Low-cost baking-free magnesium-free siliceous dry material for plain carbon steel and preparation method of low-cost baking-free magnesium-free siliceous dry material

Abstract

The invention discloses a low-cost baking-free magnesium-free siliceous dry material for plain carbon steel and a preparation method of the dry material. The dry material is prepared from silica, calcined quartz sand, fused quartz sand, fused quartz sand fine powder, borax and anhydrous dextrose. The preparation method comprises the following steps: (1) accurately weighing silica, calcined quartz sand, fused quartz sand and fused quartz sand fine powder according to the proportion, and mixing for 10-15 minutes to obtain a mixture; (2) a sintering agent and a binding agent are accurately weighed according to the proportion and are independently premixed, the mixing time is 18-22 min, and a premix is prepared; and (3) adding the premix into the mixed material, and stirring and mixing for more than 10 minutes to obtain a dry material finished product. According to the dry material provided by the invention, the production cost is greatly reduced on the basis that the breaking strength, the compression strength and the permanent linear change meet the use requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory materials for steelmaking, and in particular relates to a low-cost, baking-free, magnesium-free siliceous dry material and a preparation method thereof. Background Art

[0002] As the fourth generation of refractory materials for the tundish working lining, dry materials are widely used in major steel mills due to their convenient construction, short baking time, long service life, good slag resistance, low pollution to molten steel, good insulation effect, low energy consumption, low labor intensity, simple construction equipment, and easy ladle turning. At present, the tundish dry materials are mainly magnesia and magnesia-silica materials. Magnesia-silica dry materials are dry material working linings made of magnesia sand and forsterite as the main raw materials.

[0003] With the consolidation of steel mills, the refractory market is highly competitive, and the profitability of refractory companies has declined in recent years. As the contract price of medium-sized refractory materials continues to decline, the price of conventional magnesia and forsterite raw materials continues to rise, and the cost of products increases, the profit margin of companies has been further compressed. For refractory companies, it is necessary to develop low-cost dry materials of different materials for different steel grades to improve the profitability and market competitiveness of refractory companies.

[0004] Commonly used magnesia and magnesia-silica tundishes need to be baked online before use. Due to the high sintering temperature of magnesia sand, it is not sintered at 750-1000℃. At this time, the bonding strength of the dry material working layer is at a low stage, and the medium-temperature strength of the dry material working layer is low. The low-temperature compressive strength of phenolic resin is high, but the medium-temperature strength is low. Therefore, it needs to be baked normally for 4-4.5 hours before it can be put online. Under the guidance of macroeconomic policies that focus on the quality of economic growth and the construction of a conservation-oriented and environmentally friendly society, in order to adapt to the changes in the steel industry's industrial structure adjustment, process technology updates, and energy conservation and consumption reduction, it is necessary to study a low-cost, non-baked, magnesium-free silicon dry material for ordinary carbon steel. Summary of the invention

[0005] The present invention aims to provide a low-cost, non-baked, magnesium-free siliceous dry material for plain carbon steel and a preparation method thereof. The dry material has greatly reduced production costs while satisfying use requirements in terms of flexural strength, compressive strength and permanent linear change.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows: The invention discloses a low-cost, baking-free, magnesium-free siliceous dry material for ordinary carbon steel, which is prepared from silica, calcined quartz sand, fused quartz sand, fused quartz sand fine powder, borax and anhydrous glucose.

[0007] Furthermore, the particle size of the silica of the present invention is 5-3 mm; the particle size of the calcined quartz sand is 3-1 mm; the particle size of the fused quartz sand is 1-0 mm; the particle size of the fused quartz sand fine powder is ≤0.088 mm; and the particle size of the borax is 0.2-0 mm.

[0008] Furthermore, the mass percentages of silica, calcined quartz sand, fused quartz sand, fused quartz sand fine powder, borax and anhydrous glucose in the dry material of the present invention are 13-18%, 33-38%, 15-20%, 23-28%, 0.8%-1.2% and 4%-5.5% respectively.

[0009] Furthermore, the silicon dioxide content in the silica of the present invention is ≥95%.

[0010] Furthermore, the silicon dioxide content in the calcined quartz sand, fused quartz sand and fused quartz sand fine powder of the present invention is ≥99.5%.

[0011] Furthermore, the method for preparing the dry material of the present invention comprises the following steps: (1) Silica, calcined quartz sand, fused quartz sand and fused quartz sand fine powder are accurately weighed according to a ratio and mixed for 10-15 minutes to obtain a mixed material; (2) Accurately weigh the sintering agent and the binder according to the ratio, and premix them separately for a mixing time of 18-22 minutes to prepare a premix; (3) Add the premix to the mixed material and stir for more than 10 minutes to obtain the dry material product.

[0012] Furthermore, the method for using the dry material of the present invention is as follows: (1) Before the construction of the tundish, put the dry material finished product into the baking device, control the baking temperature at 100-150℃, bake for 30-45 minutes, and drain the moisture in the dry material finished product; (2) Place the dry material membrane into the tundish and spread the dry material with a thickness of 70-80 mm. After spreading, start the dry material membrane vibration for 6.5-8 minutes. After vibration, ignite the dry material membrane, control the temperature inside the membrane within the range of 150-200°C, bake for 15 minutes, adjust the flame control temperature within the range of 250-300°C, bake for 25 minutes, continue to adjust the flame control temperature within the range of 350-400°C, stop baking after 50 minutes, and completely drain the moisture in the dry material. (3) The upper continuous casting ladle is prepared and the tundish can be poured directly without baking.

[0013] The beneficial technical effects of the technical solution of the present invention are: (1) The present invention uses silica, calcined quartz sand and fused quartz sand as main raw materials to prepare the dry material for ordinary carbon steel. After calcination at 1500°C for 3h, the flexural strength is greater than 5MPa, the compressive strength is greater than 8Mpa, and the permanent line change is less than 4.5%, which meets the use requirements.

[0014] (2) Compared with traditional magnesium and magnesium-silica dry materials, the siliceous dry material provided by the present invention has greatly reduced production costs and has higher market competitiveness.

[0015] (3) The siliceous dry material provided by the present invention takes advantage of the strong thermal shock resistance and small expansion coefficient of siliceous materials, so that the tundish can be directly put into use without baking, thereby realizing rapid pouring of continuous casting, reducing energy consumption, improving operating efficiency, and ensuring safe and smooth production.

[0016] (4) The present invention uses low-cost borax instead of boric acid as a sintering agent, so that the siliceous dry material can be in liquid phase at a relatively low temperature, thereby promoting sintering and improving sintering strength; ensuring the volume stability of the siliceous dry material and avoiding the dry material from generating large cracks and reducing its service life.

[0017] (5) The preparation method of the siliceous dry material of the present invention is simple, easy to control, and can be mass-produced. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is further described in detail below through embodiments.

[0019] A low-cost, non-baking, magnesium-free siliceous dry material for ordinary carbon steel is prepared from silica, calcined quartz sand, fused quartz sand, fused quartz sand fine powder, borax and anhydrous glucose. The specific composition ratio and particle size of the dry materials in each embodiment are shown in Table 1.

[0020] Table 1 Ratio of dry materials in each example (%)

[0021] The preparation method of each embodiment dry material is as follows: (1) Silica, calcined quartz sand, fused quartz sand and fused quartz sand fine powder are accurately weighed according to a ratio and mixed for 10-15 minutes to obtain a mixed material; (2) accurately weighing borax and anhydrous glucose according to the ratio, premixing them separately for 18-22 minutes to prepare a premix; (3) Add the premix to the mixed material, stir and mix for more than 10 minutes to obtain the dry material finished product.

[0022] The specific preparation parameters of the dry materials in each embodiment are shown in Table 2.

[0023] Table 2 Specific preparation parameters of dry materials in various embodiments

[0024] The performance test of the dry material prepared in each embodiment was carried out: after calcination at 1500°C for 3h, its flexural strength, compressive strength and permanent linear change were tested according to GB / T3001-2007, GB / T 2072-2008 and GB / T 5988-2007, respectively. The test results are shown in Table 3.

[0025] Table 3 Test results of dry material performance of each embodiment

[0026] The dry materials prepared in each embodiment were subjected to a tundish baking-free experiment in a steel plant in Hebei Province, and the method was as follows: (1) Before the construction of the tundish, put the dry material finished product into the baking device, control the baking temperature at 100-150℃, bake for 30-45 minutes, and drain the moisture in the dry material finished product; (2) Place the dry material membrane into the tundish and spread the dry material with a thickness of 70-80 mm. After spreading, start the dry material membrane vibration for 6.5-8 minutes. After vibration, ignite the dry material membrane, control the temperature inside the membrane within the range of 150-200°C, bake for 15 minutes, adjust the flame control temperature within the range of 250-300°C, bake for 25 minutes, continue to adjust the flame control temperature within the range of 350-400°C, stop baking after 50 minutes, and completely drain the moisture in the dry material. (3) The upper continuous casting ladle is prepared and the tundish can be poured directly without baking.

[0027] The experimental parameters of the dry materials used in the tundish of each embodiment are shown in Table 4.

[0028] Table 4 Experimental parameters of dry materials used in tundish in various embodiments

[0029] The service life and offline status of the tundish are shown in Table 5.

[0030] Table 5 Service life and offline status of tundish of dry materials in various embodiments

[0031] By comprehensively analyzing the test indicators of the dry materials of each embodiment after treatment under high temperature conditions and the results after actual use on site, the flexural strength after firing is greater than 5MPa, the compressive strength is greater than 8Mpa, and the permanent line change is less than 4.5%, indicating that the dry materials are well sintered under high temperature conditions. The better expansion rate densifies the dry materials without destroying the overall structure of the dry materials, so that the dry materials can fully adapt to the environment of the steel plant.

Claims

1. A low-cost, non-baked, magnesium-free siliceous dry material for plain carbon steel, characterized in that: The dry material is prepared from silica, calcined quartz sand, fused quartz sand, fused quartz sand fine powder, borax and anhydrous glucose.

2. The low-cost, no-bake, magnesium-free siliceous dry material for plain carbon steel according to claim 1, characterized in that: The particle size of the silica is 5-3 mm; the particle size of the calcined quartz sand is 3-1 mm; the particle size of the fused quartz sand is 1-0 mm; the particle size of the fused quartz sand fine powder is ≤0.088 mm; and the particle size of the borax is 0.2-0 mm.

3. The low-cost, no-bake, magnesium-free siliceous dry material for plain carbon steel according to claim 1, characterized in that: The mass percentages of silica, calcined quartz sand, fused quartz sand, fused quartz sand fine powder, borax and anhydrous glucose in the dry material are 13-18%, 33-38%, 15-20%, 23-28%, 0.8%-1.2% and 4%-5.5% respectively.

4. The low-cost, no-bake, magnesium-free siliceous dry material for plain carbon steel according to claim 1, characterized in that: The silicon dioxide content in the silica is ≥95%.

5. The low-cost, no-bake, magnesium-free siliceous dry material for plain carbon steel according to claim 1, characterized in that: The silicon dioxide content in the calcined quartz sand, fused quartz sand and fused quartz sand fine powder is ≥99.5%.

6. The low-cost, no-bake, magnesium-free siliceous dry material for plain carbon steel according to claim 1, characterized in that: The preparation method comprises the following steps: (1) Silica, calcined quartz sand, fused quartz sand and fused quartz sand fine powder are accurately weighed according to a ratio and mixed for 10-15 minutes to obtain a mixed material; (2) Accurately weigh the sintering agent and the binder according to the ratio, and premix them separately for a mixing time of 18-22 minutes to prepare a premix; (3) Add the premix to the mixed material and stir for more than 10 minutes to obtain the dry material product.

7. The low-cost, no-bake, magnesium-free siliceous dry material for plain carbon steel according to claim 1, characterized in that: The method of use is as follows: (1) Before the construction of the tundish, put the finished dry material into the baking device, control the baking temperature to 100-150℃, bake for 30-45 minutes, and drain the moisture in the finished dry material; (2) Put the dry material membrane into the tundish and spread the dry material with a thickness of 70-80mm; (3) After the spreading is completed, start the vibration of the dry material membrane with a vibration time of 6.5-8min; (4) After the vibration is completed, ignite the dry material membrane, control the temperature inside the membrane within the range of 150-200℃, bake for 15 minutes, adjust the flame control temperature within the range of 250-300℃, bake for 25 minutes, continue to adjust the flame control temperature within the range of 350-400℃, stop baking after 50 minutes, and completely drain the moisture in the dry material; (5) Prepare the continuous casting ladle, and the tundish can be directly poured without baking.

8. The method for preparing the low-cost, non-baked, magnesium-free siliceous dry material for plain carbon steel according to claim 1, characterized in that: The following steps are involved: (1) Silica, calcined quartz sand, fused quartz sand and fused quartz sand fine powder are accurately weighed according to a ratio and mixed for 10-15 minutes to obtain a mixed material; (2) Accurately weigh the sintering agent and the binder according to the ratio, and premix them separately for a mixing time of 18-22 minutes to prepare a premix; (3) Add the premix to the mixed material and stir for more than 10 minutes to obtain the dry material product.

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