Method For Calcining Gypsum and Making a Gypsum Board

1 - 30 . (canceled)

31 . A method for making a gypsum board, the method comprising:

applying a phosphorus containing compound to a first gypsum composition to provide a phosphorus modified gypsum composition,

wherein the phosphorus containing compound comprises a phosphite, a phosphate having the formula P(O) n (X) m wherein n is from 0 to 4, m is from 0 to 6, the sum of n and m is from 3 to 6, and X is hydrogen, halogen, sulfur, or selenium, a salt thereof, or a mixture thereof;

calcining the phosphorus modified gypsum composition to provide a calcined gypsum composition;

preparing a gypsum slurry by combining water and the calcined gypsum composition;

depositing the gypsum slurry on a first facing material;

providing a second facing material on the gypsum slurry; and

allowing the calcined gypsum to convert to calcium sulfate dihydrate.

32 . The method of claim 31 , wherein the phosphorus containing compound comprises a phosphate having the formula P(O) n (X) m wherein n is from 0 to 4, m is from 0 to 6, the sum of n and m is from 3 to 6, and X is hydrogen, halogen, sulfur, or selenium, a salt thereof.

33 . The method of claim 32 , wherein X includes fluoro.

34 . The method of claim 32 , wherein n is from 2 to 3.

35 . The method of claim 32 , wherein m is from 1 to 2.

36 . The method of claim 31 , wherein the phosphorus containing compound comprises a halophosphate.

37 . The method of claim 31 , wherein the phosphorus containing compound comprises a salt including an alkali metal, an alkaline earth metal, a transition metal, or a combination thereof.

38 . The method of claim 31 , wherein the phosphorus containing compound comprises sodium monofluorophosphate.

39 . The method of claim 31 , wherein the gypsum slurry further comprises a foaming agent comprising an alkyl sulfate, an alkyl ether sulfate, or a mixture thereof.

40 . The method of claim 31 , wherein the first gypsum composition comprises reclaimed gypsum.

41 . The method of claim 31 , wherein the first gypsum composition comprises reclaimed gypsum and virgin gypsum.

42 . The method of claim 31 , wherein the first gypsum composition comprises an organosilicon compound.

43 . The method of claim 31 , wherein the first gypsum composition comprises a polysiloxane.

44 . The method of claim 31 , wherein the first gypsum composition comprises a polymethylhydrosiloxane.

45 . The method of claim 31 , wherein the first gypsum composition comprises reclaimed gypsum and an organosilicon compound.

46 . The method of claim 45 , wherein the organosilicon compound comprises a polysiloxane.

47 . The method of claim 45 , wherein the organosilicon compound comprises a polymethylhydrosiloxane.

48 . The method of claim 40 , further comprising combining the modified gypsum composition with virgin gypsum to provide a second gypsum composition, calcining the second gypsum composition to provide the calcined gypsum composition.

49 . The method of claim 45 , further comprising combining the modified gypsum composition with virgin gypsum to provide a second gypsum composition, calcining the second gypsum composition to provide the calcined gypsum composition.

50 . A gypsum board made from the method of claim 31 .

51 . A method for making a gypsum board, the method comprising:

applying a phosphorus containing compound to a first gypsum composition to provide a phosphorus modified gypsum composition,

wherein the first gypsum composition comprises reclaimed gypsum and an organosilicon compound,

wherein the phosphorus containing compound comprises a phosphite, a phosphate having the formula P(O) n (X) m wherein n is from 0 to 4, m is from 0 to 6, the sum of n and m is from 3 to 6, and X is hydrogen, halogen, sulfur, or selenium, a salt thereof, or a mixture thereof;

calcining the phosphorus modified gypsum composition to provide a calcined gypsum composition;

preparing a gypsum slurry by combining water and the calcined gypsum composition;

depositing the gypsum slurry on a first facing material;

providing a second facing material on the gypsum slurry; and

allowing the calcined gypsum to convert to calcium sulfate dihydrate.

52 . The method of claim 51 , wherein the first gypsum composition further comprises virgin gypsum.

53 . The method of claim 51 , further comprising combining the modified gypsum composition with virgin gypsum to provide a second gypsum composition, calcining the second gypsum composition to provide the calcined gypsum composition.

54 . A gypsum board made from the method of claim 51 .