ABSTRACT
Mechanical activation by a high-energy grinding apparatus is a means of increasing and/or accelerating the dissolution and leaching processes. The success of this technique is based on the following: 1) increased surface area, 2) increased surface reactivity, and 3) microstructural modifications stemming from the deformation. For example, the leaching of as-received chalcopyrite concentrate resulted in copper extractions of 75% in 5 hr of leaching, whereas leaching mechanically activated concentrates resulted in copper extractions of over 95% after 3 hr of leaching.[15] The dissolution of the mechanically activated samples of francolite and phosphorite from Epirus Area (Greece) by sulfuric acid in conditions such as the wet production of phosphoric acid indicated that the rate of dissolution processes was increased with increasing of the grinding time up to 2 hr.[16] In the past 10 years, a more focused effort has been made to quantify the kinetic enhancements due to mechanical activation, which are attributed to the following: 1) increased specific surface area, 2) enhanced surface reactivity, and 3) change in the crystalline structure.
