| 摘要 |
<p>The invention relates to a method for producing precipitated silicas, comprising: (i) forming a starter having an alkali metal silicate M concentration of less than 20 g/L; (ii) adding acid thereto until at least 50% of the quantity of M2O is neutralised; (iii) adding silicate and acid simultaneously, such that the consolidation rate is greater than 4 and at most 100; (iv) adding acid until the pH measures between 2.5 and 5.3; (v) bringing the reaction medium into contact with the acid and the silicate, such that the pH measures between 2.5 and 5.3. According to the invention, the acid used in at least one of the steps is a concentrated acid, preferably selected from the group containing sulphuric acid having a concentration of at least 80 wt.-%, in particular at least 90 wt.-%, acetic acid or formic acid having a concentration of at least 90 wt.-%, nitric acid having a concentration of at least 60 wt.-%, phosphoric acid having a concentration of at least 75 wt.-%, hydrochloric acid having a concentration of at least 30 wt.-%.</p> |
