High-temperature refractory brick taking low-grade magnesite tailings as aggregate

Abstract

The invention relates to a high-temperature refractory brick taking low-grade magnesite tailings as aggregate, which is characterized by comprising the following components in percentage by weight: 60-65wt% of low-grade magnesite tailings; 15 to 25 weight percent of bentonite; 5-10 wt% of magnesium oxide; 1-3 wt% of magnesium chloride; 5.5 to 10 wt% of a modifier; and 4-6 wt% of a binding agent. The high-temperature refractory brick blank has the beneficial effects that the low-grade magnesite tailings which are relatively high in SiO2 content and cannot be used for preparing magnesium materials are used as main materials, and a certain amount of bentonite is added to serve as aggregate, so that the high-temperature refractory brick blank is complete in binding phase, small in apparent porosity and about 14-15%, high in load deformation temperature and about 1700-1720 DEG C, and high in strength and toughness; the prepared magnesite tailings have excellent chemical mineral structures, physical properties and thermal shock resistance, so that mineral resources are saved, the problem of discharge of the magnesite tailings after mineral separation is solved, and the magnesite tailings are energy-saving and environment-friendly.

Description

Technical Field

[0001] The invention relates to the technical field of mineral product processing and environmental protection, in particular to a high-temperature refractory brick using low-grade magnesite tailings as aggregate. Background Art

[0002] Refractory bricks, referred to as fire bricks, are refractory materials generally made of refractory clay or other refractory raw materials. They are mainly used for building smelting furnaces, coke ovens, etc. They need to be able to withstand high temperatures of 1580℃ to 1770℃ and withstand various physical and chemical changes and mechanical effects at high temperatures. Commonly used refractory bricks include refractory clay bricks, silica bricks, high-alumina bricks, and magnesia bricks. With the rapid development of large-scale blast furnaces and coke ovens (carbonization chambers have increased from 4 meters to 7 meters), the requirements for the quality and size of the refractory materials used have also been further improved. In recent years, affected by the international environment, especially with the downward pressure on the economy of the entire steel industry, the market competition pressure in the refractory industry has also increased, the product profit margin has gradually shrunk, and the survival space of refractory manufacturers has also been seriously challenged. At the same time, with the vigorous development of the steel industry, the consumption of mineral resources has increased, and resources have become increasingly scarce. It is urgent to develop a high-quality and low-cost high-temperature refractory material for the regenerator of blast furnaces or coke oven hot blast furnaces.

[0003] my country is a country with abundant magnesite resources, with proven reserves of about 3.1 billion tons, accounting for a quarter of the world's total reserves. The reserves are mainly distributed in Liaoning and Shandong provinces, accounting for about 95% of the country's total reserves, of which low-grade magnesite reserves are as high as 540 million tons. The large amount of abandoned magnesite tailings after beneficiation occupies a large amount of land resources, which not only causes a great waste of resources, but also leads to ecological damage and serious environmental pollution. Therefore, the development and utilization of low-grade magnesite is imminent. Summary of the invention

[0004] In order to overcome the defects of the prior art, the technical problem solved by the present invention is to provide a high-temperature refractory brick with low-grade magnesite tailings as aggregate, and the high-temperature refractory brick blank with low-grade magnesite tailings with high SiO2 content and which cannot be used to prepare magnesia materials as the main material and a certain amount of bentonite added as aggregate has a complete bonding phase, a small apparent porosity of about 14-15%, a high load deformation temperature of about 1700-1720°C, and excellent chemical mineral structure, physical properties and thermal shock stability, which not only saves mineral resources, but also solves the discharge problem of magnesite tailings after mineral processing, and is energy-saving and environmentally friendly.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A high-temperature refractory brick using low-grade magnesite tailings as aggregate, characterized in that it comprises the following components by weight percentage:

[0007] Low-grade magnesite tailings 60-65wt%;

[0008] Bentonite 15-25wt%;

[0009] Magnesium oxide 5-10wt%;

[0010] Magnesium chloride 1-3wt%;

[0011] Modifier 5.5-10wt%;

[0012] Binder 4~6wt%.

[0013] Furthermore, the modifier is one or a mixture of two or more of sodium hexametaphosphate, zirconium oxide, ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104).

[0014] Furthermore, the binder is a mixture of water glass and phosphate cement, wherein the weight percentage of water glass to phosphate cement is 1.5-2.5:1.

[0015] Furthermore, a method for preparing high-temperature refractory bricks using low-grade magnesite tailings as aggregate is characterized by comprising the following steps:

[0016] 1) According to the composition of the above refractory bricks, 60-65wt% of low-grade magnesite tailings, 15-25wt% of slag powder, 5-10wt% of magnesium oxide, 1-3wt% of magnesium chloride, 5.5-10wt% of modifier, and 4-6wt% of binder are weighed in mass percentage to prepare ingredients;

[0017] 2) Grinding natural forsterite and bentonite for 15 minutes and mixing them evenly to obtain co-ground powder;

[0018] 3) Add magnesium oxide, magnesium chloride and improver to the co-grinded powder and continue to co-grind for 5 minutes;

[0019] 4) Finally, add the binder and grind together, stir and mix for 10 minutes;

[0020] 5) Use machine pressing to form refractory brick blanks;

[0021] 6) At room temperature, place the brick mold into a rotary kiln for calcination. First, slowly raise the temperature to 200-300°C and keep the temperature constant for 0.8-1.5 hours. After the natural water in the brick is vaporized and discharged, increase the calcination rate by 4-6°C / hour, continue to raise the temperature to 850-950°C, and keep the temperature constant for 2.5-3.5 hours. After the free water and low-melting substances in each mineral are burned out, quickly raise the temperature to 1650-1750°C and keep the temperature constant for 3.5-4.5 hours. Open the kiln when it is naturally cooled to 650-750°C, and finally naturally cool to room temperature.

[0022] Furthermore, after mixing in step 3), the particle size of the mixture is less than 1 mm, of which: 0.8-1 mm accounts for 15%, 0.5-0.8 mm accounts for 20%, 0.1-0.5 mm accounts for 30%, and less than 0.1 mm accounts for 35%.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) The high-temperature refractory brick of the present invention introduces ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104) modifier, which can effectively solve the problem of easy hydration of MgO; introduces zirconium oxide modifier, which can significantly improve the volume density, relative density, room temperature compressive strength and thermal shock resistance of the brick; adds an appropriate amount of magnesium chloride, which can effectively improve the compactness of the brick structure, reduce the porosity, and optimize various performance indicators of the brick until they reach the optimum;

[0025] 2) The forsterite checker brick of the present invention uses low-grade magnesite tailings with high SiO2 content that cannot be used to prepare magnesia materials as the main material and adds a certain amount of bentonite as aggregate. The combined phase is complete, the apparent porosity is small, about 14-15%, the load deformation temperature is high, about 1700-1720°C, and it has excellent chemical mineral structure, physical properties and thermal shock stability;

[0026] 3) The forsterite checker brick of the present invention makes effective use of low-grade magnesite tailings with high SiO2 content that cannot be used to prepare magnesia materials, which not only saves mineral resources, but also solves the problem of discharge of magnesite tailings after beneficiation, thereby saving energy and protecting the environment. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be further clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The low-grade magnesite tailings used in the embodiment of the present invention are magnesite tailings selected by a certain ore dressing plant in Haicheng, Liaoning Province, and its chemical composition is MgO 35-41%, SiO2 8.66-15.21%, CaO 2.11-6.22%, Al2O3 0.52-1.28%, Fe2O3 2.32-3.82% by weight, and the remainder is trace impurities. Features: The SiO2 content is relatively high, even up to 15%.

[0029] [Example 1]:

[0030] A high-temperature refractory brick using low-grade magnesite tailings as aggregate comprises the following components by weight percentage:

[0031] Low-grade magnesite tailings 62.5wt%;

[0032] Bentonite 17.5wt%;

[0033] Magnesium oxide 5.5wt%;

[0034] Magnesium chloride 2.0wt%;

[0035] Modifier 7.5wt%;

[0036] Binder 5.0wt%.

[0037] Furthermore, the modifier is a mixture of sodium hexametaphosphate, zirconium oxide, ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104), wherein the ratio of sodium hexametaphosphate: zirconium oxide: ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104) is 2:1.5:1.

[0038] Furthermore, the binder is a mixture of water glass and phosphate cement, wherein the weight percentage of water glass to phosphate cement is 2:1.

[0039] Furthermore, a method for preparing high-temperature refractory bricks using low-grade magnesite tailings as aggregate comprises the following steps:

[0040] 1) According to the composition of the above refractory bricks, 62.5 kg of low-grade magnesite tailings, 17.5 kg of slag powder, 5.5 kg of magnesium oxide, 2 kg of magnesium chloride, 7.5 kg of modifier, and 5 kg of binder were weighed in percentage by mass to prepare the ingredients;

[0041] 2) placing natural forsterite and bentonite in a mixing mill, rolling and mixing them for 15 minutes, and mixing them evenly to obtain co-ground powder;

[0042] 3) Add magnesium oxide, magnesium chloride and improver to the co-grinded powder, and continue to grind for 5 minutes to obtain a mixture with a particle size of less than 1 mm, of which: 0.8-1 mm accounts for 15%, 0.5-0.8 mm accounts for 20%, 0.1-0.5 mm accounts for 30%, and less than 0.1 mm accounts for 35%;

[0043] 4) Finally, add the binder, grind and mix together for 10 minutes to obtain the refractory brick blank;

[0044] 5) The refractory brick blank is pressed into refractory brick blank by a 630T brick press;

[0045] 6) At room temperature, place the brick mold into a rotary kiln for calcination. First, slowly raise the temperature to 250°C and keep the temperature constant for 1 hour. After the natural water in the brick is vaporized and discharged, increase the calcination rate by 5°C / hour, continue to raise the temperature to 900°C, and keep the temperature constant for 3 hours. After the free water and low-melting substances in each mineral are burned out, quickly raise the temperature to 1720°C and keep the temperature constant for 4 hours. Open the kiln when it cools naturally to 700°C, and finally cool naturally to room temperature.

[0046] In this embodiment, ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104) modifiers are introduced to generate magnesium alcohol compounds and hydrophobic imide groups on the surface of MgO, thereby effectively solving the problem of hydration of MgO.

[0047] In this embodiment, a zirconium oxide modifier is introduced to significantly improve the bulk density, relative density, room temperature compressive strength, and thermal shock resistance of the brick.

[0048] In this embodiment, 2 wt% of magnesium chloride (MgCl2) is added, which can effectively improve the compactness of the brick structure, reduce the porosity, and optimize the various performance indicators of the brick until they reach the optimum.

[0049] [Example 2]:

[0050] A high-temperature refractory brick using low-grade magnesite tailings as aggregate comprises the following components by weight percentage:

[0051] Low-grade magnesite tailings 65.0wt%;

[0052] Bentonite 15.0wt%;

[0053] Magnesium oxide 5.5wt%;

[0054] Magnesium chloride 3.0wt%;

[0055] Modifier 6.5wt%;

[0056] Binder 5.0wt%.

[0057] Furthermore, the modifier is a mixture of sodium hexametaphosphate, zirconium oxide, ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104), wherein the ratio of sodium hexametaphosphate: zirconium oxide: ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104) is 1.5:1.5:1.

[0058] Furthermore, the binder is a mixture of water glass and phosphate cement, wherein the weight percentage of water glass to phosphate cement is 2.5:1.

[0059] Furthermore, a method for preparing high temperature refractory bricks using low-grade magnesite tailings as aggregate comprises the following steps:

[0060] 1) According to the composition of the above refractory bricks, 65 kg of low-grade magnesite tailings, 15 kg of slag powder, 5.5 kg of magnesium oxide, 3 kg of magnesium chloride, 6.5 kg of modifier, and 5 kg of binder were weighed in percentage by mass to prepare the ingredients;

[0061] 2) placing natural forsterite and bentonite in a mixing mill, rolling and mixing them for 15 minutes, and mixing them evenly to obtain co-ground powder;

[0062] 3) Add magnesium oxide, magnesium chloride and improver to the co-grinded powder, and continue to grind for 5 minutes to obtain a mixture with a particle size of less than 1 mm, of which: 0.8-1 mm accounts for 15%, 0.5-0.8 mm accounts for 20%, 0.1-0.5 mm accounts for 30%, and less than 0.1 mm accounts for 35%;

[0063] 4) Finally, add the binder, grind and mix together for 10 minutes to obtain the refractory brick blank;

[0064] 5) The refractory brick blank is pressed into refractory brick blank by a 630T brick press;

[0065] 6) At room temperature, place the brick mold into a rotary kiln for calcination. First, slowly raise the temperature to 230°C and keep it constant for 1.2 hours. After the natural water in the brick is vaporized and discharged, increase the calcination rate by 4.5°C / hour, continue to raise the temperature to 920°C, and keep it constant for 3.5 hours. After the free water and low-melting substances in each mineral are burned out, quickly raise the temperature to 1750°C and keep it constant for 4 hours. Open the kiln when it cools naturally to 750°C, and finally cool naturally to room temperature.

[0066] [Example 3]

[0067] A high-temperature refractory brick using low-grade magnesite tailings as aggregate comprises the following components by weight percentage:

[0068] Low-grade magnesite tailings 60.0wt%;

[0069] Bentonite 20.0wt%;

[0070] Magnesium oxide 5.0wt%;

[0071] Magnesium chloride 1.0wt%;

[0072] Modifier 8.0wt%;

[0073] Binder 6.0wt%.

[0074] Furthermore, the modifier is a mixture of sodium hexametaphosphate, zirconium oxide, ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104), wherein the ratio of sodium hexametaphosphate: zirconium oxide: ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104) is 1:1:1.

[0075] Furthermore, the binder is a mixture of water glass and phosphate cement, wherein the weight percentage of water glass to phosphate cement is 1.5:1.

[0076] Furthermore, a method for preparing high-temperature refractory bricks using low-grade magnesite tailings as aggregate comprises the following steps:

[0077] 1) According to the composition of the above refractory bricks, 60 kg of low-grade magnesite tailings, 20 kg of slag powder, 5 kg of magnesium oxide, 1 kg of magnesium chloride, 8 kg of modifier, and 6 kg of binder were weighed in percentage by mass to prepare the ingredients;

[0078] 2) placing natural forsterite and bentonite in a mixing mill, rolling and mixing them for 15 minutes, and mixing them evenly to obtain co-ground powder;

[0079] 3) Add magnesium oxide, magnesium chloride and improver to the co-grinded powder, and continue to grind for 5 minutes to obtain a mixture with a particle size of less than 1 mm, of which: 0.8-1 mm accounts for 15%, 0.5-0.8 mm accounts for 20%, 0.1-0.5 mm accounts for 30%, and less than 0.1 mm accounts for 35%;

[0080] 4) Finally, add the binder, grind and mix together for 10 minutes to obtain the refractory brick blank;

[0081] 5) The refractory brick blank is pressed into refractory brick blank by a 630T brick press;

[0082] 6) At room temperature, place the brick mold into a rotary kiln for calcination. First, slowly raise the temperature to 280°C and keep it constant for 1 hour. After the natural water in the brick is vaporized and discharged, increase the calcination rate by 5.5°C / hour, continue to raise the temperature to 900°C, and keep it constant for 2.5 hours. After the free water and low-melting substances in each mineral are burned out, quickly raise the temperature to 1750°C and keep it constant for 4 hours. Open the kiln when it cools naturally to 700°C, and finally cool naturally to room temperature.

[0083] [Comparative Example 1]

[0084] A high-temperature refractory brick using low-grade magnesite tailings as aggregate comprises the following components by weight percentage:

[0085] Low-grade magnesite tailings 62.5wt%;

[0086] Bentonite 17.5wt%;

[0087] Magnesium oxide 5.5wt%;

[0088] Magnesium chloride 2.0wt%;

[0089] Modifier 7.5wt%;

[0090] Binder 5.0wt%.

[0091] Furthermore, the modifier is sodium hexametaphosphate.

[0092] Furthermore, the binder is a mixture of water glass and phosphate cement, wherein the weight percentage of water glass to phosphate cement is 2:1.

[0093] The preparation method is basically the same as that of Example 1, except that the addition amount of the zirconium oxide modifier is 0, the addition amount of ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104) is 0, the bonding phase of the refractory bricks is incomplete, and its bulk density, relative density, room temperature compressive strength, and thermal shock resistance are significantly reduced.

[0094] [Comparative Example 2]

[0095] A high-temperature refractory brick using low-grade magnesite tailings as aggregate comprises the following components by weight percentage:

[0096] Low-grade magnesite tailings 62.5wt%;

[0097] Bentonite 17.5wt%;

[0098] Magnesium oxide 5.5wt%;

[0099] Magnesium chloride 2.0wt%;

[0100] Modifier 7.5wt%;

[0101] Binder 5.0wt%.

[0102] Furthermore, the modifier is a mixture of sodium hexametaphosphate, ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104), wherein the ratio of sodium hexametaphosphate:ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104) is 2:1.

[0103] Furthermore, the binder is a mixture of water glass and phosphate cement, wherein the weight percentage of water glass to phosphate cement is 2:1.

[0104] The preparation method is basically the same as that of Example 1, except that the amount of zirconium oxide modifier added is 0, the bonding phase of the refractory brick is basically complete, and its bulk density, relative density, room temperature compressive strength, and thermal shock resistance are significantly reduced.

[0105] [Comparative Example 3]

[0106] A high-temperature refractory brick using low-grade magnesite tailings as aggregate comprises the following components by weight percentage:

[0107] Low-grade magnesite tailings 62.5wt%;

[0108] Bentonite 17.5wt%;

[0109] Magnesium oxide 5.5wt%;

[0110] Magnesium chloride 2.0wt%;

[0111] Modifier 7.5wt%;

[0112] Binder 5.0wt%.

[0113] Furthermore, the modifier is a mixture of sodium hexametaphosphate and zirconium oxide, wherein the ratio of sodium hexametaphosphate to zirconium oxide is 1.5:1.

[0114] Furthermore, the binder is a mixture of water glass and phosphate cement, wherein the weight percentage of water glass to phosphate cement is 2:1.

[0115] The preparation method is basically the same as that of Example 1, except that the addition amount of ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104) is 0, the bonding phase of the refractory bricks is incomplete, and its bulk density, relative density, room temperature compressive strength, and thermal shock resistance are reduced.

[0116] According to conventional testing methods, the performance indicators of the above-mentioned embodiments, such as apparent porosity, bulk density, room temperature compressive strength, and 0.2 MPa load softening temperature, are tested and shown in Table 1.

[0117] Table 1

[0118]

[0119] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A high temperature refractory brick using low grade magnesite tailings as aggregate, characterized in that: The components include the following by weight percentage: Low-grade magnesite tailings 60-65wt%; Bentonite 15-25wt%; Magnesium oxide 5-10wt%; Magnesium chloride 1-3wt%; Modifier 5.5-10wt%; Binder 4~6wt%.

2. The high temperature refractory brick with low grade magnesite tailings as aggregate according to claim 1, characterized in that: The modifier is one or a mixture of two or more of sodium hexametaphosphate, zirconium oxide, ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104).

3. The high temperature refractory brick with low grade magnesite tailings as aggregate according to claim 1, characterized in that: The binder is a mixture of water glass and phosphate cement, wherein the weight percentage of water glass to phosphate cement is 1.5-2.5:

1.

4. The high temperature refractory brick with low grade magnesite tailings as aggregate according to claim 1, characterized in that: The components include the following by weight percentage: Low-grade magnesite tailings 62.5wt%; Bentonite 17.5wt%; Magnesium oxide 5.5wt%; Magnesium chloride 2.0wt%; Modifier 7.5wt%; Binder 5.0wt%.

5. The high temperature refractory brick with low grade magnesite tailings as aggregate according to claim 1, characterized in that: The modifier is a mixture of sodium hexametaphosphate, zirconium oxide, ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104), wherein the ratio of sodium hexametaphosphate: zirconium oxide: ethylene glycol and polyisobutylene maleic anhydride copolymer (ISOBAM-104) is 2:1.5:

1.

6. The high temperature refractory brick with low grade magnesite tailings as aggregate according to claim 1, characterized in that: The binder is a mixture of water glass and phosphate cement, wherein the weight percentage of water glass to phosphate cement is 2:

1.

7. The high temperature refractory brick with low grade magnesite tailings as aggregate according to claim 1, characterized in that: The calcination system is as follows: 1) At room temperature, place the green bricks in a rotary kiln for calcination, slowly raise the temperature to 250°C, and keep the temperature constant for 1 hour; 2) Increase the calcination rate by 5°C / hour, continue to raise the temperature to 900°C, and keep the temperature constant for 3 hours; 3) Rapidly heat to 1720°C and keep constant temperature for 4 hours; 4) Open the kiln when it cools naturally to 700℃, and finally cool naturally to room temperature.

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