Malachite doesn't float easily simply because of the lack of sulfide in the mineral structure.  We looked at a project in Northern Chile years ago which was a malachite-silver project.  Heap leaching with acid wasn't viable because of the high acid consumption due to the carbonates and hydroxides, and heap leaching with acid wouldn't recover the silver.  So we developed a scheme to float both the malachite and silver.  The results were excellent with both Cu and Ag recoveries >80%.  Unfortunately we didn't progress the project any further as the client ran out of money, but this development could have been a game changer.  We did this when I was part owner of the Met-Solve lab.  You might want to follow-up with them, but they are a commercial group (I no longer have an ownership interest) so they will charge you.  Fortunately this is a free forum, and there are some real flotation experts available to you, so perhaps they can be more forthcoming, as I am still bound by a confidentiality agreement.  Best Regards - Andrew  

Thanks Andrew,

Malachite can sometimes be made to float using a hydroxamate collector. See an example:

https://www.scribd.com/document/127541460/A-Multistage-Sulphidisation-Flotation-Procedure-for-a-Low-Grade-Malachite-Copper-Ore

In the past, I used http://www.oxflo.com with great success over AM2.

In most cases NaHS (Sodium Hydrogen Sulphide) or Sodium Sulphide is also added to enhance the  hydroxamate collector which is often combined with xanthate PAX. 

Dear all,

In the alkyl hydroxamate family, you can also consider Aero 6493 and 6494 and a promising newer generation of reagent OX100 that Solvay will be commercializing later this year. 

Thanks

JP