Resources that could be recycled are currently used as landfill. A new report from the BIOMIMIC project shows the amount of metals and their value in money.
The report (Deliverable 2.1) is submitted by University of Limerick and GEOS. The most important aspects for the BIOMIMIC project are that the report quantified the extent of natural resources that are available for recovery but which we are currently disposed to landfills.
– While the concentrations might be quite low, the amounts are quite significant and apart from their economic value and their potential to cause long term environmental damage, it is clear that we cannot continue to dispose of these valuable materials without recovery, says Dr John Murnane, University of Limerick, who compiled the report.
Unrecovered metals
The BIOMIMIC quantified the extent of unrecovered metals in leachates from bauxite residue and incinerated bottom and fly ashes from municipal solid wastes, and examined their potential economic value.
For example an estimated global average of between 60 and 220 million m3 of bauxite residue leachate from alumina production plants is produced annually, comprising trace metals with an estimated current annual value in the range €43 – 159M. The estimated annual average EU bauxite residue leachate production is approximately 6 million m3 and represents just over 4% of that generated globally.
As well as that, an estimated 30 – 40 million tonnes of bottom ash and 2 – 6 million tonnes of fly ash are generated annually from municipal solid waste incineration processes, almost all of which is generated in the EU, China, Japan and the USA. These ashes contain trace metals with estimated current global annual economic values in the range €1,500 – 2,000 billion for bottom ashes and €27 – 82 billion for fly ashes.
Costs for processing
While these amounts reflect the potential current value of the metals if fully recovered, they do not include extraction, processing and treatment costs associated with their recovery, which are largely unknown at present.
Did you encounter any surprises, for example levels that were higher or lower than anticipated?
– Yes, I suppose you might be surprised to know that while the Bayer process is set up to remove aluminium from bauxite, the remaining aluminium concentrations in the bauxite residue leachate still remain relatively high, says John Murnane.
– More interestingly perhaps is the fact that critical raw materials such as Gallium and Vanadium are present at relatively low concentrations in the bauxite leachate while valuable metals such as titanium, nickel, cobalt and even gold can be found in municipal solid waste incineration ashes.
Challenges ahead
The calculations are based mostly on existing databases and scientific literature although estimates of bauxite residue leachate were based on industry experience also.
Apart from the contributions by GEOS and UL, Fortum Waste Solutions provided very valuable information on metals content in ashes from selected industrial incinerations
– Of course the problem is how do we recover these resources in an environmentally sustainable and economic way? This is a major technical and economic challenge and so the focus of our research will be on developing biotechnological methods to help us to recover these valuable resources, says John Murnane.
A non-scientific summary of the deliverable is available here (pdf).
