Process for removing silica from cellulosic material

A method of cellulosic raw material desilication involves the steps of impregnating the cellulosic raw material with a solution containing sodium carbonate to form a silica-containing impregnation black liquor and an at least partially desilicated raw material, separating the silica-containing impregnation black liquor from the at least partially desilicated raw material, causticizing the separated silica-containing impregnation black liquor to precipitate silica-enriched calcium carbonate and separating the precipitated silica-enriched calcium carbonate from the causticized impregnation liquor. Up to 100% of the silica contained in the cellulosic raw material can be removed before the raw material is processed by any of conventional pumping methods.