The mixture for the manufacture of refractories with an irregular grain structure

 

(57) Abstract:

The inventive mixture contains, wt%: granular refractory filler fractions of more than 0.5 mm in the number of 40 - 60% and the rest is finely dispersed mixture of a joint grinding particles less than 0.09 mm, and finely dispersed mixture comprises, by wt.%: corundum 40 - 63,5; alumina 0.5 to 25; kaolin 20 - 30; zirconium dioxide - the rest, but not less than 5. From the prepared mass is pressed blanks and burn them at 1520 - 1600oC. 1 table.

The invention relates to the technology of refractories that can be used in ferrous and nonferrous metallurgy, steklovatnojj, chemical and other industries.

Known mixture for the manufacture of corundum refractories containing 45% of the grains of 0.5 to 3 0.5 to 2 mm), 10% of the grains fraction 0.06 to 0.5 mm and 45% of the grain fraction of less than 0.06 mm, and part of it is connecting part includes chamotte, corundum (or oxide), alumina and Distin-sillimanite concentrate [1]

The disadvantages of such structure shall be considered its low manufacturability due to the lack of mineral plasticizer (clay, kaolin), for pressing such refractories, it is necessary to introduce organic plasticizer and high specific pressure presses and dispensing components, pressing raw.

Closest to the proposed charge on a set of attributes (the prototype) is the mixture for the manufacture of refractory products with an irregular grain structure that includes the following components, wt.

Granular refractory filler fraction 0.5 mm 40 80

Binder 5 10

Mix joint grinding faction 0.09 mm 15 50

the mixture of a joint grinding contains, by weight. corundum 55 80, alumina 2 15 and clay 15 30 [2]

Improving manufacturability, the authors introduce the composition of the charge of the clay component (mineral plasticizer). It is well known that the introduction of the clay component in the manufacture of corundum refractories reduces their technical properties: building strength and volume stability at high temperatures. In the invention it is proposed to link the free silica formed during thermal decomposition of kaolinite clay component (education primary mullite) in the secondary mullite. The reaction of formation of secondary mullite begins at temperatures above 1450oC, therefore, for the completion of all physical and chemical processes firing refractories should be carried out at 1560 - 1620oC.

The invention in comparison with the prototype allows acteristic refractories. This result is achieved by the fact that in the charge for the manufacture of refractories with discontinuous grain composition contains, by weight.

Granular refractory filler fraction 0.5 mm 40 60

Mix joint grinding faction Rest of 0.09 mm

the mixture of a joint grinding contains, by weight. corundum 40 63,5, alumina 0,5 25, refractory clay or kaolin 20 30, zirconium dioxide else (but not less than 5).

Mix joint grinding produced in a pipe or vibratory mill (size fraction of less than 0.09 mm).

The mechanism of formation of mullite ligament in corundum refractories of the proposed structure is that the formation of zircon from the free silica formed during thermal decomposition of kaolin,

3(Al2O32SiO22H2O) - 3Al2O32SiO2+ 4SiO2< / BR>
and added zirconium dioxide is an intermediate stage of initiation:

ZrO2+ SiO2ZrO2SiO2< / BR>
Further, decomposing at temperatures above 1450oC zircon supplies free silica for education in conjunction secondary mullite with more active participation in the chemical ratio (compared to corundum alumina.

Rasenia 30% kaolin in the mixture of a joint grinding (the maximum amount of kaolin in the mixture).

In the kaolin contains, wt.

Al2O340

SiO256

In a mixture of a joint grinding:

40 0,30=12% Al2O3< / BR>
56 0,30=16.8% of SiO2< / BR>
Part of SiO2will be spent on the education of primary mullite. The ratio of the mullite Al2O3/SiO22,55.

In primary mullite contact SiO212/2,55 4,71%

Remains unbound SiO2: 16,8 4,71 12,09

For binding in zircon (ratio of ZrO2/SiO22,03) will 5/2,03 2,46% SiO2remains 12,09 2,46 9,63% unrelated SiO2.

To tie it in the mullite will need 2,559,63 24,56% alumina.

2. The introduction of 20% kaolin in the mixture of a joint grinding (the minimum amount of kaolin in the mixture).

In the kaolin contains, wt.

40 0,20=8% Al2O3< / BR>
56 0,20=11.2% of SiO2< / BR>
Part of SiO2will be spent on the education of primary mullite. The ratio of the mullite Al2O3/SiO22,55.

In primary mullite contact SiO28/2,55 3,14%

Remains unbound SiO2: 11,2 3,14 8,06%

For binding in zircon (ratio of ZrO2/SiO22,03) will 5/2,03 2,46% SiO2remains of 8.06 2,46 5,6% unrelated SiO2.

To bind it all into a mullite patrimony technological bunch (technical solution of lignosulfonate density of 1.18 1.24 g/cm2), mix and add it to the mixture (the size fraction less 0,088 mm) composition, wt.

Oxide 55

Alumina 10

Zirconium dioxide 10

Kaolin 25

the resulting joint grinding of these components into a tubular ball mill or a vibration mill for 1 to 1.5 h at a ratio of balls material 10 to 1.

The cooked mass is pressed and fired at 1520 1600oC.

The calculation of the phase composition of the bundles shown in the example of the charge, the following.

The amount of silica to be associated in zircon is calculated as follows.

In the kaolin contains, wt.

Al2O340

SiO256

In a mixture of a joint grinding:

40 0,25=10% Al2O3< / BR>
56 0,25=14% SiO2< / BR>
Part of SiO2will go to the formation of mullite. The ratio of the mullite Al2O3/SiO22,55.

SiO210/2,55 to 3.92%

Remains unbound SiO2: 14 3,92 10,08%

In the presence of 10% ZrO2in zircon contact (the ratio in zircon ZnO2/SiO22,03) 10/2,03 4.93 per cent silica.

In the reaction of formation of secondary mullite will take only 10,08 is 4.93 5.15 silica. The ratio of the mullite Al2O3/SiO2 in the form of alumina, and the rest is in the form of corundum.

At temperatures above 1500oC, after the dissolution of zircon in combination products is the following correlation phase, wt.

ZrO2Tetragonal 10

Mullite 142,55 35,7

Corundum 100-10-35,7 54,3

The table shows the properties of the samples obtained for different compositions of the mixture.

The mixture for the manufacture of refractories with an irregular grain structure that includes granular refractory filler fraction larger than 0.5 mm, and dispersed mixture of a joint grinding particles less than 0.09 mm, containing corundum, alumina and clay component, characterized in that the finely dispersed mixture contains as kaolin clay component and optionally Zirconia in the following ratio, wt.

Corundum 40 63,5

Alumina 0,5 25

Kaolin 20 30

The Zirconia Else, but not less than 5

moreover, the mixture contains components in the following ratio, wt.

Granular refractory filler fractions of more than 0.5 mm 40 60

Finely dispersed mixture of a joint grinding of the specified structure Ostalnoe

 

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