Toxic chemicals are used in the Flotation Process to separate the copper and molybdenum out of the milled powder. This Flotation process is the major extraction method at Duval/Sierrita mine because of the poor quality of the copper at this site. Some chemicals produce bubbles that that the copper adheres to and the "bad stuff" falls to the bottom. These chemicals are hydrocarbons with complex configurations, but some are as simple as kerosene. It is claimed that the volatile organics used in the Flotation Process do not go into the slurry that goes into the tailings impoundment because they are filtered out before the slurry goes to the impoundment. This is not a sound analysis.
1) Filtration is not a treatment technology for volatile organics. Treatment is pushing air the solution which releases the volatile chemicals into the air [Bless the employess that would endure this process—it could be a violation of OSHA regulations].
2) Some are amine compounds that break down into nitrates, so the presence of nitrates in the groundwater is an indicator of travel of these compounds, which can be very mobile in an oxygen solution (H 2O). The tailings slurry water has a Nitrate level of 18.6 mg/ltr. On site monitor well BW-2 has a level of 97.5, while monitor wells at the berm, MH-14 and MH-16, show levels of 12.8 and13.2, respectively.
See Attachment G: Monitor well data for BW-2, MH 14 and MH-16
c) From the sparse data that I have on VOC’s there is an indication that there are regulated VOC’s over the “Maximum Contaminant Level” at monitor wells. See Attachment H.
Some of the Chemicals Used in Flotation Process