Recycling Solutions - Thanatia: The Destiny of the Earth's Mineral Resources - page 438

Technospheric (urban) mining is in all its possible manifestations still in its
early stages of development. That said, there are some real initiatives that could
constitute the starting point of a widespread implementation of the recovery of
technospheric materials. This is the case of The Closing the Circle project (CtC)
in Houthalen-Helchteren (Belgium), which is the first enhanced landfill mining case
study (Quaghebeur et al., 2013).
The following section explores the different technologies required for the recovery
of materials at their end-of-life (either through recycling or urban mining).
14.5EoLtechnologies
As explained in Chap. 4, on considering the life cycle of an element, three different
stages can be identified: beginning-of-life, BoL, the mining, beneficiation, smelting
and refining (extensively described in Chap. 7 and Chap. 8); the product's life i.e.
its manufacture, distribution and use; and the product's end-of-life, EoL, meaning
and as defined by UNEP (Graedel et al., 2011a), the physico-chemical recycling
operations such as collection, sorting, separation and liberation, or alternatively
landfilling with or without “urban mining” and dispersion.
Focusing on a given metal, after production it is manufactured, used or reused
and commences its EoL. As the cycle advances the metal is alloyed, mixed, oxidised
and degraded. Even whilst in each stage recycling opportunities appear, the cost
e ciency of such recycling decreases as the cycle progresses. Recycling thus follows
an exponential thermodynamic degradation trend: the further down the cycle a
recyclate is, the higher its cost as will be seen later in Sec. 14.7. This is because of
the need for de-mixing and concentrating processes.
New scrap originating from fabrication or manufacturing is easy to recycle with
high recoverable e ciency. Yield losses here derive from processes such as trim-
ming, subtractive processing, material discards, turnings, scrapings from sputtering
chambers, saw dust, or grates from casting, etc. The resulting material is homoge-
neous, concentrated and with a high enough volume to facilitate recycling. It is this
recyclate which commonly appears in recycling statistics and is in fact the main
source of secondary metal.
Old or post-consumer scrap is more di cult to recycle; it appears in components
mixed with other metals and materials like plastics, glue, glass, wood or stone and
requires careful de-mixing. Should recycling occur, there is an EoL exergy 5 , which
depends on the specific processes used. Recycling operations are composed of a
sequence of logistic and physico-chemical processes all of which consume exergy.
According to Reuter and van Schaik (2010) these are:
First, collection. No or only a small amount of collection effectively means
no recycling chain. To promote recycling, an e cient reverse logistic structure is
5 The complement to the conventional embodied exergy which accounts for the BoL and product's
life stages.