Novel method for preparing precipitated silicas containing aluminium

A process for preparing precipitated silica comprising aluminum, the process comprising conducting a precipitation reaction between a silicate and an acidifying agent, via which a suspension of precipitated silica is obtained, followed by a separation and drying of this suspension, in which:

• the precipitation reaction is performed in the following manner:
• (i) forming an initial feedstock comprising a silicate and an electrolyte, wherein a concentration of silicate (expressed as SiO2) in said initial feedstock is less than 100 g/L and a concentration of electrolyte in said initial feedstock is less than 17 g/L,
• (ii) adding the acidifying agent to said feedstock until the reaction medium has a pH value of at least 7,
• (iii) simultaneously adding acidifying agent and a silicate to the reaction medium,
• drying a suspension with a solids content of not more than 24% by weight, said process comprising one of the following three operations (a), (b) or (c):
• (a) simultaneously adding at least one compound of aluminum and a basic agent to the reaction medium, after step (iii),
• (b) simultaneously adding a silicate and at least one compound of aluminum to the reaction medium, in place of step (iii),
• (c) performing step (iii) simultaneously adding to the reaction medium acidifying agent, a silicate and at least one aluminum compound.