Blast furnace anhydrous stemming containing rare earth lanthanum and preparation method thereof

Abstract

The invention relates to the technical field of metallurgical refractory materials, and discloses rare earth lanthanum-containing blast furnace anhydrous stemming and a preparation method thereof, and the rare earth lanthanum-containing blast furnace anhydrous stemming comprises the following components: 80-120 parts of corundum particles, 50-80 parts of silicon carbide particles, 30-50 parts of graphite, 20-30 parts of silica fume, 40-60 parts of bauxite, 5-15 parts of a rare earth lanthanum compound, 20-40 parts of a binder and 5-8 parts of an additive. Through a reasonable raw material ratio and an optimized preparation process, the high-temperature strength, corrosion resistance and thermal shock resistance of the stemming can be remarkably improved, the service life of an iron notch is prolonged, and the production efficiency of a blast furnace is improved; meanwhile, the production cost is reduced, the pollution to the environment is reduced, and the development requirement of the modern blast furnace smelting technology is met.

Description

Technical Field

[0001] This invention relates to the field of metallurgical refractory materials technology, specifically to a blast furnace anhydrous taphole clay containing rare earth lanthanum and its preparation method. Background Technology

[0002] Anhydrous taphole clay is a type of refractory plastic used to seal the taphole of blast furnaces. The taphole area is the part most severely affected by slag and iron erosion, impacting the blast furnace's service life. When anhydrous taphole clay is pressed into the blast furnace, it forms a clay pocket in the taphole area, inhibiting the erosion caused by the circulating molten iron and protecting the hearth in this area. Therefore, it plays a crucial role in extending the blast furnace's lifespan.

[0003] Currently, the widely used anhydrous taphole clay in the market can meet the basic requirements of blast furnace smelting to a certain extent. However, with the continuous advancement of smelting technologies such as larger blast furnaces, higher blast temperatures, and higher oxygen enrichment, existing anhydrous taphole clay mainly uses traditional raw materials such as corundum, silicon carbide, and graphite. Although these raw materials have certain high-temperature resistance and corrosion resistance, their resource reserves are limited, and their prices fluctuate greatly, resulting in high production costs for taphole clay. At the same time, the production process of some raw materials generates a large amount of pollutants, which is inconsistent with the current green and environmentally friendly development concept. Therefore, it is urgent to address this situation. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides anhydrous taphole clay for blast furnaces containing rare earth lanthanum and its preparation method. Through reasonable raw material ratios and optimized preparation processes, this taphole clay can significantly improve high-temperature strength, erosion resistance, and thermal shock resistance, extend taphole life, and increase blast furnace production efficiency. At the same time, it reduces production costs, minimizes environmental pollution, and meets the development needs of modern blast furnace smelting technology.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: a blast furnace anhydrous taphole clay containing rare earth lanthanum, comprising the following components: 80-120 parts of corundum particles, 50-80 parts of silicon carbide particles, 30-50 parts of graphite, 20-30 parts of silica fume, 40-60 parts of bauxite, 5-15 parts of rare earth lanthanum compound, 20-40 parts of binder, and 5-8 parts of additives.

[0008] Furthermore, the corundum particles are fused alumina, and the particle size range is 0.1-5mm, of which 30-40% are 3-5mm particles, 25-35% are 1-3mm particles, and 25-40% are 0.1-1mm particles.

[0009] Furthermore, the silicon carbide particles are green silicon carbide, and the particle size ranges from 0.074 to 3 mm, of which 20-30% are 1-3 mm and 70-80% are 0.074-1 mm.

[0010] Furthermore, the rare earth lanthanum compound is one or more of lanthanum nitrate, lanthanum oxide, or lanthanum carbonate, and has a particle size of less than 0.05 mm.

[0011] Furthermore, the binder is one or more of phenolic resin, coal tar, or anthracene oil.

[0012] Furthermore, the additive is composed of an antioxidant, an expanding agent, a dispersant, metallic silicon powder, and explosion-proof fiber, and the mass ratio is (2-3):(3-4):(1-2):(2-4):(1-3). The antioxidant is boric acid, the expanding agent is kyanite, the dispersant is sodium hexametaphosphate, and the explosion-proof fiber is polypropylene fiber with a length of 3-6 mm.

[0013] A method for preparing anhydrous blast furnace taphole clay containing rare earth lanthanum, the method being used to manufacture the aforementioned anhydrous blast furnace taphole clay containing rare earth lanthanum, comprising the following steps:

[0014] Raw material pretreatment: Corundum particles and silicon carbide particles are screened separately; graphite, silica fume, bauxite, rare earth lanthanum compounds and additives are dried at a temperature of 100-120℃ for 2-3 hours.

[0015] Mixing and stirring: First, add the pretreated corundum particles and silicon carbide particles to a forced mixer and stir for 5-10 minutes; then add graphite, silica fume, bauxite, rare earth lanthanum compounds and additives, and continue stirring for 10-15 minutes; finally, add the binder and stir for 20-30 minutes at a mixer speed of 30-50 r / min.

[0016] Molding: The mixed clay is placed into a molding mold and molded using a hydraulic press. The molding pressure is 20-30 MPa and the holding time is 1-2 minutes.

[0017] Drying: Place the molded clay blanks into a drying oven and dry them at 60-80℃ for 24-36 hours;

[0018] Packaging: The dried clay is packaged after passing inspection.

[0019] (III) Beneficial Effects

[0020] This invention provides anhydrous taphole clay for blast furnaces containing rare earth lanthanum and its preparation method. It has the following beneficial effects:

[0021] (1) The rare earth lanthanum compound added in this invention can react with other raw materials to form stable solid solutions and compounds, refining the microstructure of the gunpowder and increasing its density. Simultaneously, the presence of rare earth lanthanum enhances the bonding force between raw materials, allowing the gunpowder to maintain high strength even at high temperatures. Furthermore, the addition of the rare earth lanthanum compound alters the chemical composition and structure of the gunpowder, improving its resistance to molten iron and slag. This allows the rare earth lanthanum to react with harmful components in the slag, forming high-melting-point compounds and reducing slag erosion. Meanwhile, the addition of graphite and silicon carbide provides good thermal conductivity to the gunpowder, reducing thermal stress during temperature changes; and the refined microstructure of the rare earth lanthanum compound disperses thermal stress, preventing crack initiation and propagation.

[0022] (2) The raw materials used in this invention are all non-toxic and harmless substances, free from heavy metals and other harmful components. They do not release toxic gases during use and pose no harm to the environment or the health of operators. Furthermore, the addition of rare earth lanthanum compounds increases the service life of the gunning clay and reduces its consumption, thereby reducing waste generation. Simultaneously, the gunning clay of this invention is easy to dispose of after disposal, preventing secondary pollution and aligning with the concept of green and environmentally friendly development.

[0023] (3) This invention rationally adds rare earth lanthanum compounds to the raw materials, reducing the amount of some expensive traditional raw materials used, thereby reducing the raw material cost of taphole clay. At the same time, rare earth lanthanum compounds can also extend the taphole life, reduce the number and time of taphole maintenance, and improve the blast furnace operating rate and production efficiency. Detailed Implementation

[0024] Example 1

[0025] Raw material components:

[0026] 80 parts corundum particles (30% for 3-5mm, 25% for 1-3mm, and 45% for 0.1-1mm), 50 parts silicon carbide particles (20% for 1-3mm and 80% for 0.074-1mm), 30 parts graphite, 20 parts silica fume, 40 parts bauxite, 5 parts rare earth lanthanum compound (lanthanum nitrate), 20 parts binder (phenolic resin), and 5 parts additives (1 part boric acid, 1.5 parts kyanite, 0.5 parts sodium hexametaphosphate, 1 part metallic silicon powder, and 1 part polypropylene fiber).

[0027] Preparation process:

[0028] Raw material pretreatment: Corundum particles and silicon carbide particles are screened separately; graphite, silica fume, bauxite, rare earth lanthanum compounds and additives are dried at 100℃ for 2 hours.

[0029] Mixing and stirring: First, add the pretreated corundum particles and silicon carbide particles to a forced mixer and stir for 5 minutes; then add graphite, silica fume, bauxite, rare earth lanthanum compounds and additives, and continue stirring for 10 minutes; finally, add the binder and stir for 20 minutes at a mixer speed of 30 r / min.

[0030] Molding: The mixed mud is placed into the molding mold and molded using a hydraulic press. The molding pressure is 20MPa and the holding time is 1 minute.

[0031] Drying: Place the molded clay blanks into a drying oven and dry them at 60°C for 24 hours;

[0032] Packaging: After the dried clay passes inspection, it is packaged to form anhydrous clay products.

[0033] Example 2

[0034] Raw material composition: 100 parts corundum particles (35% for 3-5mm, 30% for 1-3mm, and 35% for 0.1-1mm), 65 parts silicon carbide particles (25% for 1-3mm and 75% for 0.074-1mm), 40 parts graphite, 25 parts silica fume, 50 parts bauxite, 10 parts rare earth lanthanum compound (lanthanum oxide), 30 parts binder (coal tar), and 6.5 parts additives (1 part boric acid, 1.5 parts kyanite, 1 part sodium hexametaphosphate, 1.5 parts metallic silicon powder, and 1.5 parts polypropylene fiber).

[0035] Preparation process:

[0036] Raw material pretreatment: Corundum particles and silicon carbide particles are screened separately; graphite, silica fume, bauxite, rare earth lanthanum compounds and additives are dried at 110℃ for 2.5 hours.

[0037] Mixing and stirring: First, add the pretreated corundum particles and silicon carbide particles to a forced mixer and stir for 7 minutes; then add graphite, silica fume, bauxite, rare earth lanthanum compounds and additives, and continue stirring for 12 minutes; finally, add the binder and stir for 25 minutes at a mixer speed of 40 r / min.

[0038] Molding: The mixed mud is placed into a molding mold and molded using a hydraulic press. The molding pressure is 25MPa and the holding time is 1.5 minutes.

[0039] Drying: Place the molded clay blanks into a drying oven and dry them at 70°C for 30 hours;

[0040] Packaging: After the dried clay passes inspection, it is packaged to form anhydrous clay products.

[0041] Example 3

[0042] Raw material composition: 120 parts corundum particles (40% for 3-5mm, 35% for 1-3mm, and 25% for 0.1-1mm), 80 parts silicon carbide particles (30% for 1-3mm and 70% for 0.074-1mm), 50 parts graphite, 30 parts silica fume, 60 parts bauxite, 15 parts rare earth lanthanum compound (lanthanum carbonate), 40 parts binder (anthracene oil), and 8 parts additives (1.5 parts boric acid, 2 parts kyanite, 1 part sodium hexametaphosphate, 2 parts metallic silicon powder, and 1.5 parts polypropylene fiber).

[0043] Preparation process:

[0044] Raw material pretreatment: Corundum particles and silicon carbide particles are screened separately; graphite, silica fume, bauxite, rare earth lanthanum compounds and additives are dried at 120℃ for 3 hours.

[0045] Mixing and stirring: First, add the pretreated corundum particles and silicon carbide particles to a forced mixer and stir for 10 minutes; then add graphite, silica fume, bauxite, rare earth lanthanum compounds and additives, and continue stirring for 15 minutes; finally, add the binder and stir for 30 minutes at a mixer speed of 50 r / min.

[0046] Molding: The mixed mud is placed into a molding mold and molded using a hydraulic press at a pressure of 30 MPa for 2 minutes.

[0047] Drying: Place the molded clay blanks into a drying oven and dry them at 80°C for 36 hours;

[0048] Packaging: After the dried clay passes inspection, it is packaged to form anhydrous clay products.

[0049] Comparative Example 1 (Commonly available anhydrous clay)

[0050] Raw material composition: 110 parts corundum particles, 70 parts silicon carbide particles, 35 parts graphite, 22 parts silica fume, 55 parts bauxite, 35 parts binder (coal tar and anthracene oil mixed in a mass ratio of 1:1), and 6 parts additives (4.5 parts metallic silicon powder and 1.5 parts explosion-proof fiber).

[0051] Preparation method: Weigh each raw material according to the proportion, dry mix them in a regular mixer for 10 minutes, then add the binder, wet mix them at 60℃ for 25 minutes, and finally extrude them into shape through a regular extruder under a pressure of 12MPa to produce the clay product.

[0052] Comparative Example 2 (Steel clay lacking rare earth lanthanum compounds)

[0053] Raw material composition: 100 parts corundum particles (same particle size distribution as in Example 2), 65 parts silicon carbide particles (same particle size distribution as in Example 2), 40 parts graphite, 25 parts silica fume, 50 parts bauxite, 30 parts binder (same as in Example 2), and 6.5 parts additives (same as in Example 2).

[0054] Preparation process: Except for the absence of rare earth lanthanum compound, the other steps and parameters are completely consistent with those in Example 2.

[0055] Compressive strength and flexural strength tests:

[0056] The tests were conducted according to GB / T3001-2017 "Test Method for Flexural Strength of Refractory Materials at Room Temperature" and GB / T5072-2008 "Test Method for Compressive Strength of Refractory Materials at Room Temperature". The prepared clay was processed into cubic specimens with dimensions of (50mm × 50mm × 50mm). The compressive and flexural strengths were tested at room temperature (25℃) and after firing at 1400℃ (holding for 3 hours). Each group of samples was tested three times, and the average value was taken.

[0057] Table 1 shows the relevant data from the compressive strength and flexural strength tests.

[0058]

[0059]

[0060] As the data shows, the room temperature and high temperature compressive strength and flexural strength of the examples are significantly higher than those of the comparative examples. The compressive strength of Example 2 after firing at 1400℃ (75.3 MPa) is 66.6% higher than that of Comparative Example 1 (45.2 MPa) and 43.1% higher than that of Comparative Example 2 (52.6 MPa). This indicates that the addition of rare earth lanthanum compounds can effectively improve the high temperature strength of the gunpowder. This is because the solid solution formed by rare earth lanthanum and other raw materials strengthens the matrix bonding, and the refined microstructure reduces defects, thereby improving the overall strength. Although the strength of Comparative Example 2 is higher than that of commercially available products due to the lack of rare earth lanthanum, it is still lower than that of the examples, further proving that rare earth lanthanum is a key factor in performance improvement.

[0061] Apparent porosity test: Determined according to GB / T2997-2015 "Test Methods for Apparent Porosity, Water Absorption, Bulk Density and True Density of Dense Shaped Refractory Products". Weigh the dried sample to constant weight (m1). Then boil the sample in water for 3 hours to fully absorb water and saturate it. After removing it, wipe the surface dry with a damp cloth and weigh the saturated sample in air (m2). Then suspend the saturated sample in water and weigh its apparent mass (m3). Calculate the apparent mass according to the formula... Calculate the apparent porosity; similarly test the data of the samples after drying at room temperature and the samples after firing at 1400℃.

[0062] Table 2 shows the relevant data from the apparent porosity experiment.

[0063]

[0064]

[0065] As can be seen from the data, the apparent porosity of the examples is generally lower than that of the comparative examples, and the decrease is more significant after high-temperature firing. The apparent porosity of Example 3 at 1400℃ (14.5%) is 28.6% lower than that of Comparative Example 1 (20.3%), indicating that the addition of rare earth lanthanum promotes the sintering reaction between raw materials, making the clay structure more compact and reducing the pore channels. This is also an important reason for its improved erosion resistance.

[0066] Thermal shock resistance test: Following GB / T10299-2011 "Test Method for Thermal Shock Resistance of Refractory Materials", the water quenching method was used. The sample was heated to 1100℃, held at that temperature for 30 minutes, and then rapidly immersed in water at 20℃ for cooling. This constituted one thermal shock cycle, and a total of 10 cycles were performed. The flexural strength before and after each cycle was tested, and the strength loss rate was calculated as follows: Strength loss rate = (Flexural strength before cycle - Flexural strength after cycle) / Flexural strength before cycle × 100%

[0067] Table 3 shows the relevant data from the thermal shock resistance test.

[0068] sample Flexural strength (MPa) after 10 thermal shocks Strength loss rate (%) Example 1 7.2 13.2 Example 2 8.0 12.1 Example 3 8.5 12.4 Comparative Example 1 4.3 40.3 Comparative Example 2 5.1 34.6

[0069] As the data shows, the strength loss rate of the embodiments was less than 15%, while that of Comparative Example 1 was as high as 40.3% and that of Comparative Example 2 was 34.6%. The refined grain structure of rare earth lanthanum can effectively disperse thermal stress and inhibit crack propagation. At the same time, the high thermal conductivity of graphite and silicon carbide reduces the thermal gradient, which together improves the thermal shock resistance. This makes the taphole clay of the present invention less susceptible to damage in frequent temperature fluctuations and extends the taphole maintenance cycle.

[0070] Simulated blast furnace environment test

[0071] Slag-iron erosion experiment: The static crucible method was used. A cylindrical sample of Φ50mm×50mm was prepared from taphole clay, with a blind hole of Φ20mm×30mm drilled in the center. A mixture of simulated blast furnace slag (composition: CaO 40%, SiO2 35%, Al2O3 15%, FeO 10%) and molten iron (industrial pure iron melt) was filled in at a mass ratio of 1:1. The crucible was placed in a high-temperature furnace, heated to 1500℃, held for 5 hours, and then cooled. It was then cut along the axis, and the erosion depth and erosion area were measured. The erosion amount (eroded volume / original volume × 100%) was calculated.

[0072] High-temperature creep test: Using a high-temperature creep tester, the sample was made into a cylinder with a diameter of 30mm and a diameter of 50mm. It was continuously loaded at 1400℃ and 0.5MPa pressure for 5 hours, and the creep rate of the sample (creep deformation amount / original height × 100%) was measured.

[0073] Table 4 shows the relevant data from the simulated blast furnace environment test.

[0074] sample Slag and iron erosion (%) Creep rate at 1400℃ (%) Example 1 18.5 1.2 Example 2 15.3 0.9 Example 3 13.8 0.7 Comparative Example 1 32.6 3.5 Comparative Example 2 27.8 2.8

[0075] As the data shows, the slag-iron erosion rate in the examples was only 13.8%-18.5%, far lower than the 27.8%-32.6% in the comparative examples. Rare earth lanthanum reacts with CaO and SiO2 in the slag to form high-melting-point La2SiO5 (melting point above 1900℃), forming a protective layer that hinders further slag-iron penetration; the dense structure also reduces the intrusion path of the corrosive medium. Regarding high-temperature creep rate, the examples (0.7%-1.2%) were far lower than the comparative examples (2.8%-3.5%), indicating that the taphole clay of the present invention has better volume stability under high temperature and pressure, effectively maintaining the taphole shape and reducing the risk of iron leakage.

[0076] In summary, Example 2 demonstrates a balanced performance across all aspects, balancing strength, thermal shock resistance, and corrosion resistance, and its raw material cost is lower than that of Example 3, making it a superior formulation choice. Comparative Example 1 exhibits the worst performance due to the lack of optimized raw material ratios and processes; although Comparative Example 2 follows the same process as the examples, its performance improvement is limited due to the absence of rare earth lanthanum, further verifying the crucial role of rare earth lanthanum compounds in this invention.

[0077] It should be noted that in this paper, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

Claims

1. A blast furnace anhydrous stemming containing rare earth lanthanum, characterized in that, Corundum particles 80-120 parts, silicon carbide particles 50-80 parts, graphite 30-50 parts, silica fume 20-30 parts, bauxite 40-60 parts, rare earth lanthanum compound 5-15 parts, binder 20-40 parts, and additives 5-8 parts.

2. A blast furnace dry stemming containing rare earth lanthanum according to claim 1, characterized in that: The corundum particles are fused corundum, and the particle size range is 0.1-5 mm, wherein the proportion of particles of 3-5 mm is 30-40%, the proportion of particles of 1-3 mm is 25-35%, and the proportion of particles of 0.1-1 mm is 25-40%.

3. A blast furnace dry stemming containing rare earth lanthanum according to claim 1, characterized in that: The silicon carbide particles are green silicon carbide, and the particle size range is 0.074-3 mm, wherein the proportion of particles of 1-3 mm is 20-30%, and the proportion of particles of 0.074-1 mm is 70-80%.

4. A blast furnace dry stemming containing rare earth lanthanum according to claim 1, characterized in that: The rare earth lanthanum compound is a mixture of one or more of lanthanum nitrate, lanthanum oxide or lanthanum carbonate, and the particle size is less than 0.05 mm.

5. A blast furnace dry stemming containing rare earth lanthanum according to claim 1, characterized in that: The binder is a mixture of one or more of phenolic resin, coal tar or anthracene oil.

6. A blast furnace anhydrous stemming containing rare earth lanthanum according to claim 1, characterized in that: The additives are composed of antioxidants, expanding agents, dispersants, metal silicon powder and explosion-proof fibers, and the mass ratio is (2-3):(3-4):(1-2):(2-4):(1-3), the antioxidant is boric acid, the expanding agent is kyanite, the dispersant is sodium hexametaphosphate, and the explosion-proof fiber is polypropylene fiber with a length of 3-6 mm.

7. A method of producing a rare earth lanthanum containing anhydrous blast furnace stemming, characterized by: The method for manufacturing the rare earth lanthanum-containing blast furnace anhydrous stemming according to any one of claims 1-6 comprises the following steps: Raw material pretreatment: screen the corundum particles and the silicon carbide particles respectively; dry the graphite, silica fume, bauxite, rare earth lanthanum compound and additives at a drying temperature of 100-120°C for 2-3 hours; Mixing and stirring: first, add the pretreated corundum particles and silicon carbide particles to a forced stirrer and stir for 5-10 minutes; then add the graphite, silica fume, bauxite, rare earth lanthanum compound and additives and continue stirring for 10-15 minutes; finally, add the binder and stir for 20-30 minutes at a stirring speed of 30-50 r / min; Forming: place the mixed mud into a forming mold and pressurize forming using a hydraulic machine at a forming pressure of 20-30 MPa and a pressure holding time of 1-2 minutes; Drying: place the formed stemming blank into a drying oven and dry at 60-80°C for 24-36 hours; Packaging: after the dried stemming passes the inspection, it is packaged.

Images