A copper flotation concentrate is over limit on Fluorine (F) content and Contamination. When assaying and plotting Copper (Cu) from times concentrates and the related fluorine and Magnesium Oxide (MgO) assays in various ways as shown below; one can see the obvious relationships.
In the case, reducing Fluorine content and contamination of the copper conc with likely by using regrinds in the same way we reduce MgO from a zinc conc. The only way you can stop MgO from floating is to liberate it from the sulfides it is associated with.
I don’t know who buys copper concs with over 1000 ppm F when most smelters limit contract at 200 ppm with penalties of $1-$2 per tonne for every 100 ppm increments.
There are technical and commercial limitations to using high fluorine copper concentrates in industrial copper smelters. The presence of more than 1,000-ppm fluorine affects the sulfuric acid units generally integrated to copper smelters. Price penalties are normally applied to copper concentrates with high fluorine contents. Alternatives included modifications to conventional sulfuric acid plants so that they can use high fluorine concentrates; removal of fluorine-containing minerals by flotation using depressants or regrind; selective leaching of minerals; and sulfuric acid leaching of the copper concentrates.