CN112679201B - Cement-free aluminum-magnesium-chromium castable taking aluminum-chromium slag as main raw material and preparation method and application thereof - Google Patents
Cement-free aluminum-magnesium-chromium castable taking aluminum-chromium slag as main raw material and preparation method and application thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of refractory material castable, and particularly relates to a cement-free aluminum-magnesium-chromium castable taking aluminum-chromium slag as a main raw material, and a preparation method and application thereof. The cement-free aluminum-magnesium-chromium castable comprises aggregate, a matrix material and a bonding agent; the aggregate comprises aluminum chromium slag particles with the aluminum oxide content of more than 80 percent and the chromium oxide content of more than 5 percent, high bauxite particles with the aluminum oxide content of more than 85 percent and recycled magnesia particles with the magnesium oxide content of more than 90 percent; the base material comprises white corundum with the alumina content of less than 320 meshes and more than 98 percent; the bonding agent comprises sintered magnesia powder with the magnesia content of less than 200 meshes and more than 95 percent, silicon dioxide micro powder with the silicon dioxide content of more than 92 percent, alpha alumina micro powder with the alumina content of more than 98 percent and chromium oxide micro powder. The castable has excellent high-temperature strength, slag penetration resistance and thermal shock stability, can be used for high-temperature reduction zones in metal recovery rotary kilns and rotary hearth furnaces of solid wastes generated in the metallurgical industry, and obviously prolongs the service life of the kilns.
Description
Technical Field
The invention belongs to the technical field of refractory material castable, and particularly relates to a cement-free aluminum-magnesium-chromium castable taking aluminum-chromium slag as a main raw material, and a preparation method and application thereof.
Background
The aluminum chromium slag is solid waste generated in the process of smelting chromium by using an aluminothermic reduction method, and huge economic and environmental pressure is brought to enterprises and society due to large accumulation of the aluminum chromium slag. In the prior art, aluminum chromium slag is used for producing aluminum chromium bricks and is applied to a zinc smelting furnace, so that a good effect is achieved; however, because the high-temperature sintering of the aluminum-chromium brick has high energy consumption and is not environment-friendly, and meanwhile, the consumption of refractory bricks in the current high-temperature industry is continuously reduced, the solid waste consumption of the aluminum-chromium slag is low. Therefore, the prior art also proposes that the aluminum chromium slag is used for preparing the castable, so as to improve the application range and the usage amount of the aluminum chromium slag.
CN111004041A discloses a ladle bottom castable using aluminum chromium slag as a main material, which is prepared from the following raw materials by mass: aluminum chromium slag: 50% -60%, white corundum: 30-40%, fused magnesia: 2% -8%, pure calcium aluminate cement (binder): 4% -10%, alpha-alumina micropowder: 2% -11%, sodium tripolyphosphate (water reducing agent): 0.06% -0.1%, metal aluminum powder: 0.03% -0.1%, organic fiber (explosion-proof agent): 0.06 percent to 0.3 percent. The castable has good thermal shock stability and erosion resistance.
However, the existing research shows that calcium oxide in the cement binder can cause the refractory material to generate low-melting-point phases such as anorthite, gehlenite and tricalcium aluminate at high temperature, so that the high-temperature strength of the material is reduced, and the service life of the kiln furnace is influenced. But also requires extra care in the curing and dewatering process to avoid flaking and even popping during the primary heating process.
For this reason, existing research has developed cement-free binders, including hydrated alumina, phosphates, silica sol, and the like. For example, CN108358619A discloses a cement-free castable using aluminum chromium slag as a main material and a preparation method thereof, wherein 58-63 wt% of aluminum chromium slag particles are used as an aggregate, 12-17 wt% of aluminum chromium slag fine powder, 12-17 wt% of gamma-alumina micro powder, 5-10 wt% of fused magnesia fine powder, 1-2 wt% of titanium carbide micro powder and 1-2 wt% of silicon powder are used as matrix materials; uniformly mixing the matrix material, adding the uniformly mixed matrix material into the aggregate, and uniformly mixing to obtain a mixture; and then sequentially adding silica sol (a binding agent) accounting for 4-7 wt% of the mixture and carboxymethyl cellulose (a binding agent) accounting for 0.01-0.02 wt% of the mixture into the mixture, uniformly stirring, performing vibration molding, maintaining for 12-24 hours at room temperature, and performing heat preservation for 12-24 hours at 90-110 ℃ to prepare the circulating fluidized bed boiler flue castable. The obtained casting material has high strength, small heat conductivity coefficient and strong slag corrosion resistance.
However, the content of silicon oxide in the material is large, the forsterite with low melting point is produced under the condition of more than 1350 ℃, and the material can only be used in a flue of a circulating fluidized bed boiler with low temperature (below 1300 ℃), and cannot be used in a high-temperature environment. And the construction performance of the pouring material combined with the silica sol is not as convenient as water, and the silica sol can be used only by heating under the condition of lower air temperature.
Composite micro powder bonding agents are also developed in the prior art, for example, CN101555154A discloses a casting material, wherein the bonding agents are magnesia powder and silica micro powder. However, the castable has poor slag penetration resistance and stripping resistance.
Disclosure of Invention
The invention aims to provide a cement-free aluminum-magnesium-chromium castable which takes aluminum-chromium slag as a main raw material, has excellent high-temperature strength, slag penetration resistance and thermal shock stability, is suitable for high-temperature reduction zones in metal recovery rotary kilns and rotary hearth furnaces of solid wastes generated by metal smelting, and can greatly prolong the service life of kilns.
The cement-free aluminum-magnesium-chromium castable comprises aggregate, a matrix material and a bonding agent; wherein:
the aggregate comprises: the aluminum chromium slag particles with the aluminum oxide content of more than 80 percent and the chromium oxide content of more than 5 percent; bauxite particles having an alumina content greater than 85%; recovered magnesia particles having a magnesia content greater than 90%;
the base material comprises: white corundum with alumina content below 320 meshes of more than 98 percent;
the binding agent comprises: sintered magnesia powder with the magnesia content of less than 200 meshes being more than 95 percent, silicon dioxide micro powder with the silicon dioxide content of more than 92 percent, alpha alumina micro powder with the alumina content of more than 98 percent and chromium oxide micro powder.
According to the invention, 5-10% of recycled magnesia particles with the particle size of 3-1mm are added into the aggregate, and the recycled magnesia particles react with alumina micro powder in the binding agent in the using process to produce a spinel high-temperature phase, so that certain volume expansion is generated, and the shrinkage cracking of the material is prevented. The bonding agent obtained by compounding the silica powder and the sintered magnesia material with 200 meshes replaces a silica sol bonding agent, and when the MgO fine powder and the silica powder are used together, the silica powder is hydrated to form Si-O-Si bonds to generate strength, and the hydration of magnesia is inhibited. And the addition of the chromium oxide micro powder improves the strength and slag resistance of the casting material.
The invention screens the specific aggregate and the bonding agent components to play a synergistic effect, and obviously improves the high-temperature strength, the slag penetration resistance and the thermal shock stability of the cement-free aluminum-magnesium castable taking the aluminum-chromium slag as the main material, thereby expanding the application range of the castable, being applicable to the preparation of high, medium and low temperature thermal equipment and improving the value and the usage amount of the castable.
Preferably, the aggregate comprises 20-25% of aluminum chromium slag particles with the aluminum oxide content of more than 80% and the chromium oxide content of more than 5% by mass; 20-40% of high bauxite particles with the alumina content of more than 85%; 5-10% of recycled magnesia particles with the magnesia content of more than 90%.
Researches show that after the three particles are compounded in proportion, due to different thermal expansion coefficients, microcracks exist among the particles, thermal stress can be released, the anti-stripping performance of the castable is improved, and the castable is slightly expanded in the using process to prevent the castable from shrinking.
The grain composition of the aggregate is four grades of 8-5mm, 5-3mm, 3-1mm and 1-0 mm.
The mass ratio of the aggregate to the binding agent is (65-70): (15-20).
Researches show that the close packing of the castable can be ensured, the density of the castable is improved, the porosity is reduced, and the slag-resistant permeability is improved by adopting four-grade gradation and controlling the mass ratio of the aggregate to the binder.
As one embodiment of the invention, the cement-free aluminum-magnesium-chromium castable comprises the following components in percentage by mass:
in the cement-free aluminum-magnesium-chromium castable, the grain composition is as follows:
the high-temperature strength, the slag penetration resistance and the thermal shock stability of the castable are further improved by specifically selecting the components in the aggregate, the matrix material and the binding agent and adjusting the dosage proportion.
The cement-free aluminum-magnesium-chromium castable also comprises a water reducing agent; the addition amount of the water reducing agent is 0.15-0.2% of the total mass of the aggregate, the matrix material and the bonding agent. Preferably, the water reducing agent is sodium tripolyphosphate, P530 or sodium hexametaphosphate. By selecting a proper water reducing agent, the water adding amount in material construction can be reduced, and the normal temperature strength of the material is improved.
The cement-free aluminum-magnesium-chromium castable also comprises an explosion-proof agent; the addition amount of the explosion-proof agent is 0.05-0.1% of the total mass of the aggregate, the matrix material and the bonding agent. Researches show that the anti-explosion performance of the castable can be improved by adding a proper anti-explosion agent, and the castable can be rapidly baked conveniently.
The performance index parameters of the cement-free aluminum-magnesium-chromium castable are as follows:
TABLE 1
| Index (I) | Unit | Numerical value |
| Strength at room temperature of 110 ℃ for 24 hours | MPa | >70 |
| High temperature strength at 1500 ℃ for 3 hours | MPa | >80 |
| Linear rate of change, 1500 ℃ x 3 hours | ％ | 0-+0.6 |
| Penetration depth, 1500 ℃ for 3 hours (150 g of electric furnace dust collecting powder) | Visual inspection of | Without significant penetration |
| Bulk density | g/cm 3 | >2.90 |
| Thermal shock stability, 1100 ℃ Water Cooling | Then | >15 |
The second purpose of the invention is to provide a preparation method of the cement-free aluminum-magnesium-chromium castable taking the aluminum-chromium slag as the main raw material.
The preparation method of the cement-free aluminum-magnesium-chromium castable comprises the steps of mixing the raw materials; the method is characterized in that the binding agent is premixed and then mixed with other raw materials; the charging sequence of the mixing is as follows: aggregate, matrix material and bonding agent.
In field application, the castable product is mixed by a forced mixer, domestic water is added according to requirements, and the mixture is discharged after being mixed for 2-3 min; erecting a mould according to different requirements of thermal equipment, adding the mixed castable into the mould, vibrating by using a vibrating bar while feeding, and pouring to a proper size; and naturally curing the cast body for more than 24 hours, demoulding and baking for use.
The third purpose of the invention is to provide the application of the cement-free aluminum-magnesium-chromium castable taking the aluminum-chromium slag as the raw material in a metal recovery rotary kiln or a rotary hearth furnace of solid waste materials generated by metal smelting; preferably, the metal recovery rotary kiln and the rotary hearth furnace are applied to a high-temperature reduction zone of the metal recovery rotary kiln or the rotary hearth furnace, so that the permeation resistance and the anti-stripping capability can be improved, and the service life of the kiln can be greatly prolonged.
The beneficial effects obtained by the invention are as follows:
(1) the invention improves the utilization rate of the solid waste aluminum chromium slag and the recycled magnesia, increases the resource utilization of the solid waste and reduces the material cost.
(2) The invention adopts the aluminum-magnesium-chromium castable to replace the existing high-temperature fired aluminum-chromium brick, reduces the energy consumption of the product and protects the environment.
(3) The invention adopts cement-free binder and adds aluminum chromium slag, thus improving the high temperature performance and slag-resistant permeability of the castable.
(4) The invention adopts the composite binder to replace silica sol cement-free binder, improves the construction simplicity of the castable, improves the high-temperature performance of the castable, and can be used for high-temperature kilns.
Drawings
FIG. 1 is a comparative graph showing the slag resistance of a cement-free castable containing aluminum chromium slag and a cement-free castable containing no aluminum chromium slag. With comparative example 1 on the left and example 1 on the right.
FIG. 2 is a comparative chart of the slag resistance of the cement-free castable with aluminum chromium slag and the aluminum chromium brick. Wherein the left side is example 1 and the right side is an aluminum chrome brick.
Fig. 3 is a photograph of formwork support and casting in a rotary kiln casting material construction site.
Detailed Description
The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
Examples and comparative examples
A cement-free aluminum-magnesium-chromium castable taking aluminum-chromium slag as a raw material comprises the following specific components:
TABLE 2
The preparation method comprises the following steps:
(1) accurately weighing the bonding agent, the water reducing agent and the explosion-proof agent according to the mixture ratio, and mixing for 8-10 minutes by using a double-shaft mixing machine to obtain a premix for later use.
(2) Accurately weighing the aggregate, the matrix material and the premix according to the proportion, adding the mixture into a planetary mixer, mixing for 2-3 minutes, and discharging to obtain the finished castable.
(3) Putting the casting material product into a forced stirrer on site, adding domestic water according to the proportion, mixing for 2-3 minutes, and discharging.
(4) Adding the mixed casting material into a mold, vibrating by using a vibrating rod while adding the material, and casting to an appropriate size; and naturally curing the cast body for more than 24 hours, demoulding and baking for use.
Effect verification
1. The results of comparing the physical and chemical indexes of the cement-free aluminum magnesium chromium castable obtained in the examples and the comparative examples are shown in the following table.
Comparative example 3 is the castable material obtained in CN 108358619A.
TABLE 3
As can be seen from the above table:
(1) the addition of the chromium oxide micropowder into the binder of the embodiment 1 and the comparative example 1 can improve the normal temperature strength and the high temperature strength of the castable, and the slag penetration resistance of the castable can also be improved.
(2) Comparative example 3 does not provide the normal temperature strength, and according to the test, it is known that the normal temperature hardening of the silica sol is slow, and the strength is only about 15 MPa.
(3) The slag penetration resistance of the castable is improved by adding the aluminum chromium slag in the embodiment 1 and the comparative example 2.
2. Examination of slag resistance in example 1
FIG. 1 is a comparative graph showing the slag resistance of a cement-free castable containing aluminum chromium slag and a cement-free castable containing no aluminum chromium slag. With comparative example 1 on the left and example 1 on the right.
FIG. 2 is a comparative chart of the slag resistance of the cement-free castable with aluminum chromium slag and the aluminum chromium brick. Wherein the left side is example 1 and the right side is an aluminum chrome brick.
Fig. 3 is a picture of formwork support and casting in a rotary kiln casting material construction site.
As can be seen from the figure, in example 1, the slag penetration resistance of the castable is improved due to the addition of the aluminum chromium slag.
Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.
Claims (8)
1. A cement-free aluminum-magnesium-chromium castable comprises aggregate, a matrix material and a bonding agent; it is characterized in that the preparation method is characterized in that,
the aggregate comprises: aluminum chromium slag particles with the aluminum oxide content of more than 80 percent and the chromium oxide content of more than 5 percent; bauxite particles having an alumina content greater than 85%; recycled magnesia particles having a magnesia content of greater than 90%;
the grain composition of the aggregate is four grades of 8-5mm, 5-3mm, 3-1mm and 1-0 mm;
the base material comprises: white corundum with alumina content below 320 meshes of more than 98 percent;
the binding agent comprises: 200 meshes of sintered magnesia powder with the magnesia content of more than 95 percent, silica micropowder with the silica content of more than 92 percent, alpha alumina micropowder with the alumina content of more than 98 percent and chromium oxide micropowder;
the mass ratio of the aggregate to the binding agent is (65-70): (15-20);
the cement-free aluminum-magnesium-chromium castable comprises the following components in percentage by mass:
2. the cement-free aluminum magnesium chromium castable material of claim 1, wherein the cement-free aluminum magnesium chromium castable material has a grain composition of:
3. the cement-free aluminum magnesium chromium castable material of claim 2, further comprising a water reducing agent; the addition amount of the water reducing agent is 0.15-0.2% of the total mass of the aggregate, the matrix material and the bonding agent.
4. The cement-free aluminum magnesium chromium castable material according to claim 3, wherein the water reducing agent is sodium tripolyphosphate, P530 or sodium hexametaphosphate.
5. The cement-free aluminum magnesium chrome castable material of claim 4, further including an anti-explosive agent; the addition amount of the explosion-proof agent is 0.05-0.1% of the total mass of the aggregate, the matrix material and the bonding agent.
6. A method of producing a cement-free aluminum magnesium chromium castable material as claimed in any one of claims 1 to 5, including mulling the raw materials; the method is characterized in that the binding agent is premixed and then mixed with other raw materials; the charging sequence of the mixing is as follows: aggregate, matrix material and bonding agent.
7. Use of the cement-free almag-chrome castable material of any one of claims 1 to 5 in a rotary kiln or a rotary hearth furnace for metal recovery of solid waste material from metal smelting.
8. Use according to claim 7 in a high temperature reduction zone of a rotary kiln or rotary hearth furnace for metal recovery.
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| CN113173780B (en) * | 2021-04-26 | 2023-01-31 | 郑州大学 | Magnesia-bonded refractory castable containing in-situ spinel and preparation method thereof |
| CN113233906B (en) * | 2021-06-16 | 2022-04-08 | 浙江自立高温科技股份有限公司 | Magnesium-calcium gunning mix suitable for smelting clean steel and preparation method and application thereof |
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| EP2918564A1 (en) * | 2014-03-13 | 2015-09-16 | LANXESS Deutschland GmbH | Refractory materials containing a mixed crystal with spinel structure |
| CN106431436B (en) * | 2016-09-23 | 2019-07-09 | 武汉科技大学 | Electric furnace cover castable taking aluminum-chromium slag as main material and preparation method thereof |
| CN108623316A (en) * | 2018-05-22 | 2018-10-09 | 武汉科技大学 | Iron based on aluminium chromium slag smelts intermediate frequency furnace ramming mass and preparation method thereof |
| CN108358619B (en) * | 2018-05-24 | 2020-09-22 | 武汉科技大学 | Circulating fluidized bed boiler flue castable and preparation method thereof |
| CN111004041B (en) * | 2019-12-05 | 2022-06-21 | 上海利尔耐火材料有限公司 | Ladle bottom castable taking aluminum-chromium slag as main material and preparation method thereof |
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