Leaching and recovery of elements from CCA timber

Copper chrome arsenic (CCA) timber is a major waste that is currently being stockpiled around Australia. The strict environmental restrictions on their disposal means that this stockpile will increase annually. This project looks at optimising the choice of acids for leaching of CCA from the timber, an understanding of the rate processes and chemical equilibrium that determine the extraction efficiency of those elements, and the recovery of the copper, chromium and arsenic from the waste stream. Methods of recovery to be investigated will include precipitation, solvent extraction and membrane separation techniques. Disposal of the elements recovered will be considered including the vitrification of arsenic and the re-use of chromium and copper through metallurgical processing.

The cleaned timber should have a CCA content at least at the same level as the background level as specified by Australian Standards for mulch. It is intended that the cleaned timber can be reused for the manufacture of timber moderated concrete panels for thermally efficient buildings.

Contact:

j.liow@adfa.edu.au