Process for control of microbial contamination, mineral suspensions obtained and their uses
The invention concerns a process for disinfection and/or conservation and/or reduction and/or control of microbial contamination of aqueous dispersions and/or aqueous suspensions of mineral matter, providing satisfactory stability in terms of Brookfield™ viscosity for the said aqueous dispersions and/or suspensions of mineral matter. It also concerns the said aqueous dispersions and/or suspensions thus obtained, together with their uses in the mineral, paper and paint industries. Finally it concerns the end products obtained.
1. An aqueous suspension of mineral matter comprising calcium carbonate, at least one dispersing agent, and an antimicrobial agent consisting of one or more OH − ion donors selected from alkali oxides and alkali hydroxides, wherein the aqueous suspension is obtained by a process for disinfecting or preserving the aqueous suspension of or from microbial contamination, wherein the process comprises:
a) at least one stage to increase and maintain the OH − ion concentration of the aqueous suspension of the mineral matter comprising calcium carbonate, to a value greater than or equal to 1×10 −2 mole/l, by addition of the antimicrobial agent consisting of one or more OH − ion donors selected from alkali oxides and alkali hydroxides, for a sufficient time to disinfect or preserve the aqueous suspension of the mineral matter comprising calcium carbonate of or from microbial contamination, and
b) at least one stage of dispersion and/or grinding of the aqueous suspension of the mineral matter comprising calcium carbonate, occurring before, during or after stage a),
wherein the aqueous suspension of mineral matter has a microbe concentration of less than or equal to 100 microbes/gram.
2. The aqueous suspension according to claim 1 , wherein the OH − ion concentration value in stage a) is higher than or equal to 2×10 −2 mole/l.
3. The aqueous suspension according to claim 1 , wherein the one or more OH − ion donors added in stage a) is an alkali oxide.
4. The aqueous suspension according to claim 1 , wherein the one or more OH − ion donors added in stage a) is an alkali hydroxide.
5. The aqueous suspension according to claim 1 , wherein the one or more OH − ion donors added in stage a) is NaOH.
6. The aqueous suspension according to claim 1 , wherein stage b) is conducted using at least one dispersing agent or at least one grinding aid agent.
7. The aqueous suspension according to claim 1 , wherein a physical decontamination is introduced before, during or after stage a), and/or b).
8. The aqueous suspension according to claim 7 , wherein the physical decontamination uses at least one treatment process based on an increase of temperature.
9. The aqueous suspension according to claim 1 , wherein the mineral matter is natural and/or precipitated calcium carbonate.
10. The aqueous suspension according to claim 1 , wherein the mineral matter is natural calcium carbonate.
11. The aqueous suspension according to claim 1 , wherein the mineral matter is marble, calcite, chalk or their mixtures.
12. A paper formulation comprising or manufactured with the suspension according to claim 1 .
13. A sheet of paper comprising or manufactured with the suspension according to claim 1 .
14. A coating color comprising or manufactured with the suspension according to claim 1 .
15. A water-based paint comprising or manufactured with the suspension according to claim 1 .
16. A lacquer comprising or manufactured with the suspension according to claim 1 .
17. A varnish comprising or manufactured with the suspension according to claim 1 .