Regenerated refractory material prepared from waste refractory bricks and preparation method of regenerated refractory material

Abstract

The invention discloses a regenerated refractory material prepared from waste refractory bricks and a preparation method of the regenerated refractory material. The regenerated refractory material comprises the following components in parts by weight: 80-100 parts of silicon dioxide, 100-120 parts of a refractory powder material, 40-50 parts of fine particles, 10-20 parts of kaolin and 4-8 parts of a binder, the preparation method comprises the following steps: uniformly mixing silicon dioxide, a refractory powder material, fine particles, kaolin and a binder, aging, carrying out compression molding, and sintering in a nitrogen atmosphere to obtain the regenerated refractory material, the prepared regenerated refractory material has excellent stability, heat resistance and acid and alkali resistance, a large amount of aluminum oxide contained in the waste refractory brick is used as a main component of the regenerated refractory material, the refractory capacity of the regenerated refractory material is utilized, and a ferrochrome composite metal organic framework is generated on the surface of the aluminum oxide in situ; the stability of aluminum oxide in the waste refractory brick is greatly improved, meanwhile, inert iron and chromium elements are not prone to being eroded by acid and alkali, and the acid and alkali erosion resistance of the regenerated refractory material at the high temperature is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of refractory materials, and particularly relates to a recycled refractory material made from waste refractory bricks and a preparation method thereof. Background Art

[0002] Refractory bricks are usually made of clay rich in alumina and silica. These two elements can withstand high temperatures. Alumina is a good reflector, while silica is a good insulator. The higher the alumina content in the refractory brick, the higher the temperature it can withstand. Refractory bricks are used as high-temperature building materials and structural materials for building kilns and various thermal equipment. However, due to long-term high-temperature operation and chemical corrosion, their physical and chemical properties become unstable and new refractory bricks need to be replaced. The removed refractory bricks are waste refractory bricks.

[0003] If waste refractory bricks are not properly treated, they will cause environmental pollution and waste a large amount of alumina materials. Alumina is one of the important components in refractory materials. Reusing the alumina resources in waste refractory bricks will bring huge economic benefits.

[0004] Patent CN118184378A discloses a method for recycling waste refractory bricks and unshaped refractory materials. Through crushing, screening, ultrafine grinding, etc., the waste refractory materials are divided into aggregates of different particle sizes, and then binders, silica fume, high-alumina cement, aggregates, steel fibers, etc. are added according to the formula to make various unshaped refractory materials. However, the performance of this refractory material varies greatly due to the dispersion degree of the aggregates.

[0005] Patent CN105036716A discloses a corrosion-resistant refractory material and a preparation method thereof. By adding the particle size of glass beads, the dispersion of raw materials in the refractory material is improved, sintering is promoted, and the powder is melted under high pressure to reduce the apparent porosity of the refractory material and improve the performance and strength of the refractory material. However, the high-pressure melting cost is relatively high and is not suitable for the recycling process of waste refractory bricks.

[0006] In the application of refractory materials, the refractory materials will be penetrated and eroded by high temperatures, harmful substances such as alkali salts, and some harmful gases. When the temperature changes greatly, spalling and cracking of the deteriorated layer of the refractory material will occur. Summary of the Invention

[0007] The purpose of the present invention is to solve the problem of how to prepare a recycled refractory material with high temperature resistance and acid and alkali resistance from waste refractory bricks, and to provide a recycled refractory material made from waste refractory bricks and a preparation method thereof.

[0008] The purpose of the present invention can be achieved through the following technical solutions: A recycled refractory material made from waste refractory bricks, comprising the following components in parts by weight: 80 - 100 parts of silica, 100 - 120 parts of refractory powder material, 40 - 50 parts of fine particles, 10 - 20 parts of kaolin, and 4 - 8 parts of binder.

[0009] The fine particles are prepared by crushing waste magnesium-aluminum-based refractory bricks.

[0010] The binder is silica sol with a concentration of 10 - 15 wt%.

[0011] Furthermore, the refractory powder material is prepared by the following steps: Mix the modified powder material with DMF, add chromium(II) chloride under nitrogen protection and react for 3 - 4 h. After filtering to obtain the solid and washing its surface with DMF, heat it to 40 - 50 °C in an oxygen atmosphere and react for 15 - 20 min. Wash it with ethanol and deionized water respectively, and then dry it at 40 - 50 °C for 1 - 2 h to obtain the refractory powder material.

[0012] Furthermore, the dosage ratio of the modified powder material, DMF, and chromium(II) chloride is 100 - 150 g : 1 - 1.5 L : 2 - 3 g.

[0013] Furthermore, the modified powder material is prepared by the following steps: Take the activated powder material and add it to the mixed solution, stir for 2 - 3 h, then dropwise add a 0.5 mol / L solution of benzene-1,3,5-tricarboxylic acid. Then transfer it to an autoclave with a polytetrafluoroethylene inner lining, heat it to 100 - 110 °C and react for 12 - 15 h. After cooling, centrifuge to collect the precipitate, wash it with methanol and deionized water respectively, and dry it under vacuum at 50 - 60 °C for 20 - 24 h to obtain the modified powder material.

[0014] Furthermore, the dosage ratio of the activated powder material, the mixed solution, and the benzene-1,3,5-tricarboxylic acid solution is 100 - 150 g : 200 - 300 mL : 80 - 100 mL.

[0015] Furthermore, the mixed solution is obtained by mixing equal volumes of a 0.5 mol / L ferrous chloride solution and a 0.5 mol / L magnesium nitrate hexahydrate solution, and the solvent of the benzene-1,3,5-tricarboxylic acid solution is a 1 M NaOH aqueous solution.

[0016] Furthermore, the activated powder material is prepared by the following steps: Soak the powder material in an alkali solution and an acid solution for 90 - 120 s respectively, then wash the powder material with deionized water until the last washing liquid is neutral. Dry it under vacuum at 40 - 50 °C for 2 - 3 h, and then activate it at 130 - 150 °C in a nitrogen atmosphere for 4 - 5 h. After cooling, obtain the activated powder material.

[0017] The alkali solution is a 1 mol / L sodium hydroxide solution, and the acid solution is a 1 mol / L sulfuric acid solution.

[0018] Furthermore, the powder material is prepared by the following steps: The waste magnesium-aluminum-based refractory bricks are crushed by a jaw crusher to a particle size of 15-20 mm to obtain coarse particles. After being soaked in water, the surface slag layer is removed by knocking, shoveling or gently rolling and pressing. After sieving, the slag layer is removed to obtain fine particles. The fine particles are crushed into 1-5 mm by a pair-roll crusher to obtain powder materials.

[0019] A preparation method of a regenerated refractory material using waste refractory bricks includes the following steps: Silica, refractory powder materials, fine particles, kaolin and a binder are mixed evenly and then aged, pressed into shape, and sintered in a nitrogen atmosphere at 900-1000 °C for 3-4 h to obtain the regenerated refractory material.

[0020] The beneficial effects of the present invention: (1) The regenerated refractory material prepared by the present invention has excellent stability, heat resistance and acid and alkali resistance. Alumina contained in a large amount in the waste refractory bricks is used as the main component of the regenerated refractory material. Utilizing its own refractory ability, a chromium-iron composite metal-organic framework is in-situ generated on the surface of alumina, greatly improving the stability of alumina in the waste refractory bricks. At the same time, the inert iron and chromium elements are not easily eroded by acids and alkalis, improving the ability of the regenerated refractory material to resist acid and alkali erosion at high temperatures. The present invention utilizes the recycling of waste refractory bricks, providing a new way for the utilization of waste refractory bricks, which is environmentally friendly and economical.

[0021] (2) The regenerated refractory material prepared by the present invention first synthesizes an iron-magnesium composite metal-organic framework. By utilizing the binding ability of ferrous ions to the acidic sites on the surface of alumina, the ferrous ions are dispersed on the surface of alumina in the waste refractory bricks. Then, a uniformly dispersed iron-magnesium composite metal-organic framework is prepared by hydrothermal synthesis. Then, through the strength of the ligand binding force between chromous ions and magnesium ions, chromium elements and magnesium elements are replaced to obtain a magnesium-iron composite metal-organic framework, which is uniformly dispersed, has high thermal stability and good acid and alkali resistance. Specific embodiments

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0023] Example 1: A preparation method of a regenerated refractory material using waste refractory bricks includes the following steps: Step 1: Crush the waste magnesium-aluminum-based refractory bricks (aluminum oxide content greater than 40%) with a jaw crusher until the particle size reaches 15 mm to obtain coarse particles. After soaking them in water, remove the surface slag layer by knocking, scraping, or gently rolling and pressing. After sieving, remove the slag layer to obtain fine particles. Crush the fine particles into 1 mm with a pair-roll crusher to obtain powder materials.

[0024] Step 2: Soak the powder materials in alkali solution and acid solution for 90 s respectively, then wash the powder materials with deionized water until the last washing liquid is neutral. After vacuum drying at 40 °C for 2 h, activate them at 130 °C for 4 h under a nitrogen atmosphere. After cooling, obtain the activated powder materials. Take 100 g of the activated powder materials and add them to 200 mL of a mixed solution, and stir for 2 h. The mixed solution is obtained by mixing equal volumes of a ferrous chloride solution with a concentration of 0.5 mol / L and a magnesium nitrate hexahydrate solution with a concentration of 0.5 mol / L. Then, add 80 mL of a trimesic acid solution with a concentration of 0.5 mol / L. The solvent of the trimesic acid solution is a 1 M NaOH aqueous solution. Then transfer it to a high-pressure autoclave lined with polytetrafluoroethylene, heat it to 100 °C and react for 12 h. After cooling, centrifuge to collect the precipitate, wash it with methanol and deionized water respectively, and vacuum dry at 50 °C for 20 h to obtain modified powder materials.

[0025] Step 3: Mix 100 g of the modified powder materials with 1 L of DMF, add 2 g of chromium dichloride under nitrogen protection and react for 3 h. After filtering, wash the surface of the solid with DMF, then heat it to 40 °C and react for 15 min under an oxygen atmosphere. Wash it with ethanol and deionized water respectively and dry at 40 °C for 1 h to obtain refractory powder materials.

[0026] Step 4: Mix 80 g of silica, 100 g of refractory powder materials, 40 g of fine particles, 10 g of kaolin, and 4 g of 10 wt% silica sol evenly, then age them, press them into shape, and sinter them at 900 °C for 3 h under a nitrogen atmosphere to obtain recycled refractory materials.

[0027] Example 2: A preparation method of recycled refractory materials using waste refractory bricks, comprising the following steps: Step 1: Crush the waste magnesium-aluminum-based refractory bricks (aluminum oxide content greater than 40%) with a jaw crusher until the particle size reaches 18 mm to obtain coarse particles. After soaking them in water, remove the surface slag layer by knocking, scraping, or gently rolling and pressing. After sieving, remove the slag layer to obtain fine particles. Crush the fine particles into 3 mm with a pair-roll crusher to obtain powder materials.

[0028] Step 2: Immerse the powder materials in the lye and acid solution for 105 s respectively, then wash the powder materials with deionized water until the last washing solution is neutral. After vacuum drying at 45 °C for 2.5 h, activate them at 140 °C for 4.5 h under a nitrogen atmosphere. After cooling, the activated powder materials are obtained. Take 125 g of the activated powder materials and add them to 250 mL of the mixed solution. Stir for 2.5 h. The mixed solution is obtained by mixing equal volumes of a ferrous chloride solution with a concentration of 0.5 mol / L and a magnesium nitrate hexahydrate solution with a concentration of 0.5 mol / L. Then, add 90 mL of a trimesic acid solution with a concentration of 0.5 mol / L dropwise. The solvent of the trimesic acid solution is a 1 M NaOH aqueous solution. Then transfer it to a high-pressure autoclave with a polytetrafluoroethylene inner lining, heat it to 105 °C and react for 13 h. After cooling, centrifuge to collect the precipitate, wash it with methanol and deionized water respectively, and vacuum dry at 55 °C for 22 h to obtain the modified powder materials.

[0029] Step 3: Mix 125 g of the modified powder materials with 1.25 L of DMF, add 2.5 g of chromium dichloride under nitrogen protection and react for 3.5 h. After filtering to obtain the solid and washing the surface with DMF, heat it to 45 °C and react for 17 min under an oxygen atmosphere. Wash it with ethanol and deionized water respectively and then dry at 45 °C for 1.5 h to obtain the refractory powder material.

[0030] Step 4: Mix 90 g of silica, 110 g of the refractory powder material, 45 g of fine particles, 15 g of kaolin and 6 g of 12.5 wt% silica sol evenly, then age, press into shape, and sinter at 950 °C for 3.5 h in a nitrogen atmosphere to obtain the regenerated refractory material.

[0031] Example 3: A preparation method of a regenerated refractory material using waste refractory bricks, comprising the following steps: Step 1: Crush the waste magnesium-aluminum-based refractory bricks (aluminum oxide content greater than 40%) with a jaw crusher until the particle size is 20 mm to obtain coarse particles. After soaking treatment with water, remove the surface slag layer by knocking or scraping or lightly rolling and pressing, and remove the slag layer by sieving to obtain fine particles. Crush the fine particles into 5 mm with a pair-roll crusher to obtain powder materials.

[0032] Step 2: Immerse the powder materials in 1 mol / L sodium hydroxide solution and 1 mol / L sulfuric acid solution for 120 s respectively, then wash the powder materials with deionized water until the last washing liquid is neutral. After vacuum drying at 50 °C for 3 h, activate them at 150 °C for 5 h under a nitrogen atmosphere. After cooling, the activated powder materials are obtained. Take 150 g of the activated powder materials and add them to 300 mL of a mixed solution, stir for 3 h. The mixed solution is obtained by mixing equal volumes of a 0.5 mol / L ferrous chloride solution and a 0.5 mol / L magnesium nitrate hexahydrate solution. Then, add 100 mL of a 0.5 mol / L trimesic acid solution dropwise. The solvent of the trimesic acid solution is 1 M NaOH aqueous solution. Then transfer it to a high-pressure autoclave lined with polytetrafluoroethylene, heat it to 110 °C and react for 15 h. After cooling, centrifuge to collect the precipitate, wash it with methanol and deionized water respectively, and vacuum dry at 60 °C for 24 h to obtain the modified powder materials.

[0033] Treat the powder materials with an alkali solution and an acid solution to remove the surface oxide film and impurities, increase the acidic active sites and the effective surface area on the surface of alumina in the powder materials, and then activate them at high temperature. The carboxyl groups on the acidic active sites of the activated alumina combine with ferrous ions and are converted into carboxylates, making the ferrous ions evenly distributed on the surface of alumina, that is, on the surface of the powder materials. After adding trimesic acid dropwise, the self-assembly of trimesic acid with ferrous ions and magnesium ions forms a magnesium-iron composite metal-organic framework, which is also evenly dispersed on the surface of the powder materials.

[0034] Step 3: Mix 150 g of the modified powder materials with 1.5 L of DMF, add 3 g of chromium(II) chloride under nitrogen protection and react for 4 h. After filtering to obtain the solid and washing its surface with DMF, heat it to 50 °C and react for 20 min under an oxygen atmosphere. After washing with ethanol and deionized water respectively, dry it at 50 °C for 2 h to obtain the refractory powder material.

[0035] Under the condition that the magnesium-iron composite metal-organic framework is evenly dispersed, due to the relatively weak bonding ability between magnesium element and the ligand, and the more stable combination between chromium(II) ions and the ligand, chromium(II) ions will replace magnesium ions and combine with the ligand to form a new chromium-iron composite metal-organic framework. On the basis of the originally evenly dispersed magnesium-iron composite metal-organic framework, chromium element replaces magnesium element. Utilizing the inertness and stability of chromium element greatly improves the heat resistance and acid and alkali resistance of the chromium-iron composite metal-organic framework, making the reinforcing powder materials have heat resistance and acid and alkali resistance.

[0036] Step 4: Mix 100 g of silica, 120 g of the refractory powder material, 50 g of fine particles, 20 g of kaolin and 8 g of 15 wt% silica sol evenly, then age, press into a mold, and sinter at 1000 °C for 4 h in a nitrogen atmosphere to obtain the regenerated refractory material.

[0037] Comparative Example 1: The difference from Example 1 is that in Step 2, the mixed solution is obtained by mixing 0.5 mol / L ferrous chloride solution and 0.5 mol / L chromium chloride solution.

[0038] Comparative Example 2: The difference from Example 1 is that in Step 2, the powder material is not activated by nitrogen, and the solvent of the trimesic acid solution is water.

[0039] Comparative Example 3: The difference from Example 1 is that the refractory powder material in Step 3 is replaced with the powder material in Step 1.

[0040] The reagents in the examples and comparative examples are all commercially available.

[0041] Perform performance tests on the regenerated refractory materials prepared in Examples 1 - 3 and Comparative Examples 1 - 3. According to the test method for the cold crushing strength of dense shaped refractory products in GB / T5072.2 - 2004, test the cold crushing strength of Examples 1 - 3 and Comparative Examples 1 - 3. Immerse the regenerated refractory materials prepared in each example and comparative example in 10wt% sodium chloride solution with pH 4 and pH 12 for 7 days. The pH values are adjusted using hydrochloric acid solution and sodium hydroxide solution respectively. Measure the cold crushing strength of the regenerated refractory materials after immersion again, and the results are shown in Table 1: Table 1 Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Compressive strength (Mpa) 116.4 118.2 119.6 112.5 110.1 107.3 Compressive strength (Mpa) pH = 4 115.1 116.5 118.3 105.2 102.4 99.8 Compressive strength (Mpa) pH = 12 115.3 116.8 118.6 106.1 102.7 93.4 As can be seen from Table 1, the regenerated refractory materials prepared in Examples 1 - 3 of the present invention have high cold crushing strength, and have little influence on the cold crushing strength performance under acidic and alkaline conditions, only reducing the cold crushing strength by about 1%, and have strong acid and alkali resistance; in Comparative Example 1, since the magnesium - iron composite metal - organic framework was not prepared, chromium ions could not be replaced on the magnesium - iron composite metal - organic framework, and the obtained chromium metal - organic framework had a low dispersion degree, resulting in a low improvement in the acid and alkali resistance of the regenerated refractory material. Therefore, the cold crushing strength decreased significantly after immersion in acid and alkali solutions; in Comparative Example 2, since the alumina in the powder material was not activated at high temperature, the active sites on the surface of alumina had low activity and low binding force for ferrous ions, resulting in a low dispersion degree of the iron metal - organic framework. The solvent of the ligand trimesic acid was water, which was not conducive to the formation of the iron - magnesium composite metal - organic framework. Therefore, the improvement in the acid and alkali resistance of the regenerated refractory material was low; in Comparative Example 3, since the waste magnesium - aluminum - based refractory bricks containing alumina were directly used to prepare the regenerated refractory material, the acidic sites on the surface of alumina would be corroded when encountering alkali, resulting in a decrease in strength.

[0042] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variation thereof are intended to cover non-exclusive inclusion, such that a process, method, article or apparatus comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or apparatus.

[0043] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A regenerated refractory material using waste refractory bricks, characterized in that, It comprises the following components in parts by weight: 80 - 100 parts of silica, 100 - 120 parts of refractory powder material, 40 - 50 parts of fine particles, 10 - 20 parts of kaolin and 4 - 8 parts of binder; The fine particles are prepared by crushing waste magnesium-aluminum based refractory bricks; The binder is silica sol with a concentration of 10 - 15wt%; 2. The regenerated refractory material using waste refractory bricks according to claim 1, wherein The refractory powder material is prepared by the following steps: Mix the modified powder material with DMF, add chromium dichloride under nitrogen protection and react for 3 - 4 h. After filtration, wash the surface of the solid with DMF, then heat it to 40 - 50 °C in an oxygen atmosphere and react for 15 - 20 min. Wash it with ethanol and deionized water respectively, and then dry it at 40 - 50 °C for 1 - 2 h to obtain the refractory powder material.

3. The regenerated refractory material using waste refractory bricks according to claim 2, wherein, The dosage ratio of the modified powder material, DMF and chromium dichloride is 100 - 150 g: 1 - 1.5 L: 2 - 3 g; 4. The regenerated refractory material using waste refractory bricks according to claim 3, characterized in that, The modified powder material is prepared by the following steps: Take the activated powder material and add it to the mixed solution, stir for 2 - 3 h, then dropwise add a 0.5 mol / L solution of trimellitic acid. Then transfer it to an autoclave with a polytetrafluoroethylene lining, heat it to 100 - 110 °C and react for 12 - 15 h. After cooling, centrifuge to collect the precipitate, wash it with methanol and deionized water respectively, and vacuum dry it at 50 - 60 °C for 20 - 24 h to obtain the modified powder material.

5. The regenerated refractory material using waste refractory bricks according to claim 4, characterized in that, The dosage ratio of the activated powder material, the mixed solution and the trimellitic acid solution is 100 - 150 g: 200 - 300 mL: 80 - 100 mL; 6. The regenerated refractory material using waste refractory bricks according to claim 5, characterized in that, The mixed solution is obtained by mixing equal volumes of a 0.5 mol / L ferrous chloride solution and a 0.5 mol / L magnesium nitrate hexahydrate solution, and the solvent of the trimellitic acid solution is a 1 M NaOH aqueous solution; 7. The regenerated refractory material using waste refractory bricks according to claim 5, characterized in that, The activated powder material is prepared by the following steps: Immerse the powder material in the alkali solution and the acid solution for 90 - 120 s respectively, then wash the powder material with deionized water until the last washing solution is neutral. Vacuum dry it at 40 - 50 °C for 2 - 3 h, and then activate it at 130 - 150 °C in a nitrogen atmosphere for 4 - 5 h. After cooling, obtain the activated powder material; The alkali solution is a 1 mol / L sodium hydroxide solution, and the acid solution is a 1 mol / L sulfuric acid solution; 8. The recycled refractory material using waste refractory bricks according to claim 7, characterized in that, The powder material is prepared by the following steps: Crush the waste magnesium-aluminum based refractory bricks with a jaw crusher to a particle size of 15 - 20 mm to obtain coarse particles. Soak them in water, and then remove the surface slag layer by knocking or shoveling or gently rolling and pressing. After sieving, remove the slag layer to obtain fine particles, and crush the fine particles into 1 - 5 mm with a pair-roll crusher to obtain the powder material.

9. The preparation method of a regenerated refractory material using waste refractory bricks according to claim 1, characterized in that, It includes the following steps: Mix silica, refractory powder material, fine particles, kaolin and binder evenly, then age, press into shape, and sinter at 900 - 1000 °C in a nitrogen atmosphere for 3 - 4 h to obtain the regenerated refractory material.