# US 10,246,338 B2 · Process for preparing precipitated silica using a mixer or extruder

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- Number: US 10,246,338 B2
- Document ID: US10246338B2
- Status: Granted
- Kind: B2
- Application number: 14/386,093
- Filed: 2013-03-21
- Published: 2015-04-23
- Granted: 2019-04-02
- Earliest claimed: 2012-03-22
- Assignees: Rhodia Operations
- Applicants: Rhodia Operations
- Inventors: Sylvaine Neveu; Anne-Laure Pinault; Philippe Jost
- Web page: https://patentgrep.com/patent/US10246338B2

## CPC

- C01B 33/128: {by acidic treatment of aqueous silicate solutions}
- C01B 33/193: of aqueous solutions of silicates
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}

## Abstract

A process for preparing precipitated silica comprising a reaction of a silicate with an acidifying agent to obtain a suspension of precipitated silica (S1), followed by a separation step to obtain a cake, a disintegration step of said cake to obtain a suspension of precipitated silica (S2), and a drying step of this suspension, wherein the disintegration step is performed by mixing using a twin-screw mixer or by extrusion.

## Claims

### Claim 1

A process for preparing a precipitated silica, the process comprising:
reacting a silicate with an acidifying agent to obtain a suspension of precipitated silica (S1), followed by separation to obtain a cake having a dry matter content of at least 25% by weight,
compacting the cake at a pressure higher than 10 bars and lower than 60 bars;
disintegrating the cake to obtain a suspension of precipitated silica (S2) by mixing in a twin-screw mixer or by extrusion, and
drying the suspension of precipitated silica (S2).

### Claim 2 (depends on 1)

The process according to claim 1, wherein the disintegrating is performed in a twin-screw mixer.

### Claim 3 (depends on 1)

The process according to claim 1, wherein the disintegrating is performed in an extruder.

### Claim 4 (depends on 3)

The process according to claim 3, wherein the disintegrating is performed in a twin-screw extruder.

### Claim 5 (depends on 1)

The process according to claim 1, wherein the cake has a dwell time in the mixer or extruder of less than 10 minutes.

### Claim 6 (depends on 1)

The process according to claim 1, wherein the disintegrating is conducted in the presence of an aluminum compound.

### Claim 7 (depends on 1)

The process according to claim 1, wherein the cake has a dry matter content of between 25% and 40% by weight.

### Claim 8 (depends on 1)

The process according to claim 1, wherein the cake is compacted at a pressure of at least 20 bars.

### Claim 9 (depends on 1)

The process according to claim 1, further comprising de-agglomerating the cake prior to disintegrating the cake.

### Claim 10 (depends on 1)

The process according to claim 1, wherein the separation consists of filtration, optionally followed by washing.

### Claim 11 (depends on 10)

The process according to claim 10, wherein the filtration is performed using a vacuum filter or filter press.

### Claim 12 (depends on 1)

The process according to claim 1, wherein the drying is performed by atomization.

### Claim 13 (depends on 1)

The process according to claim 1, wherein the product derived from drying is subjected to grinding.

### Claim 14 (depends on 1)

The process according to claim 1, wherein the product derived from drying is subjected to agglomerating.

### Claim 15 (depends on 13)

The process according to claim 13, wherein the product derived from grinding is subjected to agglomerating.

### Claim 16 (depends on 1)

The process according to claim 1, wherein the cake has a dwell time in the mixer or extruder between 20 seconds and 5 minutes.

### Claim 17 (depends on 1)

The process according to claim 1, wherein the cake has a dry matter content between 25% and 35% by weight.

### Claim 18 (depends on 1)

The process according to claim 1, further comprising de-agglomerating the cake after compacting the cake and prior to disintegrating the cake.

### Claim 19 (depends on 1)

The process according to claim 1, wherein the step of compacting the cake is performed on a filter equipped with compacting means.