CN104671810A - Compact aluminum-magnesium-calcium fire-resistant clinker and preparation method thereof - Google Patents

Abstract

A dense aluminum-magnesium-calcium refractory clinker and a preparation method thereof, wherein the dense aluminum-magnesium-calcium refractory clinker contains 73-88% of Al ₂ O ₃ , 4-14% of MgO, 2-8% of CaO, and _2-2 % of ZrO 2 5%; the preparation method is: (1) Grinding limestone, magnesite and bauxite separately; (2) Mixing and adding zirconia powder to make a mixed material; (3) Ball milling to mix evenly and pressing into green balls; (4) Carry out the first calcination at 1200~1250°C; (5) Grind again and press into balls; (6) Carry out the second calcination at 1600~1650°C. The invention uses zirconia micropowder as a sintering accelerator, and can obtain dense aluminum-magnesium-calcium refractory clinker under the conditions of lower secondary calcination temperature and shorter holding time.

Description

A kind of dense aluminum magnesium calcium refractory clinker and its preparation method

technical field

The invention belongs to the field of refractory materials, in particular to a dense aluminum-magnesium-calcium refractory clinker and a preparation method thereof.

Background technique

Alumina-magnesium refractories are widely used as linings for high-temperature furnaces and kilns in metallurgy and cement industries due to their good performance in high temperature resistance, thermal shock resistance and slag erosion resistance; As the production cost of aluminum-magnesium refractory materials continues to rise, the production cost of aluminum-magnesium refractory materials also increases year by year; The heat storage loss of the kiln increases, and directly increases the discharge of refractory materials after use.

Limestone is abundant in resources all over the world, and the quicklime obtained after calcination has a relatively small theoretical density. If quicklime can be used to replace part of the corundum to produce aluminum-magnesium-calcium refractory materials, not only can the production cost be significantly reduced, but also the weight of refractory materials can be realized by reducing the bulk density, which is conducive to reducing heat storage loss and promoting energy conservation and emission reduction.

Because there are many chemical reactions inside the aluminum-magnesium-calcium refractory material under high temperature conditions, it is not suitable to obtain dense materials; therefore, limestone, magnesite and bauxite are generally used as raw materials, and dense aluminum-magnesium-calcium refractory clinker is obtained after high-temperature calcination. .

In the process of synthesizing refractory clinker of aluminum-magnesium-calcium system, the volume expansion effect accompanied by the reaction between the components and the flaky structure of the generated calcium hexaaluminate inhibit the sintering and densification process, making it difficult to obtain densification. clinker. Invention patent CN 103396127 A discloses a kind of aluminum-magnesium-calcium refractory clinker and its preparation method. Limestone, magnesite and bauxite are used as raw materials and fired at 1650-1700°C for 4-6 hours before being fired. Obtaining dense aluminum-magnesium-calcium refractory clinker not only requires high energy consumption, but also affects production efficiency.

Contents of the invention

Aiming at the above-mentioned problems existing in the current preparation technology of aluminum-magnesium-calcium refractory clinker, the present invention provides a kind of dense aluminum-magnesium-calcium refractory clinker and its preparation method. By adding zirconia to the raw material and then calcining, the Good sintering is achieved under the conditions of calcination temperature and short holding time, and dense aluminum-magnesium-calcium refractory clinker is obtained, which improves production efficiency and promotes energy saving and emission reduction.

The chemical composition of the dense Al-Mg-Ca refractory clinker of the present invention contains 73-88% of Al ₂ O ₃ , 4-14% of MgO, 2-8% of CaO and 2-5% of ZrO ₂ by weight percentage.

The relative density of the above-mentioned dense aluminum-magnesium-calcium refractory clinker is 91.8-94.6%.

The water absorption rate of the above-mentioned dense aluminum-magnesium-calcium refractory clinker is 2.4~3.2%.

The preparation method of dense aluminum-magnesium-calcium refractory clinker of the present invention is carried out according to the following steps:

1. Crush and grind limestone, magnesite and bauxite to particle size ≤ 88 mesh respectively;

2. Mix crushed limestone, magnesite and bauxite and add zirconia micropowder to make a mixed material. The mixing ratio is 2.9~12.2% of the total weight of the mixed material for limestone and 2.9-12.2% of the total weight of the mixed material for magnesite. 6.8~21.9% of the total weight of the mixture, bauxite accounts for 65.4~84.3% of the total weight of the mixture, and zirconia micropowder accounts for 1.4~3.6% of the total weight of the mixture;

3. Put the mixed material in a ball mill to mix evenly, and then press it into a green ball under a pressure of 100~150MPa;

4. Heat the raw balls at 1200-1250°C for 1-2 hours, and perform the first calcination to make primary clinker;

5. Break the primary clinker and grind it again to a particle size of ≤88 mesh, and then press it into balls under a pressure of 100~150MPa to obtain secondary balls;

6. Heat the secondary pellets at 1600-1650°C for 2-3 hours, and perform the second calcination to obtain dense aluminum-magnesium-calcium refractory clinker.

The purity of the above-mentioned zirconia micropowder is ≥99%, and the particle size is ≤10 μm.

The weight content of CaO in the above limestone is ≥50.2%, the weight content of MgO in magnesite is ≥44.5%, and the weight content of Al ₂ O ₃ in bauxite is ≥73.8%.

The dense aluminum-magnesium-calcium refractory clinker of the present invention adopts zirconia micropowder as a sintering accelerator, and zirconium ions can be dissolved in calcium hexaaluminate during the calcination process, so that the calcium hexaaluminate transforms from a plate shape to an equiaxed crystal and promotes the sintering process. Sintering; at the same time, the activated zirconia precipitated during the cooling process further promotes sintering, making the grains bond tightly, so that dense aluminum-magnesium-calcium refractory clinker can be obtained at a lower secondary calcination temperature and a shorter holding time.

Detailed ways

The equipment used for calcining in the embodiment of the present invention is a high-temperature shaft kiln.

In the embodiment of the present invention, the equipment used for pressing into balls is a GY650-180 type ball pressing machine.

Limestone, magnesite and bauxite used in the examples of the present invention are commercial products.

The zirconia micropowder used in the examples of the present invention is a commercially available product.

Example 1

The weight content of CaO in the limestone used is 53.8%, the weight content of _Al2O3 in the bauxite used is _78.6 %, and the weight content of MgO in the magnesite used is 45.8%;

Limestone, magnesite and bauxite are respectively crushed and ground to a particle size of ≤88 mesh;

Mix the crushed limestone, magnesite and bauxite and add zirconia micropowder to make a mixed material. The mixing ratio is 3.1% of the total weight of the mixed material for limestone and 12.3% of the total weight of the mixed material for magnesite. %, bauxite accounts for 82.8% of the total weight of the mixture, and zirconia micropowder accounts for 1.8% of the total weight of the mixture;

Put the mixed material in a ball mill and mix evenly, and then use a ball press machine to press it into a ball under a pressure of 150MPa to obtain a green ball;

Put the raw balls in a high-temperature shaft kiln, heat them at 1200°C for 2 hours, and perform the first calcination to make primary clinker;

The primary clinker is broken and ground to a particle size of ≤88 mesh, and then pressed into balls under a pressure of 150MPa to obtain secondary balls;

Place the secondary pellets in a high-temperature shaft kiln, heat them at 1650°C for 2 hours, and perform the second calcination to obtain dense aluminum-magnesium-calcium refractory clinker. The chemical composition contains 87.7% Al ₂ O ₃ , MgO 7.6%, CaO 2.3%, ZrO ₂ 2.4%, relative density 92.4%, water absorption 3.2%.

Example 2

The limestone, bauxite and magnesite that adopt are with embodiment 1;

Limestone, magnesite and bauxite are respectively crushed and ground to a particle size of ≤88 mesh;

Mix the crushed limestone, magnesite and bauxite and add zirconia micropowder to make a mixed material. The mixing ratio is as follows: limestone accounts for 9.1% of the total weight of the mixed material, and magnesite accounts for 13.3% of the total weight of the mixed material. %, bauxite accounts for 74.0% of the total weight of the mixture, and zirconia micropowder accounts for 3.6% of the total weight of the mixture;

Put the mixed material in a ball mill and mix evenly, and then use a ball press machine to press it into a ball under a pressure of 130MPa to obtain a green ball;

Put the raw balls in a high-temperature shaft kiln, heat them at 1250°C for 2 hours, and perform the first calcination to make primary clinker;

The primary clinker is crushed and ground to a particle size of ≤88 mesh, and then pressed into balls under a pressure of 150MPa to obtain secondary balls;

Place the secondary pellets in a high-temperature shaft kiln, heat them at 1620°C for 3 hours, and perform the second calcination to obtain dense aluminum-magnesium-calcium refractory clinker. The chemical composition contains Al ₂ O ₃ 79.9% by weight, MgO 8.4%, CaO 6.7%, ZrO ₂ 5%, relative density 94.6%, water absorption 2.4%.

Example 3

The weight content of CaO in the limestone used is 52.2%, the weight content of _Al2O3 in the bauxite used is _86.4 %, and the weight content of MgO in the magnesite used is 46.4%;

Limestone, magnesite and bauxite are respectively crushed and ground to a particle size of ≤88 mesh;

Mix the crushed limestone, magnesite and bauxite and add zirconia micropowder to make a mixed material. The mixing ratio is that limestone accounts for 12.2% of the total weight of the mixed material, and magnesite accounts for 7.0% of the total weight of the mixed material. %, bauxite accounts for 77.8% of the total weight of the mixture, and zirconia micropowder accounts for 3.0% of the total weight of the mixture;

After mixing evenly, press it into a ball under the pressure of 100MPa;

Insulate the green balls at 1250°C for 1 hour;

The primary clinker is crushed and ground to a particle size of ≤88 mesh, and then pressed into balls under a pressure of 120MPa;

Place the secondary pellets in a high-temperature shaft kiln, heat them at 1630°C for 2 hours, and perform the second calcination to obtain dense aluminum-magnesium-calcium refractory clinker. The chemical composition contains 84.2% Al ₂ O ₃ , MgO4 .1%, CaO 8%, ZrO ₂ 3.7%, relative density 93.9%, water absorption 2.6%.

Example 4

The weight content of CaO in the limestone used is 50.8%, the weight content of _Al2O3 in the bauxite used is _74.6 %, and the weight content of MgO in the magnesite used is 45.2%;

Limestone, magnesite and bauxite are respectively broken and ground to a particle size of ≤88 mesh;

Mix the crushed limestone, magnesite and bauxite and add zirconia micropowder to make a mixed material. The mixing ratio is as follows: limestone accounts for 6.3% of the total weight of the mixed material, and magnesite accounts for 13.6% of the total weight of the mixed material. %, bauxite accounts for 77.7% of the total weight of the mixture, and zirconia micropowder accounts for 2.4% of the total weight of the mixture;

Put the mixed material in a ball mill and mix evenly, and then use a ball press machine to press it into a ball under a pressure of 120MPa to obtain a green ball;

Put the raw balls in a high-temperature shaft kiln, heat them at 1200°C for 2 hours, and perform the first calcination to make primary clinker;

The primary clinker is crushed and ground to a particle size of ≤88 mesh, and then pressed into balls under a pressure of 150MPa to obtain secondary balls;

Place the secondary pellets in a high-temperature shaft kiln, heat them at 1650°C for 3 hours, and perform the second calcination to obtain dense aluminum-magnesium-calcium refractory clinker. The chemical composition contains 83.2% Al ₂ O ₃ , MgO 8.8%, CaO 4.6%, ZrO ₂ 3.4%, relative density 92.8%, water absorption 2.5%.

Example 5

The preparation process is the same as in Example 4, the difference is that the mixing ratio is that limestone accounts for 5.6% of the total weight of the mixture, magnesite accounts for 15.2% of the total weight of the mixture, and bauxite accounts for 76.4% of the total weight of the mixture by weight percentage. %, zirconia micropowder accounts for 2.8% of the total weight of the mixed material;

After mixing evenly, press it into a ball under the pressure of 100MPa;

Insulate the green balls at 1250°C for 1 hour;

The primary clinker is crushed and ground to a particle size of ≤88 mesh, and then pressed into balls under a pressure of 120MPa;

Place the secondary pellets in a high-temperature shaft kiln, heat them at 1600°C for 3 hours, and perform the second calcination to obtain dense aluminum-magnesium-calcium refractory clinker. The chemical composition contains 82% Al ₂ O ₃ , MgO 10%, CaO 4%, ZrO ₂ 4%, relative density 93.5%, water absorption 3.1%.

Example 6

The preparation process is the same as in Example 4, except that the mixing ratio is that limestone accounts for 8.3% of the total weight of the mixture, magnesite accounts for 9.1% of the total weight of the mixture, and bauxite accounts for 81.2% of the total weight of the mixture by weight percentage. %, zirconia micropowder accounts for 1.4% of the total weight of the mixed material;

After mixing evenly, press it into balls under the pressure of 120MPa;

Insulate the green balls at 1200°C for 2 hours;

The primary clinker is crushed and ground to a particle size of ≤88 mesh, and then pressed into balls under a pressure of 100MPa;

Place the secondary pellets in a high-temperature shaft kiln, heat them at 1650°C for 2 hours, and perform the second calcination to obtain dense aluminum-magnesium-calcium refractory clinker. The chemical composition contains 86.2% Al ₂ O ₃ , MgO 5.8%, CaO 6%, ZrO ₂ 2%, relative density 91.8%, water absorption 2.9%.

Example 7

The preparation process is the same as in Example 4, the difference being that the mixing ratio is that limestone accounts for 2.9% of the total weight of the mixture, magnesite accounts for 18.3% of the total weight of the mixture, and bauxite accounts for 75.5% of the total weight of the mixture by weight percentage. %, zirconia micropowder accounts for 3.3% of the total weight of the mixed material;

After mixing evenly, press it into balls under the pressure of 120MPa;

Insulate the green balls at 1250°C for 2 hours;

The primary clinker is crushed and ground to a particle size of ≤88 mesh, and then pressed into balls under a pressure of 150MPa;

Place the secondary pellets in a high-temperature shaft kiln, heat them at 1600°C for 3 hours, and perform the second calcination to obtain dense aluminum-magnesium-calcium refractory clinker. The chemical composition contains 81.2% Al ₂ O ₃ , MgO 12%, CaO 2%, ZrO ₂ 4.8%, relative density 93.8%, water absorption 2.7%.

Example 8

The preparation process is the same as in Example 4, the difference being that the mixing ratio is that limestone accounts for 10.4% of the total weight of the mixture, magnesite accounts for 20.9% of the total weight of the mixture, and bauxite accounts for 65.4% of the total weight of the mixture by weight percentage. %, zirconia micropowder accounts for 3.3% of the total weight of the mixed material;

After mixing evenly, press it into balls under the pressure of 120MPa;

Insulate the green balls at 1250°C for 2 hours;

The primary clinker is crushed and ground to a particle size of ≤88 mesh, and then pressed into balls under a pressure of 150MPa;

Place the secondary pellets in a high-temperature shaft kiln, heat them at 1600°C for 3 hours, and perform the second calcination to obtain dense aluminum-magnesium-calcium refractory clinker. The chemical composition contains Al ₂ O ₃ 73%, MgO 14%, CaO 8%, ZrO ₂ 5%, relative density 94.4%, water absorption 2.8%.

Example 9

The weight content of CaO in the limestone used is 55.6%, the weight content of _Al2O3 in the bauxite used is _78.4 %, and the weight content of MgO in the magnesite used is 44.6%;

Limestone, magnesite and bauxite are respectively broken and ground to a particle size of ≤88 mesh;

Mix the crushed limestone, magnesite and bauxite and add zirconia micropowder to make a mixed material. The mixing ratio is as follows: limestone accounts for 6.5% of the total weight of the mixed material, and magnesite accounts for 6.8% of the total weight of the mixed material. %, bauxite accounts for 84.3% of the total weight of the mixture, and zirconia micropowder accounts for 2.4% of the total weight of the mixture;

Put the mixed material in a ball mill and mix evenly, and then use a ball press machine to press it into a ball under a pressure of 150MPa to obtain a green ball;

Put the raw balls in a high-temperature shaft kiln, heat them at 1200°C for 1 hour, and perform the first calcination to make primary clinker;

The primary clinker is broken and ground to a particle size of ≤88 mesh, and then pressed into balls under a pressure of 100MPa to obtain secondary balls;

Place the secondary pellets in a high-temperature shaft kiln, heat them at 1650°C for 3 hours, and perform the second calcination to obtain dense aluminum-magnesium-calcium refractory clinker. The chemical composition contains 88.0% Al ₂ O ₃ , MgO 4.0%, CaO 4.8%, ZrO ₂ 3.2%, relative density 93.4%, water absorption 2.0%.

Example 10

The preparation process is the same as in Example 9, except that the mixing ratio is that limestone accounts for 5.8% of the total weight of the mixture, magnesite accounts for 21.9% of the total weight of the mixture, and bauxite accounts for 70.3% of the total weight of the mixture by weight percentage. %, zirconia micropowder accounts for 2.0% of the total weight of the mixed material;

After mixing evenly, press it into a ball under the pressure of 150MPa;

Insulate the green balls at 1250°C for 2 hours;

The primary clinker is crushed and ground to a particle size of ≤88 mesh, and then pressed into balls under a pressure of 150MPa;

Place the secondary pellets in a high-temperature shaft kiln, heat them at 1600°C for 3 hours, and perform the second calcination to obtain dense aluminum-magnesium-calcium refractory clinker. The chemical composition contains 78.6% Al ₂ O ₃ , MgO 13.9%, CaO 4.6%, ZrO ₂ 2.9%, relative density 92.5%, water absorption 2.8%.

According to CN 103396127 A embodiment 1 ~ 8 process, prepare aluminum magnesium calcium refractory clinker, its secondary calcination temperature is 1650 ~ 1700 ^o C, holding time is 4 ~ 6 hours; Compared with reference preparation method, the present invention provides The preparation method of dense aluminum-magnesium-calcium refractory clinker can realize good sintering of aluminum-magnesium-calcium refractory clinker under the conditions of lower calcination temperature and shorter holding time.

Claims (6)

1. A dense aluminum-magnesium-calcium refractory clinker, characterized in that the chemical composition contains 73-88% Al ₂ O _{3 ,} 4-14% MgO, 2-8% CaO, and 2-5% ZrO ₂ by weight percentage. 2. A dense aluminum-magnesium-calcium refractory clinker according to claim 1, characterized in that the relative density of the dense aluminum-magnesium-calcium refractory clinker is 91.8-94.6%. 3. A dense aluminum-magnesium-calcium refractory clinker according to claim 1, characterized in that the water absorption of the dense aluminum-magnesium-calcium refractory clinker is 2.4-3.2%. 4. the preparation method of dense aluminum-magnesium-calcium refractory clinker as claimed in claim 1 is characterized in that carrying out according to the following steps: (1) Crush and grind limestone, magnesite and bauxite separately to a particle size of ≤88 mesh; (2) Mix crushed limestone, magnesite and bauxite and add zirconia micropowder to make a mixed material. The mixing ratio is 2.9~12.2% of the total weight of the mixed material for limestone and 2.9-12.2% for magnesite 6.8~21.9% of the total weight of the mixed material, bauxite accounts for 65.4~84.3% of the total weight of the mixed material, and zirconia micropowder accounts for 1.4~3.6% of the total weight of the mixed material; (3) Put the mixed material in a ball mill to mix evenly, and then press it into a green ball under a pressure of 100~150MPa; (4) Heat the raw balls at 1200-1250°C for 1-2 hours, and perform the first calcination to make primary clinker; (5) Break the primary clinker and grind it again to a particle size of ≤88 mesh, and then press it into balls under a pressure of 100~150MPa to obtain secondary balls; (6) Heat the secondary pellets at 1600-1650°C for 2-3 hours, and perform the second calcination to obtain dense aluminum-magnesium-calcium refractory clinker. 5. The preparation method of dense Al-Mg-Ca refractory clinker according to claim 4, characterized in that the weight content of CaO in the limestone is ≥50.2%, the weight content of MgO in the magnesite is ≥44.5%, and the aluminum alum The weight content of Al ₂ O ₃ in the soil is ≥73.8%. 6. The method for preparing dense Al-Mg-Ca refractory clinker according to claim 4, characterized in that the purity of the zirconia micropowder is ≥99%, and the particle size is ≤10 μm.