Novel Al2O3-MgO-TiFe composite refractory material

Abstract

The invention belongs to the field of refractory materials. The invention provides a novel Al2O3-MgO-TiFe composite refractory material which comprises the following raw materials in percentage by weight: 50-75% of Al2O3, 30-50% of MgO, 5-15% of ferrotitanium and phenolic resin which accounts for 2-6% of the total weight of the raw materials and is used as a binding agent. The preparation method comprises the following steps: uniformly mixing the raw materials with a binding agent, carrying out compression molding, drying to obtain an Al2O3-MgO-TiFe composite blank, and sintering the Al2O3-MgO-TiFe composite blank in an air atmosphere at the temperature of 1100-1600 DEG C; the designed Al2O3-MgO-TiFe series new material can react under the oxidizing atmosphere to generate a multi-component compound, Ti and Fe react with Al2O3 and MgO through in-situ oxidation under the oxidizing atmosphere to generate a compound of a MgO-Al2O3-TiO2 and Al2O3-MgO-FeO system, metal directly participates in the reaction, the oxygen partial pressure of the system can be regulated and controlled, and stable existence of ferrous ions is ensured. The series of compounds have good calcium ion corrosion resistance and anti-stripping performance.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials, and particularly relates to a novel Al2O3-MgO-TiFe composite refractory material. Background Technology

[0002] Magnesium-iron-aluminum spinel bricks, a refractory material proposed by RHI in the 1990s, are composed of magnesium oxide (MgO) and iron-aluminum spinel (FeAl2O4). This refractory material possesses a relatively high toughness structure, significantly reducing its brittleness. When the iron-aluminum spinel mineral phase comes into contact with cement clinker, it reacts with calcium oxide to form high-viscosity calcium ferrite and aluminum ferrite phases. The reaction layer on the hot surface of the material greatly promotes the formation of the binder layer within the rotary kiln. The preparation of magnesium-iron-aluminum spinel using the electrofusion method is currently the most advanced industrial method. The mainstream method usually involves high temperatures above 2200℃. This process consumes a lot of energy and requires precise control of the furnace atmosphere (usually under a weak reducing atmosphere) to ensure that iron exists stably in the form of Fe²⁺. If not properly controlled, it can lead to the oxidation of FeO or its excessive reduction to metallic iron, affecting the phase composition and properties of the final product. When preparing iron-aluminum spinel and magnesium-iron-aluminum spinel using FeO or other iron oxides as raw materials, controlling the valence state of iron compounds under an oxidizing atmosphere is a key technical challenge.

[0003] MgO-Al2O3-TiO2 series refractories replace Cr-containing materials in cement rotary kiln firing, heavy non-ferrous metal smelting, and RH refining. 6+ It exhibits good performance; when used in a cement kiln, MgO reacts with TiO2 to form Mg2TiO4, and the generated Mg2TiO4 reacts with Ca3SiO5, Ca2SiO4, Ca3Al2O6 and Ca4Al present in the cement. l2 Fe2O 10 The reaction exhibits good kiln coating performance, and the CaTiO3 formed in the reaction layer enhances the material's erosion resistance. When applied in heavy non-ferrous metal smelting and RH, it enhances the material's erosion resistance by forming a dense (Mg, Mn, Fe)2TiO4-(Mg, Mn, Fe)Al2O4 spinel solid solution. Summary of the Invention

[0004] Due to the excellent performance of titanium-containing compounds in oxide refractory materials, a novel Al2O3-MgO-TiFe system refractory material was designed. The Al2O3-MgO-TiO2-FeO system multi-component compound was obtained through in-situ metal oxidation. When used in areas with severe calcium pollution such as cement kilns, it has good anti-erosion and anti-spasting properties. This invention further improves the performance of refractory materials.

[0005] The technical solution adopted by the present invention to achieve the above objectives is as follows: A novel Al2O3-MgO-TiFe composite refractory material, by weight percentage, comprises: 50-75% Al2O3, 30-50% MgO, 5-15% titanium-iron alloy, plus 2-6% phenolic resin as a binder; the titanium-iron alloy is one of low titanium-iron (25wt%-30wt%), medium titanium-iron (35wt%-45wt%), and high titanium-iron (65wt%-75wt%).

[0006] The Al2O3 includes tabular corundum, fused alumina, and brown corundum.

[0007] The MgO mentioned includes sintered magnesia, fused magnesia, and brine magnesia.

[0008] The Al2O3 has three particle sizes: 3-1 mm, 1-0.1 mm, and 0.1-0 mm; the magnesia has three particle sizes: 1-0.1 mm and 0.1-0 mm; the titanium-iron alloy has a particle size of 1-0.1 mm; the ratio of the three different particle sizes is as follows: 3≤particle size<1mm 45-65%; 1% ≤ Particle size < 0.1mm; 18-30% 0.1 ≤ particle size < 0 mm 17-30%.

[0009] The preparation method of the above-mentioned Al2O3-MgO-TiFe composite refractory material includes the following steps.

[0010] (1) Weigh all the raw materials according to the proportions, mix them evenly, and knead them to obtain the mud. (2) Press the prepared mud into shape and dry it.

[0011] (3) The dried blank is fired at high temperature to obtain the required refractory material.

[0012] Furthermore, the drying temperature is 120-600℃, and the holding time is 5-25h.

[0013] Furthermore, the firing temperature is 1100-1600℃, the heating rate is 5-15℃ / min, the holding time is 2-16h, and the firing atmosphere is air.

[0014] Furthermore, the firing methods include tunnel kilns, shuttle kilns, and electric furnaces.

[0015] Titanium-iron alloys are a type of intermediate alloy between titanium and iron. In addition to titanium and iron, they also contain small amounts of aluminum, silicon, and carbon. Based on the percentage of titanium by mass, they are mainly divided into three categories: low-titanium ferroalloys (25wt%-30wt%), medium-titanium ferroalloys (35wt%-45wt%), and high-titanium ferroalloys (65wt%-75wt%). The production of titanium-iron alloys differs from the complex production process of sponge titanium. It is prepared using the aluminothermic reduction method, which uses metallic aluminum to reduce and replace iron and titanium in the raw materials. The aluminothermic reaction is accompanied by a large amount of heat release, which ensures the smooth progress of the reaction and the separation of slag and metal. This method has the advantages of wide availability of raw materials, low energy consumption, and low production cost.

[0016] The present invention proposes a novel Al2O3-MgO-TiFe composite refractory material, which, by adopting the above-mentioned technical solution, has the following beneficial effects: Introducing TiFe alloys into refractory materials and forming MgO-Al2O3-TiO2 and Al2O3-MgO-FeO systems through high-temperature sintering processes; the TiFe element in the system is introduced in the form of alloys, which, compared to the form of oxides, can introduce highly active titanium source compounds and simultaneously promote the formation of iron-aluminum spinel (FeAl2O4) and magnesium-iron-aluminum spinel by maintaining a low oxygen partial pressure during sintering. When preparing iron-aluminum spinel and magnesium-iron-aluminum spinel using FeO or other iron oxides as raw materials, controlling the valence state of iron compounds under oxidizing atmosphere sintering processes is a technical challenge. However, by introducing TiFe, the formation of iron-aluminum spinel can be promoted on the basis of titanium compound reinforcement.

[0017] Due to the presence of numerous intermediate compounds, metallic Ti undergoes stepwise oxidation during heating, which facilitates its direct participation in the formation of ternary oxide systems under high-temperature conditions. Meanwhile, the relatively low oxygen partial pressure promotes the stable presence of ferrous ions, ensuring the formation of iron-aluminum spinel or magnesium-iron-aluminum spinel within the system.

[0018] During the sintering process, oxides undergo significant volume shrinkage, resulting in a material with numerous pores and a loose volume after sintering. Introducing them in the form of TiFe alloys, which have high density and undergo volume expansion during oxidation, helps to fill the pores and create a compact structure.

[0019] By introducing the metallic phase TiFe, the problems of atmosphere control during the firing process of magnesium-iron-aluminum spinel and the difficulty in firing MgO-Al2O3-TiO2 refractory materials were solved simultaneously. Detailed Implementation

[0020] The present invention will be described in detail with reference to specific embodiments: Example 1:

[0021] The raw material composition, by weight percentage, is: 65wt% corundum, 30wt% magnesia, 5wt% ferrotitanium alloy, and 3% thermosetting phenolic resin. During production, the various raw materials are weighed according to the formula, mixed evenly, and kneaded to obtain a clay mixture. This clay is then pressed into shape using a friction press and dried at 260℃ for 20 hours. The added corundum is sintered corundum with particle sizes of 3-1mm and 1-0.1mm; the added magnesia is sintered magnesia with particle sizes of 1-0.1mm and 0.1-0mm; and the added ferrotitanium alloy is medium-sized ferrotitanium with a titanium content of 42wt% and a particle size of less than 200 mesh. The mixture is then sintered in an electric furnace at 1300℃ in an air atmosphere for 4 hours. The sintered phases consist of Al2O3, Mg2TiO4, and MgFeAlO4. The performance indicators of the obtained product are: apparent porosity 7.9%, and bulk density 3.34 g / cm³. 3 Its compressive strength at room temperature is 109 MPa. Example 2:

[0022] The raw material composition, by weight percentage, is: 60wt% corundum, 32wt% magnesia, 8wt% ferrotitanium alloy, and 3wt% thermosetting phenolic resin. During production, the various raw materials are weighed according to the formula, mixed evenly, and kneaded to obtain a clay mixture. This clay is then pressed into shape using a friction press and dried at 260℃ for 20 hours. The added corundum is sintered corundum with particle sizes of 3-1mm and 1-0.1mm; the added magnesia is sintered magnesia with particle sizes of 0.1-0mm; and the added ferrotitanium alloy is medium-sized ferrotitanium with a titanium content of 42wt% and a particle size of less than 200 mesh. The mixture is then sintered in an electric furnace at 1300℃ in an air atmosphere for 4 hours. The sintered phases consist of Al2O3, MgAl2O4, Mg2TiO4, and MgFeAlO4. The performance indicators of the obtained product are: apparent porosity 13.4%, and bulk density 3.19 g / cm³. 3 Its compressive strength at room temperature is 88 MPa. Example 3:

[0023] The raw material composition, by weight percentage, is: 60wt% corundum, 32wt% magnesia, 8wt% ferrotitanium alloy, and 3wt% thermosetting phenolic resin. During production, the various raw materials are weighed according to the formula, mixed evenly, and kneaded to obtain a clay mixture. This clay is then pressed into shape using a friction press and dried at 260℃ for 20 hours. The added corundum is sintered corundum with particle sizes of 3-1mm and 1-0.1mm; the added magnesia is sintered magnesia with particle sizes of 1-0.1mm and 0.1-0mm; and the added ferrotitanium alloy is medium-sized ferrotitanium with a titanium content of 42wt% and a particle size of less than 200 mesh. The mixture is then sintered in an electric furnace at 1300℃ in an air atmosphere for 10 hours. The sintered phases consist of MgAl2O4, Mg2TiO4, and MgFeAlO4. The performance indicators of the obtained product are: apparent porosity 14.7%, and bulk density 3.06 g / cm³. 3 Its compressive strength at room temperature is 72 MPa. Example 4:

[0024] The raw material composition, by weight percentage, is: 60wt% corundum, 32wt% magnesia, 8wt% ferrotitanium alloy, and 3wt% thermosetting phenolic resin. During production, the various raw materials are weighed according to the formula, mixed evenly, and kneaded to obtain a clay mixture. This clay is then pressed into shape using a friction press and dried at 260℃ for 20 hours. The added corundum is sintered corundum with particle sizes of 3-1mm and 1-0.1mm; the added magnesia is sintered magnesia with particle sizes of 1-0.1mm and 0.1-0mm; and the added ferrotitanium alloy is low-titanium ferroalloy with a titanium content of 30wt% and a particle size of less than 200 mesh. The mixture is then sintered in an electric furnace at 1400℃ in an air atmosphere for 4 hours. The sintered phases consist of MgAl2O4, Mg2TiO4, and MgFeAlO4. The performance indicators of the obtained product are: apparent porosity 14.9%, and bulk density 3.02 g / cm³. 3 Its compressive strength at room temperature is 65 MPa. Example 5:

[0025] The raw material composition, by weight percentage, is: 65 wt% corundum, 32 wt% magnesia, 3 wt% ferrotitanium alloy, and 3.5 wt% thermosetting phenolic resin. During production, the various raw materials are weighed according to the formula, mixed evenly, and kneaded to obtain a clay mixture. This clay is then pressed into shape using a friction press and dried at 260℃ for 20 hours. The added corundum is sintered corundum with particle sizes of 3-1 mm and 1-0.1 mm; the added magnesia is sintered magnesia with particle sizes of 1-0.1 mm and 0.1-0 mm; and the added ferrotitanium alloy is high-titanium iron with a titanium content of 68 wt% and a particle size of less than 200 mesh. The mixture is then sintered in an electric furnace at 1100℃ in an air atmosphere for 10 hours. The resulting phases consist of Al₂O₃, MgO, MgAl₂O₄, Mg₂TiO₄, and MgFeAlO₄. The performance indicators of the obtained product are: apparent porosity 12.3%, bulk density 3.10 g / cm³. 3 Its compressive strength at room temperature is 68 MPa.

Claims

1. A novel Al2O3-MgO-TiFe composite refractory material, characterized in that: The refractory material is composed of the following components by weight percentage: 50-75% Al2O3, 30-50% MgO, 5-15% ferro-titanium alloy, plus 2-6% phenolic resin as a binder; the ferro-titanium alloy is one of low ferro-titanium (25wt%-30wt%), medium ferro-titanium (35wt%-45wt%), and high ferro-titanium (65wt%-75wt%).

2. The novel Al2O3-MgO-TiFe composite refractory material as described in claim 1, characterized in that: The Al2O3 includes tabular corundum, fused alumina, and brown corundum.

3. The novel Al2O3-MgO-TiFe composite refractory material as described in claim 1, characterized in that: The MgO mentioned includes sintered magnesia, fused magnesia, and brine magnesia.

4. The novel Al2O3-MgO-TiFe composite refractory material as described in claim 1, characterized in that: The Al2O3 has three particle sizes: 3-1 mm, 1-0.1 mm, and 0.1-0 mm; the magnesia has three particle sizes: 1-0.1 mm and 0.1-0 mm; the titanium-iron alloy has a particle size of 1-0.1 mm; the ratio of the three different particle sizes is as follows: 3≤particle size<1mm 45-65%; 1% ≤ Particle size < 0.1mm; 18-30% 0.1 ≤ particle size < 0 mm 17-30%.