Recycling Automotive Materials - Lead - Acid Batteries and Polyethylene Terapthalate (PET)

Topics Covered

Background

Recycled Materials Replacing Virgin Materials

Batteries

Reclamation of Used Batteries

Recycling of Battery Materials

Evaluation of Recycled Batteries

Recycled Batteries and the Market

Recycling Other Automotive Materials

Recycled Polyethylene Terapthalate

Summary

Background

When dealers go into raptures at the end of August about how many new cars they have sold, materials scientists should allow themselves a knowing smile. Because most of the vehicles sporting the new ‘S’ registration plates will have already experienced several years’ life on the road - albeit as part of another car. The proportion of materials recycled from old vehicles into new is rising rapidly as the automotive industry tackles environmental regulations and tries to make itself appear as ‘green’ as possible.

Recycled Materials Replacing Virgin Materials

Ford, along with all the other vehicle manufacturers, is studying ways to reclaim and recycle nearly all the different parts in its range of models. With the help of its suppliers, it is gradually replacing its virgin materials with recycled counterparts.

Batteries

Last year, the company announced that it had tackled one of the most difficult components to recycle and to produce in recycled materials - the battery. Batteries are essentially composed of polypropylene, acid and lead, and so when they come to the end of their lives, they have to be treated as toxic waste. Any recycling process has to ensure there is virtually no contamination to allow the recovered materials to be reused.

Ford’s aim was to manufacture a battery made entirely from reclaimed lead and plastic - in other words, made solely from end-of-life components. Widespread recovery and recycling of batteries would have a big impact - Ford alone uses 1500 new batteries each week in the UK. So in conjunction with its supplier, Exide, the company’s European Recycling Awareness Team began studying how to break down and reclaim battery materials, and how the recycled materials performed when reconstituted as another battery.

Reclamation of Used Batteries

In fact, reclaiming all the materials from batteries can be done using a remarkably simple yet effective process. At the end of its life, a lead-acid battery is collected by an authorised company for reprocessing. It is fed into an automated hopper, which then delivers it on to a hammer mill where the battery is smashed into very small pieces. These pieces are washed by high pressure jets while being carried along on a vibrating mesh, which eventually allows the lead, plastic and acid to be separated and treated.

Recycling of Battery Materials

The lead is re-smelted and turned into new battery plates, paste and connecting lugs. The plastic meanwhile is separated by flotation, dried and granulated before being re-extruded to form new battery cases. The acid is simply neutralised. Using this process, Ford claims to have closed the recycling loop for its batteries.

Evaluation of Recycled Batteries

More than 80 police cars received batteries made from recycled materials as part of Ford’s tests to see how well the second generation parts performed. The cars were on the go continuously, 24 hours a day, allowing accelerated durability testing of the new batteries. Overall durability, warranty and fluid levels were monitored, and Exide also carried out a full range of tests on the components, including drop tests, temperature an tumbling tests. The batteries in the police cars performed extremely well with no problems, and passed all of Exide’s tests with flying colours too.

Recycled Batteries and the Market

The batteries made from recycled materials are clearly a great success with a reduction in warranty of 85% and a reduced number of components being rejected during manufacture of the battery casings from the recycle material. Having announced its breakthrough at the 1997 Motor Show, Ford is now looking to extend the use of recycled batteries - as well as battery reclamation - worldwide. It is introducing the recycled batteries into it older vehicles as well as new models, and is stocking its dealerships and parts and accessory suppliers with the batteries.

Recycling Other Automotive Materials

Ultimately, the real benefit is to the environment, as less material buried in landfill sites and fewer raw materials are used up. But as Ford and the other major car manufacturers are finding, the use of recycled materials can have both cost and performance benefits too. The battery is just one of Ford’s examples. The company is also seeing the benefits introducing a recycled grade of plastic into some of its North American models.

Recycled Polyethylene Terapthalate

Recycled polyethylene terephthalate from old drinks bottles and of sources is now being used to make the heating, ventilation and air conditioning duct vent doors in Ford’s Taurus, Mercury Sable and Lincoln Continental models. These components, which mix and direct air from heating and cooling systems into the passenger compartment, were normally made from 45% glass-filled polyester, mainly virgin material. But Ford wanted to maximise its use of recycled materials, while maintaining quality and performance and not increasing costs.

Impet 3408 recycled PET, made by Ticona, was chosen to replace the virgin material as it has overall performance processing characteristics at least as good as those of the original material. These properties are critical for the vent doors because the parts contain some fine moulded-in detail, including snap fittings for other components. The recycled grade actually performs better than the virgin material in terms of dimensional stability - according to Ticona this is because the history of the recycled polymer reduces its viscosity and improves fibre dispersion in the material. The result is that the flatness of Ford’s doors seems to be better with the recycled material.

Summary

If these sort of developments continue to be introduced by the new car makers, eventually all the materials making up the main bodies of cars could be being reclaimed and being taken from recycled sources. So next time you splash out for a new car, or even a new battery, you will in fact be buying a bunch of materials going round and round their recycling loop. Query it with your dealer. It might even get you a discount.

 

Source: Materials World, Vol. 6, no. 7, pg. 414, July 1998.

 

For more information on this source please visit The Institute of Materials Minerals and Mining.

 

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