A type of intermediate ladle cap castable and its preparation method

Abstract

This invention relates to the field of iron and steel smelting, and provides a tundish cover castable and its preparation method. The raw materials and their contents are as follows: 40-70% aluminum ash, 3-5% magnesium olivine powder, 3-5% calcined coke powder, 4-6% potassium feldspar powder, 0-10% water, 1-3% sodium hydroxide, 0.1-0.5% hydrochloric acid, 0.3-1% carboxymethyl cellulose, 3-5% iron filings, 5-7% coke powder, 4-8% synthetic mullite grains, 0.5-1% sodium polyphosphate, 2-3% aluminum dihydrogen phosphate, 1-2% silicon carbide, and 10-20% aluminate cement. By using aluminum ash as the main raw material, not only are the production costs of enterprises reduced, but the aluminum ash, which was originally a hazardous waste, is also recycled and reused, which has certain environmental protection significance. This invention is made by mixing treated aluminum powder with various auxiliary materials. Due to the different thermodynamic properties between different raw materials, the castable has a complex structural layer during high-temperature use, which reduces the thermal conductivity of the castable and effectively reduces the surface temperature of the tundish cover.

Description

Technical Field

[0001] This invention relates to the field of iron and steel smelting, specifically to a tundish cover castable and its preparation method. Background Technology

[0002] The tundish is a refractory container used in short-process steelmaking. It first receives molten steel poured from the ladle, and then distributes it to various crystallizers through the tundish nozzle. The main functions of the tundish are pressure reduction, flow stabilization, inclusion removal, storage, and diversion of molten steel. The tundish cover is an important component of the tundish, playing a role in heat insulation during the tundish baking and pouring process, improving the baking efficiency of the tundish and reducing heat loss from the molten steel, thereby protecting the ladle slide mechanism from direct heat radiation damage from the high temperature of the molten steel. It also provides safety protection for personnel conducting on-site temperature measurement and sampling.

[0003] The working environment of the tundish cover is relatively harsh, and it is frequently subjected to mechanical vibration and collision; it is repeatedly subjected to drastic changes in the temperature of molten steel; during the baking of the tundish, the working surface, holes and seams of the tundish are subjected to the scorching of high-temperature flames and the scouring of high-temperature airflow, and the working surface of the cover is also corroded by steel slag.

[0004] There are two main types of structures for tundish covers used in continuous casting: one is an all-cast steel or all-cast iron tundish cover; the other is a metal-refractory castable composite structure.

[0005] All-cast steel or all-cast iron tundish covers are tundish covers made of all-cast steel or all-cast iron parts. After a few casting cycles, in addition to severe surface oxidation and steel adhesion, the cover plate as a whole will be severely deformed and warped. This not only weakens the heat preservation effect of the cover but also affects the up-and-down movement of the stopper rod.

[0006] The main types of refractory castables used in metal-refractory castable composite structures include high-alumina, alumina-magnesia, alumina-silica, and alumina-magnesia-carbon. The main failure modes of this type of structure include: large overall deformation, refractory material detachment, and steel structure burn-off. For large trough-shaped tundishes, due to their large size, the tundish cover is also constructed using a multi-segment combination. The tundish cover has stopper rod holes and burner holes. The refractory castable covering layer of the cover is severely peeled off, the middle part of the cover is prone to sinking and damage under high temperature conditions, and the metal structure frame is prone to ablation.

[0007] Chinese Patent Publication No. CN113200753A discloses a refractory for intermediate ladle caps and a method for preparing intermediate ladle caps therefrom, the purpose of which is to prevent cap cracking, peeling, and chipping. The formulation of the refractory for intermediate ladle caps is: 55-65 wt% bauxite particles, 10-20 wt% fine bauxite powder, 2-4 wt% silica powder, 3-5 wt% precast powder, 5-10 wt% precast particles, 3-6 wt% alumina powder, 0.1 wt% metallic aluminum powder, 3-6 wt% aluminate cement, 1-3 wt% stainless steel fiber, 0.1 wt% sodium tripolyphosphate, and 0. The mixture contains 0.2-0.1 wt% propylene glycol alginate and 4-6 wt% water. The method for preparing intermediate ladle caps using this castable is as follows: the mixed castable is placed in a mold and vibrated to form the shape, then left to stand at room temperature for 24 hours, followed by heat treatment at 110℃ for 24 hours. This invention features high thermal shock stability, excellent thermal insulation, and high mechanical strength. However, the production process of bauxite granules is complex, requiring multiple steps such as ore beneficiation, ore crushing, and batching. It also generates a large amount of waste and pollutants, causing a certain degree of environmental impact. Furthermore, it requires a large amount of energy and raw materials, resulting in high manufacturing costs.

[0008] In summary, the present invention provides an intermediate ladle cap castable and its preparation method to solve the above problems. Summary of the Invention

[0009] This invention provides an intermediate ladle cap castable and its preparation method. The castable is prepared by mixing treated aluminum powder with various auxiliary materials to solve the problem of high manufacturing cost in the prior art.

[0010] A type of intermediate ladle cap castable, the raw materials and their contents are as follows:

[0011] Aluminum ash 40-70%, magnesium olivine powder 3-5%, calcined gemstone powder 3-5%, potassium feldspar powder 4-6%, water 0-10%, sodium hydroxide 1-3%, hydrochloric acid 0.1-0.5%, carboxymethyl cellulose 0.3-1%, iron filings 3-5%, coke powder 5-7%, synthetic mullite grains 4-8%, sodium polyphosphate 0.5-1%, aluminum dihydrogen phosphate 2-3%, silicon carbide 1-2%, aluminate cement 10-20%.

[0012] In a preferred embodiment, the aluminum ash contains 10-80% metallic aluminum, 40-70% alumina, 10-30% aluminum nitride, and 3-15% chloride.

[0013] In a preferred embodiment, the calcined gemstone powder has an alumina content of 42-46%, a silicon dioxide content of 51-53%, a sodium oxide content of less than 0.3%, and a potassium oxide content of less than 0.3%.

[0014] In a preferred embodiment, the mass ratio of alumina to silicon oxide in the synthesized mullite grains is less than 4:1.

[0015] In a preferred embodiment, the particle size of the synthesized mullite crystals is less than 3 mm.

[0016] In a preferred embodiment, the iron content of the iron filings is above 92%.

[0017] In a preferred embodiment, the silicon carbide contains 30% carbon and 70% silicon.

[0018] The present invention also provides a method for preparing intermediate ladle cap castable, comprising the following steps:

[0019] Step 1: Prepare the raw materials according to the ratio. Put the measured amount of aluminum powder into the crusher and crush it to reduce the diameter of the aluminum ash particles to less than 3mm. Then put the crushed aluminum ash into a 50℃ dehydration dryer and dry it for one to two days. After drying, put the aluminum ash into a drum screen fine separator for screening to remove grease and impurities from the aluminum ash.

[0020] Step 2: Place the pretreated aluminum ash into a boiler at 900℃ and roast for 1-3 hours to convert the aluminum hydroxide in the aluminum ash into aluminum oxide.

[0021] Step 3: Mix the baked aluminum ash with other raw materials except water, then put the mixed raw materials into a container and dry stir for 5 minutes. After dry stirring, add 6-10% water and then wet stir for 5 minutes to obtain a uniformly mixed wet raw material.

[0022] Step 4: Vibrate the well-mixed wet raw materials to form a mold, and cure at room temperature for 3-5 days;

[0023] Step 5: Place the cured refractory material into a boiler at 150℃ for drying. After drying for 30 minutes, place it into a boiler at 1300℃ for baking for 4 hours. After baking, the finished product can be obtained.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention uses aluminum ash as the main raw material, which not only reduces the production cost of enterprises, but also recycles aluminum ash, which was originally a hazardous waste, thus having certain environmental significance. This invention is made by mixing treated aluminum powder with a variety of auxiliary materials. Due to the different thermodynamic properties between different raw materials, the castable has a complex structural layer during high-temperature use, which reduces the thermal conductivity of the castable and can effectively reduce the surface temperature of the tundish cover. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the intermediate package cover structure of the present invention.

[0027] Figure 2 This is a flowchart of the method of the present invention.

[0028] In the picture:

[0029] 1. Intermediate bag cover; 2. Preheating hole; 3. Stopper rod hole; 4. Lifting lug. Detailed Implementation

[0030] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0031] like Figure 1-2 As shown, the present invention provides a refractory for intermediate ladle caps, the raw materials and their contents being:

[0032] Aluminum ash 40-70%, magnesium olivine powder 3-5%, calcined gemstone powder 3-5%, potassium feldspar powder 4-6%, water 0-10%, sodium hydroxide 1-3%, hydrochloric acid 0.1-0.5%, carboxymethyl cellulose 0.3-1%, iron filings 3-5%, coke powder 5-7%, synthetic mullite grains 4-8%, sodium polyphosphate 0.5-1%, aluminum dihydrogen phosphate 2-3%, silicon carbide 1-2%, aluminate cement 10-20%.

[0033] In one embodiment of the present invention, the aluminum ash contains 10-80% metallic aluminum, 40-70% aluminum oxide, 10-30% aluminum nitride, and 3-15% chloride salts.

[0034] In one embodiment of the present invention, the calcined gemstone powder has an alumina content of 42-46%, a silicon dioxide content of 51-53%, a sodium oxide content of less than 0.3%, and a potassium oxide content of less than 0.3%.

[0035] In one embodiment of the present invention, the mass ratio of alumina to silicon oxide in the synthesized mullite grains is less than 4:1.

[0036] In one embodiment of the present invention, the particle size of the synthesized mullite crystals is less than 3 mm.

[0037] In one embodiment of the present invention, the iron content of the iron filings is above 92%.

[0038] In one embodiment of the present invention, the silicon carbide contains 30% carbon and 70% silicon.

[0039] The present invention also provides a method for preparing intermediate ladle cap castable, comprising the following steps:

[0040] Step 1: Prepare the raw materials according to the ratio. Put the measured amount of aluminum powder into the crusher and crush it to reduce the diameter of the aluminum ash particles to less than 3mm. Then put the crushed aluminum ash into a 50℃ dehydration dryer and dry it for one to two days. After drying, put the aluminum ash into a drum screen fine separator for screening to remove grease and impurities from the aluminum ash.

[0041] Step 2: Place the pretreated aluminum ash into a boiler at 900℃ and roast for 1-3 hours to convert the aluminum hydroxide in the aluminum ash into aluminum oxide.

[0042] Step 3: Mix the baked aluminum ash with other raw materials except water, then put the mixed raw materials into a container and dry stir for 5 minutes. After dry stirring, add 6-10% water and then wet stir for 5 minutes to obtain a uniformly mixed wet raw material.

[0043] Step 4: Vibrate the well-mixed wet raw materials to form a mold, and cure at room temperature for 3-5 days;

[0044] Step 5: Place the cured refractory material into a boiler at 150℃ for drying. After drying for 30 minutes, place it into a boiler at 1300℃ for baking for 4 hours. After baking, the finished product can be obtained.

[0045] Specific working principle:

[0046] Before pouring the intermediate ladle cover 1, the frame is first welded with a steel mesh. After the steel mesh is welded, the steel bars are cut off at the corresponding positions according to the size of the preheating hole 2 and the stopper rod hole 3, and the iron pipe is used to place and position it. Then the castable is poured, and finally the hanging lug 4 is welded on.

[0047] Aluminum ash is a waste product generated in the primary and secondary aluminum industries. It mainly comes from three sources: first, aluminum ash produced by electrochemically smelting aluminum from alumina; second, aluminum ash produced during the processes of ingot casting, multiple remelting, alloy preparation, and component casting of aluminum; and third, the secondary aluminum industry, which involves recycling waste aluminum products and their processing waste, as well as waste products generated during the primary aluminum ash recycling process.

[0048] The chemical composition of aluminum ash varies significantly due to differences in raw materials and processes. It is mainly composed of a mixture of metallic aluminum, alumina, and salt flux, with the following specific proportions: aluminum 10-30%, alumina 20-40%, silicon, magnesium, and iron oxides 7-15%, potassium, sodium, calcium, magnesium chlorides, and a small amount of fluorides 15-30%.

[0049] Roasted gemstones are formed from raw roasted gemstone ore through high-temperature calcination. They are usually discovered during coal mining and have characteristics such as volume stability, high strength, and low water absorption.

[0050] Magnesia olivine is a refractory material mainly composed of magnesium oxide and silicon dioxide. It is a mineral with relatively high temperature resistance among magnesium refractory materials.

[0051] Carboxymethyl cellulose is a non-toxic, odorless, white flocculent powder with stable properties. It is easily soluble in water, and its aqueous solution is a neutral or alkaline transparent viscous liquid.

[0052] During the calcination process, potassium feldspar powder softens and decomposes to form a glassy phase. This glassy phase can fill the spaces between the mullite grains in the semi-finished castable, making the castable denser and reducing voids.

[0053] Phosphoric acid itself has no binding properties, but when it is mixed with castable, it reacts rapidly to form phosphate, thus exhibiting good binding properties.

[0054] Silicon carbide has properties such as high hardness, high thermal conductivity, low thermal expansion coefficient, and resistance to neutral and acidic slags.

[0055] Compared to the use of high-cost bauxite particles in existing technologies, this invention uses aluminum ash as the main raw material, which not only reduces the production cost of enterprises, but also recycles aluminum ash, which was originally a hazardous waste, thus having certain environmental significance. This invention is made by mixing treated aluminum powder with a variety of auxiliary materials. Due to the different thermodynamic properties between different raw materials, the castable has a complex structural layer during high-temperature use, which reduces the thermal conductivity of the castable and effectively reduces the surface temperature of the tundish cover.

[0056] The embodiments of the present invention are given for the purposes of illustration and description. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A type of intermediate ladle cap castable, characterized in that, The raw materials and their contents are as follows: The composition of the raw materials is as follows: aluminum ash 40-70%, magnesium olivine powder 3-5%, calcined gemstone powder 3-5%, potassium feldspar powder 4-6%, water 0-10%, sodium hydroxide 1-3%, hydrochloric acid 0.1-0.5%, carboxymethyl cellulose 0.3-1%, iron filings 3-5%, coke powder 5-7%, synthetic mullite crystals 4-8%, sodium polyphosphate 0.5-1%, aluminum dihydrogen phosphate 2-3%, silicon carbide 1-2%, aluminate cement 10-20%; the sum of the contents of all raw materials is 100%. The aluminum ash contains 10-80% metallic aluminum, 40-70% aluminum oxide, 10-30% aluminum nitride, and 3-15% chloride salts; the sum of the contents of all components in the aluminum ash is 100%. The calcined gemstone powder has an alumina content of 42-46%, a silicon dioxide content of 51-53%, a sodium oxide content of less than 0.3%, and a potassium oxide content of less than 0.3%; the sum of the contents of all components of the calcined gemstone powder is 100%.

2. The intermediate ladle cap castable as described in claim 1, characterized in that, The mass ratio of alumina to silicon dioxide in the synthesized mullite grains is less than 4:

1.

3. The intermediate ladle cap castable as described in claim 1, characterized in that, The particle size of the synthesized mullite crystals is less than 3 mm.

4. The intermediate ladle cap castable as described in claim 1, characterized in that, The iron content of the iron filings is above 92%.

5. The intermediate ladle cap castable as described in claim 1, characterized in that, The silicon carbide in question contains 30% carbon and 70% silicon.

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