Method of forming silicate polishing pad

The method provides a method of preparing a silicate-containing polishing pad useful for polishing at least one of semiconductor, magnetic and optical substrates. The method includes introducing a feed stream of gas-filled polymeric microelements into a gas jet. The polymeric microelements have varied densities, varied wall thickness and varied particle size. Passing the gas-filled microelements in the gas jet adjacent a Coanda block, the Coanda block having a curved wall for separates the polymeric microelements with Coanda effect, inertia and gas flow resistance. The coarse polymeric microelements from the curved wall of the Coanda block to clean the polymeric microelements. The polymeric microelements collected contain less than 0.1 weight percent total of the polymeric microelements being associated with i) silicate particles having a particle size of greater than 5 μm; ii) silicate-containing regions covering greater than 50 percent of the outer surface of the polymeric microelements; and iii) polymeric microelements agglomerated with silicate particles to an average cluster size of greater than 120 μm. Inserting the cleaned polymeric microelements into a polymeric matrix forms the polishing pad.