Calcium enriched refractory material by the addition of calcium carbonate

Abstract

The composition applied to the refractory structure has a magnesia-based refractory material, calcia source and a binder. After application of the refractory material to a refractory structure and upon application of heat to the applied refractory material a matrix is formed which protects against penetration of the slag into the refractory material. The resulting refractory material has improved hot strength, slag resistance and durability.

1 . A composition suitable for providing a refractory material having a high density matrix comprising: 20 to 95 weight percent magnesia-based refractory material; 0.1 to 5.0 weight percent of a binder; and 2.0 to 10 weight percent of calcium carbonate for reacting upon exposure to heat to provide the refractory material having a high density matrix and provide reactive calcium oxide for improved corrosion resistance. 
     
     
         2 . The composition according to  claim 1  wherein the binder is selected from the group consisting of an organic acid, an alkali silicate and an alkali phosphate. 
     
     
         3 . The composition according to  claim 1  wherein the magnesia-based refractory material is present in an amount of 60 to 88 weight percent. 
     
     
         4 . The composition according to  claim 1  further comprising calcium hydroxide in amount of 0.2 to 8.0 weight percent. 
     
     
         5 . The composition according to  claim 1  further comprising a plasticizer in an amount of 0.1 to 2.0 weight percent. 
     
     
         6 . The composition according to  claim 5  wherein the plasticizer is bentonite. 
     
     
         7 . The composition according to  claim 1  further comprising a dispersant in an amount of from 0.1 to 1.0 weight percent. 
     
     
         8 . The composition according to  claim 7  wherein the dispersant is citric acid. 
     
     
         9 . The composition according to  claim 1  wherein the binder is sodium hexametaphosphate wherein the sodium hexametaphosphate is present in an amount of 0.2 to 5.0 weight percent. 
     
     
         10 . The composition according to  claim 1  wherein the binder is sulfamic acid wherein the sulfamic acid is present in an amount of 0.2 to 3.0 weight percent. 
     
     
         11 . The composition according to  claim 1  wherein the calcium carbonate is present in an amount of 2.0 to 7.0 weight percent wherein the calcium carbonate has a particle size of generally less than 325 mesh. 
     
     
         12 . The composition according to  claim 1  wherein the calcium carbonate is present in a very fine portion having a particle size of generally less than 325 mesh and a coarser portion wherein the coarser portion has a particle size generally less than 20 mesh, 15 weight percent larger than 40 mesh, 75 weight percent larger than 100 mesh and 92 weight percent larger than 200 mesh. 
     
     
         13 . The composition according to  claim 12  wherein the very fine portion is present in an amount of 2.5 to 3.5 weight percent and the coarser portion is present in an amount of 2.5 to 3.5 weight percent. 
     
     
         14 . The composition according to  claim 12  wherein the very fine portion is present in an amount of 3.5 to 4.5 weight percent and the coarser portion is present in an amount of 3.5 to 4.5 weight percent. 
     
     
         15 . The composition according to  claim 13  further comprising 0.2 to 3.0 weight percent sulfamic acid. 
     
     
         16 . The composition according to  claim 14  further comprising 0.2 to 5.0 weight percent sodium hexametaphosphate. 
     
     
         17 - 19 . (canceled) 
     
     
         20 . A composition suitable for providing a refractory material having a high density matrix comprising:
 20 to 97.9 weight percent magnesia-based refractory material;   0.1 to 6.0 weight percent of a binder;   2.0 to 10 weight percent of calcium carbonate for reacting upon exposure to heat to provide the refractory material having a high density matrix and provide reactive calcium oxide for improved corrosion resistance; and   0.2 to 8.5 weight percent calcium hydroxide.   
     
     
         21 - 26 . (canceled) 
     
     
         27 . A method of providing a refractory material having a high density matrix to a lining in a molten metal containing vessel comprising applying to the lining 20 to 97.9 weight percent magnesia-based refractory material;
 0.1 to 6.0 weight percent of a binder;   2.0 to 10 weight percent of calcium carbonate for reacting upon exposure to heat to provide the refractory material having a high density matrix and provide reactive calcium oxide for improved corrosion resistance; and   0.2 to 8.5 weight percent calcium hydroxide;   whereby both the calcium carbonate and the calcium hydroxide react upon exposure to heat to provide the refractory material a high density matrix and provide reactive calcium oxide for improved corrosion resistance.   
     
     
         28 . The method according to  claim 27  wherein the refractory material is applied to the lining by gunning, spraying, casting, ramming, shotcreting, slurry coating, troweling, hot pouring, manual application, dry application or a hybrid method. 
     
     
         29 . The method according to  claim 27  wherein the refractory material is applied to the lining in a layer having a thickness of from 1 to 12 inches.