Rheology modifying agents for slurries

1. A method of modifying rheology of a magnesium oxide slurry comprising:

adding a rheology modifying agent to the magnesium oxide slurry,

wherein the rheology modifying agent is a composition comprising a high molecular weight polymer having a number average molecular weight of greater than about 200,000 comprising hydrolyzed polyacrylamide, a chelating agent, polymaleic acid, and a copolymer comprising acrylic acid (AA) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS).

2. The method of claim 1 , wherein the rheology modifying agent is added to the magnesium oxide slurry in an amount that is selected from the group consisting of about 10 ppm to about 300 ppm and about 30 ppm to about 250 ppm.

3. The method of claim 1 , wherein the high molecular weight polymer has a number average molecular weight of greater than 1,000,000.

4. The method of claim 1 , wherein the composition comprises about 2% of the hydrolyzed polyacrylamide and about 0.5% ethylenediaminetetraacetic acid.

5. The method of claim 1 , wherein the chelating agent is selected from the group consisting of ethylenediaminetetraacetic acid, citric acid, a ligno sulfonate, dimercaprol (2,3-dimercapto-1-propanol), porphine, and any combination thereof.

6. A method of modifying rheology of a magnesium oxide slurry, comprising:

adding a rheology modifying agent to the magnesium oxide slurry, wherein the rheology modifying agent comprises:

a high molecular weight polymer and

a low molecular weight anionic polymer

wherein the low molecular weight anionic polymer has a number average molecular weight of less than about 20,000, and the high molecular weight polymer has a number average molecular weight of greater than about 200,000,

wherein the low molecular weight anionic polymer is a copolymer of acrylic acid and 2-acrylamido-2-methylpropane sulfonic acid.

7. The method of claim 6 , wherein the high molecular weight polymer comprises acrylamide.

8. The method of claim 6 , wherein the high molecular weight polymer is selected from a copolymer of acrylic acid and acrylamide, a polymer of hydrolyzed polyacrylamide, and any combination thereof.

9. The method of claim 8 , wherein the high molecular weight polymer comprises a copolymer of from about 1 mol % to about 15 mol % acrylic acid and about 99 mol % to about 85 mol % acrylamide.

10. The method of claim 6 , wherein the rheology modifying agent is added to the magnesium oxide slurry in an amount that is selected from the group consisting of about 10 ppm to about 300 ppm and about 30 ppm to about 250 ppm.

11. A method of modifying rheology of a magnesium oxide slurry, comprising:

adding a rheology modifying agent to the magnesium oxide slurry, wherein the rheology modifying agent comprises a low molecular weight anionic polymer selected from polymaleic acid; a copolymer of acrylic acid and 2-acrylamido-2-methylpropane sulfonic acid; a terpolymer of acrylic acid, acrylamide, and sulfonated acrylamide; and any combination thereof, wherein the low molecular weight anionic polymer has a number average molecular weight of less than about 20,000.

12. The method of claim 11 , wherein the rheology modifying agent is added to the magnesium oxide slurry in an amount that is selected from the group consisting of about 10 ppm to about 300 ppm and about 30 ppm to about 250 ppm.

13. The method of claim 11 , wherein the low molecular weight anionic polymer is a terpolymer comprising about 40% acrylic acid, about 20% acrylamide, and about 40% sulfonated acrylamide.

14. A method of modifying rheology of a magnesium oxide slurry comprising:

adding a rheology modifying agent to the magnesium oxide slurry, wherein the rheology modifying agent is a composition comprising about 2% hydrolyzed polyacrylamide and about 0.5% ethylenediaminetetraacetic acid.