Landfills are commonly considered only in association with their negative aspects: long-term methane emissions, local pollution, ground water pollution, and limitations on urban development. The Organization for Economic Co-operation and Development says 3 billion tons of trash a year will contribute to landfills worldwide by 2030, up from 1.6 billion in 2005. However, recent endeavors to reuse waste materials found in dumps suggest the potential of this number as a vast new resource as opposed to a useless burden.
Landfills are a largely untapped resource for many strategic metals (Kennedy, 2012). Valuable recyclable materials formerly regarded as waste can be mined from landfills, providing a new source of such material (Fisher 1995). The scope of this resource is vast: In the UK alone, 2 billion tons of waste sit untouched in landfills (Stein). In the US, more than 4.6 million tons of electronic waste were disposed of in American landfills in 2000 ("Where Does E-Waste End Up?"). Such material has potential to provide a new supply for declining supplies of metals such as the platinum group elements and rare earths, both of which are found frequently in electronic products.
In addition to providing an untapped resource for many strategic elements, landfill mining alleviates space and local pollution concerns related to landfills. In 1997, the Environmental Protection Agency (EPA) published a brochure on landfill reclamation that summarized potential benefits. Benefits include reducing pollution or the risk of pollution from substandard landfill or dump sites, reclaiming soil, extending the life of the landfill by reducing the volume of waste or reducing the area of land the landfill occupies, recovering materials such as aluminum and ferrous metals, and producing energy at municipal waste-to-energy facilities (US Environmental Protection Agency, 1997).
In order to take advantage of landfill mining, we propose a series of incentives:
Landfill mining projects and mining companies will receive renewable energy credit, which will be administered by a program put in place by the World Trade Organization (visit the inernational regulations page for more information. These incentives make landfill mining more economically viable to new companies wishing to enter the market.
The UN Strategic Mineral Association will encourage governments to put in place regulations concerning landfill mining comparable to those of New York. In October 1993, the New York State Department of Environmental Conservation included landfill reclamation in New York's solid waste management plan. This plan mandated the government's provision of sufficient facilities, materials, and knowledgeable personnel for landfill reclamation projects (New York State, Department of Environmental Conservation). Additionally, a financial stipend will be rewarded to cities with lower rates of landfill growth relative to local population density, funded by environmental grants such as the Pollution Prevention Grant (US Environmental Protection Agency). This would motivate the extension of landfill life through landfill mining.
The implementation of recycling of strategic minerals will prevent density of these precious resources in waste in the future, preventing the need for landfill mining following the recovery of the majority of strategic metals from the world's landfills.
Although the development of landfill mining as a general solution to excessive waste has proved very economically and industrially viable (US Environmental Protection Agency), the application of this method to the harvesting of strategic metals still has fundamental issues.
A major hurdle for the mining of landfills for strategic metals is the current limited nature of rare earth recycling. Until rare earths can be extracted and separated from used products in an economically beneficial manner, however, such products can be stockpiled upon reclamation until a time when their strategic elements can be extracted and removed.
Secondly, the environment in which some of these products are stored can render them unfit for recycling. This issue was encountered in the Edinburg demonstration project in New York. Even though 50 percent of recovered nonsoil materials from that landfill (12.5 percent of the recovered materials overall) were deemed potentially recyclable, they could not be cleaned to market standards (US Environmental Protection Agency). However, as landfill mining becomes more prevalent for other uses such as soil recovery and landfill life extension, new processes for cleaning and reclaiming such materials can be developed and perfected by corporations hoping to financially benefit from the recyclable coproducts of their landfill mining. At that point, landfill mining primarily for the purpose of recovering strategic metals will become more prevalent.
When considering the economic viability of landfill mining, it is important to note that the size of the landfill is crucial (Webb, 2010). In total, soil excavation, screening, testing and deposition account for 80% of the cost of landfill mining, meaning that the volume of the landfill plays a huge part in cost analysis. For example, a 30 acre x 30 foot deep site has 1 million cubic yards of soil. This means that for every dollar added to the cost of soil processing, approximately twelve percent is added to the cost of the project.
Another large contributor to mining costs is hazardous waste disposal. Things like the toxicity characteristic leaching procedure (TCLP) may be required by state authorities for every 1,000 cubic yards shipped, which can cost $1,500. This will make finding an economically viable solution more difficult, since some large landfills may be more than 50 acres in size.
Despite these challenges, there are ways to mitigate costs. Decreasing costs can be achieved by increasing excavator bucket capacities, decreasing cycle rates, cycling of screens, and grouping landfills to mine together. For example, "a drop in excavator cycle rate from four to two cycles per minute increases costs by $3 per cubic yard" (Fisher). Additionally, changing from a 3- to a 5-yard bucket can decrease costs by $1.20 per cubic yard.
Although the costs at first may present an obstacle in gaining the necessary momentum for company participation in landfill mining, the cost of landfill mining will continue to decline as the industry gains experience and as new equipment and techniques become available (Vijayaraghavan, 2011). With enough time, landfill mining will become more appealing to local areas facing landfill closure or operators desiring to extend the lives of their landfills. Based on the rising prices and the projected restricted availability stemming from the mining of virgin resources like platinum group elements and rare earths, landfill mining presents a viable, feasible alternative. Still, the supply of necessary resources coming from landfills would be limited, and the recuperation of these elements would only create a temporary supply. Recycling rare earth metals from electronic waste, for example, would recover a larger amount of the much needed metals that are ever-increasingly in demand.
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