Biological Leaching

 

Biological leaching

Bioleaching process scheme
Introduction:

Biological leaching aims to extract metals from insoluble compounds, such as inorganic waste, by microorganisms. Following to the bioleaching process the metals are recovered from the leaching solution. Bioleaching is a well known process in metal extraction from ores from natural deposits.


Bioleaching process overview

Potential:

Biological leaching has the potential to gain valuable metals from waste materials, such as mixed municipal wastes from landfill sites or electric and electronic scrap.

Aim:

The pilot plant will evaluate the release of valuable metals and investigate the boundary conditions for an optimal growth and activity of the relevant bacteria.

Difference to BAU technology/approach:

Inorganic waste is generally treated using physical or chemical processes. Physical treatment processes are generally resource intensive and have a high energy demand, while chemical treatment processes need a range of chemical inputs. Biological treatments typically have a low energy demand and entail relatively low costs.

Input stream requirements:

Solid waste materials from landfill sites (municipal and industrial) and special waste stream like electric and electronic waste are suitable input streams.

Municipal solid waste


Electronic scrap

 

Available quantity:

Estimations of the metal content in landfills suggest huge amounts of valuable metals, such as copper, aluminum and ferrous scrap. Europe currently produces around 8 mill. tons waste electric and electronic equipment, with an annual growth rate around 3-5 %.

Drivers for treating this stream:

The increasing amounts of waste from different sectors, especially electronic waste, demands for efficient treatment methods. As biological leaching is already a well known process for the treatment of ores from natural deposits, its application can be extended towards other solid inputs. The biological process is less harmful for the environment in comparison with conventional methods.

Potential environmental risks related to this waste stream:

Effective treatment avoids the amount of waste that goes to landfill.

Economic/technical barriers to collect this stream:

There is a need for a detailed map of different waste streams in different sectors.

Output stream:

After leaching, a leachate containing the released metals is obtained.

Potential uses of this output stream:

The leachate contains a variety of metals depending on the input stream: copper, aluminium, ferrous, rare earth metals, etc. These metals can be recovered for recycling.

Potential environmental risks/benefits related to this output stream:

The output stream holds high concentrations of heavy metals.
This technique can increase the recycling rates of metals.

Economic barriers/drivers for market introduction of this output stream:

The growing demand for rare earth and heavy metals in combination with decreasing amounts of this materials in naturel ores makes recycling of metals from waste more interesting. 

Technical barriers for market introduction of this output stream:

The process of bioleaching is well known from the ore mining process. But it is necessary to collect more information and experience to scale up production plants for waste streams.

Legislative barriers for market introduction of this output stream:

No special barriers. Similar products are already available and free for trade.

Pilot description:

The pilot plant will evaluate the release of valuable metals and investigate the boundary conditions for an optimal growth and activity of the relevant bacteria. The most important bacteria species and the composition of the leachate will be analysed.

Installation:

Reactor set up with control and measuring system

Capacity:

The pilot plant will handle around 10 L of waste material, the large pilot plant will contain the tenfold.

Scale of the equipment:

Pilot scale

Main technological barriers for market introduction:

Results from lab and pilot plants are necessary for an estimation of the potential for production plants.

Main economic barriers/drivers for market introduction:

Relatively low costs and energy demand, economic viable also for low concentrated metals.

Research steps:

Development of new and improvement of existing bioleaching systems is needed. For different waste streams, the optimal bioleaching systems and process parameters need to be investigated.

Economic steps:

The leaching process has to be established in Europe. The price of the gained metals has to be lower than the price of worldwide trade.
The price of metals has to increase steadily.

Legislative steps:

None

Other:

Expected time to market: approximately 5 years

Contact details:
Organisation: UDE

Department: Waste and Urban Water management

Leading researcher: Prof. Martin Denecke & Jan Möller

Phone number: +49 201 1832742

E-mail: martin.denecke@uni-due.de

 

Documentation:

Presentation: Needs and potential for bioleaching, Jan Möller University of Duisburg-Essen, RENEW Technology Foresight Conference 25/04/2013.