阅读说明：本技术 一种镁铬耐火材料的制备方法 (Preparation method of magnesium-chromium refractory material ) 是由 钱凡 李红霞 刘国齐 杨文刚 马渭奎 于建宾 于 2019-10-15 设计创作，主要内容包括：本发明属于镁铬耐火材料制备技术领域,提出的一种镁铬耐火材料的制备方法：制备方法为以基质原料反应生成的CaO·6Al<Sub>2</Sub>O<Sub>3</Sub>为最终基质,以镁铬砂颗粒、铬精矿颗粒为骨料,将基质原料在振动罐里进行充分混匀后与镁铬砂颗粒、铬精矿颗粒一起在强制搅拌机中进行混炼得到坯料,得到的坯料在液压机上成型砖坯,将成型后的砖坯送入干燥窑内进行干燥,干燥窑热风温度为100℃,干燥时间为30h,将干燥的砖坯在窑炉里进行热处理形成以CaO·6Al<Sub>2</Sub>O<Sub>3</Sub>为主要结合相的镁铬耐火材料。该耐火材料与传统镁铬砖相比,具有强度高,烧成温度低,抗热震性好、抗碱性溶渣侵蚀优的特点。(The invention belongs to the technical field of preparation of a magnesium-chromium refractory material, and provides a preparation method of the magnesium-chromium refractory material, which comprises the following steps: the preparation method is that CaO.6 Al generated by the reaction of the substrate raw material 2 O 3 Taking the magnesia-chromite particles and the chrome concentrate particles as aggregates as final substrates, fully mixing the substrate raw materials in a vibration tank, mixing the mixture with the magnesia-chromite particles and the chrome concentrate particles in a forced mixer to obtain blanks, forming the blanks on a hydraulic press to obtain adobes, feeding the formed adobes into a drying kiln for drying, controlling the hot air temperature of the drying kiln to be 100 ℃ and the drying time to be 30 hours, and carrying out heat treatment on the dried adobes in the kiln to form the CaO 6Al aggregate 2 O 3 Is a magnesium-chromium refractory material of a main binding phase. Compared with the traditional magnesia-chrome brick, the refractory material has the characteristics of high strength, low firing temperature, good thermal shock resistance and excellent alkaline slag corrosion resistance.)

1. A preparation method of a magnesium-chromium refractory material is characterized by comprising the following steps: the preparation method is that CaO.6 Al generated by the reaction of the substrate raw material₂O₃Taking the magnesite-chrome sand particles and the chrome concentrate particles as aggregates as final matrixes, fully mixing the raw materials of the matrixes in a vibration tank, mixing the raw materials of the matrixes, the magnesite-chrome sand particles and the chrome concentrate particles together in a forced mixer to obtain blanks, forming the blanks on a hydraulic press to obtain adobes, feeding the formed adobes into a drying kiln for drying, performing heat treatment on the dried adobes in the kiln at the hot air temperature of 100 ℃ for 30h, wherein the heat treatment temperature is 1350 ~ 1500 ℃, and CaO and Al are generated on the matrixes in the heat treatment process₂O₃→CaO·6Al₂O₃Form CaO.6 Al₂O₃A magnesium-chromium refractory material as a primary binder phase; the matrix raw materials comprise fine alumina powder, fine magnesia powder, fine chromium powder, calcium carbonate and a bonding agent.

2. The method for preparing the magnesium-chromium refractory according to claim 1, wherein the median diameter of the fine alumina powder is less than 3 μm, and the addition amount of the fine alumina powder is 20 ~ 30% of the total mass of the raw materials.

3. The method of claim 1, wherein the refractory material comprises: the alumina fine powder is one of calcined alumina or activated alumina.

4. The method for preparing the magnesia-chrome refractory material according to claim 1, wherein the granularity of the magnesite fine powder is less than 44 μm, and the addition amount of the magnesite fine powder is 3 ~ 6% of the total mass of the raw materials.

5. The method of claim 1, wherein the refractory material comprises: the fine magnesia powder is one of light-burned magnesia, heavy-burned magnesia or electric-melted magnesia.

6. The method of claim 1, wherein the refractory material comprises: the granularity of the chromium fine powder is less than 44 mu m, and SiO in the chromium fine powder₂Content of (3) is less than 1.5%, Cr₂O₃The mass ratio of FeO is more than 3.0, and the adding amount is 3 ~ 8 percent of the total mass of the raw materials.

7. The method for preparing the magnesium-chromium refractory material of claim 1, wherein the grain size of the calcium carbonate is less than 4 μm, the CaCO3 is more than 99.5 percent, and the addition amount is 1 ~ 4 percent of the total mass of the raw materials.

8. The method for preparing the magnesium-chromium refractory material according to claim 1, wherein the binder is anhydrous and non-hydroxyl resin, and the addition amount of the anhydrous and non-hydroxyl resin is 1.5 ~ 2.5.5% of the total mass of the raw materials.

9. The method of claim 1, wherein the refractory material comprises: the magnesite-chrome sand particles are fused magnesite-chrome sand, and the composition of the fused magnesite-chrome sand particles meets the following conditions: cr (chromium) component₂O₃＞20%，Fe₂O₃＜8.0%，SiO₂Less than 1 percent, the granularity of 5-3mm is 20 ~ 30 percent, the granularity of 3-1mm is 15 ~ 30 percent, and the granularity of 1-0.044mm is 5 ~ 15 percent.

10. The method of claim 1, wherein the refractory material comprises: the composition of the chromium concentrate particles needs to meet the condition SiO₂＜1.5%，Cr₂O₃The mass ratio of FeO is more than 3.0, the granularity is less than 1mm and more than 0.044mm, and the adding amount is 4 ~ 15 percent of the total mass of the raw materials.

Technical Field

The invention belongs to the technical field of magnesium-chromium refractory materials, and mainly relates to a preparation method of a magnesium-chromium refractory material.

Background

The magnesium-chromium refractory material is a basic refractory material taking periclase, magnesium and hercynite (Mg, Fe) (Cr, Al, Fe)2O4 as main crystal phases, has high refractoriness, high-temperature strength, excellent thermal shock stability, slag erosion resistance and economy, is widely applied to high-temperature industries such as steel, nonferrous metal, cement and the like, and is a leading material of key parts of furnace linings of a plurality of high-temperature equipment. Chrome ore, sintered magnesite and fused magnesite are basic raw materials for producing magnesia-chrome refractory materials, and magnesia-chrome refractory materials suitable for different working conditions can be prepared by adopting different proportions and brick making processes, such as patents ZL201310030945.3, ZL2009100332773 and ZL 201310242270.9. Said invention is characterized by that the firing temp. of the described magnesium-chromium brick can be up to above 1700 deg.C, so that the magnesium-chromium refractory material of magnesium-chromium spinel binding phase can be formed.

Calcium hexaluminate (CaAl)₁₂O₁₉Abbreviated as CA₆) Is CaO-Al₂O₃In system Al₂O₃The calcium aluminate phase with the highest content has a melting point higher than 1875 ℃ and a thermal expansion coefficient of 8.0 x 10-6 DEG C^-1Low solubility in iron-containing slag; high stability in reducing atmosphere (CO), good chemical stability in alkaline environment, low wettability to molten metal and slag (steel and nonferrous metals), large main crystal region, low solubility in several kinds of multicomponent systems, and high thermal expansion coefficient and Al₂O₃Similarly, it can be used in combination with alumina in any proportion, and these properties make CA₆Has wide application prospect in high temperature industry.

From the above, magnesium chromium spinel and calcium hexaluminate belong to basic refractory materials, so that the characteristics of the magnesium chromium spinel and the calcium hexaluminate are combined to develop a high-cost-performance basic refractory material.

Disclosure of Invention

The invention aims to overcome the defects and provides a preparation method of a magnesium-chromium refractory material.

The technical scheme is as follows:

alumina, calcium carbonate, magnesite and chrome ore as main materialReaction occurring during the heat treatment, CaO + Al₂O₃→CaO·6Al₂O₃Thus forming the calcium hexaluminate bonded magnesium chromium refractory material.

The specific preparation method of the invention is as follows: the preparation method is that CaO.6 Al generated by the reaction of the substrate raw material₂O₃Taking the magnesite-chrome sand particles and the chrome concentrate particles as aggregates as final matrixes, fully mixing the raw materials of the matrixes in a vibration tank, mixing the raw materials of the matrixes, the magnesite-chrome sand particles and the chrome concentrate particles together in a forced mixer to obtain blanks, forming the blanks on a hydraulic press to obtain adobes, feeding the formed adobes into a drying kiln for drying, performing heat treatment on the dried adobes in the kiln at the hot air temperature of 100 ℃ for 30h, wherein the heat treatment temperature is 1350 ~ 1500 ℃, and CaO and Al are generated on the matrixes in the heat treatment process₂O₃→CaO·6Al₂O₃Form CaO.6 Al₂O₃A magnesium-chromium refractory material as a primary binder phase; the matrix raw materials comprise fine alumina powder, fine magnesia powder, fine chromium powder, calcium carbonate and a bonding agent.

The alumina fine powder has a median diameter of less than 3 μm, an addition amount of 15 ~ 25%, and is one of calcined alumina and activated alumina, the calcium carbonate fine powder has a median diameter of less than 3 μm, an addition amount of 5 ~ 10%, and CaCO₃＞99.5%。

The fine powder of magnesium oxide is less than 44 μm, MgO is more than 97%, the addition amount is 3 ~ 6%, and the fine powder can be one of light-burned magnesium oxide, heavy-burned magnesium oxide or electric-melted magnesium oxide, the fineness of chromium fine powder is less than 44 μm, and SiO is₂＜1.5%，Cr₂O₃FeO (mass ratio) is more than 3.0, the adding amount is 3 ~ 8%, and the binding agent is anhydrous hydroxyl-free resin, and the adding amount is 1.5 ~ 2.5.5%.

The granular material comprises fused magnesia-chrome sand and Cr₂O₃＞20%，Fe₂O₃＜8.0%，SiO₂Less than 1%, granularity of 20 ~ 30% for 5-3mm, 15 ~ 30% for 3-1mm, 4 ~ 15% for 1-0.044mm, chromium concentrate, SiO₂＜1.5%，Cr₂O₃FeO (mass ratio) is more than 3.0, the particle size is less than 1mm and more than 0.044mm, and the addition amount is 5 ~ 15%.

Effect of the inventionThe calcium carbonate and the alumina in the matrix can form a calcium hexaluminate binding phase at 1350 ~ 1500 ℃ and part of the alumina in the matrix can be dissolved into the magnesia-chromite and the chrome concentrate particles to promote the binding of the matrix and the aggregate, and the following reaction of MgO + Al occurs at the dry start at 1000 ℃ or so₂O₃→MgO·Al₂O₃And when the alumina is excessive, the alumina can be dissolved into the spinel in a solid way to form aluminum-rich magnesia-alumina spinel, magnesia-chromite sand or partial silicate phase in the magnesia grain boundary, and CaCO3 can further promote the precipitation of the substances and newly form a high-alkali phase, further promote the connection between aggregates and improve the compactness of the material.

Compared with the common magnesia-chrome brick, the calcium hexaluminate combined magnesia-chrome brick has low firing temperature, the price of calcium carbonate in the raw materials for preparation is low, the conventional physical properties are obviously characterized by high strength and low porosity compared with the conventional magnesia-chrome brick, and the thermal expansion coefficient of the calcium hexaluminate is lower than that of magnesia-chrome spinel, so that the thermal shock resistance of the calcium hexaluminate combined magnesia-chrome brick is better than that of the conventional magnesia-chrome refractory material.

Detailed Description