Electric melting zirconia powder and preparation method thereof

Abstract

The invention relates to the technical field of zirconia materials, in particular to electric melting zirconia powder and a preparation method thereof. The preparation method comprises the following steps that S1, zircon sand and coke are mixed and smelted, and then zirconium oxide hollow spheres are obtained through injection molding; and S2, sequentially carrying out iron removal, screening and grinding on the zirconium oxide hollow spheres to obtain the electric melting zirconium oxide powder. According to the preparation method, impurities in the materials are removed through smelting, iron removal and screening, then the spherical fused zirconia powder is obtained through grinding, the spherical form can provide more surfaces for the powder to participate in the reaction, and more excellent sintering performance is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of zirconium oxide materials, and in particular to fused zirconium oxide powder and a preparation method thereof. Background Art

[0002] Industrially produced zirconium oxide powder is widely used in refractory materials, ceramic glazes, and zirconium sponge. The main production methods are chemical method and electric melting method. The conventional electric melting method, as shown in the Chinese invention patent with application number 202010212707.4, uses zircon sand as raw material and carbon reducing agent in an electric arc furnace, undergoes high-temperature melting, desiliconization, and molding to obtain an electric fused zirconium oxide semi-finished product, which is then subjected to subsequent fine processing to obtain a powder with appropriate particle size distribution requirements.

[0003] When fused zirconia powder is used to produce advanced refractory products, it is necessary to select products with different particle size distributions according to the bulk density requirements of the products. The general rule is that the finer the powder particle size, the higher the bulk density of the refractory product, and the better the high-temperature erosion performance it can withstand. However, the finer the zirconia powder, the higher the sintering shrinkage rate, which increases the risk of sintering cracking of refractory products. To obtain products with higher bulk density under the same particle size distribution, it is necessary to use zirconia powder with better sintering performance. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing fused zirconia powder with excellent sintering performance.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing fused zirconium oxide powder, comprising the following steps: S1: Mix zircon sand and coke for smelting, and then spray-blow mold to obtain hollow zirconia balls; S2: removing iron from the hollow zirconia balls, screening and grinding them in sequence to obtain fused zirconia powder.

[0006] Another technical solution adopted by the present invention is: the fused zirconia powder is prepared by the above-mentioned method for preparing the fused zirconia powder.

[0007] The beneficial effect of the present invention is that: the preparation method of the present invention removes impurities in the material through smelting, iron removal and screening, and then obtains spherical fused zirconia powder through grinding. The spherical shape can provide more surface for the powder to participate in the reaction and obtain better sintering performance. DETAILED DESCRIPTION

[0008] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in conjunction with the implementation modes.

[0009] A method for preparing fused zirconium oxide powder comprises the following steps: S1: Mix zircon sand and coke for smelting, and then spray-blow mold to obtain hollow zirconia balls; S2: removing iron from the hollow zirconia balls, screening and grinding them in sequence to obtain fused zirconia powder.

[0010] From the above description, it can be seen that the beneficial effects of the present invention are: the present invention removes impurities by desiliconization through smelting, and then obtains hollow zirconia balls by blow molding; the hollow zirconia balls are further deironed and sieved to further remove impurities, and then ground to obtain spherical fused zirconia powder, the spherical shape can provide more surface for the powder to participate in the reaction, and obtain better sintering performance.

[0011] Furthermore, zircon sand includes the following components by weight: 31-33% SiO 2 , ≤0.45% Al 2 O 3 , ≤0.15%Fe 2 O 3 , ≤0.25% TiO 2 , ≤0.15% CaO, and ≥66% ZrO 2 With HfO 2 mixture.

[0012] From the above description, it can be seen that SiO 2 Can be removed during the smelting process.

[0013] Furthermore, the mass ratio of zircon sand to coke in S1 is 100:7~9.

[0014] From the above description, it can be seen that in the smelting process, the role of coke is to remove silicon. The mass ratio of zircon sand to coke affects the desiliconization effect. A low mass ratio will increase the content of silicon oxide in the fused zirconium, and a high mass ratio will affect the appearance color of the fused zirconium oxide.

[0015] Furthermore, the smelting time in S1 is 90 to 180 minutes.

[0016] From the above description, it can be seen that the melting time will affect the desiliconization effect and energy consumption level.

[0017] Further, the hollow zirconia spheres include the following components by weight: ≤0.3% SiO 2 , ≤0.45% Al 2 O 3 , ≤0.1%Fe 2 O 3 , ≤0.22% TiO 2 , ≤0.12% CaO, and ≥98.5% ZrO 2 With HfO2 mixture.

[0018] Furthermore, after screening in S2, materials with a particle size of 0.2 to 6 mm are retained.

[0019] From the above description, it can be seen that materials with a particle size less than 0.2 mm and a particle size greater than 6 mm contain unreacted zircon sand and coke and cannot enter the next process.

[0020] Furthermore, the particle size range of the fused zirconia powder in S2 is D 50 :0.5~5μm.

[0021] From the above description, it can be seen that the change in the particle size range of fused zirconia is related to the operating parameters of the processing equipment; the particle size distribution will affect the use effect. The finer the particle size, the higher the activity provided, and the denser the product can be.

[0022] Furthermore, when removing iron in S2, at least one of a magnetic drum iron remover, a permanent magnetic belt iron remover and an electromagnetic iron remover is used.

[0023] Furthermore, at least one of a Raymond mill, a fluidized bed jet mill, a ball mill, a flat jet mill, a wet stirred mill, a spray dryer and a sand mill is used for grinding in S2.

[0024] Another technical solution adopted by the present invention is: the fused zirconia powder is prepared by the above-mentioned method for preparing the fused zirconia powder.

[0025] It can be seen from the above description that the fused zirconia powder of the present invention has excellent sintering performance and can obtain a higher volume density after sintering.

[0026] Embodiment 1 of the present invention is: a method for preparing fused zirconium oxide powder, the steps are as follows: S1: 1600kg zircon sand and 130kg coke were added into a 3200KVA electric arc furnace for smelting for 120min, and then the molten metal in the furnace was sprayed and formed using high-pressure air, and then a 8mm screen was used to remove block materials larger than 8mm to obtain hollow zirconia balls; The main components of zircon sand in weight percentage are shown in Table 1, and the main components of zirconia hollow spheres are shown in Table 2. The chemical composition is tested according to GB T 21114-2007; Table 1

[0027] Table 2

[0028] S2: Use a magnetic drum de-ironing device to demagnetize (de-ironize) the hollow zirconia balls twice, then sieve with 0.2mm and 6mm sieves to retain materials with a particle size of 0.2~6mm; use a Raymond mill to grind the materials to D 50 The particle size is 14 μm, and then the fluidized bed jet mill is used to grind the particle size to D 50 The particle size was 5.5 μm, and fused zirconia powder was obtained.

[0029] Comparative Example 1 of the present invention is: The difference between Comparative Example 1 and Example 1 is that hollow zirconia balls without iron removal and screening are ground to D using a ball mill. 50 It is 5.5μm.

[0030] Under the same conditions, the fused zirconia powders prepared in Example 1 and Comparative Example 1 were sintered, and the volume density of the sintered products is shown in Table 3; The specific conditions for sintering are adding MgO (stabilizer) and PVA aqueous solution (mass concentration of 10wt%), the mass ratio of fused zirconia powder to MgO is 97:3, and the amount of PVA aqueous solution added is 14wt% of the total mass of the material; the molding pressure is 18MPa, and the sintering temperature is 1650℃.

[0031] Table 3

[0032] Embodiment 2 of the present invention is: a method for preparing fused zirconium oxide powder, the steps are as follows: S1: 2000kg zircon sand and 165kg coke were added into a 3600KVA electric arc furnace for smelting for 150min, and then the molten metal in the furnace was sprayed and formed using high-pressure air, and then a 8mm screen was used to remove block materials larger than 8mm to obtain hollow zirconia balls; The main components of zircon sand in weight percentage are shown in Table 4, and the main components of zirconia hollow spheres are shown in Table 5. The chemical composition is tested according to GB T 21114-2007; Table 4

[0033] Table 5

[0034] S2: Use an electromagnetic iron remover to demagnetize the hollow zirconia balls once, then sieve them with 0.2mm and 6mm sieves to retain materials with a particle size of 0.2~6mm; use a ball mill to grind the materials to D 50 8μm, and then use a stirring mill to grind to D 50 The particle size of the fused zirconia powder was 2.8 μm.

[0035] Comparative Example 2 of the present invention is: The difference between Comparative Example 2 and Example 2 is that hollow zirconia balls that have not been treated by the above process are ground to a thickness of D using a ball mill. 50 It is 2.8μm.

[0036] Under the same conditions, the fused zirconia powders prepared in Example 2 and Comparative Example 2 were sintered, and the volume density of the sintered products is shown in Table 6; The specific conditions for sintering are: adding MgO (stabilizer) and PVA, the mass ratio of fused zirconia powder to MgO is 97:3, the amount of PVA added is 14wt% of the total mass of the material; the molding pressure is 18MPa, and the sintering temperature is 1650℃.

[0037] Table 6

[0038] Embodiment 3 of the present invention is a method for preparing fused zirconium oxide powder, and the steps are as follows: S1: 1200kg zircon sand and 100kg coke were added into a 2000KVA electric arc furnace for smelting for 100min, and then the molten metal in the furnace was sprayed and formed using high-pressure air, and then a 8mm screen was used to remove block materials larger than 8mm to obtain hollow zirconia balls; The main components of zircon sand in weight percentage are shown in Table 7, and the main components of zirconia hollow spheres are shown in Table 8. The chemical composition was tested according to GB T 21114-2007; Table 7

[0039] Table 8

[0040] S2: Use a magnetic drum iron remover to demagnetize the hollow zirconia balls twice, then sieve with 0.2mm and 6mm sieves to retain materials with a particle size of 0.2~6mm; use a ball mill to grind the materials to D 50 3.5μm, and then use a flat jet mill to grind to D 50 The particle size of the fused zirconia powder was 3.2 μm.

[0041] Comparative Example 3 of the present invention is: The difference between Comparative Example 3 and Example 3 is that hollow zirconia balls that have not been treated by the above process are ground to a thickness of D using a ball mill. 50 It is 3.2μm.

[0042] Under the same conditions, the fused zirconia powders prepared in Example 3 and Comparative Example 3 were sintered, and the volume density of the sintered products is shown in Table 9; The specific sintering conditions are as follows: adding MgO (stabilizer) and PVA, the mass ratio of fused zirconia powder to MgO is 97:3, and the addition amount of PVA is 14 wt% of the total mass of the materials; the forming pressure is 18 MPa, and the sintering temperature is 1650 °C.

[0043] Table 9

[0044] Example 4 of the present invention is as follows: The difference between Example 4 and Example 1 is only that: the addition amount of zircon sand is 1600 kg, the addition amount of coke is 112 kg, and the melting time is 90 min.

[0045] Example 5 of the present invention is as follows: The difference between Example 5 and Example 1 is only that: the addition amount of zircon sand is 1600 kg, the addition amount of coke is 144 kg, and the melting time is 180 min.

[0046] Example 6 of the present invention is: the fused zirconia powder prepared by the preparation method of Example 1.

[0047] In summary, there are many factors affecting the sintering performance of fused zirconia powder, such as particle size distribution, microscopic morphology, composition, grinding method, etc. The fused zirconia powder and its preparation method provided by the present invention obtain a fused zirconia powder with excellent and stable sintering performance by restricting the raw material composition, auxiliary material addition amount, melting parameters, composition and treatment method of the semi-finished product after melting, and grinding process, and can be applied to the production of high-grade refractory products with higher requirements for bulk density.

[0048] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. All equivalent transformations made using the description of the present invention, directly or indirectly applied in the relevant technical fields, are similarly included in the patent protection scope of the present invention.

Claims

1. A method for preparing fused zirconium oxide powder, characterized in that: The following steps are involved: S1: Mix zircon sand and coke for smelting, and then spray-blow mold to obtain hollow zirconia balls; S2: removing iron from the hollow zirconia balls, screening and grinding them in sequence to obtain fused zirconia powder.

2. The method for preparing fused zirconium oxide powder according to claim 1, characterized in that: The zircon sand comprises the following components in weight percentage: 31-33% SiO2, ≤0.45% Al2O3, ≤0.15% Fe2O3, ≤0.25% TiO2, ≤0.15% CaO, and ≥66% of a mixture of ZrO2 and HfO2.

3. The method for preparing fused zirconium oxide powder according to claim 1, characterized in that: The mass ratio of zircon sand to coke in S1 is 100:7-9.

4. The method for preparing fused zirconium oxide powder according to claim 1, characterized in that: The smelting time in S1 is 90 to 180 minutes.

5. The method for preparing fused zirconium oxide powder according to claim 1, characterized in that: The hollow zirconia spheres include the following components in weight percentage: ≤0.3% SiO2, ≤0.45% Al2O3, ≤0.1% Fe2O3, ≤0.22% TiO2, ≤0.12% CaO, and ≥98.5% of a mixture of ZrO2 and HfO2.

6. The method for preparing fused zirconium oxide powder according to claim 1, characterized in that: After screening in S2, the material with a particle size of 0.2-6 mm is retained.

7. The method for preparing fused zirconium oxide powder according to claim 1, characterized in that: The particle size range of the fused zirconium oxide powder in S2 is D 50 :0.5~5μm.

8. The method for preparing fused zirconium oxide powder according to claim 1, characterized in that: When removing iron in S2, at least one of a magnetic drum iron remover, a permanent magnetic belt iron remover and an electromagnetic iron remover is used.

9. The method for preparing fused zirconium oxide powder according to claim 1, characterized in that: The grinding in S2 adopts at least one of a Raymond mill, a fluidized bed airflow mill, a ball mill, a flat airflow mill, a wet stirring mill, a spray dryer and a sand mill.

10. A fused zirconia powder prepared by the method for preparing fused zirconia powder according to any one of claims 1 to 9.

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