Nils Johansson.Pdf

Extended Abstract Why don’t we mine the landfills? - The race between different metal stocks Nils Johansson Department of Management and Engineering, Environmental Technology and Management, Linköping University, SE-581 83 Linköping, Sweden 1. Introduction Landfills are commonly defined as a site for the disposal of waste. Such a treatment method assumes that the waste simply has no value, i.e., it is useless and therefore buried and shielded from the economy. Accumulated waste is however not only worthless; it can even have a negative value and pose a serious threat to humans and the environment, including the leakage of hazardous substances (Baun and Christensen, 2004) and methane emissions (Bogner et al., 1995). Hence, the orphaned, abandoned and neglected waste “bites back” (Tenner, 1997) on the society that created it. Meanwhile, for some, especially birds and birdwatchers, landfills may be considered an important ecological oasis in the urban environment, sometimes more popular than city parks. Increasingly, waste is defined as surplus material (Gourlay, 1992); a byproduct; material we have failed to use. From such a perspective, disposal is commonly regarded as a lost opportunity and a waste of resources. What is often forgotten in this context, however, is that the isolated events of deposition combined make a new potential resource base, which to some extent can be compared to traditional mines in terms of quality and quantity (Kapur and Graedel, 2006; Johansson et al., 2012). Research in industrial metabolism (e.g. Graedel et al., 2004) has shown how resources and metals in particular are extracted from the lithosphere, turned into products, consumed and then usually end up in landfills. In countries like Sweden, where incineration has largely replaced landfills, significant amounts of metals end up in ash, which is commonly landfilled (Kuo et al., 2007). However, landfills contain not only metals like conventional mines but are also filled with plastic, wood, paper and other valuable resources. The potential extraction of secondary minerals1 has been conceptualized through various mining- concepts such as urban mining (Brunner and Rechberger, 2004), technoshperic mining (Johansson et al., 2012), waste mining (Ayres, 1999) and landfill mining (Krook et al., 2012). Most of these concepts embrace minerals recovery throughout the technosphere, while landfill mining focus on landfills in isolation by excavating and recovering deposited waste. Hence, it revives what is buried by digging up a landfill and gives the waste a new chance. However, mining the technosphere and in particular landfills are not common practice in developed countries (Johansson et al., 2012). Hence, a critical question becomes: why? By interweaving the articles published under Linköping University’s project Landfill mining for integrated remediation and resource recovery, we address the question why landfills are not mined. An indirect purpose is to draw a general conclusion from the first 3 years of the project. After analyzing the obstacles to Landfill mining, the article concludes with a discussion on the realization of landfill mining and way forward. 2. Method and material 1 Minerals once already extracted, and therefore found not in the lithosphere but in the technosphere. The literature review is based only on articles from the project Landfill mining for integrated remediation and resource recovery: economic and environmental potentials in Sweden. According the above purpose, only articles is included which discuss the opportunities and obstacles of landfill mining. Articles for example describing tools for calculating the environmental performance or metal amounts have been excluded. The articles that forms the basis of this literature review is Landfill mining: A critical review of two decades of research (Krook et al., 2012), An Integrated Review of Concepts for Mining the Technosphere: Towards a New Taxonomy (Johansson et al., 2012) and Transforming Dumps into Gold Mines. Experiences from Swedish Case Studies (Johansson et al., submitted). 3. Landfills compared to other technospheric stocks A sufficient starting point to assess why landfills are not extracted is to compare the size, concentration and dispersion of metal stocks in the technosphere as well as traditional virgin mines. The largest stock in the technosphere is according Johansson et al. (2012) the current in-use stock, estimated to comprise at least 50% of the total amount of iron and copper in the technosphere. From a resource perspective, the size of the in-use metal stock is often significant. At present, for instance, the global in-use stock of copper corresponds to 50% of the virgin reserves remaining in known ores (Gerst and Graedel, 2008; USGS, 2010). Landfills and tailing ponds may hold approximately 10-20% of the technospheric metal resources. The large amount of metals in-use may explain why recovering in-use metals as they successively turn into waste is common practice. Another contributing factor may be the high metal concentrations of refined products. Mobile phones, for instance, can have a copper content of 5-15% by weight (Huisman, 2004; Boliden, 2008) and power cables may have concentrations reaching above 30% of weight of copper (SwedEnergy, 2009). Several studies support that the typical concentration of metals in goods tends to be higher than in geological stocks in ores currently mined (Allen and Behmanesh, 1994; Johnson et al., 2007). In Sweden, copper is currently mined at a profit from ore with a concentration of 0.37 % copper by weight per ton (Boliden, 2008). According to Gordon (2002), the average copper content of tailings, for example, fell from about 0.75% to 0.14% during the 20th century. The concentration of metals in landfills is uncertain and varies according to time and space, where landfills located near communities with high consumption of metals lacking sophisticated recycling systems tend to have higher contents. Ongoing research on landfill mining in Sweden estimates that a typical municipal landfill contains about 3.6% iron and 0.3% copper (Frändegård et al., 2012). A disadvantage of the metals in use is nevertheless that they are very dispersed over the society, which puts high demand on the organization needed to collect these metals. In landfills and tailings, on the other hand, the amount of metals clustered in one place puts lower demands on the organization according to the principles that make virgin mining profitable, i.e., economy of scale. However tailings are unlike landfills, actually extracted on a regular basis. For example, in 1994, 250 Gg. copper, corresponding to 2% of the global production of copper, was derived from reworked tailings (Graedel et al., 2004). The reasons why tailings but not landfills are mined despite resemble metal concentration and supply is many. For example, the metals in tailings are in general homogenous including iterative residues from one actor, while metals in landfills are disorganized and placed together with other types of waste. Furtermore, tailings have many similarities to virgin ores including characterization, methods for extraction, ownership and actors involved, which probably explains why tailing mining commonly occurs. Landfills are generally under the ownership of actors without any knowledge to operate such a project. 4. Uncertainties in Landfill mining In addition to the obstacles identified on a macro level by comparing the landfills with other metal stocks, many barriers on the micro level may also be identified by reviewing previously cases studies as done by Krook et al. (2012). These authors suggest that uncertainty is an overall factor prohibiting implementation since it complicates for companies to foresee the outcome of mining operations. These uncertainties can be further subcategorized. One of these uncertainties is that the prediction of the content and thus determination of valuable resources in the landfill is difficult. Research focusing on waste composition of landfills has shown, even within specific sites, as hinted above, large variations in physical and chemical characteristics as well as material composition (Cossu et al., 1996; Reith and Salerni, 1997). Such a figuratively uncertain black box makes prospecting a key challenge. Previously reported case studies (e.g. Dickinson, 1995; Reeves and Murray, 1997; Zhao et al., 2007) have shown difficulties in sorting out the deposited waste into desired pure fractions. Few recycling agents are interested in accepting unsorted masses. The availability and performance of technology thus becomes another critical question. Further recurring conclusion from the reported cases is that the obtained quality of exhumed materials, soil excluded, is often not good enough to compete with virgin as well as secondary resources from traditional waste flows. The market for excavated deposited waste is thus uncertain, i.e., is there any demand for products from a landfill? What safety, administrative and regulatory requirements landfill mining will involve, and how such demands will influence its viability, is also largely unclear, although authorities will most likely require an approved safety and health plan (Cossu et al., 1996; US EPA, 1997). For example, should re-deposited waste, once excavated, be interpreted as “new waste” and thus subject to waste tax and waste bans? Is permission required at all, and if so, which regulations are applicable? Although the previous cases had low impact on environment and health,

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