Compound of calcium carbonate and of tobermorites, its manufacture and its applications

• US 3,998,651 A
• Filed: 11/01/1974
• Issued: 12/21/1976
• Est. Priority Date: 10/24/1973
• Status: Expired due to Term

• Current Assignee: Lafarge SA (Holcim Limited)
• Original Assignee: Lafarge SA (Holcim Limited)
• Inventors: Baudouin, Jacques, Caspar, Jean-Pierre
• Primary Examiner(s): Douglas, Winston A.
• Assistant Examiner(s): Howard, J. V.
• Application Number:
  US05/520,103
• Time in Patent Office: 781 Days
• Field of Search: 106/306, 106/102
• US Class Current: 106/464
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C08K 3/22 of metals
• CPC Class Codes: C08K 3/26 Carbonates; Bicarbonates
• CPC Class Codes: C08K 3/34 Silicon-containing compounds
• CPC Class Codes: C09C 1/0081 Composite particulate pigments or fillers, i.e. containing at least two solid phases, except those consisting of coated particles of one compound C09C1/0015, C09C1/0078 take precedence
• CPC Class Codes: C09C 1/28 Compounds of silicon C09C1/0009, C09C1/0015, C09C1/0078 take precedence
• CPC Class Codes: C09D 7/61 inorganic
• CPC Class Codes: D21H 19/385 Oxides, hydroxides or carbonates
• CPC Class Codes: D21H 19/40 siliceous, e.g. clays

Abstract

A compound of calcium carbonate and of hydrated tobermorites, constituted of 70 to 15% tobermorites, which may contain free hydrated silica in amounts to 0 to 15% in weight expressed in SiO₂, and of 30 to 85% calcium carbonate. The process includes completely hydrating white Portland cements between about 5 and 100° C to form a paste having a dry extract of 5 to 70% by weight until at least a decrease in the pH-value occurs.

The compound is an industrial charge particularly for paper-making and paint-making industries.

Claims

1. A composition of calcium carbonate and hydrated tobermorites, consisting of from about 70 to about 15 per cent by weight of tobermorites, which may contain an amount from 0 to 15 per cent by weight of free hydrated silica expressed as SiO₂, and of from about 30 to about 85 per cent by weight of calcium carbonate.

2. The composition as claimed in claim 1 for use as an industrial charge, in the form of a powder having a particle size of about 2 microns.

3. The composition as claimed in claim 2, further comprising water to form a paste.

4. In a process for preparing a composition of calcium carbonate and tobermorites, the improvement in combination therewith comprising the steps of:

hydrating a white Portland cement at a temperature from about 5°

to about 100°

C with water and agitation to form a paste including lime and having a dry extract of from about 5 to 70 per cent by weight; and

carbonating said paste at least until all of said lime has been chemically changed into calcium carbonate, whereby a decrease of the pH-value of said paste occurs.

5. The process as claimed in claim 4, wherein said carbonating is with carbon dioxide or a source capable of supplying carbon dioxide.

6. The process as claimed in claim 4, further comprising measuring the pH-value of said paste.

7. The process as claimed in claim 4, wherein the decrease in the pH-value is an abrupt change.

8. In the preparation of a paint, the improvement in combination therewith comprising the steps of:

hydrating a white Portland cement at a temperature from about 5°

to about 100°

C with water and agitation to form a paste including lime and having a dry extract of from about 5 to about 70 per cent by weight;

carbonating said paste at least until all of said lime has been chemically changed into calcium carbonate, whereby a decrease of the pH-value of said paste occurs; and

adding the carbonated paste to the paint.

9. In the preparation of a coating for paper, the improvement in combination therewith comprising:

hydrating a white Portland cement at a temperature from about 5°

to about 100°

C with water and agitation to form a paste including lime and having a dry extract of from about 5 to about 70 per cent by weight;

carbonating said paste at least until said lime has been chemically changed into calcium carbonate, whereby a decrease of the pH-value of said paste occurs; and

applying the carbonated paste to the surface of the paper.