Recycling 1153 ELVs From Theory to Practice

The developed theory as described in the previous section provides a fundamental basis for proper collection of data, supported by a good mass balance based on data reconciliation, and the corresponding statistics and how this should be performed when carrying out experiments or auditing a plant. This theory is essential to characterize and control the material and element flows in recycling

Table 1 The reasons for certain materials being compatible or not (also see Figures 11 and 12) explained on a thermodynamic basis

Input streams (secondary) = recyclates

Industrial streams (metals) Aluminum cast

Copper

Steel + cast iron

Aluminum cast

Similar material

During copper processing Al is lost to slag

Loss of Al; Al less noble

Copper

Cu is more noble than Al cast; a certain % of Cu is allowed being one of the alloying elements for Al cast

Similar material

Cu is more noble than steel

Steel + cast iron

Steel+cast iron more noble than Al cast

Creates excessive slags, loss of steel to slag

Similar material

Plastics

Limited due to reaction of Al with C and subsequent loss of Al (AL,C3)

Affects energy balance of processing; fillers affect slag properties; possible dioxine creation

Affects energy balance of processing; fillers affect slag properties; possible dioxine creation

plants and through the complete recycling system, which is extremely important for good metal/material accounting, the calculations of recycling rate on a sound statistical basis, as well as quality control of recycling streams. In fact this is the basis of any meaningful discussion on 'material and metal ecology'.

Experimental and industrial data on the composition of the car, the separation efficiency of the various processes, liberation and particle-size reduction in the shredder, the quality (or grade) of the recycling (intermediate) material streams is typical information that becomes available through a good understanding of the theory of recycling as discussed in the previous section. Furthermore, the collection of industrial data on recycling based on best available technology is essential to predict and calculate the recyclability of passenger vehicles, using the developed models. This is of extreme importance for a realistic definition of the type approval and end-of-life legislation of vehicles or any other consumer product. This type of data hence underpins the viability of material and metal ecology.

The theory is applied to provide a procedural basis from which the recycling rate can be calculated from an industrial experiment, in which 1153 ELVs were recycled. This experiment was executed at a large-scale industrial recycling plant and clearly illustrates how statistically sound recycling rates can and therefore should be calculated from data collected from recycling experiments based on the developed theory and classical sampling theory and statistics.

Practical Procedures for Performing Large-Scale Industrial Recycling Experiments

Mass balances of plants based on measured data mostly do not close due to inevitable weighing and sampling errors, as is also the case for the shredding and 'postshredder technology (PST)' trial as discussed here. Data reconciliation has been applied to close total and element/ compound mass balances over the plant and its unit operations. A large body of data renders the mass balance more accurate and makes it possible to calculate the recovery and grade for each of the different materials over the various process steps. These data are used to calibrate the models in the optimization and dynamic models mentioned above. Classical sampling theory has been applied to calculate statistically correct sample sizes for analyses of the various material flows throughout the plant (see Figure 4). The mass flows and composition of the streams were measured and analyzed over all unit operations in the plant that is, on the input, intermediate, and output streams, in order to increase the amount of data available for data reconciliation, which increases the accuracy of the mass balance and its statistics.

Calculation of Recycling/Recovery Rate

Based on the mass balance and its statistics, the recycling rate of ELVs based on the discussed test could be calculated for best available technology as shown in Figure 13. For the first time a test was therefore concluded in which the recycling rate was calculated within a statistical framework, crucial to proving the validity of the recycling rate calculation. Ultimately the recycling rate is determined by the possibility of the market to absorb the produced output streams (either for direct application or in metallurgical or thermal processes) and is therefore determined by the quality of the recycling (intermediate) products as well as by the geographic location of the plant (due to local environmental legislation).

Statistics

Only data reported within a statistical and theoretical framework can have a legal basis and can find their

Recycle ll-liberated)

Organic fraction

—Organic fraction

Figure 13 Simplified flowsheet of the shredding and postshredding technology (PST) plant. Reproduced from Reuter MA, Heiskanen K, Boin UMJ, etal. (2005) The Metrics of Material and Metal Ecology, ISBN - 13: 978-0-444-51137-9, 760pp. Amsterdam: Elsevier Science, with permission from Elsevier.

Recycle ll-liberated)

Organic fraction

Plastic (PP/PE) - Combustibles -

—Organic fraction

Nonferrous metals Plastics

Flotation

Plastic (PP/PE) - Combustibles -

Metals

Figure 13 Simplified flowsheet of the shredding and postshredding technology (PST) plant. Reproduced from Reuter MA, Heiskanen K, Boin UMJ, etal. (2005) The Metrics of Material and Metal Ecology, ISBN - 13: 978-0-444-51137-9, 760pp. Amsterdam: Elsevier Science, with permission from Elsevier.

way into design software for cars in order to perform 'DfR' and hence real 'material and metal ecology' on a large industrial scale. Moreover the statistics around the calculation of the recycling rate based on plant data indicates that the (calculations for the) recycling/recovery rates and requirements for type-approval of cars as imposed by legislation in Europe should also be based on a statistical basis and are meaningless if represented by a single value as is required at the moment. Any methodology to assess end-of-life systems has to take into account the statistics of design and end-of-life technology.

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