CN-121800523-B - Magnesium-chromium refractory material containing magnesium sand and chromite and preparation method thereof

CN121800523BCN 121800523 BCN121800523 BCN 121800523BCN-121800523-B

Abstract

The invention relates to the technical field of refractory materials, in particular to a magnesia-chromite refractory material containing magnesia and chromite and a preparation method thereof. The phosphate group grafted on the surface of the modified silicon dioxide adsorbs and complexes Cr 3+ /Al 3+ metal ions in advance, and the metal ions are released gradually along with the pH rise of a system in the synchronous dropwise adding process of alkali liquor, so that the controlled and uniform coprecipitation of the metal ions on the surface of the modified LDH nanosheet is realized, and a gradient spinel coating layer with uniform thickness and continuous crystal lattice is constructed on the magnesia surface in situ. Cr 3+ /Al 3+ is adopted for cooperative deposition, so that the thermal shock resistance is greatly improved. Silicate in the modified LDH generates magnesium aluminosilicate in situ in high-temperature calcination, and realizes interfacial chemical connection.

Inventors

XU CHANGSONG
LIU LIN
Wu Dianxu
YU YONGSHENG
SHU JINGHUI
XU HONG

Assignees

营口高科合成耐火材料有限公司

Dates

Publication Date: 20260508
Application Date: 20260310

Claims (4)

1. The magnesium-chromium refractory material containing the magnesium sand and the chromite is characterized by comprising, by weight, 35-45 parts of chromite particles, 15-25 parts of magnesia fine powder, 15-25 parts of modified magnesium oxide, 2-5 parts of phenolic resin powder, 0.2-0.6 part of sodium tripolyphosphate and 0.1-0.2 part of magnesium stearate; The modified magnesium oxide is powder prepared by high-temperature calcination of Cr-Al codeposition coated MgO precursor powder induced by modified LDH and modified silicon dioxide; The preparation method of the modified magnesium oxide comprises the following steps: S11, ultrasonically dispersing modified LDH and modified silicon dioxide in absolute ethyl alcohol, heating in an oil bath, stirring for reaction under the protection of nitrogen, centrifugally collecting solid from the obtained reaction liquid, washing with absolute ethyl alcohol, and vacuum drying to obtain a first compound; S12, dispersing the first compound in deionized water to obtain a dispersion liquid, dispersing magnesium oxide powder in deionized water, adding sodium hexametaphosphate, performing ultrasonic treatment, adding dilute hydrochloric acid to adjust pH under stirring, slowly dropwise adding the dispersion liquid, continuously stirring, stopping stirring and standing, pouring out the supernatant, and supplementing deionized water to obtain a second compound; S13, dissolving Cr (NO 3 ) 3 ·9H 2 O and Al (NO 3 ) 3 ·9H 2 O) in deionized water to obtain a metal salt solution, heating a second compound, synchronously dropwise adding the metal salt solution and a NaOH solution under stirring, continuously stirring and aging, heating and aging, centrifugally collecting a solid of the obtained product, washing with deionized water and absolute ethyl alcohol, vacuum drying, calcining in a segmented manner, and grinding sintered powder to obtain modified magnesium oxide; The preparation method of the modified LDH comprises the following steps: S21, dissolving Mg (NO 3 ) 2 ·6H 2 O and Al (NO 3 ) 3 ·9H 2 O in deionized water to obtain a salt solution; dissolving NaOH and Na 2 SiO 3 ·9H 2 O in deionized water, adding sodium citrate, and uniformly stirring to obtain an alkali-silicon mixed solution; S22, synchronously and slowly dropwise adding the salt solution and the alkali-silicon mixed solution into deionized water, stirring and aging under the protection of nitrogen, centrifugally collecting the obtained reaction solution, and washing with deionized water and absolute ethyl alcohol to obtain wet gel; S23, dispersing wet gel in absolute ethyl alcohol by ultrasonic, dropwise adding 3-carboxypropyl trimethoxy silane, carrying out reflux reaction under the protection of nitrogen, centrifugally collecting solid from the obtained reaction liquid, washing with absolute ethyl alcohol, vacuum drying, and grinding to obtain modified LDH; The preparation method of the modified silicon dioxide comprises the following steps: S31, stirring cetyl trimethyl ammonium bromide in a mixed solvent of absolute ethyl alcohol and deionized water, adding concentrated ammonia water, uniformly stirring, slowly dropwise adding tetraethoxysilane, continuing to react, centrifugally collecting the obtained reaction liquid, alternately washing with absolute ethyl alcohol and deionized water, drying, and calcining in a muffle furnace to obtain mesoporous silica; S32, ultrasonically dispersing mesoporous silicon dioxide in anhydrous toluene, adding gamma-glycidol ether oxypropyl trimethoxy silane under the protection of nitrogen, carrying out reflux reaction, centrifugally collecting solid from the obtained reaction liquid, washing with the anhydrous toluene, acetone and absolute ethyl alcohol in sequence, and carrying out vacuum drying to obtain a third compound; s33, dispersing the third compound in absolute ethyl alcohol, adding triethylamine, slowly dropwise adding a phosphoric acid aqueous solution under the protection of nitrogen, stirring for reaction, centrifugally collecting the obtained reaction liquid, washing with deionized water and absolute ethyl alcohol, and vacuum drying to obtain the modified silicon dioxide.
2. The magnesia-chromite refractory containing magnesia and chromite according to claim 1, wherein the staged calcination in S13 is divided into an organic removal stage, a temperature rise of 3 ℃ to 550 ℃ and a temperature hold of 2 hours at 3 ℃ per min, a gradient spinel and silicate formation stage, a temperature rise of 5 ℃ to 1350 ℃ and a temperature hold of 4 hours at 5 ℃ per min.
3. The magnesia-chromite refractory material containing magnesia and chromite as defined in claim 1, wherein the mass ratio of the modified LDH to the modified silica is 1.5-2:1, and the mass ratio of the first compound to the magnesia powder is 1:20-25.
4. A method for preparing a magnesia-chromite refractory material containing magnesia and chromite, which is applied to preparing the magnesia-chromite refractory material containing magnesia and chromite according to any one of claims 1-3, and is characterized by comprising the following steps: S1, placing chromite particles, magnesia fine powder and modified magnesium oxide into a mixer, stirring and mixing uniformly, adding phenolic resin powder, stirring and mixing uniformly, continuously adding sodium tripolyphosphate and magnesium stearate, continuously stirring, and sieving to obtain the refractory material.

Description

Magnesium-chromium refractory material containing magnesium sand and chromite and preparation method thereof Technical Field The invention belongs to the technical field of refractory materials, and particularly relates to a magnesia-chromite refractory material containing magnesia sand and chromite and a preparation method thereof. Background The magnesium-chromium refractory material is widely applied to high-temperature equipment liners of converters, electric furnaces, ladles and the like for steel smelting due to the excellent alkaline slag corrosion resistance and thermal shock stability. The traditional magnesia-chromite brick is mainly prepared by mechanically mixing magnesia and chromite, but chromium elements are unevenly distributed on a microscopic scale to form a chromium-rich island and a chromium-poor area, so that unstable performance is caused, and the difference of local slag resistance is obvious. Prior attempts to deposit Cr 2O3 or Cr (OH) 3 on MgO surface by chemical precipitation method, but the thickness and uniformity of the chromium layer are difficult to control and the interface bonding energy of MgO and Cr 2O3 is low, resulting in easy spalling at high thermal cycles. Disclosure of Invention (1) Technical problem to be solved The invention aims to provide a magnesia-chromite refractory material containing magnesia and chromite and a preparation method thereof, which are used for solving the problems that when Cr 2O3 or Cr (OH) 3 is deposited on the surface of MgO by a chemical precipitation method, the thickness and uniformity of a chromium layer are difficult to control, the binding force between a deposited layer and a substrate is weak, and the deposited layer is easy to peel off at a high temperature. (2) Technical proposal In order to achieve the aim, on the one hand, the invention provides a magnesia-chromite refractory material containing magnesia and chromite, which comprises the following components, by weight, 35-45 parts of chromite particles, 15-25 parts of magnesia fine powder, 15-25 parts of modified magnesium oxide, 2-5 parts of phenolic resin powder, 0.2-0.6 part of sodium tripolyphosphate and 0.1-0.2 part of magnesium stearate; The modified magnesium oxide is powder prepared by high-temperature calcination of Cr-Al codeposition coated MgO precursor powder induced by modified LDH and modified silicon dioxide. Further, the preparation method of the modified magnesium oxide comprises the following steps: S11, ultrasonically dispersing modified LDH and modified silicon dioxide in absolute ethyl alcohol, heating in an oil bath, stirring for reaction under the protection of nitrogen, centrifugally collecting solid from the obtained reaction liquid, washing with absolute ethyl alcohol, and vacuum drying to obtain a first compound; S12, dispersing the first compound in deionized water to obtain a dispersion liquid, dispersing magnesium oxide powder in deionized water, adding sodium hexametaphosphate, performing ultrasonic treatment, adding dilute hydrochloric acid to adjust pH under stirring, slowly dropwise adding the dispersion liquid, continuously stirring, stopping stirring and standing, pouring out the supernatant, and supplementing deionized water to obtain a second compound; s13, dissolving Cr (NO 3)3·9H2 O and Al (NO 3)3·9H2 O) in deionized water to obtain a metal salt solution, heating a second compound, synchronously dropwise adding the metal salt solution and a NaOH solution under stirring, continuously stirring and aging, heating and aging, centrifugally collecting a solid of the obtained product, washing with deionized water and absolute ethyl alcohol, vacuum drying, calcining in a segmented mode, and grinding sintered powder to obtain the modified magnesium oxide. Further, the step S13 is divided into a stage of removing organic matters, a stage of heating to 550 ℃ at 3 ℃ per min and preserving heat for 2 hours, a stage of gradient spinel and silicate formation, and a stage of heating to 1350 ℃ at 5 ℃ per min and preserving heat for 4 hours. Further, the mass ratio of the modified LDH to the modified silicon dioxide is 1.5-2:1, and the mass ratio of the first compound to the magnesia powder is 1:20-25. Further, the preparation method of the modified LDH comprises the following steps: S21, dissolving Mg (NO 3)2·6H2 O and Al (NO 3)3·9H2 O in deionized water to obtain a salt solution; dissolving NaOH and Na 2SiO3·9H2 O in deionized water, adding sodium citrate, and uniformly stirring to obtain an alkali-silicon mixed solution; S22, synchronously and slowly dropwise adding the salt solution and the alkali-silicon mixed solution into deionized water, stirring and aging under the protection of nitrogen, centrifugally collecting the obtained reaction solution, and washing with deionized water and absolute ethyl alcohol to obtain wet gel; S23, dispersing wet gel in absolute ethyl alcohol by ultrasonic, dropwise adding 3-carboxypropyl trimethoxy silane, carrying out