The Extraction of copper from Crysocolla with NTA

The trisodium salt of nitrilotriacetic acid was used as a chelation leachant for the dissolution of copper from chrysocolla. Increasing the temperature and concentration of NTA and decreasing the pH resulted in a faster leaching rate. A rate equation is presented which explains the observed linear logarithmic time dependence of the fraction reacted. This equation evolves from assuming a linear increase in the free energy of activation as copper is removed from the silicate lattice. An increase in the free energy of activation of 6660 cal/mole was calculated for the reaction at 60°C, and a = 1.