Hi Tewks,
I asked Mike previously about the lead/zinc contamination and he indicated where the contamination was too high they intended to isloate that lot of baghouse dust and put it through the process to encapsualte it in Ferric Oxide pellets which was then classed as non-toxic (as it didn't become dust anymore) and it could simply go to landfill. This amde it significantly cheaper than getting it handled as toxic material.
Cheers
Seik