Aqueous slurry of amorphous silica and method for its production
An aqueous slurry of amorphous silica, the amorphous silica having a particle size less than 1 μm. The slurry contains sepiolite as a stabiliser.
1. An aqueous slurry comprising:
water;
amorphous silica, the amorphous silica having a particle size less than 1 μm; and
sepiolite as a stabilizer in an amount of 0.1 to 1% by weight of the slurry.
2. The slurry of claim 1 , wherein the sepiolite is present as 0.2 to 0.5% by weight of the slurry.
3. The slurry of claim 1 , wherein the slurry has a solids content in the range 40 to 80 wt% of the slurry.
4. The slurry of claim 1 , further comprising silica flour.
5. The slurry of claim 1 , wherein the silica flour has a particle size in the range 2 to 200 μm.
6. The slurry of claim 1 , wherein the silica flour constitutes up to 50 wt% of the total solids content of the slurry.
7. The slurry of claim 1 , further comprising an anionic dispersant in an amount in the range 0.1 to 0.5% by weight of slurry.
8. A method for the production of aqueous slurry comprising:
combining water, amorphous silica having a particle size less than 1 μm, and sepiolite in an amount in the range 0.1 to 1.0% by weight of the slurry as a stabiliser.)
9. The method of claim 8 , wherein combining is accomplished by using a high shear mixer.
10. The method of claim 8 , wherein the combining is accomplished by hydrating the sepiolite with water and then adding the hydrated sepiolite to the slurry of water and amorphous silica, and mixed to form a stabilised slurry.
11. The method of claim 10 , wherein the amount of sepiolite added is the range 0.2 to 0.5% by weight of the slurry.
12. The method of claim 8 , wherein the amount of water and the amount of solids are arranged so that the solids content of the slurry is in the range 40 to 80 wt% of the slurry.
13. The method of claim 8 , wherein silica flour is added to the slurry.
14. The method of claim 13 , wherein the silica flour has a particle size in the range 2 to 200 μm.
15. The method of claim 13 , wherein the silica flour constitutes up to 65 wt% of the total solids content of the slurry.
16. The method of claim 8 , wherein the silica flour is added to the slurry of water and amorphous silica after the addition of the sepiolite.