阅读说明：本技术 碳化硅结合莫来石复相耐火材料及其制备方法 (Silicon carbide and mullite composite phase refractory material and preparation method thereof ) 是由 高永涛 周丽 林炼 赵凯燕 于 2021-06-30 设计创作，主要内容包括：本发明公开了一种碳化硅结合莫来石复相耐火材料及其制备方法,包括以质量份数：煤矸石一为45～70份、煤矸石二为10～50份、煤矸石三为0～25份、煤粉为5～15份、矿化剂为5～10份、成型添加剂为2～8份；煤矸石一包括Al-(2)O-(3)为40～46％、SiO-(2)为51～56％、C为2～5％；煤矸石二包括Al-(2)O-(3)为36～52％、SiO-(2)为40～45％、C为12～18％；煤矸石三包括Al-(2)O-(3)为46～52％、SiO-(2)为41～45％、C为5～8％。本发明的碳化硅结合莫来石复相耐火材料,具有耐火度高,可达到1800℃,高温稳定性好,热膨胀系数低,热导率小,耐腐蚀,强度高,断裂韧性好等特点,广泛应用于耐火材料领域的高温结构件原料、特种耐火砖、匣钵生产等领域。(The invention discloses a silicon carbide and mullite combined complex phase refractory material and a preparation method thereof, wherein the silicon carbide and mullite combined complex phase refractory material comprises the following components in parts by mass: 45-70 parts of coal gangue I, 10-50 parts of coal gangue II, 0-25 parts of coal gangue III, 5-15 parts of coal powder, 5-10 parts of mineralizer and 2-8 parts of forming additive; coal gangue-Al 2 O 3 40 to 46 percent of SiO 2 51-56% of C and 2-5% of C; the coal gangue II comprises Al 2 O 3 36-52% of SiO 2 40-45% of C and 12-18% of C; coal gangue III including Al 2 O 3 46-52% of SiO 2 41-45% of C and 5-8% of C. The silicon carbide and mullite composite refractory material of the inventionThe high-temperature-resistant high-strength refractory brick has the characteristics of high refractoriness which can reach 1800 ℃, good high-temperature stability, low thermal expansion coefficient, small thermal conductivity, corrosion resistance, high strength, good fracture toughness and the like, and is widely applied to the fields of high-temperature structural component raw materials, special refractory bricks, saggar production and the like in the field of refractory materials.)

1. A silicon carbide and mullite composite refractory material is characterized in that,

comprises the following components in parts by mass: 45-70 parts of coal gangue I, 10-50 parts of coal gangue II, 0-25 parts of coal gangue III, 5-15 parts of coal powder, 5-10 parts of mineralizer and 2-8 parts of forming additive;

the coal gangue I comprises Al₂O₃40 to 46 percent of SiO₂51-56% of C and 2-5% of C;

the coal gangue II comprises Al₂O₃36-52% of SiO₂40-45% of C and 12-18% of C;

the coal gangue III comprises Al₂O₃46-52% of SiO₂41-45% of C and 5-8% of C.

2. The silicon carbide-mullite composite refractory of claim 1,

comprises the following components in parts by mass: 45-70 parts of coal gangue I, 10-40 parts of coal gangue II, 10-20 parts of coal gangue III, 5-15 parts of coal powder, 5-8 parts of mineralizer and 3-5 parts of forming additive.

3. The silicon carbide-mullite composite refractory of claim 1 or 2,

the mineralizer comprises potassium feldspar, kyanite, a mixture of CaO and BaO, and Li₂And one or more of O.

4. The silicon carbide-mullite composite refractory of claim 1 or 2,

the molding additive comprises one or more of butcher's-broom, industrial potato starch, sodium lignosulfonate, yellow dextrin or sodium carboxymethyl cellulose.

5. The silicon carbide-mullite composite refractory of claim 1 or 2,

the silicon carbide and mullite combined complex phase refractory material comprises: al (Al)₂O₃43-48% of SiO₂40 to 48%, C8 to 12%,

the mineral phases of the silicon carbide combined mullite complex phase refractory material comprise: the SiC phase is 8-10%, the mullite phase is 55-65%, and the rest is fused quartz and does not contain cristobalite and corundum.

6. A preparation method for in-situ synthesis of a silicon carbide and mullite composite refractory material by utilizing coal gangue is characterized by comprising the following steps:

crushing and grinding the coal gangue I, the coal gangue II, the coal gangue III, the coal powder and the mineralizer respectively, sieving with a 325-mesh sieve after the fineness reaches 1250-2000 meshes to obtain coal gangue I slurry, coal gangue II slurry, coal gangue III slurry, coal powder slurry and mineralizer slurry, mixing the coal gangue I slurry, the coal gangue II slurry, the coal gangue III slurry, the coal powder slurry and the mineralizer slurry to obtain a mixed material, carrying out superfine grinding on the mixed material, and sieving with the 325-mesh sieve after the fineness reaches 4000-6000 meshes to obtain superfine powder;

mixing the forming additive with water to obtain a forming additive solution, uniformly mixing the forming additive solution with the superfine powder, ageing, forming, drying, calcining, crushing and screening to obtain the silicon carbide and mullite combined composite refractory material.

7. The method for preparing the silicon carbide and mullite composite refractory material by utilizing coal gangue in-situ synthesis as claimed in claim 6,

the drying adopts two-stage drying;

the first stage is a low-temperature slow drying stage, drying is carried out by weak convection, the low-temperature slow drying stage comprises a low-temperature high-humidity stage and a constant-temperature low-humidity stage, the atmosphere humidity of the low-temperature high-humidity stage is 70 RH% -90 RH%, the drying temperature is 35-60 ℃, the air speed is controlled to be 10-14 m/s, the drying time is 3-6 h, the atmosphere humidity of the constant-temperature low-humidity stage is gradually reduced from 70 RH% -90 RH% to 10 RH% -30 RH%, the drying temperature is 40-100 ℃, the air speed is 12-16 m/s, and the drying time is 10-26 h;

the second stage is a high-temperature quick-drying stage, and strong convection is adopted for drying, wherein the drying temperature is 300-800 ℃, the drying time is 10-60 min, the atmosphere humidity is less than 10 RH%, and the wind speed is more than 16 m/s.

8. The method for preparing the silicon carbide and mullite composite refractory material by utilizing coal gangue in-situ synthesis as claimed in claim 6,

and calcining in a tunnel kiln at the temperature of 1300-1420 ℃ for 12-36 h, wherein the air coefficient in the tunnel kiln is 0.95-1.2.

9. The method for preparing the silicon carbide and mullite composite refractory material by utilizing coal gangue in-situ synthesis as claimed in claim 6,

the staling time is 3 to 4 days.

10. The method for preparing the silicon carbide and mullite composite refractory material by utilizing coal gangue in-situ synthesis as claimed in claim 6,

the mass concentration of the forming additive in the forming additive solution is 10-50%, and the mass ratio of the forming additive solution to the superfine powder is (0.03-0.11) to 1;

the molding adopts a semi-dry pressing molding method, and the pressure of the semi-dry pressing molding method is 50 t-500 t.

Technical Field

The invention relates to the field of coal gangue, in particular to a silicon carbide and mullite composite refractory material. In addition, the invention also relates to a preparation method of the silicon carbide and mullite combined complex phase refractory material.

Background

The refractory materials can be divided into the following components according to chemical mineral compositions: aluminum silicate products (clay bricks, high-alumina bricks and semi-silica bricks), siliceous products (silica bricks and fused quartz sintered products), magnesian products (magnesia bricks, magnesia-alumina bricks, magnesia-chrome bricks and the like), carbonaceous products (carbon bricks, graphite bricks and the like), dolomite products, zircon products, special refractory products (high-purity oxide products, insoluble compound products and high-temperature composite materials) and the like. The bauxite type refractory raw materials are various in variety, and mainly comprise bauxite and hard clay clinker (flint clay), wherein the demand of the bauxite clinker is large. In addition, capacitance corundum, sintered corundum, silicon carbide, light refractory raw materials and various synthetic refractory raw materials.

The gangue mineral belongs to hard clay, and the main component of the gangue mineral is SiO₂、Al₂O₃A small amount of residual carbon, and SiO in coal gangue in different regions₂、Al₂O₃And residual carbon content. The mullite is an aluminium silicate (Al)₂O₃-SiO₂) The unique and stable binary compound in the system has a plurality of excellent performances such as high melting point, good thermal shock performance, high refractoriness under load, creep resistance, good high-temperature volume stability and the like. Al in gangue raw material₂O₃The content is not high and is generally between 40 and 45 percent, and the mullite is artificially synthesized, because the content of the mullite mineral phase is only 50 to 60 percent and excessive SiO is generated₂The quartz crystal phase-change material exists in the forms of cristobalite, phosphorosilicate quartz and fused quartz, and the quartz crystal phase-change material has poor volume stability and low strength in the high-temperature use process, so that the use field of the material is limited.

Based on the characteristics of the coal gangue raw material, a part of SiO in the raw material is removed₂And C is converted into SiC crystal phase, so that the high-temperature volume stability and creep resistance of the material are enhanced, and the toughness and impact resistance of the material are improvedStrength, and greatly improves the material performance. Currently, the main methods are as follows:

firstly, silicon carbide is used as aggregate, coal gangue and bauxite are used as matrixes, mullite fiber and other mineralizers are introduced, and the mullite-combined silicon carbide composite phase material is prepared by mechanical pressing and high-temperature calcination. Mullite fiber and silicon carbide aggregate are introduced to be used as seed crystals, and the growth of the crystal whiskers is promoted through sintering. Because the method directly introduces larger seed crystals, the mullite whiskers in the material tend to wrap the silicon carbide crystal grains to grow in the heating process, and the two crystals do not grow in a staggered mode, so that the advantages of the two materials cannot be fully exerted, and the method has limitations.

Secondly, selecting alumina sol as an aluminum source, quickly curing and molding the foam slurry to obtain a blank by using a method combining a sol-gel method and a foaming method, then oxidizing alumina nano particles in the alumina gel and silicon carbide powder at a high temperature to generate silicon dioxide to react to generate mullite, and enabling the silicon carbide powder to generate strength in an air atmosphere to finally obtain the mullite-combined silicon carbide material. The method uses alumina sol and silicon carbide powder as raw materials, has high cost, adopts a sol-gel method for preparation, and is difficult to industrialize, so that certain limitations exist.

Disclosure of Invention

The invention provides a silicon carbide and mullite combined complex phase refractory material and a preparation method thereof, aiming at solving the technical problems that the existing method for directly synthesizing the silicon carbide and mullite combined complex phase refractory material is not suitable for mass production under the condition of introducing seed crystals, has the defects of high cost, difficult uniform mixing, poor mineral phase combination and large product quality fluctuation, and is not suitable for mass production under the condition of not introducing the seed crystals.

The technical scheme adopted by the invention is as follows:

a silicon carbide and mullite composite refractory material comprises the following components in parts by mass: 45-70 parts of coal gangue I, 10-50 parts of coal gangue II, 0-25 parts of coal gangue III, 5-15 parts of coal powder, 5-10 parts of mineralizer and 2-8 parts of forming additive; the coal gangue I comprises Al₂O₃40 to 46 percent of SiO₂51 to 56 percent, C2 to E5 percent; the coal gangue II comprises Al₂O₃36-52% of SiO₂40-45% of C and 12-18% of C; the coal gangue III comprises Al₂O₃46-52%, 41-45% of SiO2 and 5-8% of C.

Further, the method comprises the following steps of: 45-70 parts of coal gangue I, 10-40 parts of coal gangue II, 10-20 parts of coal gangue III, 5-15 parts of coal powder, 5-8 parts of mineralizer and 3-5 parts of forming additive.

Further, the mineralizer comprises potassium feldspar, kyanite, a mixture of CaO and BaO, and Li₂And one or more of O.

Further, the molding additive comprises one or more of purple wood knot, industrial potato starch, sodium lignosulfonate, yellow dextrin or sodium carboxymethylcellulose.

Further, the silicon carbide combined mullite complex phase refractory material comprises: al (Al)₂O₃43-48% of SiO₂40-48% of the silicon carbide and mullite composite refractory material, wherein C is 8-12%, and the mineral phases of the silicon carbide and mullite composite refractory material comprise: the SiC phase is 8-10%, the mullite phase is 55-65%, and the rest is fused quartz and does not contain cristobalite and corundum.

According to another aspect of the invention, the preparation method for in-situ synthesizing the silicon carbide and mullite combined composite refractory material by using the coal gangue comprises the following steps: crushing and grinding the coal gangue I, the coal gangue II, the coal gangue III, the coal powder and the mineralizer respectively, sieving with a 325-mesh sieve after the fineness reaches 1250-2000 meshes to obtain coal gangue I slurry, coal gangue II slurry, coal gangue III slurry, coal powder slurry and mineralizer slurry, mixing the coal gangue I slurry, the coal gangue II slurry, the coal gangue III slurry, the coal powder slurry and the mineralizer slurry to obtain a mixed material, carrying out superfine grinding on the mixed material, and sieving with the 325-mesh sieve after the fineness reaches 4000-6000 meshes to obtain superfine powder; mixing the forming additive with water to obtain a forming additive solution, uniformly mixing the forming additive solution with the superfine powder, ageing, forming, drying, calcining, crushing and screening to obtain the silicon carbide and mullite combined composite refractory material.

Further, the drying adopts two-stage drying; the first stage is a low-temperature slow drying stage, drying is carried out by weak convection, the low-temperature slow drying stage comprises a low-temperature high-humidity stage and a constant-temperature low-humidity stage, the atmosphere humidity of the low-temperature high-humidity stage is 70 RH% -90 RH%, the drying temperature is 35-60 ℃, the air speed is controlled to be 10-14 m/s, the drying time is 3-6 h, the atmosphere humidity of the constant-temperature low-humidity stage is gradually reduced from 70 RH% -90 RH% to 10 RH% -30 RH%, the drying temperature is 40-100 ℃, the air speed is 12-16 m/s, and the drying time is 10-26 h; the second stage is a high-temperature quick-drying stage, and strong convection is adopted for drying, wherein the drying temperature is 300-800 ℃, the drying time is 10-60 min, the atmosphere humidity is less than 10 RH%, and the wind speed is more than 16 m/s.

Further, the calcination is carried out in a tunnel kiln, the calcination temperature is 1300-1420 ℃, the calcination time is 12-36 h, and the air coefficient in the tunnel kiln is 0.95-1.2.

Further, the ageing time is 3 to 4 days.

Further, the mass concentration of the forming additive in the forming additive solution is 10-50%, and the mass ratio of the forming additive solution to the superfine powder is (0.03-0.11) to 1; the molding adopts a semi-dry pressing molding method, and the pressure of the semi-dry pressing molding method is 50 t-500 t.

The invention has the following beneficial effects:

the silicon carbide and mullite combined composite refractory material disclosed by the invention comprises coal gangue I, coal gangue II, coal gangue III, coal powder, a mineralizer and a forming additive, wherein the coal gangue I, the coal gangue II and the coal gangue III are reasonably compounded to meet the requirements of the silicon carbide and mullite combined composite refractory material on the chemical components of raw materials, and the mineralizer and the forming additive are added, so that cristobalite in the silicon carbide and mullite combined composite refractory material can be completely converted into fused quartz at a lower preparation temperature in the preparation process, and the forming is promoted, so that the silicon carbide and mullite combined composite refractory material has the characteristics of strong creep resistance, and excellent toughness and impact strength. The silicon carbide and mullite combined complex phase refractory material has the characteristics of high refractoriness which can reach 1800 ℃, good high-temperature stability, low thermal expansion coefficient, small thermal conductivity, corrosion resistance, high strength, good fracture toughness and the like, and is widely applied to the fields of high-temperature structural member raw materials, special refractory bricks, saggar production and the like in the field of refractory materials. The proportion of the solid waste of the coal gangue reaches more than 80 percent, the solid waste of the coal gangue can be utilized, the production cost is reduced, the solid waste resource is recycled, and waste is changed into valuable.

The preparation method of the silicon carbide and mullite combined composite refractory material in situ synthesized by coal gangue selects coal gangue solid wastes as main raw materials, has wide raw material sources and low price, has stable components, can reduce the production cost, and improves the product stability. The raw materials are crushed, ground, mixed with slurry and then subjected to superfine grinding to prepare the 4000-6000-mesh superfine powder, and compared with other wet ball milling methods, the method has the advantages of energy and water conservation, simple process, fine powder, high efficiency and the like. The ultrafine powder and the forming additive solution containing the forming additive are uniformly mixed and then are aged, the aged powder has uniform moisture, the plasticity is greatly improved, the forming is easier, the forming strength is high, and after subsequent heat treatment, the forming additive is volatilized to form micro-pores which are easier to crush. And after long-time calcination, mullite phases in the product are in staggered growth with SiC, redundant quartz is continuously converted from phosphorosilicate quartz and cristobalite to fused quartz, and the high-temperature volume stability, creep resistance, toughness and impact strength of the product are greatly improved.

In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention is described in further detail below.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic diagram showing the transition temperature and volume change of a quartz crystal modification according to the present invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.

The silicon carbide and mullite combined complex phase refractory material comprises the following components in parts by mass: 45-70 parts of coal gangue I, 10-50 parts of coal gangue II, 0-25 parts of coal gangue III, 5-15 parts of coal powder, 5-10 parts of mineralizer and 2-8 parts of forming additive; coal gangue-Al₂O₃40 to 46 percent of SiO₂51-56% of C and 2-5% of C; the coal gangue II comprises Al₂O₃36-52% of SiO₂40-45% of C and 12-18% of C; coal gangue III including Al₂O₃46-52% of SiO₂41-45% of C and 5-8% of C.

The silicon carbide and mullite combined composite refractory material disclosed by the invention comprises coal gangue I, coal gangue II, coal gangue III, coal powder, a mineralizer and a forming additive, wherein the coal gangue I, the coal gangue II and the coal gangue III are reasonably compounded to meet the requirements of the silicon carbide and mullite combined composite refractory material on the chemical components of raw materials, and the mineralizer and the forming additive are added, so that cristobalite in the silicon carbide and mullite combined composite refractory material can be completely converted into fused quartz at a lower preparation temperature in the preparation process, and the forming is promoted, so that the silicon carbide and mullite combined composite refractory material has the characteristics of strong creep resistance, and excellent toughness and impact strength. The silicon carbide and mullite combined complex phase refractory material has the characteristics of high refractoriness which can reach 1800 ℃, good high-temperature stability, low thermal expansion coefficient, small thermal conductivity, corrosion resistance, high strength, good fracture toughness and the like, and is widely applied to the fields of high-temperature structural member raw materials, special refractory bricks, saggar production and the like in the field of refractory materials. The proportion of the solid waste of the coal gangue reaches more than 80 percent, the solid waste of the coal gangue can be utilized, the production cost is reduced, the solid waste resource is recycled, and waste is changed into valuable.

The coal gangue I comprises Al₂O₃40 to 46 percent of SiO₂51-56% of C and 2-5% of C, based on the requirements of the silicon carbide and mullite composite refractory material on chemical components, coal gangue II, coal gangue III and coal powder are required to be introduced, and the chemical components are adjusted to Al₂O₃43-48% of SiO₂40-48% of C and 8-12% of C. The silicon carbide and mullite composite refractory material is different from the conventional aluminum-silicon refractory material in the requirements on the raw materials, has requirements on Ai and Si in the raw materials and also makes certain requirements on C in the raw materials. The gangue mineral belongs to hard clay, and the main component is Al₂O₃、SiO₂And a small amount of C remaining with the coal. The coal gangue I is coal gangue of Shanxi Shuizhou, and the Shanxi Shuizhou has abundant coal gangue solid waste resources, wherein most coal gangue components are close to three-level high-alumina bauxite components, and Al of the coal gangue components is₂O₃40 to 46 percent of SiO₂51-56 percent of the total carbon content, 2-5 percent of the total carbon content, and has a certain difference with the chemical components of the silicon carbide combined mullite complex phase refractory material. Therefore, the coal gangue II, namely the coal gangue in the inner Mongolia clear water river region is introduced, and the chemical component of the coal gangue is Al₂O₃36-52% of SiO₂40-45 percent of coal gangue, 12-18 percent of C, 46-52 percent of coal gangue, and SiO₂41-45% of C and 5-8% of C. After the two coal gangues are introduced, the requirements of the silicon carbide and mullite composite refractory material on the chemical components of the raw materials are met.

As shown in figure 1, when the raw materials of the silicon carbide combined mullite complex phase refractory material are used for synthesizing a mullite product, Al₂O₃/SiO₂The ratio is 1.7-1.77, and SiO is used for synthesizing silicon carbide (SiC)₂The ratio of/C is 1 to 1.20. In the silicon carbide combined mullite multiphase refractory material, Al₂O₃43-48% of SiO₂40-48% of C and 8-12% of C, so that S is generated in the preparation process of the used raw materials coal gangue I, coal gangue II and coal gangue IIIiO₂The quartz crystal has 6-17% surplus, and the transformation temperature and volume change conditions of the quartz crystal are as follows:

quartz (SiO)₂) Will show different crystal forms with different heating temperatures, and quartz (SiO) at different temperatures₂) The crystal morphology is converted back and forth in several morphologies of quartz, phosphorosilicate quartz, cristobalite and fused quartz, the conversion process is accompanied with the change of volume, the change of volume of cristobalite is the largest in all crystal morphologies of quartz, and the volume change rate is more than 3% in the mutual conversion process of beta-cristobalite and alpha-temperature cristobalite. The reconstruction type crystal form transformation of quartz is also accompanied with huge volume change, and excessive SiO is generated if the silicon carbide and mullite composite refractory material is not treated in the preparation process of the silicon carbide and mullite composite refractory material₂Three crystal forms of the quartz, the cristobalite and the fused quartz coexist, and the service performance of the material is seriously influenced. The key for solving the problem of quartz form transformation in the silicon carbide and mullite combined complex phase refractory material is to ensure Al₂O₃Complete conversion to mullite phase, complete conversion of C to SiC phase, and excess SiO₂And (4) processing. Because the conversion temperature of mullite, SiC and quartz is higher, wherein the quartz is required to be heated to 1713 ℃ for being converted into amorphous quartz, a certain additive is required to be introduced to reduce the reaction temperature and excess SiO₂The quartz is converted into fused silica, and the cristobalite phase with large volume change is eliminated as much as possible. The additive is required to not cause excessive influence on the use temperature of the silicon carbide and mullite combined complex phase refractory material, and can convert quartz into fused quartz and convert medium cristobalite into fused quartz at a reasonable temperature. Among them, controlling the cristobalite phase transition in the product is a key to the technology. In Al₂O₃-SiO₂the-SiC system selects a mineralizer with melting-assisting effect, so that SiO is obtained₂And converted to fused silica. The converted fused silica is amorphous glass. The crystal form can not be changed when the high temperature is heated, so the strength, the heat-conducting property, the refractoriness under load, the volume stability and the creep resistance can be greatly improved. In the process of using as a refractory material, the softened fused quartz can be used as a buffer phase to buffer the silicon carbide and mullite combined complex phase resistanceVolume changes in the mineral phase system in the fire material to improve the high temperature volume stability of the entire system.

Preferably, the method comprises the following steps of: 45-70 parts of coal gangue I, 10-40 parts of coal gangue II, 10-20 parts of coal gangue III, 5-15 parts of coal powder, 5-8 parts of mineralizer and 3-5 parts of forming additive.

In this embodiment, the mineralizer comprises potash feldspar, kyanite, a mixture of CaO and BaO, and Li₂And one or more of O. Because the initial temperature of mullite synthesis is 1250 ℃ to 1700 ℃, the crystal form is completely developed. The initial temperature of the synthesis of SiC is 1300 ℃, the growth of the crystal form is completed at 1700 ℃, the production processes of the SiC and the mullite are similar, but the residual quartz exists in the forms of cristobalite, phosphorosilicate and fused quartz after the mullite phase and the SiC phase are formed by considering the actual production condition and high-temperature calcination. And the cristobalite is easy to generate crystal form transformation at high temperature, and the volume change of the cristobalite is large, so that the cristobalite is unfavorable for the high-temperature volume temperature property of the silicon carbide and mullite composite refractory material. Meanwhile, quartz is converted into fused silica at an alkali metal oxide or a proper temperature, and thus, the calcination temperature is optimized and the crystal phase conversion of quartz is adjusted by adding a mineralizer. The addition of the mineralizer enables mullite and SiC to alternately grow at a proper temperature and makes SiO superfluous₂All converted to fused silica form. The mineralizer comprises potassium feldspar, kyanite, a mixture of CaO and BaO, and Li₂And O. The mineralizer comprises potassium feldspar, kyanite, a mixture of CaO and BaO, and Li₂The total mixture of O and 1 percent of potassium feldspar in the total mixture can reduce the firing temperature by 10 ℃; potassium feldspar and K₂O content of not less than 12% so as to make K in the mixed powder₂The content of O is 1.5-2.1%; the kyanite is selected from Henan south Yang, and the addition amount is 1-3%; CaO is introduced in a form of dolomite, CaO and BaO are mixed according to the weight ratio of CaO to BaO being 2: 1, and the addition amount of the mixture is 0.6-1%; li₂The addition amount of O is 0.3-0.6%. Taking kyanite as an example, kyanite firstly undergoes decomposition reaction at high temperature to form mullite and simultaneously generate SiO in a melt phase₂In the melt phaseSintering is realized; al in cyanite ore family crystals₂O₃、SiO₂The distribution is uniform, the impurity content is low, the product structure is uniform, the phase composition after heating is closer to the thermal equilibrium state, and the performance of the silicon carbide and mullite combined complex phase refractory material is favorably improved. In addition, the mullite formed by decomposing the ground kyanite micro powder is mostly in fibrous one-way extension and disordered arrangement, so that the silicon carbide and mullite composite refractory material is endowed with fiber reinforcement, and the mechanical strength is increased.

In this embodiment, the molding additive includes one or more of butcher's-broom, industrial potato starch, sodium lignosulfonate, yellow dextrin, or sodium carboxymethylcellulose. The raw materials used above: the coal gangue I, the coal gangue II and the coal gangue III belong to raw materials with poor plasticity in the following steps, and in order to facilitate forming, a certain amount of substances with good plasticity needs to be introduced, so that forming additives are added, and the forming additives comprise purple wood knots, industrial potato starch, sodium lignin sulfonate, yellow dextrin or sodium carboxymethyl cellulose. The coal gangue in the silicon carbide and mullite composite phase refractory material is used as a main raw material, the coal gangue raw material has poor shaping performance, and after superfine grinding is carried out, the raw material is soft and has a wire drawing characteristic, so that improvement is carried out by adding a forming additive. The lignum sappan section has certain shaping property, chemical composition similar to that of coal gangue, and Al₂O₃The content is 42-45%, and the product has compatibility with the whole raw material system. The plasticity of the purple lignum sappan of Shanxi, Nemeng, etc. is not as good as that of Guangzhou white mud, but the Al thereof₂O₃42-45% of Fe₂O₃The content of (b) is 0.7-0.9%, the grade of the coal gangue raw material is closer to that of the coal gangue raw material, the integral grade of the mixed powder cannot be reduced even if the consumption is increased, the purple wood knots can be obtained from local materials, and the raw material cost is low. The potato starch, the sodium lignosulfonate, the yellow dextrin and the sodium carboxymethyl cellulose are introduced, have certain viscosity, can escape at the temperature of 100-300 ℃, and have no influence on a formula system. The potato starch, the sodium lignosulfonate, the yellow dextrin and the sodium carboxymethyl cellulose can improve the forming quality. The above-mentioned forming additive is added into the spray-dried superfine powder material in the form of aqueous solution.

In this embodiment, the silicon carbide and mullite composite refractory includes: al (Al)₂O₃43-48% of SiO₂40-48% of the silicon carbide and mullite composite refractory material, wherein the C is 8-12%, and the mineral phases of the silicon carbide and mullite composite refractory material comprise: the SiC phase is 8-10%, the mullite phase is 55-65%, and the rest is fused quartz and does not contain cristobalite and corundum. Also includes Fe₂O₃Not more than 1.5%.

According to another aspect of the invention, the preparation method for in-situ synthesizing the silicon carbide and mullite combined composite refractory material by using the coal gangue comprises the following steps: crushing and grinding the coal gangue I, the coal gangue II, the coal gangue III, the coal powder and the mineralizer respectively, sieving with a 325-mesh sieve after the fineness reaches 1250-2000 meshes to obtain coal gangue I slurry, coal gangue II slurry, coal gangue III slurry, coal powder slurry and mineralizer slurry, mixing the coal gangue I slurry, the coal gangue II slurry, the coal gangue III slurry, the coal powder slurry and the mineralizer slurry to obtain a mixed material, carrying out superfine grinding on the mixed material, and sieving with the 325-mesh sieve after the fineness reaches 4000-6000 meshes to obtain superfine powder; mixing the forming additive with water to obtain a forming additive solution, uniformly mixing the forming additive solution with the superfine powder, ageing, forming, drying, calcining, crushing and screening to obtain the silicon carbide and mullite combined composite refractory material. The fineness of the ground detection slurry is detected by a laser particle sizer.

According to the preparation method for in-situ synthesis of the silicon carbide and mullite combined composite refractory material by utilizing the coal gangue, the coal gangue solid waste is selected as a main raw material, the raw material source is wide, the price is low, the components are stable, the production cost can be reduced, and the product stability is improved. The raw materials are crushed, ground, mixed with slurry and then subjected to superfine grinding to prepare the 4000-6000-mesh superfine powder, and compared with other wet ball milling methods, the method has the advantages of energy and water conservation, simple process, fine powder, high efficiency and the like. The ultrafine powder and the forming additive solution containing the forming additive are uniformly mixed and then are aged, the aged powder has uniform moisture, the plasticity is greatly improved, the forming is easier, the forming strength is high, and after subsequent heat treatment, the forming additive is volatilized to form micro-pores which are easier to crush. And after long-time calcination, mullite phases in the product are in staggered growth with SiC, redundant quartz is continuously converted from phosphorosilicate quartz and cristobalite to fused quartz, and the high-temperature volume stability, creep resistance, toughness and impact strength of the product are greatly improved.

The coal gangue solid waste is used as a main raw material, in order to mix the raw materials uniformly and increase the surface activation energy, each raw material except a forming additive is crushed and ground independently to achieve the effect of homogenizing the raw materials, and then the raw materials are formed into a formula and are ground in an ultra-fine mode, so that different materials are mixed uniformly and ground again to achieve the target fineness. And drying the superfine ground mixed material in a spray drying mode, wherein all raw materials except the forming additive are subjected to spray drying. And adding water and a forming additive into the dried powder, uniformly mixing the powder by a mixer, and feeding the powder into a bin for ageing. Mixing the dried superfine powder with a forming additive solution, wherein the forming additive is dissolved in water and then uniformly mixed with the superfine powder in a concentrated manner because the water and the forming additive are required to be added for forming the superfine powder. The ultrafine powder and water are intensively mixed and stirred to be fully mixed, otherwise, ash packing is easily caused, and then aging is carried out, so that the moisture has enough 'migration' time, and the aim of uniformly mixing the water and the ultrafine powder is fulfilled.

The internal crystalline phase of the silicon carbide and mullite composite refractory material grows uniformly in the product, and the principle of staggered growth of the mullite phase and the SiC whiskers is taken as a principle, the silicon carbide and mullite composite refractory material can achieve the best performance in this state, the SiC whiskers are mullite crystals and toughen, increase the physical strength and increase the high-temperature volume stability, so that the uniformity and the stability of each component of the raw materials are required to be ensured, the raw materials are required to reach quite high fineness, different coal gangue raw ores are independently crushed and ground, ingredients are uniformly mixed and then subjected to superfine grinding, wherein the superfine grinding fineness reaches 4000-6000 meshes, and the internal components are uniformly mixed.

In this embodiment, the drying is performed in two stages; the first stage is a low-temperature slow drying stage, drying is carried out by weak convection, the low-temperature slow drying stage comprises a low-temperature high-humidity stage and a constant-temperature low-humidity stage, the atmosphere humidity of the low-temperature high-humidity stage is 70 RH% -90 RH%, the drying temperature is 35-60 ℃, the air speed is controlled to be 10-14 m/s, the drying time is 3-6 h, the atmosphere humidity of the constant-temperature low-humidity stage is gradually reduced from 70 RH% -90 RH% to 10 RH% -30 RH%, the drying temperature is 40-100 ℃, the air speed is 12-16 m/s, and the drying time is 10-26 h. And drying the semi-finished product obtained after molding, drying the moisture of the semi-finished product, increasing the strength of the semi-finished product, and preventing the surface of the semi-finished product from cracking by using a weak convection low-temperature high-humidity and constant-temperature low-humidity drying mode so as to synchronously dry the interior and the exterior of the semi-finished product. The second stage is a high-temperature quick-drying stage, and strong convection is adopted for drying, wherein the drying temperature is 300-800 ℃, the drying time is 10-60 min, the atmosphere humidity is less than 10 RH%, and the wind speed is more than 16 m/s. The surface of the semi-finished product is quickly contracted, the air holes are closed, the surface hardening and closing effects are achieved, and oxygen is better prevented from entering the interior of the semi-finished product during calcination.

In the embodiment, the calcination is carried out in a tunnel kiln, the calcination temperature is 1300-1420 ℃, the calcination time is 12-36 h, and the air coefficient in the tunnel kiln is 0.95-1.2. Because the production condition of SiC needs a reducing atmosphere to be carried out, and based on the requirements of mullite and SiC on a firing system, the firing system is flexibly adjusted by adopting a tunnel kiln for calcining, the tunnel kiln can adjust the air coefficient, the heat preservation time is long, the yield is large, and the production is suitable for production. The traditional SiC material production method generally adopts a carbothermic reduction method, namely a commonly-known carbon-burying process, excessive C is needed to ensure sufficient combination of C and Si, and the method is not suitable for producing silicon carbide combined mullite complex phase refractory materials, and a precursor conversion method, a chemical gas phase machine method, a Si/C direct synthesis method and the like are only suitable for laboratory tests and are not suitable for industrial production. However, the calcination treatment in the tunnel kiln can still form ideal mullite phase and SiC phase even under the conditions of limited C content and weak reducing atmosphere, so that the mullite and the SiC whisker can synchronously and alternately grow under a reasonable firing system, and the invention is the inventionOne of the key processes of (1). When the tunnel kiln is fired, the atmosphere and the firing degree in the kiln can be flexibly conditioned, so that the internal crystal phase of the product is completely developed, after the long-time firing, mullite phase and SiC in the product are in staggered growth, redundant quartz is continuously converted from phosphorite and cristobalite to fused quartz, and the high-temperature volume stability, creep resistance, toughness and impact strength of the product are greatly improved. The silicon carbide and mullite combined complex phase refractory material comprises: al (Al)₂O₃43-48% of SiO₂40-48%, C8-12%, Fe₂O₃Not more than 1.5%. Under the weak reducing atmosphere, part of C can not be combined with Si to form SiC, so that part of C is introduced in a form of adding coal powder, the coal powder is also crushed, ground and superfine ground, and the ash component after the coal powder is combusted is similar to that of coal-series kaolin calcined by coal gangue.

Preferably, the time period of staling is 3 to 4 days.

In the embodiment, the mass concentration of the forming additive in the forming additive solution is 10-50%, and the mass ratio of the forming additive solution to the superfine powder is (0.03-0.11) to 1; the molding adopts a semi-dry pressing molding method, and the pressure of the semi-dry pressing molding method is 50 t-500 t. The raw material is ground by adopting the superfine grinding process, and the superfine grinding has great influence on the physical properties of the raw material, so the raw material is formed by adopting a semi-dry pressing forming method. Wherein, the water content of the semi-dry pressing is controlled to be 3-11%, the pressing pressure is controlled to be 50-500 t according to different formulas.

Examples

Example 1

The silicon carbide and mullite combined complex phase refractory material comprises the following components in parts by mass: 47 parts of coal gangue I, 20 parts of coal gangue II, 20 parts of coal gangue III, 5 parts of coal powder, 5 parts of potash feldspar and 3 parts of purple wood knots;

the coal gangue I is selected from coal gangue Al in the Shanxi Shuiao₂O₃40 to 46 percent of SiO₂51-56%, C2-5%, Fe₂O₃0.2-1.2%;

the coal gangue II is selected from inner Mongolia clear water river coal gangue and Al₂O₃36-52% of SiO₂40-45%, C12-18%, Fe₂O₃0.5 to 0.9 percent;

the coal gangue III is selected from high-aluminum coal gangue and Al in the Shanxi Shuozhou region₂O₃46-52% of SiO₂41 to 45 percent of C, 5 to 8 percent of C and Fe₂O₃1.2 to 1.5 percent.

The preparation method for in-situ synthesizing the silicon carbide and mullite composite refractory material by utilizing the coal gangue comprises the following steps:

crushing the coal gangue I, the coal gangue II, the coal gangue III, the coal powder and the mineralizer by a jaw crusher respectively, feeding the crushed coal gangue I, the coal gangue II, the coal gangue III, the coal powder and the mineralizer into a superfine grinding machine for grinding, sieving the crushed coal gangue I, the coal gangue II, the coal gangue III, the coal powder and the mineralizer to 1500 meshes, and then mixing the coal gangue I, the coal gangue II, the coal gangue III, the coal powder and the mineralizer to obtain a mixed material;

the mixed material is sent into a superfine grinding machine for superfine grinding, is ground to 4000 meshes and then is sieved by a 325-mesh sieve, and is spray-dried by a spray drying tower to obtain superfine powder which is conveyed to a storage bin for standby;

mixing the forming additive with water to obtain a forming additive solution, wherein the mass concentration of the forming additive in the forming additive solution is 50%;

uniformly mixing the forming additive solution and the superfine powder, wherein the forming additive solution accounts for 5% of the mass of the superfine powder;

aging for 3 days, molding in high pressure press mud, and extruding into cylindrical semi-finished product of 5cm × 5 cm;

drying the semi-finished product in a two-stage manner, wherein the first stage is a low-temperature slow drying stage, drying is carried out by weak convection, the drying temperature is 100 ℃, and the drying time is 5 hours; the second stage is a high-temperature quick-drying stage, and drying is carried out by adopting strong convection, wherein the drying temperature is 350 ℃, and the drying time is 20 min;

and (3) feeding the dried semi-finished product into a tunnel kiln for calcination at 1400 ℃ for 26h, wherein the air coefficient in the tunnel kiln is 1.2, crushing and screening to obtain the silicon carbide and mullite combined complex phase refractory material.

Example 2

The silicon carbide and mullite combined complex phase refractory material comprises the following components in parts by mass: 67 parts of coal gangue I, 10 parts of coal gangue II, 11 parts of coal powder, 7 parts of kyanite and 5 parts of butea monosperma;

the coal gangue I is selected from coal gangue Al in the Shanxi Shuiao₂O₃40 to 46 percent of SiO₂51-56%, C2-5%, Fe₂O₃0.2-1.2%;

the coal gangue II is selected from inner Mongolia clear water river coal gangue and Al₂O₃36-52% of SiO₂40-45%, C12-18%, Fe₂O₃0.5 to 0.9 percent;

the coal gangue III is selected from high-aluminum coal gangue and Al in the Shanxi Shuozhou region₂O₃46-52% of SiO₂41 to 45 percent of C, 5 to 8 percent of C and Fe₂O₃1.2 to 1.5 percent.

The preparation method for in-situ synthesizing the silicon carbide and mullite composite refractory material by utilizing the coal gangue comprises the following steps:

crushing the coal gangue I, the coal gangue II, the coal gangue III, the coal powder and the mineralizer by a jaw crusher respectively, feeding the crushed coal gangue I, the coal gangue II, the coal gangue III, the coal powder and the mineralizer into a superfine grinding machine for grinding, sieving the crushed coal gangue I, the coal gangue II, the coal gangue III, the coal powder and the mineralizer to 1800 meshes, and mixing the coal gangue I, the coal gangue II, the coal gangue III, the coal powder and the mineralizer to obtain a mixed material;

carrying out superfine grinding on the mixed material, grinding the mixed material to 5000 meshes, then sieving the ground material by a 325-mesh sieve, carrying out spray drying on the ground material by a spray drying tower to obtain superfine powder, and conveying the superfine powder to a storage bin for later use;

mixing the forming additive with water to obtain a forming additive solution, wherein the mass concentration of the forming additive in the forming additive solution is 30%;

uniformly mixing the forming additive solution and the superfine powder, wherein the mass of the forming additive solution is 11 percent of that of the superfine powder;

aging for 3 days, molding in high pressure press mud, extruding into cylindrical semi-finished product of 5cm × 5cm,

drying the semi-finished product in a two-stage manner, wherein the first stage is a low-temperature slow drying stage, and drying is carried out by weak convection, the drying temperature is 120 ℃, and the drying time is 3.5 hours; the second stage is a high-temperature quick-drying stage, drying is carried out by adopting strong convection, the drying temperature is 420 ℃, and the drying time is 15 min;

and (3) feeding the dried semi-finished product into a tunnel kiln for calcination at 1380 ℃ for 36 hours, wherein the air coefficient in the tunnel kiln is 1, crushing and screening to obtain the silicon carbide and mullite combined complex phase refractory material.

Example 3

The silicon carbide and mullite combined complex phase refractory material comprises the following components in parts by mass: 47 parts of coal gangue I, 20 parts of coal gangue II, 20 parts of coal gangue III, 5 parts of coal powder, 1.8% of potassium feldspar, 1.7% of kyanite, 1% of mixture of CaO and BaO, and Li₂The total mixture of O is 0.5 percent, and the rosewood knot is 3 parts;

the coal gangue I is selected from coal gangue Al in the Shanxi Shuiao₂O₃40 to 46 percent of SiO₂51-56%, C2-5%, Fe₂O₃0.2-1.2%;

the coal gangue II is selected from inner Mongolia clear water river coal gangue and Al₂O₃36-52% of SiO₂40-45%, C12-18%, Fe₂O₃0.5 to 0.9 percent;

the coal gangue III is selected from high-aluminum coal gangue and Al in the Shanxi Shuozhou region₂O₃46-52% of SiO₂Is 41 ℃

45%, 5-8% of C and Fe₂O₃1.2 to 1.5 percent.

The preparation method for in-situ synthesizing the silicon carbide and mullite composite refractory material by utilizing the coal gangue comprises the following steps:

crushing the coal gangue I, the coal gangue II, the coal gangue III, the coal powder and the mineralizer by a jaw crusher respectively, feeding the crushed coal gangue I, the coal gangue II, the coal gangue III, the coal powder and the mineralizer into a superfine grinding machine for grinding, sieving the crushed coal gangue I, the coal gangue II, the coal gangue III, the coal powder and the mineralizer to obtain coal gangue I slurry, coal gangue II slurry, coal gangue III slurry, coal powder slurry and mineralizer slurry, and mixing the coal gangue I slurry, the coal gangue II slurry, the coal gangue III slurry, the coal powder and the mineralizer slurry to obtain a mixed material;

the mixed material is sent into a superfine grinding machine for superfine grinding, the mixed material is ground to 4800 meshes and then is sieved by a 325-mesh sieve, and spray drying is carried out by a spray drying tower to obtain superfine powder which is conveyed to a storage bin for standby;

mixing the forming additive with water to obtain a forming additive solution, wherein the mass concentration of the forming additive in the forming additive solution is 40%;

uniformly mixing the forming additive solution and the superfine powder, wherein the forming additive solution accounts for 6% of the mass of the superfine powder;

aging for 4 days, molding in high pressure press mud, and extruding into cylindrical semi-finished product of 5cm × 5 cm;

drying the semi-finished product in a two-stage manner, wherein the first stage is a low-temperature slow drying stage, drying is carried out by weak convection, the drying temperature is 100 ℃, and the drying time is 5 hours; the second stage is a high-temperature quick-drying stage, and drying is carried out by adopting strong convection, wherein the drying temperature is 350 ℃, and the drying time is 20 min;

and (3) feeding the dried semi-finished product into a tunnel kiln for calcination at 1400 ℃ for 26h, wherein the air coefficient in the tunnel kiln is 1.2, crushing and screening to obtain the silicon carbide and mullite combined complex phase refractory material.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.