Refractory lining repair material

Abstract

A formulation containing polymer, resin and cement combined with aggregate can be used as a gunnable mix that is applied to a surface by being conveyed pneumatically in dry form to a nozzle, where water is added. Polymer in the gunnable mix enables it to adhere and bond to a surface, such as carbon brick, of a lining of a vessel used for the containment of molten metals. The formulation may be used, for example, to repair and protect blast furnace hearth linings.

Claims

1. A dry refractory composition, comprising: 5 wt % to 97 wt % of an aggregate comprising a material selected from the group consisting of calcined flint clay, calcined kaolin, calcined bauxitic kaolin, andalusite, tabular alumina, silicon carbide, silicon nitride, calcined alumina, reactive alumina, hydrated alumina, silica fume, white fused alumina, brown fused alumina, calcined bauxite, silica sand, silica, clay, kyanite, spinel, fused silica, zircon, zirconia, and combinations of each thereof; 0.01 wt % to 32 wt % of a water-soluble polymer selected from the group consisting of cellulose, dextran, poly(N-vinylpyridine), poly(acrylamide/acrylic acid), poly(acrylic acid), poly(ethylene glycol), poly(ethylene oxide), poly(N-vinylpyrrolidone), poly(vinyl alcohol), polyacrylamide, polyethyleneimine and combinations of each thereof; 0.01 wt % to 32 wt % of a resin selected from the group consisting of phenolic novolac resin, phenolic resole resin, epoxy resin, polyester resin, polyurethane resin, acrylic resin and combinations of each thereof; and 0.01 wt % to 15 wt % of a cement comprising a material selected from the group consisting of silicon dioxide, aluminum oxide, iron (III) oxide, calcium oxide and combinations of each thereof.

2. The refractory composition of claim 1, wherein the aggregate comprises a material selected from the group consisting of calcined bauxitic kaolin, andalusite, tabular alumina, silicon carbide, silicon nitride, calcined alumina, reactive alumina, hydrated alumina, silica fume, white fused alumina, brown fused alumina, calcined bauxite, and combinations thereof.

3. The refractory composition of claim 1, wherein the water-soluble polymer comprises poly(N-vinylpyrrolidone).

4. The refractory composition of claim 1, wherein the cement comprises calcium aluminate cement.

5. The refractory composition of claim 1, wherein the cement comprises a material selected from the group consisting of Portland cement, blast furnace cement, flue ash Portland cement, ciment compos, puzzolane cement, high alumina cement, Brunauer cement, Grenoble cement, Roman cement, and combinations thereof.

6. The refractory composition of claim 1, wherein the aggregate is present in an amount from and including 40 wt % to and including 90 wt % of the dry refractory composition.

7. The refractory composition of claim 1, wherein the cement is present in an amount from and including 0.01 wt % to and including 15 wt % of the dry refractory composition.

8. The refractory composition of claim 1, further comprising a dispersant.

9. The refractory composition of claim 8, wherein the dispersant is selected from the group consisting of sodium phosphates, naphthalene sulfonate salts, and sodium lignosulfates.

10. The refractory composition of claim 1, further comprising a dry powder accelerator.

11. The refractory composition of claim 10, wherein the dry powder accelerator is a material selected from the group consisting of hydrated lime, magnesium hydroxide, and lithium-containing compounds.

12. The refractory composition of claim 1, further comprising polymer fibers.

13. The refractory composition of claim 12, wherein the polymer fibers are comprised of a material selected from the group consisting of polyolefin, polyethylene, polypropylene, a combination of polyethylene and polypropylene, and combinations of these materials.

14. The refractory composition of claim 1, wherein the resin is selected from the group consisting of phenolic novolac resin, phenolic resole resin, epoxy resin, acrylic resin and combinations thereof.

15. The refractory composition of claim 14, wherein the resin comprises phenolic novolac resin.

16. The refractory composition of claim 15, further comprising hydrated lime and sodium phosphate.

17. The refractory composition of claim 16, further comprising a component selected from the group consisting of aluminum, silicon, ferrosilicon, ferrosilicon nitride, titanium dioxide, and combinations of each thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a photograph of a layer of inventive formulation A on a carbon brick after firing;

(2) FIG. 2 is a photograph of a layer of prior art formulation B on a carbon brick after firing;

(3) FIG. 3 is a photograph of a cross-section of a block of inventive formulation A after a Zn/Fe exposure cup test;

(4) FIG. 4 is a photograph of a cross-section of a block of prior art formulation B after a Zn/Fe exposure cup test;

(5) FIG. 5 is a photograph of a cross-section of a block of inventive formulation A after a Pb/Fe exposure cup test;

(6) FIG. 6 is a photograph of a cross-section of a block of prior art formulation B after a Pb/Fe exposure cup test;

(7) FIG. 7 is a photograph of a cross-section of a block of inventive formulation A after a blast furnace slag exposure cup test;

(8) FIG. 8 is a photograph of a cross-section of a block of prior art formulation B after a blast furnace slag exposure cup test;

(9) FIG. 9 is a perspective drawing of the components of a slant shear test block; and

(10) FIG. 10 is a line drawing of a photograph of a slant shear test block.

DETAILED DESCRIPTION OF THE INVENTION

(11) Vessels designed for containing molten metals are lined with a protective layer containing refractory aggregate. A blast furnace, which is a large vessel that is used to process iron ore into iron, is an example of such a vessel.

(12) A formulation that contains refractory aggregate, cement, resin and polymer can be combined with water at the nozzle and can be applied to the interior of a vessel, a blast furnace for example, designed for containing molten metal. This formulation forms a protective layer in the lining of the vessel. Also, this inventive formulation could be used to repair a current protective lining.

(13) This formulation, when combined with water, produces a gunning material (or gunite) that can be bonded to carbon brick that is within the blast furnace (BF) hearth. This gunite will be used to repair and protect the blast furnace hearth carbon brick. This gunite is the key component of a blast furnace hearth repair procedure because it can be applied in a single layer that is gunned directly onto the carbon brick. Also, it contains resin that may produce, depending on the resin used, thermal setting at a temperature of approximately 200 F. (93 C.).

(14) When water dissolves the polymer of the inventive formulation, it creates a clear, highly viscous, and sticky mixture. This sticky mixture, when combined with the other components of the formulation, enables the formulation to adhere to the carbon bricks of the vessel lining to protect them. The polymer, along with the resin, provides elemental carbon to enable the formulation to covalently bond to the carbon brick. This chemical bond enables the formulation to protect the carbon brick from chemical and mechanical attack at the bottom of the vessel. The cement present in the formulation is a type of binder that sets by forming hydrated compounds when mixed with water, and is used to bind the aggregate components together.

(15) The dry components of the inventive formulations may be combined in a mixer. Dry blending may be carried out for about 10 to 20 minutes in a Simpson mixture, and the blended formulation may be bagged in 50 pound (22.6 kilogram) bags. Bags of the blended formulation should be kept in a dry, moisture-free environment to prevent the formation of clumps from the reaction of water with the cement.

(16) Vessels are cooled for application of inventive materials in the same manner that they were cooled for application of previously known materials. To apply repair material according to the invention, the vessel is cooled to about 70 F. (21 C.). Then, once the material is installed, the vessel is heated according to procedures used for the prior art material. Gradual or stepwise increases in temperature allow sufficient time for the free water and chemical water to escape without spelling the material off the carbon brick.

Example 1

(17) In a comparison of the difference in properties obtained from the prior art formulation and the inventive formulation, two test materials were made with the same refractory aggregate.

(18) Inventive formulation A contains 20.5 wt % Mulcoa 60, 38.5 wt % tabular alumina, 12 wt % silicon carbide, 2 wt % water soluble polymer, 0.5 wt % Phenolic Novolac resin, 1.2 wt % titanium dioxide, 10 wt % alumina, 10 wt % calcium aluminate cement, 5 wt % silica fume and 0.3 wt % additives. Then 7.25 wt % of water is added to this combination to make it castable. The dry ingredients were mixed in a conventional refractory mixer. Resulting samples of cast material were subjected to modulus of rupture (MOR), cold crushing strength (CCS), bulk density, and percent apparent porosity after drying the material to 230 F. (110 C.).

(19) The results in Table I are average values for three samples of inventive formulation A.

(20) TABLE-US-00001 TABLE I Inventive Formulation A Dried at 230 F. (110 C.) for 24 h MOR, psi 2264 psi 15600 kPa CCS, psi 7759 psi 53500 kPa Bulk Density, pcf 153 pcf (lb/ft.sup.3) 2.45 g/cm.sup.3 % Apparent Porosity 16.3

(21) Prior art formulation B contains 20.5 wt % Mulcoa 60, 38 wt % tabular alumina, 12 wt % silicon carbide, 2 wt % silica sand, 2 wt % kyanite, 15 wt % alumina, 5 wt % calcium aluminate cement, 5 wt % Silica Fume, and 0.5 wt % additives. 5.8 wt % of water was then added to the mix to make it castable. These ingredients were mixed in a conventional refractory mixer. Resulting samples were subjected to modulus of rupture (MOR), cold crushing strength (CCS), bulk density, and percent apparent porosity after drying the material to 230 F. (110 C.). Results of these tests on a sample of prior art formulation B are shown in Table II.

(22) TABLE-US-00002 TABLE II Prior Art Formulation B Dried at 230 F. (110 C.) for 24 h MOR, psi 1054 psi 7270 kPa CCS, psi 4183 psi 28800 kPa Bulk Density, pcf 163 pcf (lb/ft.sup.3) 2.61 g/cm.sup.3 % Apparent Porosity 15.1

Example II

(23) Testing was performed on samples of inventive formulation A and prior art formulation B to compare their abilities to adhere to carbon brick. Layers of inventive formulation A and prior art formulation approximately a half inch (12 mm) thick were placed on top of respective pieces of carbon brick. Both pieces of carbon brick, covered with the respective formulations, were fired in a reducing atmosphere at 2500 F. (1371 C.). FIG. 1 shows inventive formulation A on a carbon brick after firing. FIG. 2 shows prior art formulation B on a carbon brick after firing. Inventive formulation A adhered to the brick; prior art formulation B did not adhere; prior art formulation B could be pulled from the carbon brick by hand.

Example III

(24) Testing was performed on samples of inventive formulation A and prior art formulation B to compare their abilities to withstand chemical erosion. In a blast furnace, chemical attack is the result of exposure to lead/iron, zinc/iron, and slag. A block of each material, measuring 2 inches by 2 inches (5 cm5 cm), was prepared. A hole was drilled in the middle of each block to hold metal samples within the material.

(25) Cup tests were performed on samples of inventive formulation A and prior art formulation B into which Zn/Fe was placed. The samples containing the Zn/Fe were exposed to a reduced atmosphere at 1400 F. (760 C.) for 5 hours. 1400 F. (760 C.) is slightly below the temperature at which Zn boils and becomes a vapor. The weight ratio of the Zn/Fe sample used was approximately 1 Zn:6 Fe.

(26) FIG. 3 shows a section of a block of the inventive formulation after testing. FIG. 4 shows a section of a block of the prior art formulation after testing. These pictures show no difference in the erosion of the inventive formulation sample and the prior art sample after the Zn/Fe exposure test.

Example IV

(27) Blocks of inventive formulation A and prior art formulation B, each measuring 2 inches by 2 inches (5 cm5 cm), were prepared. A hole was drilled in the middle of each block to hold metal samples within the material. Cup tests were performed on samples of inventive formulation A and prior art formulation B into which Pb/Fe was placed. The samples containing the Pb/Fe were exposed to a reduced atmosphere at 2500 F. (1400 C.) for 5 hours. 2500 F. (1400 C.) is slightly below the temperature at which Pb boils and becomes a vapor. The weight ratio of the Pb/Fe sample used was approximately 1 Pb:3.5 Fe.

(28) FIG. 5 shows a section of a block of the inventive formulation after testing. FIG. 6 shows a section of a block of the prior art formulation after testing. These pictures show no difference in the erosion of the inventive formulation sample and the prior art sample after the Pb/Fe exposure test.

Example V

(29) Blocks of inventive formulation A and prior art formulation B, each measuring 2 inches by 2 inches (5 cm5 cm), were prepared. A hole was drilled in the middle of each block to hold metal samples within the material. Cup tests were performed on samples of inventive formulation A and prior art formulation B with which 100% blast furnace slag C was used. The composition of samples of blast furnace slag C is provided in Table III. The samples containing the slag were exposed to a reduced atmosphere at 2800 F. (1540 C.) for 5 hours. Slag is molten at 2800 F. (1540 C.), and this is the temperature of the molten iron coming out of a blast furnace taphole.

(30) TABLE-US-00003 TABLE III Composition of Blast Furnace Slag C, Uniquant Semi-Quantitative Analysis 2/2007 sample, 9/2009 sample, Component wt % wt % Average wt % CaO 39.1 33.58 36.34 SiO.sub.2 35.68 40.33 38.005 MgO 9.87 11.61 10.74 Al.sub.2O.sub.3 11.43 11.08 11.255 SO.sub.3, S 1.51 1.39 1.45 Fe.sub.2O.sub.3 0.24 0.13 0.185 TiO.sub.2 1.09 0.53 0.81 MnO 0.25 0.3 0.275 K.sub.2O 0.29 0.38 0.335 BaO 0.08 0.16 0.12 Na.sub.2O 0.23 0.24 0.235 SrO ZrO.sub.2 Other (WO.sub.3, light 0.15 0.09 0.12 elements, etc.) Total 99.91 99.82 99.865 (CaO + MgO)/SiO.sub.2 1.37 1.12 1.245 (CaO + MgO)/ 1.04 0.88 0.96 (Al.sub.2O.sub.3 + SiO.sub.2)

(31) FIG. 7 shows a section of a block of the inventive formulation after testing. FIG. 8 shows a section of a block of the prior art formulation after testing. The drilled section of the inventive formulation block retained the blast furnace slag, whereas the block of prior art composition exhibited slag penetration extending nearly through the block from the cup to the exterior of the block.

Example VI

(32) Physical properties of blocks cast from inventive formulation A were measured after exposure to 1500 F., 2000 F., 2500 F., and 2700 F., followed by cooling. Testing results are presented in Table IV.

(33) TABLE-US-00004 TABLE IV Physical Properties of Inventive Formulation A Linear Change, TP-151 (%): 1500 F. (820 C.)/5 hrs 0.32 2000 F. (1100 C.)/5 hrs 0.43 2500 F. (1400 C.)/5 hrs 0.52 2700 F. (1500 C.)/5 hrs 0.03 Cold MOR, TP-57 (psi and kPa) 230 F. (110 C.)/16+ hrs 2264 psi 15600 kPa 1500 F. (820 C.)/5 hrs 943 psi 6500 kPa 2000 F. (1100 C.)/5 hrs 1080 psi 7450 kPa 2500 F. (1400 C.)/5 hrs 1317 psi 9080 kPa 2700 F. (1500 C.)/5 hrs 2021 psi 13900 kPa Cold Crushing Strength, TP-57 (psi and kPa) 230 F. (110 C.)/16+ hrs 7759 psi 53500 kPa 1500 F. (820 C.)/5 hrs 3649 psi 25200 kPa 2000 F. (1100 C.)/5 hrs 5119 psi 35300 kPa 2500 F. (1400 C.)/5 hrs 6319 psi 43600 kPa 2700 F. (1500 C.)/5 hrs 6385 psi 44000 kPa Bulk Density, TP-56 (pcf and g/cm.sup.3) 230 F. (110 C.)/16+ hrs 153 pcf 2.45 g/cm.sup.3 1500 F. (820 C.)/5 hrs 145 pcf 2.32 g/cm.sup.3 2000 F. (1100 C.)/5 hrs 146 pcf 2.34 g/cm.sup.3 2500 F. (1400 C.)/5 hrs 150 pcf 2.40 g/cm.sup.3 2700 F. (1500 C.)/5 hrs 149 pet 2.39 g/cm.sup.3 Apparent Porosity, TP-56 (%) 230 F. (110 C.)/16+ hrs 16.3 1500 F. (820 C.)/5 hrs 29.2 2000 F. (1100 C.)/5 hrs 28.4 2500 F. (1400 C.)/5 hrs 24.3 2700 F. (1500 C.)/5 hrs 22.6 Hot MOR, ASTM C-583 (psi and kPa) @ 1500 F. (820 C.) 1567 psi 10800 kPa @ 2000 F. (1100 C.) 1564 psi 10800 kPa @ 2500 F. (1400 C.) 401 psi 2760 kPa @ 2700 F. (1500 C.) 120 psi 830 kPa

Example VII

(34) An alkali cup test was performed on samples of the inventive formulation to determine alkali resistance. Three cup samples of the inventive formulation were placed in an oxidizing atmosphere, and three samples of the inventive formulation were placed into a sagger coke box having a reducing atmosphere. Four grams of salt were placed into each of the cups. Samples A2 contained Na.sub.2CO.sub.3, samples B2 contained K.sub.2CO.sub.3, and samples C2 had a 50:50 mixture of the two. The cup samples were slowly ramped (300 F. (149 C.)/hour) to 2500 F. (1371 C.) and kept at 2500 F. (1371 C.) for 5 hours. Table V shows the data for the cubes placed into an oxidizing atmosphere and Table VI shows the data for the cubes placed into a reducing atmosphere.

(35) TABLE-US-00005 TABLE V Alkali Cup Test of Samples in Oxidizing Atmosphere A2 B2 C2 Good/Excellent Fair to Poor Fair Contained Salt No Salt No Salt No Cracking Large Crack Open Crack No Distortion (Swelling) Distortion No Distortion

(36) TABLE-US-00006 TABLE VI Alkali Cup Test of Samples in Reducing Atmosphere A3 B3 C3 Good Fair Good No Salt No Salt No Salt No Cracking Open Crack No Cracking No Swelling No Swelling No Swelling

Example VIII

(37) A thermal shock test was performed on blocks formed from gunned inventive formulation. Ten cubes were cut out of gunned panels of the inventive formulation that were already dried at 230 F. (110 C.) for 24 hours. Then the 10 cubes were fired to 2000 F. (1093 C.) for 5 hours before beginning the thermal cycling test. The thermal cycling was performed at 2000 F. (1093 C.). A set of 5 cubes at 77 F. (25 C.) were placed into a furnace at 2000 F. (1093 C.) for 30 minutes. Then the specimens were immediately placed in a container filled with flowing cool water in order to shock the samples. They were left in water for 5 minutes, and then cooled at room temperature onto an alumina setter for 30 minutes with a fan blowing air over them. Finally, each of the samples was inspected for fractures. This process was repeated for 10 cycles. The results for the test are shown in Table VII. The ratings for the cubes are reported on a scale from 0 to 5, in which 0 represents no cracks, 1 represents mild cracking, 2 represents moderate cracking, 3 represents heavy cracking, 4 represents severe cracking, and 5 represents a piece of the cube completely breaking off. Ratings are reported for the condition of the cube after cycle 10 (on a scale of 0 to 5), and as a sum of the ratings after each of cycles 1 through 10 (on a scale of 0 to 50).

(38) TABLE-US-00007 TABLE VII Thermal Shock Test Results for Samples of Inventive Formulation A Cube Cube Cube Cube Cube Cube Cube Cube Cube Cube A4 B4 C4 D4 E4 F4 G4 H4 J4 K4 After cycle 10 4 4 3 3 4 4 3 3 3 3 Sum of 10 cycles 23 25 15 18 26 28 21 21 17 21

Example IX

(39) A slant shear test was performed on block assemblies formed from carbon brick (which is the same type that is used inside a blast furnace hearth), inventive formulation, and a combination of gunned inventive composition onto carbon brick. FIG. 9 shows a testing block assembly 10 having a top 12, a bottom 14, and an upper portion 20 in contact with a lower portion 22 along a contact plane 24 inclined with respect to the horizontal. Testing block assembly has a length 30, a width 32 and a height 34. Upper portion minimum facial height 36 represents the minimum facial distance on upper portion 20 between the contact plane 24 and the top 12. Lower portion minimum facial height 38 represents the minimum facial distance on lower portion 22 between the contact plane 24 and the bottom 14. Dimensions used for sample testing are: 2.5 inches or 63.5 mm for length 30, 2 inches or 50.8 mm for width 32, 3 inches or 76.2 mm for height 34, 0.5 inch or 12.7 mm for upper portion minimum facial height 36 and 0.5 inches or 12.7 mm for lower portion minimum facial height 38. The angle of inclination of contact plane 24 with the horizontal is 39.

(40) The following procedure was used to perform the analysis: 1. Dry the carbon brick/Inventive formulation material for 24 hours at 230 F. (110 C.) 2. Cut the carbon brick, inventive formulation, and the carbon brick with the gunned inventive formulation in a way to form the cube design of FIG. 9. 3. Coke the cubes in a saggar coke box at 2000 F. (1093 C.) for 5 hours with a ramp rate of 300 F. (149 C.) per hour 4. Perform the cold crushing strength test on each cubes, photograph each cube, and record pressure to crush 5. Crush the cubes at a constant rate of 7000 lbs (3200 kg)/minute.

(41) Table VIII contains results for the cold crushing of each sample and an average.

(42) TABLE-US-00008 TABLE VIII Slant Shear Test Data Carbon Brick Sample A5 5762 psi 39700 kPa Sample B5 5963 psi 41100 kPa Sample C5 5712 psi 39400 kPa Average 5812 psi 40100 kPa Inventive Formulation A Sample A6 2958 psi 20400 kPa Sample B6 2976 psi 20500 kPa Sample C6 3224 psi 22200 kPa Average 3053 psi 21000 kPa Mix Shear (Inventive Formulation on Carbon Brick) Sample A7 2954 psi 20400 kPa Sample B7 4268 psi 29400 kPa Sample C7 4050 psi 27900 kPa Average 3757 psi 25900 kPa

(43) FIG. 10 shows the mix shear sample C7 after it has been crushed. The carbon brick is on top of the inventive formulation material.

(44) Numerous modifications and variations of the present invention are possible. It is, therefore, to be understood that within the scope of the following claims, the invention may be practiced otherwise than as specifically described.