An acid dry material for a medium frequency furnace based on a micro-fined raw material and a preparation method thereof

Abstract

The application belongs to the field of acid dry materials, and specifically provides an acid dry material for a medium-frequency furnace based on micro-fined raw materials and a preparation method thereof.The acid dry material for a medium-frequency furnace based on micro-fined raw materials comprises the following raw materials in mass fractions: 70-80 parts of silica aggregate, 20-25 parts of micro-fined silicon powder, and 0.7-0.85 parts of a sintering agent.The micro-fined silicon powder is prepared by the following steps: S1: taking small-grained silica, drying, and then coarsely grinding to obtain coarse grinding material;S2: adding high-purity silicon dioxide powder and nano zirconium oxide to the coarse grinding material, mixing uniformly, and continuing to grind to obtain the micro-fined silicon powder.The acid dry material for a medium-frequency furnace based on micro-fined raw materials prepared by the application has the advantages of good sintering state, excellent high-temperature resistance, and corrosion resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of acid dry material, and particularly relates to an acid dry material for a medium-frequency furnace based on micro-fined raw materials and a preparation method thereof. BACKGROUND

[0002] In modern industrial production, smelting equipment plays a key role in the development of many industries. The medium-frequency furnace occupies an important position in the field of metal smelting due to its fast heating speed, high smelting efficiency, precise temperature control and other advantages. For example, in the steel industry, it is used for the smelting of special steel and alloy steel, which can accurately adjust the composition of the molten steel to meet the quality requirements of different steel materials. In the non-ferrous metal industry, such as the smelting and casting of copper, aluminum and other metals, the medium-frequency furnace can realize efficient metal melting and refining process.

[0003] With the development of industry, the performance requirements of the medium-frequency furnace are continuously improved. Not only is it expected to further improve the smelting efficiency and reduce energy consumption, but also it is necessary to ensure the stable operation of the equipment and reduce the downtime for maintenance caused by problems such as furnace lining damage. At present, the material of the medium-frequency furnace crucible part is mainly dry ramming material, which has three types of acid, alkaline and neutral. When used, it is formed by vibration in the furnace and smelting operation is carried out by baking to obtain strength.

[0004] Among them, the acid dry material has become an important choice for the medium-frequency furnace lining due to its good acid slag erosion resistance, convenient construction and short baking time. The traditional acid dry material mainly uses quartz sand and other materials as the main raw material, and is prepared by adding appropriate binders and additives. However, in actual use, the existing acid dry material still has some problems to be solved: on the one hand, its thermal shock resistance is insufficient, and during the frequent temperature rise and fall of the medium-frequency furnace, the furnace lining is prone to cracking, which leads to slag penetration and affects the service life of the furnace lining. On the other hand, its high-temperature strength is limited, and in a high-temperature smelting environment, the furnace lining may soften and deform, reducing the protection of the furnace body and increasing the safety hazard. These problems limit the application of acid dry material in higher requirement smelting conditions, and also promote the industry to continuously explore methods to improve the performance of acid dry material.

[0005] In order to improve the performance of acid dry material, micro-fining of raw materials has become an important research direction. The micro-fining process is based on the micro-powder theory in refractory materials. During sintering, small particles can be more tightly packed, reducing porosity and increasing material density. This not only enhances the strength of the material, but also effectively blocks the penetration of slag, improving the erosion resistance of the furnace lining. At the same time, micro-fined raw materials can accelerate the chemical reaction speed, and finer raw material particles can make the reaction more complete, forming a more stable and firm binding phase, thereby improving the overall performance of the acid dry material.

[0006] However, the micro-fine raw material has the following problems: 1. poor dispersibility; 2. single anti-erosion effect. In view of the importance of intermediate frequency furnace in industrial production and the problems of acid dry material and micro-fine raw material, there is an urgent need to develop a new acid dry material for intermediate frequency furnace. SUMMARY

[0007] In view of the above problems, in order to further improve the technical defects of micro-fine raw material and improve the overall performance of acid dry material, the application provides an acid dry material for intermediate frequency furnace based on micro-fine raw material and a preparation method thereof.

[0008] The application first provides a preparation method of an acid dry material for intermediate frequency furnace based on micro-fine raw material, which comprises the following raw materials in mass fraction: silica aggregate 70-80 parts, micro-fine silicon powder 20-25 parts, sintering agent 0.7-0.85 parts; the micro-fine silicon powder is prepared by the following steps:

[0009] S1: Take small-grained silica, dry it first, and then coarsely grind it to obtain coarse grinding material;

[0010] S2: Add high-purity silicon dioxide powder and nano-zirconium oxide to the coarse grinding material and mix them evenly, and then continue to grind to obtain the micro-fine silicon powder.

[0011] Further, in the step S1, the grain size of the small-grained silica is less than 50 μm;

[0012] And / or, in the step S1, the average particle size of the coarse grinding material is 150-300 μm;

[0013] And / or, in the step S1, the content of silicon dioxide in the small-grained silica is greater than 99.8%.

[0014] Further, in the step S2, the mass ratio of the coarse grinding material, high-purity silicon dioxide powder and nano-zirconium oxide is 1:(0.1-0.15):(0.005-0.01);

[0015] And / or, in the step S2, the average particle size of the high-purity silicon dioxide powder is 5-10 μm;

[0016] And / or, in the step S2, the purity of the high-purity silicon dioxide powder is greater than 99.95%;

[0017] And / or, in the step S2, the average particle size of the nano-zirconium oxide is 50-100 nm;

[0018] And / or, in the step S2, the average particle size of the micro-fine silicon powder prepared after grinding is less than 38 μm.

[0019] Further, the sintering agent comprises raw materials in the following proportions by weight: boric anhydride 20-35 parts, boric acid 5-10 parts, modified silicon carbide nanosheet 10-15 parts.

[0020] Further, the modified silicon carbide nanosheet is made by the following method:

[0021] 1) Mix deionized water, tetrabutylphosphonium hydroxide, hydroxyethyl cellulose, and N-hydroxysuccinimide uniformly to prepare a base solution;

[0022] 2) Add silicon carbide and amino-modified graphene to the base solution, disperse uniformly, and then ball mill at a speed of 200-350 rpm / min for 1-1.5 h to obtain an intermediate solution;

[0023] 3) Take the intermediate solution, vacuum degas, then dry, crush and grind the obtained solid material, and press the ground material to obtain a green body. After sintering the green body, it is crushed and ball milled to obtain the product.

[0024] Further, in step 1), the content of tetrabutylphosphonium hydroxide in the base solution is 2-3 wt%;

[0025] And / or, in step 1), the content of hydroxyethyl cellulose in the base solution is 5-10 wt%;

[0026] And / or, in step 1), the content of N-hydroxysuccinimide in the base solution is 0.2-0.25 wt%.

[0027] Further, in step 2), the mass-volume ratio of the base solution, silicon carbide, and amino-modified graphene is (100-150) mL:(65-100) g:(15-20) g;

[0028] And / or, in step 2), the average particle size of the silicon carbide is 750-900 nm;

[0029] And / or, in step 2), the amino-modified graphene is amino acid-modified graphene.

[0030] Further, in step 3), a penetrating liquid is sprayed during the grinding process, and the penetrating liquid comprises deionized water, ammonium carbonate, hydroxytyrosol, and modified yttrium powder. The spraying amount of the penetrating liquid is 1.5-2% of the mass of the silicon carbide.

[0031] Further, in the penetrating liquid, the mass ratio of deionized water, ammonium carbonate, hydroxytyrosol, and modified yttrium powder is 1:(0.05-0.08):(0.1-0.2):(0.5-0.65).

[0032] The application also provides a preparation method of acid dry material for a medium-frequency furnace based on micro-fined raw materials, which comprises the following steps: weighing silica aggregate, micro-fined silica powder and sintering agent according to proportions, and mixing them uniformly.

[0033] Compared with the prior art, the application has the following beneficial effects:

[0034] 1. The micro-fined silica powder obtained by introducing a new process in the application can control the phase change speed in the heating process of the acid dry ramming material, strengthen the combination, reduce the cracking probability of the aggregate, improve the sintering performance and slag penetration resistance of the furnace lining, and obtain a new type of acid dry ramming material with excellent physical properties, the performance of which can reach SiO2≥97%, bulk density≥2.0g / cm 3 , linear change at 1550℃×3h≤7.8%, and compressive strength at 1550℃≥10MPa. In practical application, the medium-frequency furnace life is ≥250 furnaces when smelting ductile cast iron, and the medium-frequency furnace life is ≥40 furnaces when smelting ordinary carbon steel.

[0035] 2. The application introduces a higher proportion of micro-fined silica powder, which has high reactivity, but poor dispersion performance, single corrosion resistance, and large expansion and cracks at high temperature. To solve this problem, the application introduces a multi-component compounded sintering agent, which is based on boric anhydride and boric acid and adds modified silicon carbide nanosheets. The three-dimensional interlocking structure can be formed in the sintering layer, which can play a very good stress extraction and crack deflection role, can dissipate the energy generated by the furnace lining under high and low temperature cyclic impact, has a very good toughening effect, and can improve the slag penetration corrosion resistance and cracking resistance of the furnace lining. The linear change of the sample after firing is ≤5%, and the compressive strength after firing is ≥10MPa.

[0036] 3. During the preparation of the modified silicon carbide nanosheet in the application, the base fluid can provide a stable physicochemical environment for silicon carbide and amino-modified graphene, so that the two can be fully and uniformly dispersed and fused. In the drying process, the driving force generated by the evaporation of water molecules can be balanced by the base fluid, improving the orientation degree of silicon carbide and amino-modified graphene, which is helpful to the formation of a bridge connection structure between silicon carbide and amino-modified graphene, and the interface bonding force of the interlayer components is stronger, which can inhibit the transformation of the system from a layered structure to a porous structure. In the sintering process, the mass transfer can improve the lamellar structure state and improve the mechanical stability of the material. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The figure is a schematic diagram of the compressive strength test data of the samples of examples 1-3 and control group 1 of the application.

[0038] Figure 2 The figure is a schematic diagram of the XRD analysis of the sample after firing of example 2 of the application.

[0039] Figure 3The schematic diagram of the phase XRD analysis of the sample after burning of the embodiment 3 of the present application is shown in the figure;

[0040] Figure 4 The schematic diagram of the anti-slag erosion penetration test of the sample of the embodiment 1-3 and the control group 1 of the present application is shown in the figure;

[0041] Figure 5 The schematic diagram of the SEM test of the sample of the control group 1 of the present application is shown in the figure.

[0042] Figure 6 The schematic diagram of the SEM test of the sample of the embodiment 2 of the present application is shown in the figure.

[0043] Figure 7 The schematic diagram of the SEM test of the sample of the embodiment 3 of the present application is shown in the figure. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0045] The present application provides an acid dry material for medium frequency furnace based on micro-fined raw materials through a large number of experimental researches, which comprises the following raw materials in mass fraction: silica aggregate 70-80 parts, micro-fined silicon powder 20-25 parts, sintering agent 0.7-0.85 parts; the micro-fined silicon powder is prepared by the following steps:

[0046] S1: taking small-grained silica, drying and then performing coarse grinding to obtain coarse grinding material;

[0047] S2: adding high-purity silicon dioxide powder and nano zirconium oxide into the coarse grinding material, mixing uniformly and continuing to grind to obtain the micro-fined silicon powder.

[0048] Further, in the step S1, the grain size of the small-grained silica is less than 50 μm;

[0049] And / or, in the step S1, the average particle size of the coarse grinding material is 150-300 μm;

[0050] And / or, in the step S1, the content of silicon dioxide in the small-grained silica is greater than 99.8%.

[0051] In some specific embodiments, generally, the acid dry material for medium frequency furnace based on micro-fined raw materials comprises the following raw materials in mass fraction: silica aggregate 80 parts, micro-fined silicon powder 20 parts, sintering agent 0.8 parts, and better experimental results can be obtained.

[0052] In some embodiments, the average particle size of the coarse abrasive in step S1 can be 150 μm, 200 μm, 250 μm, or 30 μm. In general, the average particle size of the coarse abrasive is 200 μm, and the experimental results are better.

[0053] In some embodiments, the small-grained silica in step S1 is made of high-quality silica. In the embodiments of the present application, the small-grained silica is made of high-quality silica from Gucheng County, Xiangyang City.

[0054] Further, in step S2, the mass ratio of the coarse abrasive, the high-purity silica powder, and the nano zirconium oxide is 1:(0.1-0.15):(0.005-0.01).

[0055] And / or, in step S2, the average particle size of the high-purity silica powder is 5-10 μm.

[0056] And / or, in step S2, the purity of the high-purity silica powder is greater than 99.95%.

[0057] And / or, in step S2, the average particle size of the nano zirconium oxide is 50-100 nm.

[0058] And / or, in step S2, the average particle size of the micro-silica powder prepared after grinding is less than 38 μm.

[0059] In some embodiments, in step S2, the mass ratio of the coarse abrasive, the high-purity silica powder, and the nano zirconium oxide can be 1:0.1:0.005, 1:0.12:0.005, 1:0.13:0.005, 1:0.15:0.005, 1:0.1:0.006, 1:0.1:0.007, 1:0.1:0.008, 1:0.1:0.009, 1:0.1:0.01, 1:0.12:0.006, 1:0.12:0.007, 1:0.12:0.008, 1:0.12:0.009, 1:0.12:0.01, 1:0.15:0.006, 1:0.15:0.007, 1:0.15:0.008, 1:0.15:0.009, or 1:0.15:0.01. In general, the mass ratio of the coarse abrasive, the high-purity silica powder, and the nano zirconium oxide is 1:0.15:0.005, and the experimental results are better.

[0060] More preferably, in general, in step S2, the average particle size of the high-purity silica powder is 10 μm, and the average particle size of the nano zirconium oxide is 50 nm, and the experimental results are better.

[0061] Further, the sintering agent comprises raw materials in the following proportions by weight: boron anhydride 20-35 parts, boric acid 5-10 parts, modified silicon carbide nanosheet 10-15 parts.

[0062] Further, the modified silicon carbide nanosheet is made by the following method:

[0063] 1) Mix deionized water, tetrabutylphosphonium hydroxide, hydroxyethyl cellulose, and N-hydroxysuccinimide uniformly to prepare a base solution;

[0064] 2) Add silicon carbide and amino-modified graphene to the base solution, disperse uniformly, and then ball mill at a speed of 200-350 rpm / min for 1-1.5 h to obtain an intermediate solution;

[0065] 3) Take the intermediate solution, vacuum degas, then dry, crush and grind the obtained solid material, and press the ground material to obtain a green body. After sintering the green body, crush and ball mill to obtain the product.

[0066] Further, in step 1), the content of tetrabutylphosphonium hydroxide in the base solution is 2-3 wt%;

[0067] And / or, in step 1), the content of hydroxyethyl cellulose in the base solution is 5-10 wt%;

[0068] And / or, in step 1), the content of N-hydroxysuccinimide in the base solution is 0.2-0.25 wt%.

[0069] In some embodiments, in step 1), the content of tetrabutylphosphonium hydroxide in the base solution can be 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, or 3%. In general, when the content of tetrabutylphosphonium hydroxide in the base solution is 2.8%, better experimental results can be obtained.

[0070] In some embodiments, in step 1), the content of hydroxyethyl cellulose in the base solution can be 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, or 10 wt%. In general, when the content of hydroxyethyl cellulose in the base solution is 8.5%, the experimental results are best.

[0071] In some embodiments, in step 1), the content of N-hydroxysuccinimide in the base solution can be 0.2 wt%, 0.21 wt%, 0.22 wt%, 0.23 wt%, 0.24 wt%, or 0.25 wt%. In general, when the content of N-hydroxysuccinimide in the base solution is 0.25 wt%, better results can be achieved.

[0072] Further, in the step 2), the mass-volume ratio of the base solution, silicon carbide and amino-modified graphene is (100-150) mL:(65-100) g:(15-20) g;

[0073] Further, in the step 2), the average particle size of the silicon carbide is 750-900 nm;

[0074] Further, in the step 2), the amino-modified graphene is amino acid-modified graphene.

[0075] In some embodiments, in the step 2), the mass-volume ratio of the base solution, silicon carbide and amino-modified graphene can be 100 mL:65 g:15 g, 120 mL:65 g:15 g, 150 mL:65 g:15 g, 120 mL:80 g:15 g, 150 mL:80 g:15 g, 120 mL:65 g:17.5 g, 120 mL:65 g:20 g, 150 mL:65 g:17.5 g, 150 mL:65 g:20 g, 120 mL:100 g:15 g, 120 mL:100 g:17.5 g, 120 mL:100 g:20 g, 150 mL:100 g:15 g, 150 mL:100 g:17.5 g, 150 mL:100 g:20 g, 150 mL:80 g:15 g. In general, when the mass-volume ratio of the base solution, silicon carbide and amino-modified graphene is 150 mL:100 g:15 g, better experimental results can be obtained. More preferably, the average particle size of the silicon carbide is 800 nm.

[0076] In some embodiments, the amino acid-modified graphene can be L-hydroxyproline-modified graphene, aspartic acid-modified graphene, tyrosine-modified graphene. In general, when the amino acid-modified graphene is aspartic acid-modified graphene, better experimental results can be obtained.

[0077] Further, in the step 3), a penetrating solution is sprayed during the grinding process, and the penetrating solution includes deionized water, ammonium carbonate, hydroxytyrosol and modified yttrium powder; the spraying amount of the penetrating solution is 1.5-2% of the mass of the silicon carbide.

[0078] Further, in the penetrating solution, the mass of the deionized water, ammonium carbonate, hydroxytyrosol and modified yttrium powder is 1:(0.05-0.08):(0.1-0.2):(0.5-0.65). In general, when the mass of the deionized water, ammonium carbonate, hydroxytyrosol and modified yttrium powder is 1:0.05:0.15:0.55, better experimental results can be obtained.

[0079] Further, the modified yttrium powder is prepared by the following steps:

[0080] I, in a beaker 100ml N, N dimethylformamide and 2g terephthalic acid configuration into a mixed solution for later use;

[0081] II, to the mixed solution 3.5g yttrium chloride hexahydrate, fast stirring 30min after adding 30g yttrium powder, heated to 120℃, incubation for 3h after filtration, the filtrate washed for later use;

[0082] III, configuration 150ml 10% concentration of sodium methyl silicate solution, add 0.2g octadecyl phosphate, then the washed filtrate is added, stirring 2h after filtration, drying. Example 1

[0083] The micro fine raw material based on the acid dry type material for medium frequency furnace of the embodiment includes the following mass: silica aggregate 80kg, micro fine silicon powder 20kg, sintering agent 0.8kg.

[0084] The micro fine silicon powder of the embodiment is prepared by the following steps:

[0085] S1: take the small crystal silica with the content of silicon dioxide greater than 99.8% and place it in the drying room for hot air drying at 200℃, then pre-pulverize it into small particles, and then transfer it to the ball mill for coarse grinding, and sieve to obtain coarse grinding material, the average particle size of which is 200μm;

[0086] S2: add high-purity silicon dioxide powder and nano zirconium oxide to the coarse grinding material and mix them evenly, the average particle size of the high-purity silicon dioxide powder is 10μm, and the average particle size of the nano zirconium oxide is 50nm, control the mass ratio of the coarse grinding material, high-purity silicon dioxide powder and nano zirconium oxide to be 1:0.15:0.005, continue to grind and sieve, so that the average particle size of the micro fine silicon powder prepared after grinding is less than 38μm, and it is obtained.

[0087] The sintering agent of the embodiment includes the following raw materials by weight: boric anhydride 632g, boric acid 168g.

[0088] The preparation method of the micro fine raw material based acid dry type material for medium frequency furnace of the embodiment includes the following steps: weigh the silica aggregate, micro fine silicon powder and sintering agent in proportion and mix them evenly. Example 2

[0089] The micro fine raw material based on the acid dry type material for medium frequency furnace of the embodiment includes the following mass: silica aggregate 80kg, micro fine silicon powder 20kg, sintering agent 0.8kg.

[0090] The micro fine silicon powder of the embodiment is prepared by the following steps:

[0091] S1: Small crystal silica with silica content greater than 99.8% is placed in an oven, dried by hot air at 200°C, then pre-pulverized into small particles, then transferred to a ball mill for coarse grinding, and sieved to obtain coarse grinding material, the average particle size of the coarse grinding material is 200μm;

[0092] S2: Add high-purity silica powder and nano-zirconium oxide to the coarse grinding material and mix evenly, the average particle size of the high-purity silica powder is 10μm, the average particle size of the nano-zirconium oxide is 50nm, control the mass ratio of the coarse grinding material, high-purity silica powder and nano-zirconium oxide to be 1:0.15:0.005, continue to grind and sieve, so that the average particle size of the micro-silicon powder prepared after grinding is less than 38μm.

[0093] The sintering agent of the present embodiment includes the following weights of raw materials: boric anhydride 500g, boric acid 133g, modified silicon carbide nanosheet 167g.

[0094] The modified silicon carbide nanosheet of the present embodiment is made by the following method:

[0095] 1) Add deionized water, tetrabutylphosphonium hydroxide, hydroxyethyl cellulose, and N-hydroxysuccinimide to a stirred tank and mix evenly at a speed of 350rpm to prepare a base solution; the content of tetrabutylphosphonium hydroxide in the base solution is 2.8%, the content of hydroxyethyl cellulose is 8.5%, and the content of N-hydroxysuccinimide is 0.25wt%;

[0096] 2) Add the base solution to the ball mill, then add silicon carbide and amino-modified graphene, disperse evenly, then ball mill at a speed of 300rpm / min for 1.5h to obtain an intermediate solution; the mass-volume ratio of the base solution, silicon carbide and amino-modified graphene is 150mL:100g:15g; the average particle size of the silicon carbide is 800nm; the amino acid modified graphene is aspartic acid modified graphene;

[0097] 3) Vacuum degassing of the intermediate solution at a vacuum degree of -0.05, then vacuum drying at 100°C to obtain a solid material, crushing and grinding the solid material, then placing it in a stainless steel mold to press a green body, placing the green body in a muffle furnace, heating to 1250°C at a heating rate of 10°C / min, sintering for 3.5h, then naturally cooling, crushing and ball milling to obtain the product.

[0098] The preparation method of the acid dry material for medium frequency furnace based on micro-fine raw materials of the present embodiment includes the following steps: weighing the silica aggregate, micro-fine silicon powder and sintering agent in proportion and mixing evenly. Example 3

[0099] The acid dry material for the medium frequency furnace based on the micro-fined raw material of the embodiment comprises the following mass: 80 kg of silica aggregate, 20 kg of micro-fined silicon powder, and 0.8 kg of sintering agent.

[0100] The micro-fined silicon powder of the embodiment is prepared by the following steps:

[0101] S1: Small crystal silica with a silicon dioxide content of more than 99.8% is placed in an oven, dried by hot air at a temperature of 200°C, and then pre-pulverized into small particles, and then transferred to a ball mill for coarse grinding, and sieved to obtain coarse grinding material, and the average particle size of the coarse grinding material is 200 μm;

[0102] S2: High-purity silicon dioxide powder and nano-zirconium oxide are added to the coarse grinding material and mixed uniformly, the average particle size of the high-purity silicon dioxide powder is 10 μm, the average particle size of the nano-zirconium oxide is 50 nm, the mass ratio of the coarse grinding material, the high-purity silicon dioxide powder, and the nano-zirconium oxide is controlled to be 1:0.15:0.005, and the grinding and sieving are continued, so that the average particle size of the micro-fined silicon powder prepared after grinding is less than 38 μm, and the micro-fined silicon powder is obtained.

[0103] The sintering agent of the embodiment comprises the following raw materials by weight: 453 g of boric anhydride, 121 g of boric acid, and 226 g of modified silicon carbide nanosheets.

[0104] The modified silicon carbide nanosheets of the embodiment are prepared by the following method:

[0105] 1) Deionized water, tetrabutylphosphonium hydroxide, hydroxyethyl cellulose, and N-hydroxysuccinimide are added to a stirred tank, and mixed uniformly at a speed of 350 rpm to prepare a base solution; in the base solution, the content of tetrabutylphosphonium hydroxide is 2.8%, the content of hydroxyethyl cellulose is 8.5%, and the content of N-hydroxysuccinimide is 0.25 wt%;

[0106] 2) The base solution is added to a ball mill, and then silicon carbide and amino-modified graphene are added, and after being dispersed uniformly, the ball milling is carried out at a speed of 300 rpm / min for 1.5 h to obtain an intermediate solution; when the mass-volume ratio of the base solution, the silicon carbide, and the amino-modified graphene is 150 mL:100 g:15 g; the average particle size of the silicon carbide is 800 nm; and the amino acid-modified graphene is aspartic acid-modified graphene;

[0107] 3) The intermediate liquid is vacuum degassed at a vacuum degree of -0.05, and then vacuum dried at 100℃ to obtain a solid material, which is crushed and ground, and a permeation liquid is sprayed during the grinding process, the permeation liquid is composed of deionized water, ammonium carbonate, hydroxytyrosol and modified yttrium powder in a mass ratio of 1:0.05:0.15:0.55, the spraying amount of the permeation liquid is 1.65% of the mass of the silicon carbide, and after grinding, the body is placed in a stainless steel mold to obtain a blank, the blank is placed in a muffle furnace and heated to 1250℃ at a heating rate of 10℃ / min for sintering for 3.5h, and then naturally cooled, crushed and ball milled to obtain the product.

[0108] The modified yttrium powder of the embodiment is prepared by the following steps:

[0109] I. 100mL of N,N-dimethylformamide and 2g of terephthalic acid are added to a beaker to prepare a mixed solution;

[0110] II. 3.5g of yttrium chloride hexahydrate is added to the mixed solution, stirred quickly for 30min, then 30g of yttrium powder is added, heated to 120℃, and kept for 3h, then filtered, and the filtrate is washed and prepared for use;

[0111] III. 150mL of 10% sodium methylsilicate solution is prepared, 0.2g of octadecyl phosphoric acid is added, then the washed filtrate is added, stirred for 2h, filtered, and dried to obtain the product.

[0112] The preparation method of the acid dry material for a medium frequency furnace based on micro-fined raw materials of the embodiment comprises the following steps: the silica aggregate, micro-fined silicon powder and sintering agent are weighed according to the proportion and mixed uniformly.

[0113] Control group 1

[0114] The acid dry material for a medium frequency furnace of the control group comprises the following mass: 100kg of quartz sand and 0.8kg of sintering agent.

[0115] The particle size and grading of the quartz sand are as follows: 4-2mm, 12.6%; 2-1mm, 13.8%; 1-0.2mm, 45.3%; 0.2-0.06mm, 19.7%; and ≤0.06mm, 8.6%.

[0116] The sintering agent of the control group comprises the following raw materials by weight: 632g of boric anhydride and 168g of boric acid.

[0117] The preparation method of the acid dry material for a medium frequency furnace based on micro-fined raw materials of the control group comprises the following steps: the quartz sand and sintering agent are weighed according to the proportion and mixed uniformly.

[0118] Performance detection

[0119] 1. Take the acid dry material for intermediate frequency furnace based on the micro-fine raw material of examples 1-3 and the acid dry material for intermediate frequency furnace of control group 1, adopt dry pressing forming method, forming pressure 150 MPa, pressure holding time 1 min, make Φ50 mm cylindrical blank, then sinter at 1150 DEG C and 1550 DEG C temperature respectively for 3 h to make sample, then carry out compression strength test on the universal mechanical testing machine according to GB / T 5072-2008, and the results are shown in Figure 1 The phase composition of the sintered samples of examples 2 and 3 is analyzed, and the results are shown in Figure 2 and Figure 3 It can be seen that more cristobalite is generated in the sample of example 3, and the phase change state is better.

[0120] 2. Take the acid dry material for intermediate frequency furnace based on the micro-fine raw material of examples 1-3 and the acid dry material for intermediate frequency furnace of control group 1, pour the material into the mold, and machine-press forming under 76 MPa pressure to obtain Φ50*50 mm crucible samples with small holes (Φ18*24 mm) on the top. The formed green crucible is placed in an oven at 110 DEG C for drying, and then the static crucible method is used to test the corrosion and penetration resistance of the material according to GB / T 8931-2007 standard, and the surface erosion state of the sample is observed, and the test results are shown in Figure 4 It can be seen that the addition of modified silicon carbide nanosheets in examples 2 and 3 of the present application can effectively improve the corrosion resistance of the sample.

[0121] 3. Take the samples of control group 1, example 2 and example 3, and carry out scanning electron microscope test after brittle fracture and polishing, and the test results are shown in Figure 5 , Figure 6 and Figure 7 , wherein, Figure 5 is control group 1, Figure 6 is example 2, Figure 7 is example 3, it can be seen that the sintering structure of control group 1 is loose, and there are more pores between the aggregate particles. The sintering structure of examples 2 and 3 is relatively fine and uniform, the compatibility between the modified silicon carbide nanosheet and the matrix is good, and the modified silicon carbide nanosheet in example 3 is added with a penetration liquid in the preparation process, which can improve the sintering structure of the sample, the compatibility between various components is better, the structure is more fine, and the interface bonding force is stronger.

[0122] Although the present application has been described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement to part of the technical features, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An acidic dry feedstock for medium-frequency furnaces based on micronized raw materials, characterized in that: The raw materials include the following parts by weight: 70-80 parts silica aggregate, 20-25 parts micronized silicon powder, and 0.7-0.85 parts sintering agent; the micronized silicon powder is prepared by the following steps: S1: Take small-grained silica, dry it, and then coarsely grind it to obtain coarse abrasive. S2: Add high-purity silica powder and nano-zirconia to the coarse abrasive, mix evenly, and continue grinding to obtain the final product; The sintering agent comprises the following raw materials in parts by weight: 20-35 parts boric anhydride, 5-10 parts boric acid, and 10-15 parts modified silicon carbide nanosheets; The modified silicon carbide nanosheets were prepared using the following method: 1) Mix deionized water, tetrabutylphosphine hydroxide, hydroxyethyl cellulose, and N-hydroxysuccinimide evenly to prepare the base solution; 2) Add silicon carbide and amino-modified graphene to the base liquid, disperse evenly, and ball mill at a speed of 200-350 rpm / min for 1-1.5 h to obtain the intermediate liquid; 3) Take the intermediate liquid and degas it under vacuum. Then dry it and crush and grind the resulting solid material. After grinding, press it to obtain a green body. After sintering the green body, crush it and ball mill it to obtain the final product.

2. The acidic dry feed for medium-frequency furnaces based on micronized raw materials according to claim 1, characterized in that: In step S1, the grain size of the small-grained silica is less than 50 μm; And / or, in step S1, the average particle size of the coarse abrasive is 150-300 μm; And / or, in step S1, the silica content in the small-grained silica is greater than 99.8%.

3. The acidic dry feed for medium-frequency furnaces based on micronized raw materials according to claim 1, characterized in that: In step S2, the mass ratio of the coarse abrasive, high-purity silica powder, and nano-zirconia is 1:(0.1-0.15):(0.005-0.01). And / or, in step S2, the average particle size of the high-purity silica powder is 5-10 μm; And / or, in step S2, the purity of the high-purity silica powder is greater than 99.95%; And / or, in step S2, the average particle size of the nano-zirconia is 50-100 nm; And / or, in step S2, the average particle size of the micronized silicon powder obtained after grinding is less than 38 μm.

4. The acidic dry feed for medium-frequency furnaces based on micronized raw materials according to claim 1, characterized in that: In step 1), the content of tetrabutylphosphine hydroxide in the base solution is 2-3 wt%. And / or, in step 1), the content of hydroxyethyl cellulose in the base solution is 5-10 wt%; And / or, in step 1), the content of N-hydroxysuccinimide in the base solution is 0.2-0.25 wt%.

5. The acidic dry feed for medium-frequency furnaces based on micronized raw materials according to claim 1, characterized in that: In step 2), the mass-to-volume ratio of the base liquid, silicon carbide, and amino-modified graphene is (100-150) mL:(65-100) g:(15-20) g. And / or, in step 2), the average particle size of silicon carbide is 750-900 nm; And / or, in step 2), the amino-modified graphene is amino acid-modified graphene.

6. The acidic dry feed for medium-frequency furnaces based on micronized raw materials according to claim 1, characterized in that: In step 3), a penetrating liquid is sprayed during the grinding process. The penetrating liquid includes deionized water, ammonium carbonate, hydroxytyrosol, and modified yttrium powder. The amount of penetrating liquid sprayed is 1.5-2% of the mass of silicon carbide.

7. The acidic dry feed for medium-frequency furnaces based on micronized raw materials according to claim 6, characterized in that: In the permeate, the mass ratio of deionized water, ammonium carbonate, hydroxytyrosol, and modified yttrium powder is 1:(0.05-0.08):(0.1-0.2):(0.5-0.65).

8. A method for preparing acidic dry feedstock for medium-frequency furnaces based on micronized raw materials as described in claim 1, characterized in that: The process includes the following steps: Weigh out the silica aggregate, micronized silicon powder, and sintering agent according to the specified proportions and mix them evenly.

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