Liquid gypsum set accelerator
A liquid accelerator composition for accelerating the setting reaction of calcium sulfate hemihydrate and water and methods of forming a liquid gypsum accelerator are provided. The liquid accelerator composition includes a liquid media in which calcium sulfate dihydrate is less than fully soluble and a ground product of a mill grinding of a mixture comprising calcium sulfate dihydrate.
1. A gypsum set accelerator composition, comprising:
a slurry including:
ground gypsum in an amount of about 95 wt % to about 20 wt % of the slurry, the ground gypsum having a particle size distribution with at least about 15% of the mass of ground gypsum having a particle size of about 5.5 μm or less; and
a non-aqueous liquid medium in which gypsum has a solubility of about 10 g/l or less at 25° C.
2. The gypsum set accelerator composition of claim 1 , wherein the ground gypsum is in an amount of about 40 wt % to about 20 wt % of the slurry.
3. The gypsum set accelerator composition of claim 1 , wherein the ground gypsum is in an amount of about 35 wt % of the slurry.
4. The gypsum set accelerator composition of claim 1 , wherein gypsum has a solubility of about 2.5 g/l or less in the liquid medium.
5. The gypsum set accelerator composition of claim 1 , wherein gypsum has a solubility of about 1 g/l or less in the liquid medium.
6. The gypsum set accelerator composition of claim 1 , wherein the liquid medium is selected from the group consisting of: an alcohol, glycerin and combinations thereof.
7. The gypsum set accelerator composition of claim 1 , wherein the liquid medium is anhydrous isopropyl alcohol.
8. The gypsum set accelerator composition of claim 1 , wherein the liquid medium includes a solubility inhibitor.
9. The gypsum set accelerator composition of claim 8 , wherein the solubility inhibitor is a phosphate.
10. The gypsum set accelerator composition of claim 8 , wherein the solubility inhibitor is sodium trimetaphosphate.
11. The gypsum set accelerator composition of claim 1 , further comprising an additive selected from the group consisting of: a soap, a surfactant, a dispersant, naphthalene sulfonate, a lignosulfonate, an alginate, a saccharide, a phosphate, a complexing agent and combinations thereof.
12. The gypsum set accelerator composition of claim 1 , wherein the ground gypsum has a particle size distribution with at least about 40 wt % of the mass of ground gypsum having a particle size of about 5.5 μm or less.
13. The gypsum set accelerator composition of claim 1 , wherein the ground gypsum has a particle size distribution with a mass median diameter of less than 15 μm.
14. The gypsum set accelerator composition of claim 1 , wherein the ground gypsum has a particle size distribution with a mass median diameter of about 5.5 μm or less.
15. A method of making a gypsum set accelerator, comprising the steps of:
providing gypsum and a non-aqueous liquid medium in which gypsum has a solubility of about 10 g/l or less at 25° C.;
grinding the gypsum to a particle size distribution with at least about 15% of the mass of ground gypsum having a particle size of about 5.5 μm or less; and
combining the liquid medium and the ground gypsum to form a slurry comprising about 95 wt % to about 20 wt % gypsum.
16. The method of claim 15 , wherein the slurry comprises about 40 wt % to about 20 wt % gypsum.
17. The method of claim 15 , wherein gypsum has a solubility in the liquid medium of about 2.5 g/l or less.
18. The method of claim 15 , wherein the liquid medium is anhydrous isopropyl alcohol.
19. The method of claim 15 , wherein the liquid medium includes a solubility inhibitor.
20. The method of claim 19 , wherein the solubility inhibitor is a phosphate.
21. The method of claim 15 , wherein the gypsum is ground to a particle size distribution with a mass median diameter of less than 15 μm.
22. The method of claim 15 , wherein the gypsum is ground to a particle size distribution with a mass median diameter of about 5.5 μm or less.
23. The method of claim 15 , wherein the gypsum is ground in at least a portion of the liquid medium.
24. The method of claim 15 , wherein the gypsum is ground in a planetary ball mill.
25. A method of making a gypsum board composition, comprising the steps of:
providing dry ingredients including stucco, and wet ingredients including water;
mixing the dry and wet ingredients to form a gypsum slurry;
providing gypsum and a liquid medium in which gypsum has a solubility of about 10 g/l or less at 25° C.;
grinding the gypsum to a particle size distribution with at least about 15% of the mass of ground gypsum having a particle size of about 5.5 μm or less;
combining the liquid medium and the gypsum to form a gypsum set accelerator comprising about 95 wt % to about 20 wt % gypsum;
adding an aqueous foam to the gypsum slurry; and
adding the gypsum set accelerator to the gypsum slurry with the foam.
26. A method of making a gypsum set accelerator, comprising the steps of:
combining stucco and an aqueous liquid medium in which gypsum has a solubility of about 10 g/l or less at 25° C., to undergo a hydration reaction and precipitate gypsum from the aqueous liquid medium; and
grinding the gypsum during precipitation to a particle size distribution with at least about 15% of the mass of ground gypsum having a particle size of about 5.5 μm or less;
wherein the liquid medium and the ground gypsum form a slurry comprising about 95 wt % to about 20 wt % gypsum.
27. The method of claim 26 , wherein the liquid medium includes a phosphate.
28. The method of claim 27 , wherein the solubility inhibitor is sodium trimetaphosphate.