Serpentine ore microtextures occurring in the Magnola magnesium process

Serpentine ore was leached at 95 degrees C and 100 degrees C in 7.0 M HCl m edia to study the reactions occurring in Noranda's Magnola magnesium proces s. Magnesium leaches rapidly from the serpentine Mg3Si2O5(OH)(4), and the s ilicon remains in-situ as an amorphous silica pseudomorph after the origina l serpentine particles. Negligible silica dissolution occurs, anti silica g elation was never observed. The reaction interface extends over 300-400 mu m; as a consequence, fine grinding does not significantly accelerate the ra te of magnesium dissolution. Associated inclusions of brucite Mg(OH)(2), aw aruite Ni8Fe3, and magnetite Fe3O4 dissolve rapidly; whereas, chromite FeCr 2O4 and a chromium-rich spinel (Cr,Fe,Al,Mg)(3)O-4 remain largely unaffecte d.