The dynamic development of the automotiv industry in this century, especially after the World War II, has had the logical consequence of ever-growing stacks and heaps of old cars, in particularin industrial countries. At present, about 30 milion cars are yearly put to scrap world-wide. At the beginning, the scrap cars were merely placed in dumps, giving rise to unattractive car cementeries. However, dumping of cars is very uneconomical and enviromentally unbearable. Recycling technologies have therefore been gradually introduced.
Materials composition
Passengers cars contain on average 74.5% metals and 25.5% non-metals materials. The majority of metals is iron in the form of different types of steel and cast iron. A smaller proportion is due to non-iron metals such as aluminium, tin, lead, copper, nickel, precious metals, etc. The main non-metal components are plastics, rubbers, glass, textiles, composites, paints, operation liquids (oils, fats, brake fluids, coolants) and ceramics. In the last two decades, car manufacturers have been reducing the vehicle weight in order to spare fuel ahd thereby suppres emissions. This is reflected in the growing proportion of plastics (from 40 kg to 130 kg plastics per car). At present, about 10 000 different plastics brands are used world-wide, which represents a serious drawback in recycling. It is necessary that only a few basic types of plastics be used throughout the world. A ban on PVC-based plastics is espected to come into force after 2000.
Recycling technologies
1. The currently predominant technology is so-called shredding, which represents pressing and grinding the used car to pieces. This step is followed by grading of the shredded material. The cars are assumed to be previously stripped of all fluids and of the storage battery, which is recycled separately. Metals are then separated from non-metal materials (pneumatic separators, water cyclones) and non-iron metals are separated from iron (magnetic separators). The glass fraction of the non-metal waste can be used as filler into asphalts, for manufacturing tiles, heat insulation materials or for solidification of toxic wastes. When the glass parts are first dismounted , they can be recycled in glass factories. Rubbers and plastic can be processed by incineration or by depolymeration, gassification, chemical processing techniques, or pressing (plastics). (For rubber waste - see the project "Tyres" 1997).
2. A more expensive technology is a complete disassembly. The car is stripped into its component parts and these are then, after certain modifications, returned into the production or are recycled separately. The degree of revalorization of the used cars in this case is higher than with shredding (70 - 75% materials are revalorized at present, and this proportion should increase to 85% after 2000). The recycling by disassembly should of course be taken into consideration already by the car manufacturers.
The year 1994 witnessed the starting of the Q-REC project which creates a system concept for the recycling of dicarded and damaged cars. The project proceeds under the participation of a number of West- and Central-European countries including the Czech Republic. It represents the first step towards an industrial concept of recycling. Briefly - certain unifying principles should be implemented in car production, disassembly technologies should be created for different car types, and a network of recycling stations and facilities should be establish.
Situation in Czech republic
In the Czech republic, 36 000 passenger cars have been put to scrap out of the total of 3 milion cars. For comparison, in Germany 2.6 milion cars out of 40 milion have been put to scrap. The proportion is thus 1.2% for the Czech Republic and 6.5% for Germany. These data show that the problems with used cars in our country are not yet so pressing, but the number of cars put to scrap is certain to increase in the near future.
