Recycling Solutions - Thanatia: The Destiny of the Earth's Mineral Resources - page 436

The implications of the above are clear; the only way of superseding extraction
is by reducing demand to a figure lower than the rate of recycling. Mathematically
speaking this means that the current rate of demand (2%) needs to fall to less than
0.25%. And, as these indices will need time to converge, the temporal limit of
societal demand is the amount of crustal resources. Whilst aluminium presents no
geological scarcity problems, at least not into the medium to long term, the analysis
can be extended to any metal or other resource.
Nevertheless, as Wernick and Themelis (1998) comment: “One hundred percent
recovery to satisfy demand represents more of a goal than an attainable reality, even
for precious metals, where the incentive to recover value is greatest”.
14.4 Urban mining
The ever decreasing ore grades of natural mineral deposits together with increasing
concerns about the future raw material supply, leads one to reconsider a new source
of mineral resources, the so-called technospheric or anthropospheric reservoirs. Such
stocks are growing faster than ever due to the exponential demand of resources
as shown in the previous section with the aluminium case. In fact for certain
commodities, the global technospheric stock may be greater than that left in natural
deposits. For instance, as pointed out by Gerst and Graedel (2008), the global in-
use stock of copper corresponds to 50% of the virgin reserves remaining in known
ores. Furthermore, metals in in-use stocks, landfills and leftovers in tailings and
slags could be even more concentrated than their counterpart in existing geological
deposits (Allen and Behmanesh, 1994; Johnson et al., 2007). Consequently, once
the scarcity of “virgin” material becomes acute and should commodity prices rise,
the recovery of secondary resources from technospheric stocks, popularly referred
to as urban mining (Brunner and Rechberger, 2004) may become a realistic option.
Indeed, this possibility is gaining increasing attention and has been addressed as
a suitable and necessary alternative by the UNEP International Resource Panel
(Graedel et al., 2010) or the Swedish Environmental Protection Agency (SEPA,
2012).
Urban mining has been alternatively defined by Brunner (2011) as the syste-
matic reuse of anthropogenic materials from urban areas. In fact, as discussed by
Johansson et al. (2013), different terms are used in the literature to partly or to-
tally describe this concept: “mining above the ground” as stated by UNEP (Graedel
et al., 2010), “waste mining” (Ayres, 1999; Ayres et al., 2001), “secondary mining”
(Pirrone and Mahaffey, 2005), “landfill mining” (Savage et al., 1993; Cossu et al.,
1996) or “enhanced landfill mining” (Quaghebeur et al., 2013). In order to address
this semantic confusion and to further clarify the distinction between metal recovery
from technospheric stocks, primary resource extraction and traditional waste man-
agement, Johansson et al. (2013) developed the umbrella concept of “technospheric
mining”. The adjective “urban” thus disappears, since technospheric stocks are not