Patent ID: 7524478

Claim:
A process for preparing a low water-uptake precipitated silica, comprising the following successive steps: (a) producing an initial feedstock comprising a silicate, the silicate concentration in the feedstock, expressed in SiO 2 equivalent, being less than 15 g/l; (b) adding an acidifying agent to form an acidified feedstock, bringing the pH of the medium to a value of between 7 and 8; (c) simultaneously adding a silicate and an acidifying agent to the feedstock resulting from step (b) to form a reaction medium, the respective amounts of added silicate and acidifying agent over time being specifically selected such that, throughout the entire addition: the pH of the reaction medium remains between 7 and 8; the silicon concentration in the reaction medium, expressed in SiO 2 equivalent, remains less than or equal to 35 g/l; (d) adding an acidifying agent to the reaction medium resulting from step (c), so as to bring the reaction medium to a pH of between 3 and 6.5; and (e) filtering the resulting aqueous silica dispersion, then drying the filter cake obtained at the end of the filtering step.