Zinc-aluminum spinel refractory material and preparation method thereof

Abstract

The invention belongs to the technical field of refractory materials, and particularly relates to a zinc-aluminum spinel refractory material and a preparation method thereof. Aiming at the problems of high cost, high sintering temperature, poor refractory material performance and the like of spinel refractory material preparation in the prior art, mineral bauxite and zinc oxide powder are doped with a mineral additive for sintering, and the raw materials comprise 30-60% of bauxite and 30-60% of zinc oxide. The addition amount of the mineral substances is 1-15%. The preparation process comprises the following steps: weighing bauxite, zinc oxide and a mineral additive in percentage by mass, carrying out wet ball-milling and mixing on the three kinds of powder by using deionized water, drying the ball-milled slurry, grinding the dried blocky powder by using a mortar, sieving, carrying out dry pressing on the sieved powder to form a green body, and carrying out hot pressing on the green body to obtain the high-strength ceramic tile. And putting the green body into a silicon-molybdenum rod sintering furnace or a rotary kiln, sintering according to a sintering schedule, and cooling to obtain the zinc-aluminum spinel refractory material.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory materials, and in particular relates to a zinc-aluminum spinel refractory material and a preparation method thereof. Background Art

[0002] With the continuous and rapid development of the global high-temperature industry and the proposal of the "dual carbon" goal, the traditional refractory linings currently used in industrial kilns can no longer meet the requirements of energy conservation and emission reduction. Therefore, in order to save energy, protect the environment and achieve sustainable utilization of resources, it is necessary to develop refractory materials with low thermal conductivity, high strength and excellent anti-erosion and penetration properties as industrial kiln linings.

[0003] It is generally believed that refractory materials are a type of material that can maintain stable performance under high temperature conditions and can withstand special environments such as wear resistance and corrosion resistance. Due to its unique properties, refractory materials are used in high-temperature working fields such as steel, cement, ceramics, and petrochemicals. They are basic materials to ensure the production and operation of industries and the continuous development of technology. In recent years, they have played an irreplaceable and important role in the development of high-temperature industries.

[0004] Zinc-aluminum spinel and magnesium-aluminum spinel belong to the same spinel compound, cubic crystal system, and the general structural formula is AB2O4. The unique structure makes it have many excellent physical and chemical properties, such as high melting point, high hardness, high strength, small thermal expansion coefficient, good thermal shock resistance, strong chemical corrosion resistance and strong resistance to alkali slag, etc. Compared with magnesium-aluminum spinel, zinc-aluminum spinel has a strong resistance not only to alkaline substances, but also to acidic substances. Therefore, zinc-aluminum spinel refractory materials have good chemical stability when used in acid and alkali working environments.

[0005] At present, no preparation method of zinc-aluminum spinel refractory has been retrieved, but there are disclosed preparation methods of magnesium-aluminum spinel refractory. For example, a Chinese patent (publication number: CN104961485A) discloses a high thermal shock magnesium-spinel refractory and its preparation method, which uses high-purity magnesia sand, fused magnesia sand, fused magnesium-aluminum spinel, α-Al2O3 powder as main raw materials, pulp as binder, and is pressed and calcined at 1740°C for not less than 6 hours. A Chinese patent (publication number: CN111908899A) discloses an energy-saving corrosion-resistant magnesium-aluminum refractory, which uses high-purity magnesia sand, magnesium-aluminum spinel, ultrafine calcium oxide powder, graphene oxide powder as main raw materials, boron nitride or silicon dioxide as pulp as auxiliary additives, phenolic resin as binder, and is pressed and tunnel kiln dried. Summary of the invention

[0006] In view of the problems of high cost, high sintering temperature and poor performance of spinel refractory materials in the prior art, the present invention uses mineral bauxite as an aluminum source and mineral materials as additives to prepare a zinc-aluminum spinel refractory material. The prepared refractory material can reduce the sintering temperature, has the advantages of high hardness and strength, good thermal shock resistance, etc., and greatly reduces the production cost, meeting the requirements of energy conservation and emission reduction.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for preparing a zinc-aluminum spinel refractory material, comprising the following steps:

[0009] Step 1, weighing bauxite, zinc oxide and mineral additives according to mass percentage;

[0010] Step 2, mixing the three powders and performing wet ball milling;

[0011] Step 3, drying the ball-milled slurry;

[0012] Step 4, grinding and sieving the dried bulk powder;

[0013] Step 5, forming the sieved powder into a green body by dry pressing;

[0014] Step 6, sintering the green body, and obtaining the zinc-aluminum spinel refractory material after cooling.

[0015] Furthermore, in step 1, the mass percentages of bauxite, zinc oxide and mineral additives are 30% to 60%, 30% to 60% and 1% to 15% respectively.

[0016] Furthermore, the Al2O3 content of the bauxite is 45% to 80%, the SiO2 content is 7.5% to 19.5%, the TiO2 content is 2.2% to 4.1%, the Fe2O3 content is 1.0% to 1.9%, and the loss on ignition is 10% to 16%.

[0017] The zinc oxide includes chemically pure zinc oxide, active zinc oxide, industrial-grade zinc oxide, nano zinc oxide, etc., and the ZnO content is ≥99.0%.

[0018] The mineral additive is at least one of pyrolusite, dolomite, potassium feldspar, calcium feldspar, etc. The content of MnO2 in pyrolusite is 40% to 75%, the content of Fe2O3 is 4.0% to 10.5%, the content of MgO is 0.2% to 4.5%, the content of Al2O3 is 3.5% to 8.6%, the content of CaO is 1.3% to 7.3%, and the content of SiO2 is 5.2% to 15.0%. The content of CaO in dolomite is 27.4% to 42.5%, the content of MgO is 16.6% to 29.6%, the content of SiO2 is 0.1% to 12.5%, and the loss on ignition is 30.4% to 47.9%. The content of SiO2 in potassium feldspar is 46.2% to 68%, the content of Al2O3 is 9.0% to 20.8%, the content of K2O is 10.2% to 15.5%, and the content of Na2O is 0.3% to 4.5%. The CaO content in calcium feldspar is 18.6% to 24.2%, the Al2O3 content is 31.5% to 40.9%, and the SiO2 content is 40.4% to 47.5%.

[0019] Furthermore, the specific conditions of wet ball milling in step 2 are: ball milling in deionized water of 30-50% of the total mass of the three powders, the ball milling medium is agate beads, the ball milling speed is 300-500 r / min, and the ball milling time is 2-6 h.

[0020] Furthermore, the drying temperature in step 3 is 60-100°C.

[0021] Furthermore, in step 4, a 60-200 mesh sieve is used for screening.

[0022] Furthermore, in step 5, the pressure of dry pressing is 20 to 80 MPa, and the holding time is 30 to 60 seconds.

[0023] Furthermore, in step 6, the sintering temperature is 1300-1600° C., the heating rate is 5° C. / min, and the holding time is 2-5 h.

[0024] The invention also provides a zinc-aluminum spinel refractory material prepared by the preparation method.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] A zinc-aluminum spinel refractory material was successfully prepared by using bauxite, a mineral with abundant raw material sources and low cost, as the aluminum source, zinc oxide as the zinc source and a variety of common minerals as additives. The preparation process is simple and easy, easy to operate, and easy to achieve large-scale production. This technology uses low-cost mineral raw materials and prepares refractory materials by adding different mineral additives. Some oxide impurities in the mineral additives have a low melting point and first melt into a liquid phase during the sintering process. Densification sintering is achieved through the liquid phase, which can not only reduce the sintering temperature and improve the performance of the refractory material, but also greatly reduce the production cost, meeting the requirements of energy conservation and emission reduction. DETAILED DESCRIPTION

[0027] In order to further illustrate the technical solution of the present invention, the present invention is further described below through embodiments.

[0028] The raw materials of the present invention are: bauxite and zinc oxide, and mineral additives (pyrolusite, dolomite, potassium feldspar, calcium feldspar). The Al2O3 content of the bauxite is 45% to 80%, the SiO2 content is 7.5% to 19.5%, the TiO2 content is 2.2% to 4.1%, the Fe2O3 content is 1.0% to 1.9%, the ignition loss is 10% to 16%, and the addition amount thereof is 30% to 60%. The zinc oxide comprises chemically pure zinc oxide, active zinc oxide, industrial-grade zinc oxide, nano zinc oxide, etc., and the ZnO content is ≥99.0%, and the addition amount thereof is 30% to 60%. The mineral additive comprises pyrolusite, dolomite, potassium feldspar, calcium feldspar, etc., and the addition amount thereof is 1% to 15%.

[0029] Example 1

[0030] The preparation method of zinc-aluminum spinel refractory material comprises the following steps:

[0031] (1) Weigh 40% bauxite, 50% zinc oxide and 10% pyrolusite according to mass percentage.

[0032] (2) The three powders were weighed and wet-milled in deionized water (40% of the total mass of the three powders). The milling medium was agate beads, the milling speed was 400 r / min, and the milling time was 5 h.

[0033] (3) The ball-milled slurry was placed in an oven and dried at 100°C.

[0034] (4) The dried bulk powder is ground into powder in a mortar and sieved through a 100-mesh sieve to obtain a precursor powder.

[0035] (5) The precursor powder is poured into a mold and pressed into a green body on a pressure testing machine with a molding pressure of 40 MPa and a holding time of 50 s.

[0036] (6) The green body is placed in a silicon-molybdenum rod box furnace and sintered at 1550°C for 3 hours at a heating rate of 5°C / min to obtain a zinc-aluminum spinel refractory material.

[0037] Example 2

[0038] The preparation method of zinc-aluminum spinel refractory material comprises the following steps:

[0039] (1) Weigh 50% bauxite, 45% zinc oxide, and 5% dolomite by mass.

[0040] (2) The three powders were weighed and wet-milled in deionized water (50% of the total mass of the three powders), with agate beads as the milling medium, a milling speed of 300 r / min, and a milling time of 6 h.

[0041] (3) The ball-milled slurry was placed in an oven and dried at 80°C.

[0042] (4) The dried bulk powder is ground into powder in a mortar and sieved through a 120-mesh sieve to obtain a precursor powder.

[0043] (5) The precursor powder is poured into a mold and pressed into a green body on a pressure testing machine with a molding pressure of 50 MPa and a holding time of 40 s.

[0044] (6) The green body is placed in a silicon-molybdenum rod box furnace and sintered at 1500° C. for 4 h at a heating rate of 5° C. / min to obtain a zinc-aluminum spinel refractory material.

[0045] Example 3

[0046] The preparation method of zinc-aluminum spinel refractory material comprises the following steps:

[0047] (1) Weigh 51% bauxite, 40% zinc oxide, and 9% potassium feldspar according to mass percentage.

[0048] (2) The three powders were weighed and wet-milled in deionized water (30% of the total mass of the three powders). The milling medium was agate beads. The milling speed was 500 r / min and the milling time was 3 h.

[0049] (3) The ball-milled slurry was placed in an oven and dried at 70°C.

[0050] (4) The dried bulk powder is ground into powder in a mortar and sieved through a 140-mesh sieve to obtain a precursor powder.

[0051] (5) The precursor powder is poured into a mold and pressed into a green body on a pressure testing machine with a molding pressure of 60 MPa and a holding time of 40 s.

[0052] (6) The green body is placed in a silicon-molybdenum rod box furnace and sintered at 1450°C for 5 h at a heating rate of 5°C / min to obtain a zinc-aluminum spinel refractory material.

[0053] Example 4

[0054] The preparation method of zinc-aluminum spinel refractory material comprises the following steps:

[0055] (1) Weigh 53% bauxite, 34% zinc oxide, and 13% calcium feldspar according to mass percentage.

[0056] (2) The three powders were weighed and wet-milled in deionized water (45% of the total weight of the three powders). The milling medium was agate beads. The milling speed was 400 r / min and the milling time was 5 h.

[0057] (3) The ball-milled slurry was placed in an oven and dried at 100°C.

[0058] (4) The dried bulk powder is ground into powder in a mortar and sieved through a 180-mesh sieve to obtain a precursor powder.

[0059] (5) The precursor powder is poured into a mold and pressed into a green body on a pressure testing machine with a molding pressure of 70 MPa and a holding time of 30 s.

[0060] (6) The green body is placed in a silicon-molybdenum rod box furnace and sintered at 1350°C for 5 hours to obtain zinc-aluminum spinel refractory material. The heating rate is 5°C / min.

[0061] Comparison example:

[0062] The preparation method of zinc-aluminum spinel refractory material comprises the following steps:

[0063] (1) Weigh 50% bauxite and 50% zinc oxide by mass.

[0064] (2) The two powders were weighed and wet-milled in deionized water (40% of the total weight of the two powders), with agate beads as the milling medium, a milling speed of 400 r / min, and a milling time of 4 h.

[0065] (3) The ball-milled slurry was placed in an oven and dried at 80°C.

[0066] (4) The dried bulk powder is ground into powder in a mortar and sieved through an 80-mesh sieve to obtain a precursor powder.

[0067] (5) The precursor powder is poured into a mold and pressed into a green body on a pressure testing machine with a molding pressure of 40 MPa and a holding time of 40 s.

[0068] (6) The green body is placed in a silicon-molybdenum rod box furnace and sintered at 1600° C. for 3 h at a heating rate of 5° C. / min to obtain a zinc-aluminum spinel refractory material.

[0069] Table 1 shows a comparison of the zinc-aluminum spinel refractory properties of Examples 1 to 4 and the control example (without adding mineral additives).

[0070] Table 1 Comparison of the performance of zinc-aluminum spinel refractory materials of Examples 1-4 and those without mineral additives

[0071]

[0072] It can be seen from Table 1 that by adding minerals, the performance of the zinc-aluminum spinel refractory is greatly improved, its density is increased, and the porosity is significantly reduced, indicating that the density of the zinc-aluminum spinel refractory is significantly improved, thereby greatly improving the strength. Secondly, from the results of the embodiment, after adding mineral additives, the sintering temperature of the zinc-aluminum spinel refractory can be lower than 1600°C, which greatly reduces the preparation cost in terms of raw materials and energy consumption, and achieves the purpose of liquid phase promoting sintering.

[0073] The above shows and describes the main features and advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention.

[0074] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a zinc-aluminum spinel refractory material, characterized in that: The following steps are involved: Step 1, weighing bauxite, zinc oxide and mineral additives according to mass percentage; Step 2, mixing the three powders and performing wet ball milling; Step 3, drying the ball-milled slurry; Step 4, grinding and sieving the dried bulk powder; Step 5, forming the sieved powder into a green body by dry pressing; Step 6, sintering the green body, and obtaining the zinc-aluminum spinel refractory material after cooling.

2. The method for preparing a zinc-aluminum spinel refractory material according to claim 1, characterized in that: In the step 1, the mass percentages of bauxite, zinc oxide and mineral additives are 30% to 60%, 30% to 60% and 1% to 15% respectively.

3. The method for preparing a zinc-aluminum spinel refractory material according to claim 2, characterized in that: The mineral additive is at least one of pyrolusite, dolomite, potassium feldspar and calcium feldspar.

4. The method for preparing a zinc-aluminum spinel refractory material according to claim 1, characterized in that: The specific conditions of wet ball milling in step 2 are: ball milling in deionized water of 30-50% of the total mass of the three powders, the ball milling medium is agate beads, the ball milling speed is 300-500 r / min, and the ball milling time is 2-6 hours.

5. The method for preparing a zinc-aluminum spinel refractory material according to claim 1, characterized in that: The drying temperature in step 3 is 60-100°C.

6. The method for preparing a zinc-aluminum spinel refractory material according to claim 1, characterized in that: In step 4, a 60-200 mesh sieve is used for screening.

7. The method for preparing a zinc-aluminum spinel refractory material according to claim 1, characterized in that: The pressure of the dry pressing in step 5 is 20-80 MPa, and the holding time is 30-60 s.

8. The method for preparing a zinc-aluminum spinel refractory material according to claim 1, characterized in that: In step 6, the sintering temperature is 1300-1600° C., the heating rate is 5° C. / min, and the holding time is 2-5 hours.

9. The zinc-aluminum spinel refractory material obtained by the preparation method according to any one of claims 1 to 8.

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