The breakage and particle size redistributions in an ultrasound-intensified leaching process were explored experimentally and analyzed statistically. It was found that particle size distributions (PSDs) of this atomic crystal silica may be changed to a certain extent by ultrasound, but the width of PSD cannot be altered under the conditions considered. Chemical reactions played an important reciprocal causality to the breakage and the particle size redistributions, and the contribution was about a half on the mean particle size. The most severe breakup happened at the maximum volume percentage of PSD rather than in the region of the largest particle size end. The ability of conventional stirring to break the silica particles may be larger as expected when the same power was used. The morphology of the silica particles verified that the change before and after leaching is small.