Page 123 - Materials Chemistry, Second Edition

3.3 Allocation 107

400 kg iron ore

Iron production
E : 1000 MJ 300 kg slag
1
100 kg pig iron

Converter

100 kg crude steel

: 300 MJ
E 2 Rolling
100 kg sheet metal

E 3 : 200 MJ Punching and 20 kg clipping/scrap
moulding

80 kg product

3.3.4
Allocation and Recycling for Open-Loop Recycling (COLR)

3.3.4.1 Definition of the Problem
OLR, contrary to CLR, represents a difficult case for allocations comparable to
coupled production. 102) We first have a look at two systems A and B. Note that
the originally separated systems A and B are now contained in a common system
boundary and connected by a box ‘collection, transport, upgrade’ (Figure 3.18). The
reason is that for the production in system B, the product in system A after its use
phase can be (fully or partially) used as secondary raw material. A and B now form
one system and the problem is on how environmental burdens and resource uses
to the subsystems are to be allocated – one of which is being investigated.
By the small boxes (waste disposal of A) in subsystem A and (raw material
extraction for B) in subsystem B it is suggested that a certain fraction of A despite the
recycling has to be disposed as waste and a fraction from B has to be produced from
primary raw material. Since product B is not recycled here – according to the model
assumption – the process chain of B ends with the disposal. Generally of course,
product B can also be employed for other products after use, collection, and so on.

102) SETAC, 1991; Hunt et al., 1992; Society of Environmental Toxicology and Chemistry – Europe,
1992; Society of Environmental Toxicology and Chemistry (SETAC), 1993; Curran, 1996, 2007,
2008; Kl¨ opffer, 1996a; Ekvall and Tillman, 1997; International Standard Organization (ISO),
1998a; UBA, 2000; UBA, 2002; ISO, 2006b.