Hidden treasure? The landfill mining option

Written by: RWW | Published:

In the first of a two-part series on landfill mining and metals recovery, David Burrows looks at the option of landfill mining and its potential in the UK. With over half a million landfill sites containing over 5,000,000,000 (five thousand million) tonnes of waste, it should offer ample pickings of valuable materials such as metals.

The first landfill mining operation took place in Israel way back in 1953. Since then there have been 60 or so similar projects; a rate of about one per year. It is not much considering the number of landfill sites. And while material sorting and recovery in particular soils often feature in many projects, it is seldom the main driver. 

But is this about to change? Resource scarcity, after all, is a hot topic. 

There are growing fears about the availability of some key industrial metals, used in everything from plasma TVs and wind turbines to smartphones and energy-saving light bulbs. 

Could landfill mining unearth a gold mine, so to speak, of ‘lost’ resources and encourage a shift to a circular economy?

LFMR projects?

Last year, consultants Ricardo-AEA published an in-depth review of landfill mining and reclamation (LFMR) operations for Zero Waste Scotland (ZWS). 

With reference to metal recovery, the academic papers on landfill mining it reviewed focused on the recovery of ferrous metals and aluminium. 

Ricardo-AEA found other metals, including precious metals and rare earth metals, rarely featured in the literature and only in a ‘maybe one day’ perspective. 

In fact, the authors found no examples of LFMR projects undertaken for the recovery of precious and rare earth metals and no papers specifically discussing the viability of recovery of such materials. 

The report reads: “While these metals are present in some landfills, possibly at relatively high content in comparison to their concentration in their respective ores, they will be present in a range of different applications, typically in WEEE and in some industrial wastes. 

“Recovery of precious and rare earth metals would give rise to significantly greater technical complexity than for the types of LFMR operations discussed in this report.” 

But that doesn’t mean it won’t happen, says Adam Read, practice director for waste at the consultancy firm. 

Metals are “absolutely” a key target for landfill mining, given their value and the ability to sort them using magnets. 

A paper presented at the 13th International Waste Management and Landfill Symposium in Sardinia in 2011 considered the feasibility of sustainable material and energy recovery from landfills in Europe. 

Their assessment, as summarised in the Ricardo-AEA study for ZWS, considers processing which uses a range of techniques including handpicking (incompatibles), shredder, drum sieve (soil), magnet (ferrous metals), drum separator (paper and plastic as the light fraction, construction waste, stones and glass as the heavy fraction and wood, organics and textiles as the medium fraction), eddy current separator (non-ferrous metals) and air knife (plastics and wood). 

The authors, who primarily focused on metal recovery, concluded that separation techniques are available and proven and, therefore, landfill mining is technically feasible. 

But was it economically viable?

Maybe. They calculated that the revenue from extracted metal is sufficient to offset mining costs by 8.2% where full separation of the waste occurs and by 18% where only ferrous metal is separated from the waste excavated. 

These percentage cost reductions are significant given that the assessment considers only 2% metal content in the landfill. The paper’s authors concluded that after the revenue from metal recovery is considered, there remains a “large deficit” to be addressed in order to make landfill mining profitable. 

Re-using the freed landfill capacity as new landfill, reusing the landfill area for urban development and selling the other recovered material streams are cited as ways of making landfill mining more profitable. 

The authors noted: “acquiring these additional benefits strongly depends upon specific local circumstances and conditions. 

“In the optimal case, these additional benefits might compensate the total costs and might generate a return on investment of 10 to 20%. From this point it cannot be excluded that a landfill mining project might become financially profitable.”

Ricardo-AEA recognise that it’s technically feasible. But while the techniques are available and proven for certain waste streams, that is not necessarily the case for LFMR. 

As Read summarised recently: “The general view obtained from [our] extensive literature review is that, unless other drivers are also considered (land for redevelopment, pollution clean-ups and so on), landfill mining for the purpose of resource recovery is not currently economically viable. 

“This was confirmed through some high level economic analysis undertaken as part of the [ZWS] study, which concluded that LFMR projects in Scotland would only be economically viable if a ‘best case’ scenario was achieved, and such a scenario would require on-site energy recovery and either void reuse (landfill site life extension) or land reuse (perhaps for land redevelopment) to be part of the business case.” 

Others tend to agree. Richard Fisher produced a concise paper for the International Solid Waste Association on the subject last year. He concluded that while the LFM excavation itself is relatively simple, a holistic approach to wastes management and mining is required to fully understand the implications. 

As such, he feels that LFM is “unlikely to happen in the short- or medium-term in the UK”, he tells RWW, adding: “There’s still sufficient resources and space not to need to undertake LFM pro-actively; however, I would expect to see rudimentary LFM taking place on a site-specific level if there is an alternative reason for digging out a site, such as engineering works or other remediation. 

“If there was a need, high value or high volume items such as metals or inerts may be recovered.”

Enhanced Landfill Mining

In Belgium, a company called Advanced Plasma Power is about to embark on a project that all those with an interest in landfill mining will be watching very closely. 

APP, alongside Group Michaels, is currently working on what will be the world’s first full-scale enhanced landfill mining (ELFM) project at the Remo Milieubeheer landfill site in Houthalen-Helchteren, Belgium, where there are 16 million tonnes of waste buried. 

Opened in the 1970s, Group Michaels told BBC Radio 4 recently that the site could be “full of metals”. It is the first project of its kind. 

Can it work? Can it pave the way to more mainstream landfill mining? 

And, critically, can it work in the UK? Look out for the second part of this RWW analysis, published on March 6, to find out. 

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