows once again how versatile it is when deployed for the separation of composite materials. The QZ will be presented at the IFAT in Munich from September 13 - 17, 2010, in Hall C2, Booth 421/520 and at the RWM in Birmingham from September 14 - 16, 2010, in Hall 17, Booth 422.
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