Andalusite low cement castable and its preparation method and application

Abstract

The application discloses androandite low cement castable and belongs to the technical field of refractory materials. The androandite low cement castable comprises a base material, a binding agent and an additive, the base material and the binding agent comprise the following raw materials proportioned according to weight percentages: 31-39% of coke bauxite, 19-31% of androandite, 12-18% of fused mullite, 10-16% of white corundum, 2-8% of alumina micropowder, 1-5% of silicon micropowder, 3-4% of the binding agent; the mass of the additive is 0.1-0.5% of the mass of the base material. The application further discloses a preparation method and application of the androandite low cement castable. The androandite low cement castable adopts coke bauxite, androandite, fused mullite, white corundum and alumina micropowder as main raw materials, adds calcium aluminate cement as a binding agent, and adds a mixture of sodium hexametaphosphate and an explosion-proof agent fiber as an additive, so that the problems of easy peeling of a desulfurization spray gun castable cover layer, mismatching of expansion performance and a steel structure gun core and easy cracking are solved, and the service life of the desulfurization spray gun is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of refractory materials technology, specifically to a andalusite low-cement castable, its preparation method, and its application. Background Technology

[0002] Powder injection desulfurization is a widely used external desulfurization method in steel plants. The desulfurization nozzle is a key piece of equipment in the powder injection desulfurization system, and its service life directly affects the desulfurization production cost and capacity. The desulfurization nozzle mainly consists of a metal injection pipe and auxiliary steel structure, refractory material for the nozzle body, and metal components connecting to the powder supply system. It is a relatively complex functional component. Existing research and application practices both domestically and internationally indicate that the apparent factors affecting the service life of the desulfurization nozzle include: deformation of the metal nozzle core under hot conditions, erosion of the refractory material layer by molten iron and slag, cracking or detachment of the refractory material layer, and blockage of the injection pipe. The causes of these phenomena are related to the structure of the metal nozzle core, the erosion resistance and structural stability of the refractory material, the thermal expansion matching between the metal structure and the refractory material, the flowability of the desulfurization powder, and the stability of the injection operation.

[0003] In actual use, severe longitudinal cracks and burn-through of the refractory coating layer are the most critical issues affecting the service life of desulfurization spray guns. To address the durability of the refractory layer, existing methods include using steel fiber-reinforced mullite-corundum castables, high-alumina andalusite castables, and low-cement castables with added magnesium aluminum spinel powder or silicon carbide. Other methods utilize organic fiber explosion-proof additives to improve the thermal shock resistance of refractory castables and add heat-resistant steel fibers to enhance the structural strength of the refractory coating layer.

[0004] When vanadium-titanium magnetite is used as the main ore for steelmaking, the sulfur content of the molten iron is higher than that of ordinary iron ore. To address this, a top-blown desulfurization process using magnesia powder and passivated lime can be employed. The molten iron temperature is 1300℃-1400℃, and the desulfurization lance is inserted to a depth of 3.5m-4m into the high-temperature molten iron, with an average desulfurization time of 17.23 minutes per furnace. However, the relatively long single-furnace blowing time and deep immersion depth result in the average lifespan of the desulfurization lance hovering around 30-70 heats, making further improvements difficult. Research and analysis indicate that the refractory coating of the desulfurization lance is prone to severe peeling and cracking at high temperatures, eventually leading to burn-through, which is the primary reason affecting the lance's lifespan. Summary of the Invention

[0005] The purpose of this invention is to provide a low-cement castable of andalusite, its preparation method and application, to solve the technical problem in the prior art where the refractory castable used in desulfurization spray guns is prone to severe spalling and cracking at high temperatures, which in turn affects the service life of the desulfurization gun.

[0006] To achieve the above objectives, one embodiment of the present invention provides a andalusite low-cement castable, which includes a base material, a binder, and additives. The base material and binder include the following raw materials in weight percentages: 31%-39% fused alumina, 19%-31% andalusite, 12%-18% fused mullite, 10%-16% white corundum, 2%-8% alumina micropowder, 1%-5% silica micropowder, and 3%-4% binder.

[0007] The additive should be 0.1%-0.5% of the base material's mass.

[0008] In one preferred embodiment of the present invention, the andalusite comprises 8%-14% andalusite with a particle size of 1mm-3mm and 11%-17% andalusite with a particle size of 0mm-1mm, based on the total weight of the base material and binder.

[0009] In one preferred embodiment of the present invention, based on the total weight of the base material and binder, the fused bauxite comprises 18%-22% fused bauxite with a particle size of 5mm-10mm and 13%-17% fused bauxite with a particle size of 3mm-5mm; the fused mullite comprises 7%-10% fused mullite with a particle size of 0mm-3mm and 5%-7% fused mullite powder with a particle size ≤0.088mm.

[0010] In one preferred embodiment of the present invention, the white fused alumina is white fused alumina powder with a particle size of less than 200 mesh, and the alumina micro powder is α-type alumina micro powder.

[0011] In one preferred embodiment of the present invention, the binder is calcium aluminate cement.

[0012] In one preferred embodiment of the present invention, the additive is a mixture of sodium hexametaphosphate and explosion-proof fiber.

[0013] Based on the andalusite low-cement castable disclosed in this invention, this invention also discloses a method for preparing andalusite low-cement castable, comprising the following steps: mixing the base material, binder and additives evenly to obtain andalusite low-cement castable.

[0014] This invention also discloses an application of andalusite low-cement castable, which is applied to spray gun casting at a temperature of less than 1450°C.

[0015] One preferred embodiment of the present invention, when the andalusite low-cement castable is applied to desulfurization spray gun casting, includes the following steps:

[0016] Add water to the andalusite low-cement castable and mix.

[0017] The mixed mud is poured into a desulfurization mold for shaping and demolding.

[0018] After demolding, the product is cured, heat-treated and dried to obtain the desulfurization spray gun anddalite low cement castable product.

[0019] One preferred embodiment of the present invention involves adding water to andalusite low-cement castable and stirring, comprising: adding water at a mass ratio of 5%-6% to andalusite low-cement castable and stirring for 3-5 minutes to obtain a fluid mud.

[0020] In summary, the beneficial effects of the present invention are as follows:

[0021] 1. The andalusite low-cement castable of the present invention uses calcined gemstone, andalusite, fused mullite, white corundum and alumina micro powder as the main raw materials, and adds calcium aluminate cement as a binder, and a mixture of sodium hexametaphosphate and anti-explosion fiber as an additive to produce low-cement castable products for desulfurization spray guns in steelmaking. It has the advantages of suitable strength, good thermal shock stability and good erosion resistance.

[0022] 2. The andalusite low-cement castable of this invention features a rational design that combines raw materials such as calcite, andalusite, mullite, white corundum, and alumina micro powder in terms of variety and particle size. This differs from traditional methods that often use a small proportion (less than 6 wt%) of fine andalusite powder (≤0.088 mm). Instead, it uses a large proportion (greater than 20 wt%) of andalusite granules (0 mm-1 mm, 1 mm-3 mm) as the main raw material. Simultaneously, by using calcite as coarse aggregate and introducing ultrafine alumina micro powder, the thermal stability and thermal expansion properties of the castable are optimized. This solves the problems of easy peeling of the desulfurization spray gun's coating layer and mismatch between its expansion properties and the steel structure gun core, which leads to easy cracking. This significantly improves the service life of the desulfurization spray gun and makes it widely applicable to desulfurization spray guns used in the hot metal powder desulfurization process in steel plants.

[0023] 3. The desulfurization spray gun andalusite low-cement castable product prepared by the present invention has excellent thermal shock resistance and matching with the thermal expansion of the metal gun core. At the same time, it reduces the thermal conductivity of the material, thereby significantly improving the service life of the desulfurization spray gun. Attached Figure Description

[0024] Figure 1 A comparative graph showing the thermal expansion properties of andalusite samples with different particle sizes and amounts added in this invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0026] This invention provides a andalusite low-cement castable, which includes a base material, a binder, and additives. The base material and binder include the following raw materials in weight percentages: 31%-39% fused alumina, 19%-31% andalusite, 12%-18% fused mullite, 10%-16% white corundum, 2%-8% alumina micro powder, 1%-5% silica micro powder, and 3%-4% binder.

[0027] The additive should be 0.1%-0.5% of the base material's mass.

[0028] The binder is calcium aluminate cement, specifically, the calcium aluminate cement is CA70 aluminate cement conforming to GB / T201-2015 standard; the additive is a mixture of sodium hexametaphosphate and explosion-proof fiber.

[0029] Based on the total weight of the base material and binder, andalusite comprises 8%-14% andalusite with a particle size of 1mm-3mm and 11%-17% andalusite with a particle size of 0mm-1mm; fused alumina comprises 18%-22% fused alumina with a particle size of 5mm-10mm and 13%-17% fused alumina with a particle size of 3mm-5mm, wherein the 5mm-10mm and 3mm-5mm fused alumina are obtained by crushing and screening to obtain the preferred size, and the total addition amount of fused alumina is 35%.

[0030] The fused mullite comprises 7%-10% fused mullite with a particle size of 0mm-3mm and 5%-7% fused mullite powder with a particle size ≤0.088mm. Preferably, the fused mullite comprises 9% fused mullite with a particle size of 0mm-3mm and 6% fused mullite powder with a particle size ≤0.088mm.

[0031] White fused alumina is white fused alumina powder with a particle size of less than 200 mesh, and alumina micro powder has a median particle size D. 50 It is an α-type alumina micro powder with a size of 2μm.

[0032] This invention discloses a low-cement castable containing andalusite, which uses calcined gemstone as the large-particle aggregate, and andalusite granules as the medium-particle aggregate. It also incorporates mullite combined with andalusite granules as the medium-particle aggregate and adds ultrafine alumina powder. Specifically:

[0033] ① Use calcined gemstones as large-sized aggregate in castables:

[0034] Fumed gemstone, like mullite, belongs to the aluminosilicate mineral family, with an Al2O3 content of approximately 45% and a SiO2 content of approximately 48%. It is composed of mullite and a high-silica glass phase, thus exhibiting excellent high-temperature volume stability, comparable to that of mullite. Furthermore, fumed gemstone has a much lower bulk density than mullite and lower thermal conductivity. Its particles contain numerous layered cracks and pores, enabling it to absorb internal stresses generated during thermal shock. This effectively reduces core temperature and thermal expansion, preventing material cracking. Therefore, adding it to castables can improve their thermal shock resistance.

[0035] ② Use andalusite granules as medium-sized aggregate in castables:

[0036] andalusite is a high-alumina kyanite group refractory material in the aluminum-silicon series, with a chemical composition of 55%-60% Al2O3 and 37%-42% SiO2. The transformation process of andalusite at high temperatures is as follows:

[0037] 3(Al2O3.SiO2)→3Al2O3.2SiO2+SiO2;

[0038] This reaction process will cause a volume expansion of about 4% in the material, which can overcome the shrinkage caused by the high-temperature sintering reaction of the components in the castable matrix. Andalusite differs from other kyanite group minerals (kyanite and sillimanite). In andalusite, most of the excess SiO2 is located within the mullite crystals, with only a small portion on the surface. At high temperatures, the softened or liquefied SiO2 within the mullite crystals can absorb the volume changes caused by temperature variations. This makes the mullite obtained from andalusite conversion more stable at high temperatures than mullite prepared from other raw materials. Andalusite begins to convert to mullite (80%) and glassy SiO2 (20%) at 1200℃-1400℃, depending on its particle size. The coarser the particle size, the higher the conversion temperature and the slower the conversion rate. The coarser the particle size, the smaller the specific surface area, and the less SiO2 is on the particle surface. The glassy phase generated by the andalusite reaction is absorbed by Al2O3 in the matrix more slowly. Replacing fine andalusite powder with andalusite granules and increasing the amount added can maintain the volume expansion and thermal expansion effect of the material for a longer period of time. This has a positive effect on reducing the difference in expansion rate between the material and the metal gun core and overcoming the material cracking caused by excessive shrinkage when the temperature drops.

[0039] ③ Use mullite mixed with andalusite granules as medium-sized aggregate in castables:

[0040] Mullite has good high-temperature volume stability and chemical stability. When used in combination with andalusite granules as aggregate, the microcracks formed by the difference in thermal expansion rates of the two can alleviate thermal expansion stress and block the propagation of coarse cracks, thereby improving the thermal shock stability of the material.

[0041] ④ Applications of ultrafine alumina powder:

[0042] Alumina micro powder reacts with silica micro powder (main component SiO2) and andalusite particles added to the material matrix to transform into mullite. Excess surface SiO2 reacts at high temperature to produce mullite. The ultrafine alumina micro powder has good activity and high dispersibility, and can quickly form needle-like interlaced mullite crystals in situ with silica micro powder in the matrix. This is very effective in improving the thermal stability and high-temperature strength of the material.

[0043] This invention also discloses a method for preparing andalusite low-cement castable, comprising the following steps: mixing the base material, binder and additives evenly to obtain andalusite low-cement castable; specifically, mixing the base material, binder and additives by a forced mixing mill for 5 min-10 min to obtain andalusite low-cement castable.

[0044] This invention also discloses an application of andalusite low-cement castable, which is applied to spray gun casting at a temperature of less than 1450°C.

[0045] When andalusite low-cement castable is used in desulfurization spray gun casting, the following steps are included:

[0046] Step (1): Add water to the andalusite low-cement castable and stir. Specifically: put the prepared andalusite low-cement castable into a forced mixer or mixer, add 5%-6% domestic water by mass, stir and mix for 3-5 minutes to obtain a fluid mud.

[0047] Step (2): Pour the mixed mud into the desulfurization model for molding and demolding; Specifically: Pour the mixed mud from step (1) into the assembled desulfurization gun model, let it stand naturally for more than 24 hours and then remove the model;

[0048] Step (3): After demolding, the product is cured, heat-treated and dried to obtain the desulfurization spray gun anddalite low-cement castable product; specifically, the product after demolding in step (2) is left to stand naturally for more than 48 hours, and then placed in a drying kiln and heated from room temperature (30℃) to 400℃ for heat treatment. The heat treatment heating rate is 10℃ / h, and the temperature is kept constant at 150℃, 250℃ and 400℃ for 24 hours respectively. The total heat treatment time is 109 hours. The qualified product after heat treatment and drying is the desulfurization spray gun anddalite low-cement castable product.

[0049] The mixing time of the mixture can be adjusted according to the weight of the mixture and the mixing intensity of the mixer; the curing time can be extended according to the different ambient temperatures in winter and summer. In winter, extending the curing time by 1 to 2 times is beneficial for the natural evaporation of moisture from the product.

[0050] The aforementioned desulfurization spray gun made of andalusite low-cement castable has achieved good application results at Panzhihua Iron and Steel Group's steelmaking plant. The maximum service life of the desulfurization gun reached 330 heats in 2023, with an average of 198 heats. This not only improved the efficiency of desulfurization operations at the steel plant but also reduced the consumption of refractory materials, demonstrating green, low-carbon, and environmentally friendly benefits. It represents a significant breakthrough in the technological advancement of refractory materials for Panzhihua Iron and Steel Group's desulfurization process, and has good economic and social benefits.

[0051] Example 1

[0052] A desulfurization spray gun andalusite low-cement castable and its preparation method:

[0053] 1. Add 18wt% of 5mm-10mm fused alumina, 17wt% of 3mm-5mm fused alumina, 9wt% of 0mm-3mm fused mullite, 6wt% of fused mullite powder with a particle size ≤0.088mm, 8wt% of 1mm-3mm andalusite, 17wt% of 0mm-1mm andalusite, 13wt% of 200-mesh white corundum powder, 5wt% of 2μm alumina micropowder, 3wt% of silica micropowder, 4wt% of binder (calcium aluminate cement), and 0.2wt% of other additives (a mixture of sodium hexametaphosphate and anti-explosion fiber). Mix the mixture for 7 minutes using a forced mixer to prepare a uniform mixture. The qualified mixture is a low-cement castable of andalusite suitable for desulfurization guns.

[0054] 2. Application method of andalusite low-cement castable on desulfurization spray gun: Put the prepared castable into a forced mixer or agitator, add 5wt% domestic water, stir and mix for 4 minutes to prepare a fluid mud, pour it into the assembled desulfurization gun mold, let it stand naturally for 24 hours, remove the mold, let it stand naturally for another 48 hours, and put it into a drying kiln to heat treatment from room temperature (30℃) to 400℃, with a heating rate of 10℃ / h. The temperature is kept constant at 150℃, 250℃ and 400℃ for 24 hours respectively, and the total heat treatment time is 109 hours. The qualified product after heat treatment is the andalusite castable product for desulfurization spray gun.

[0055] Example 2

[0056] A desulfurization spray gun andalusite low-cement castable and its preparation method:

[0057] 1. Add 20wt% of 5mm-10mm fused alumina, 15wt% of 3mm-5mm fused alumina, 9wt% of 0mm-3mm fused mullite, 6wt% of fused mullite powder with a particle size ≤0.088mm, 14wt% of 1mm-3mm andalusite, 11wt% of 0mm-1mm andalusite, 13wt% of 200-mesh white corundum powder, 5wt% of 2μm alumina micro powder, 3wt% of silica micro powder, 4wt% of binder (calcium aluminate cement), and 0.2wt% of other additives (a mixture of sodium hexametaphosphate and anti-explosion fiber). Mix the mixture for 7 minutes using a forced mixer to prepare a uniform mixture. The qualified mixture is a low-cement castable of andalusite suitable for desulfurization guns.

[0058] 2. Application method of andalusite low-cement castable on desulfurization spray gun: Put the prepared castable into a forced mixer or agitator, add 5wt% domestic water, stir and mix for 4 minutes to prepare a fluid mud, pour it into the assembled desulfurization gun mold, let it stand naturally for 24 hours, remove the mold, let it stand naturally for another 48 hours, and put it into a drying kiln to heat treatment from room temperature (30℃) to 400℃, with a heating rate of 10℃ / h. The temperature is kept constant at 150℃, 250℃ and 400℃ for 24 hours respectively, and the total heat treatment time is 109 hours. The qualified product after heat treatment is the andalusite castable product for desulfurization spray gun.

[0059] Example 3

[0060] A desulfurization spray gun andalusite low-cement castable and its preparation method:

[0061] 1. Add 19wt% of 5mm-10mm fused alumina, 16wt% of 3mm-5mm fused alumina, 9wt% of 0mm-3mm fused mullite, 6wt% of fused mullite powder with a particle size ≤0.088mm, 11wt% of 1mm-3mm andalusite, 14wt% of 0mm-1mm andalusite, 13wt% of 200-mesh white corundum powder, 5wt% of 2μm alumina micropowder, 3wt% of silica micropowder, 4wt% of binder (calcium aluminate cement), and 0.2wt% of other additives (a mixture of sodium hexametaphosphate and anti-explosion fiber). Mix for 7 minutes using a forced mixer to prepare a uniform mixture. The qualified mixture is a low-cement castable of andalusite suitable for desulfurization guns.

[0062] 2. Application method of andalusite low-cement castable on desulfurization spray gun: Put the prepared castable into a forced mixer or agitator, add 5wt% domestic water, stir and mix for 4 minutes to prepare a fluid mud, pour it into the assembled desulfurization gun mold, let it stand naturally for 24 hours, remove the mold, let it stand naturally for another 48 hours, and put it into a drying kiln to heat treatment from room temperature (30℃) to 400℃, with a heating rate of 10℃ / h. The temperature is kept constant at 150℃, 250℃ and 400℃ for 24 hours respectively, and the total heat treatment time is 109 hours. The qualified product after heat treatment is the andalusite castable product for desulfurization spray gun.

[0063] Sample testing

[0064] (1) The physical and chemical properties of the refractory raw materials of andalusite low-cement castable are shown in Table 1.

[0065] Table 1. Physicochemical properties of refractory raw materials for andalusite low-cement castables

[0066]

[0067] (2) The physicochemical properties of the desulfurization spray gun andalusite castable product prepared in Example 1 are shown in Table 2.

[0068] Table 2 Physicochemical properties of andalusite castable products for desulfurization spray guns

[0069]

[0070] (3) The thermal expansion properties of several samples with different particle sizes and amounts of andalusite were compared, and the results are as follows: Figure 1 As shown in Table 3, the specific proportions of andalusite with different particle sizes and amounts in each sample are shown in Table 3. T2 is the sample prepared in Example 1 above, and T0, T1 and T3 are comparative samples for comparing thermal expansion properties.

[0071] Table 3. Ratio of andalusite with different particle sizes and addition amounts (addition amount, %)

[0072] Sample number T0 T1 T2 T3 Calcium Gemstone Granules 35 35 35 35 Electrofused mullite 34 17 15 8 Andalusite Granular Material 0 17 25 34 Andalusite fine powder 8 8 - - White corundum 11 11 13 11 Alumina micro powder 5 5 5 5 Silica powder 3 3 3 3 binder 4 4 4 4 additive 0.2 0.2 0.2 0.2

[0073] From Table 3 and Figure 1It can be seen that the thermal expansion rate of the castable sample with added andalusite granules is higher than that of the sample with added fine powder. As the proportion of granules increases, the difference between the thermal expansion rate of the sample and that of the desulfurization gun metal core narrows. Meanwhile, in the high-temperature operating temperature range of the desulfurization gun (1200℃-1400℃), the T2 sample with the same proportion as in Example 1 still maintains a thermal expansion rate of 0.5%-1.0%, but the thermal expansion rate of the T3 sample is greater than 1%. A thermal expansion rate greater than 1% can easily lead to a decrease in the mechanical properties of the product. Therefore, the appropriate addition of andalusite granules is beneficial to reduce the stress generated between the surface castable and the internal metal core of the desulfurization gun due to the difference in thermal expansion rates, thereby overcoming castable cracking and improving the service life of the desulfurization gun.

[0074] In summary, the desulfurization spray gun prepared by this invention solves the problems of easy peeling of the desulfurization spray gun casting layer and mismatch between the expansion performance and the steel structure gun core, which cause easy cracking, and greatly improves the service life of the desulfurization gun.

[0075] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A low-cement castable for andalusite, characterized in that: The andalusite low-cement castable includes a base material, a binder, and additives. The base material and binder include the following raw materials in the following weight percentages: 31%-39% fused alumina, 19%-31% andalusite, 12%-18% fused mullite, 10%-16% white corundum, 2%-8% alumina micro powder, 1%-5% silica micro powder, and 3%-4% binder. The additive is present in an amount of 0.1%-0.5% of the base material.

2. The andalusite low-cement castable as described in claim 1, characterized in that: Based on the total weight of the base material and binder, the andalusite comprises 8%-14% andalusite with a particle size of 1mm-3mm and 11%-17% andalusite with a particle size of 0mm-1mm.

3. The andalusite low-cement castable as described in claim 1, characterized in that: Based on the total weight of the base material and binder, the fused bauxite comprises 18%-22% fused bauxite with a particle size of 5mm-10mm and 13%-17% fused bauxite with a particle size of 3mm-5mm; the fused mullite comprises 7%-10% fused mullite with a particle size of 0mm-3mm and 5%-7% fused mullite powder with a particle size ≤0.088mm.

4. The andalusite low-cement castable as described in claim 1, characterized in that: The white fused alumina is white fused alumina powder with a particle size of less than 200 mesh, and the alumina micro powder is α-type alumina micro powder.

5. The andalusite low-cement castable as described in claim 1, characterized in that: The binder is calcium aluminate cement.

6. The andalusite low-cement castable as described in claim 1, characterized in that: The additive is a mixture of sodium hexametaphosphate and explosion-proof fiber.

7. A method for preparing a andalusite low-cement castable according to any one of claims 1-6, characterized in that, The process includes the following steps: mixing the base material, binder, and additives evenly to obtain andalusite low-cement castable.

8. An application of a andalusite low-cement castable according to any one of claims 1-6, characterized in that: The andalusite low-cement castable is applied to spray gun casting at a temperature of less than 1450°C.

9. The application of the andalusite low-cement castable as described in claim 8, characterized in that, When andalusite low-cement castable is used in desulfurization spray gun casting, the following steps are included: Add water to the andalusite low-cement castable and mix. The mixed mud is poured into a desulfurization mold for shaping and demolding. After demolding, the product is cured, heat-treated and dried to obtain the desulfurization spray gun anddalite low cement castable product.

10. The application of the andalusite low-cement castable as described in claim 9, characterized in that: The process of adding water to the andalusite low-cement castable and stirring it includes: adding water at a mass ratio of 5%-6% to the andalusite low-cement castable and stirring for 3-5 minutes to obtain a fluid mud.

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