Alchema Limited

The rich vein of valuable metals locked up in electronic equipment is being mined by a novel metal selective leaching and bio-electro- chemical recovery process.
The technology is being developed by C-Tech Innovation, the University of Birmingham, and Alchema under a one year Demonstrator project jointly funded in part by the DTI's BIO-WISE programme and the Onyx Environmental Trust through the Landfill Tax Credit Scheme. The project will develop a pilot scale ver- sion of the process, which sequentially extracts solder metals, copper and precious metals from waste printed cir- cuit boards with previously unattainable selectivity.
"The ability to selectively recover tin and lead from sol- der separately from circuit copper adds value to all three streams for the recycler", explains C-Tech managing director, Ged Barlow.
"C- Tech's expertise in this area provides a sound platform for further development of this technology." C-Tech previous- ly developed the patented selective leaching technology at the heart of the process with Cambridge University and Alpha-Fry.

New technology taps into a rich vein


The rich vein of valuable metals locked up in electronic equipment is being mined by a novel metal selective leaching and bio-electro- chemical recovery process. The technology is being developed by C-Tech Innovation, the University of Birmingham, and Alchema under a one year Demonstrator project jointly funded in part by the DTI's BIO-WISE programme and the Onyx Environmental Trust through the Landfill Tax Credit Scheme. The project will develop a pilot scale ver- sion of the process, which sequentially extracts solder metals, copper and precious metals from waste printed cir- cuit boards with previously unattainable selectivity. "The ability to selectively recover tin and lead from sol- der separately from circuit copper adds value to all three streams for the recycler", explains C-Tech managing director, Ged Barlow. "C- Tech's expertise in this area provides a sound platform for further development of this technology." C-Tech previous- ly developed the patented selective leaching technology at the heart of the process with Cambridge University and Alpha-Fry.	Precious metals A novel biotechnology step introduces enhanced possibili- ties for the recovery of pre- cious metals from the circuit board waste according to Lynne Macaskie, professor of Applied Microbiology at Birmingham University. "We know that certain micro- organisms can capture pre- cious metals from aqueous solutions produced by recov- ery processes. Coupling the organism to an electroehemi- cal source of hydrogen leads not only to faster and more efficient recovery of the metals than by using conventional routes, but has the potential for producing precious metals nanoparticles, with all the exciting possibilities of additional catalytic properties that opens up." Further synergy The project also provides for further synergy between the leaching and recovery stages through a new microwave assisted leaching step devel oped at Birmingham's School of Chemical Engineering which achieves metal dissolution from the circuit boards at lower concentration of the mineral acid leachants.	"Lower acid concentration means a better environment for our microbes to do their job", says Lynne Macaskie. After bio-electro ehemical recovery of precious metals, the spent plastic boards are reduced in weight, free of met- als, and no longer classed as hazardous waste. "This approach could significantly help organisations withelectronic scrap issues to meet their obligations under the forthcoming WEEE landfill directive", concludes Ged Barlow.
		Industrial Environmental Management: June 2003