Effect of base type on the dissolution of quartz with triisopropanolamine in minerals with silver occluded in quartz

Abstract

The processing of refractory minerals of gold and / or silver occluded in quartz in sizes less than 1 μm is not viable, due to the chemical inertness of the silica. The treatment of these minerals is usually carried out by reduction of particle size by fine grinding that allows the release of the occluded particles. As an alternative to processing these minerals, has proposed the partial dissolution of the silica with diols in basic medium; in these studies partial dissolution of the matrix has been observed in 25% with triisopropanolamine and 3% mol KOH. The present work shows the effect of the type of base (organic-amines) in the dissolution of the matrix, observing a greater dissolution with the basic character of these and with the chelating effect of the same ones. Et3N was the weak base that showed the highest dissolution of the matrix, observing a dissolution rate (0.67 mmolmin-1) 2.5 times lower than that observed with KOH (1.66 mmolmin-1), similarly the observed effective diffusion coefficient was of an order of magnitude lower than that observed with KOH.