In a certain case study of “high” Arsenic in Copper Concentrate (almost 0.5% As) produced by flotation, and where the Cu Conc is mostly chalcopyrite and therefore the main form of copper; the content of secondary copper minerals was variable. Tennantite/Enargite/Freibergite, a copper-arsenic sulphide mineral, as well as covellite, was present in significantly higher amounts today. The presence of secondary copper minerals, especially covellite, may pose sphalerite activation problems due to dissolved copper from the minerals.
Tennantite/enargite contributes to elevated levels of arsenic, which may incur smelter penalties. Copper concentrates recently tested for mineralogy both measured about 0.44 percent arsenic content. This is above typical levels where penalties occur. Tennantite and enargite as well as Freibergite are copper arsenic sulphide minerals that respond to flotation in a similar manner to other copper sulphides. As such, depression of these minerals would tend to result in depression of other copper sulphides.
In this case arsenic comes Copper Arsenic Species called Enargite and Tennantite. These coppers have a molecule that actually contains arsenic Cu3AsS4 and (Cu,Fe)12As4S13 from http://webmineral.com/data/Enargite.shtml#.UosyWcSsjLQ
and http://webmineral.com/data/Tennantite.shtml#.UosyWsSsjLQ
The Voodoo around arsenic comes from those dataless speculators thinking the plant is facing the most common and simple source of arsenic, the Arsenopyrite FeAsS http://en.wikipedia.org/wiki/Arsenopyrite which is depressable and removable from concentrates for it in is Pyrite, not copper.
Lets not forget Freibergite (Ag,Cu,Fe)12(Sb,As)4S13 http://webmineral.com/data/Freibergite.shtml#.Uos_WsSsjLQ
and (Cu,Fe)12Sb4S13 http://webmineral.com/data/Tetrahedrite.shtml#.Uos_7cSsjLQ both great Antimony carriers.
The more Enargite and Tennantite you mine and put in the mill feed, the more you will get in the concentrate. As you see in the historic data her below, if you put 0.07% arsenic in the mill feed, you get about 10X that or 0.7% in the copper conc for the Enargite and Tennantite cannot be separated.
Today, the only known way to prevent this type of arsenic from getting into the concentrate, is to not mine this type of copper. Garbage-in, garbage-out!
