CN100491251C

CN100491251C - Method for preparing mullite from kaoline

Info

Publication number: CN100491251C
Application number: CNB200710051659XA
Authority: CN
Inventors: 严春杰; 李予晋; 肖国琪
Original assignee: YUNNAN TIANHONG KAOLIN MINING Co Ltd; China University of Geosciences
Current assignee: YUNNAN TIANHONG KAOLIN MINING Co Ltd; China University of Geosciences
Priority date: 2007-03-13
Filing date: 2007-03-13
Publication date: 2009-05-27
Anticipated expiration: 2027-03-13
Also published as: CN101049939A

Abstract

This invention relates to a method for preparing mullite by calcining kaolin. The method comprises: (1) mixing kaolin powder and additive uniformly; (2) heating the mixed raw materials at a rate of 2-10 deg.C/min to 1300 deg.C, and keeping the temperature for 3h to obtain the product. The additive is composite catalyst of KCl and CeO2. The addition amounts of KCl and CeO2 are 1-2 wt. % and 0.1-0.5 wt. % of kaolin powder, respectively. The method has such advantages as low energy consumption etc. The mullite product does not contain quartz phase.

Description

The method of preparing mullite from kaoline

Technical field

The present invention relates to a kind of method for preparing mullite by calcining kaolin.

Technical background

Mullite (mullite) is an aluminium silicate mineral, character such as have refractoriness height, good thermal shock, chemical resistance of concrete, creep resistance, refractoriness under load height, volume stability is good, electrical insulating property is strong, be the ideal high grade refractory, it is industrial to be widely used in metallurgy, glass, pottery, chemistry, electric power, national defence, combustion gas and cement etc.The natural mineral of mullite (mullite) is very rare in the earth's crust, because of nineteen twenty-four is found in Scottish Ma Er island (islandofmull) the earliest and gains the name.But artificial mullite is common and widely used a kind of mineral.The chemical ingredients of mullite is also unstable, and common have a 3Al ₂O ₃2SiO ₂And 2Al ₂O ₃SiO ₂Two kinds of forms.Mullite is rather similar to sillmanite family mineral.Its crystalline structure can be regarded as by the sillmanite structural evolution, and each structure cell is made up of 4 sillmanite structure cells, and each sillmanite structure cell is by 4 Al ₂O ₃SiO ₂Form, therefore, the mullite structure cell is equivalent to by 16 Al ₂O ₃SiO ₂Form.

At present, the technology by kaolin calcined preparation mullite mainly contains two kinds: 1. directly with kaolin calcined preparation mullite, name of product is M45, and product requirement does not contain the crystallization phases SiO that has a strong impact on its performance ₂(cristobalite); 2. kaolin is calcined after adding commercial alumina, obtains high aluminium content and highly purified mullite product.

The production technique of producing M45 at present is: kaolin 1500 ℃ of calcinings, is incubated 10 hours.Domestic only have one piece of patent report, kaolin directly prepares mullite, and product does not contain the cristobalite phase of damaging the mullite performance, its method is: coal series kaolin rock is through being crushed to the 40-250 order, through high-temperature calcination more than 1400 ℃ more than 8 hours, then 1300 ℃ of constant temperature 2 hours, perhaps coal series kaolin rock is through being crushed to the 40-250 order, add 1% (weight) mineralizer, 1.5% (weight) fusing assistant was calcining more than 1350 ℃ 8 hours, 1150 ℃ of constant temperature 2 hours, mineralizer was a magnesium oxide then, and fusing assistant is a calcium sulfate.

The main drawback of above method is the energy consumption height, and cost has high input.

Summary of the invention

The object of the present invention is to provide a kind of method of preparing mullite from kaoline, this method has the advantages that energy consumption is low, cost is low, and prepared mullite does not contain the cristobalite phase.

To achieve these goals, technical scheme of the present invention is: the method for preparing mullite from kaoline is characterized in that it comprises the steps:

1), kaolin powder and outer doping are mixed, must admixtion, described additive is KCl and CeO ₂The composite catalyst of being formed, the add-on of KCl are 1%-2% of kaolin powder weight, CeO ₂Add-on be 0.1%-0.5% of kaolin powder weight;

2), admixtion is warming up to 1300 ℃ with the speed of 2 ℃-10 ℃ of per minutes, 1300 ℃ of calcining insulations 3 hours, mullite greater than 55%, do not contain the product of cristobalite phase.

The particle diameter of described kaolin powder is less than 200 orders (0.074mm), and Al ₂O ₃Greater than 36%.

The present invention adopts outer doping (KCl and CeO ₂The composite catalyst of being formed) can make kaolin can change principal crystalline phase in 3 hours 1300 ℃ of insulations is mullite, and does not contain the product of cristobalite phase, thereby significantly reduces energy consumption, reduces production costs.

The present invention compared with prior art has following outstanding beneficial effect:

With calcining temperature from present technology greater than 1500 ℃, be reduced to 1300 ℃.

With soaking time from 10 hours, be reduced to 3 hours.

3. meanwhile, the product of preparing is gone up mutually from thing and do not contained the cristobalite phase that diminishes the mullite performance, and is approaching with the product Molochite sand of the ECC of Britain leading company on the composition.

Description of drawings

Fig. 1 is not adding 1300 ℃ of phase-change catalysts calcining insulation 3 hours for comparative example 1[Yunnan kaolin powder (less than 200 orders)] the XRD figure spectrum of gained.

To be comparative example 2[Yunnan kaolin powder (less than 200 orders) adding 40% aluminum oxide to Fig. 2,1500 ℃ of calcining insulations 6 hours] the XRD figure spectrum of gained.

To be comparative example 3[Yunnan kaolin powder (less than 200 orders) adding 15 ‰ Repone K to Fig. 3, and 5 ‰ cerium oxide were 1300 ℃ of calcining insulations 3 hours] the XRD figure spectrum of gained.

Fig. 4 is the XRD figure spectrum of the embodiment of the invention one [Yunnan kaolin powder (less than 200 orders) is adding 18 ‰ Repone K, and 2 ‰ cerium oxide were 1300 ℃ of calcining insulations 3 hours] gained.

Fig. 5 is the XRD figure spectrum of the embodiment of the invention two [Yunnan kaolin powder (less than 200 orders) is adding 16 ‰ Repone K, and 4 ‰ cerium oxide were 1300 ℃ of calcining insulations 3 hours] gained.

Fig. 6 is the XRD figure spectrum of the embodiment of the invention three [Yunnan kaolin powder (less than 200 orders) is adding 19 ‰ Repone K, and 3 ‰ cerium oxide were 1300 ℃ of calcining insulations 3 hours] gained.

Fig. 7 is the XRD figure spectrum of the embodiment of the invention four [Yunnan kaolin powder (less than 200 orders) is adding 20 ‰ Repone K, and 5 ‰ cerium oxide were 1300 ℃ of calcining insulations 3 hours] gained.

Fig. 8 is the XRD figure spectrum of the embodiment of the invention five [Yunnan kaolin powder (less than 200 orders) is adding 13 ‰ Repone K, and 5 ‰ cerium oxide were 1300 ℃ of calcining insulations 3 hours] gained.

Among the figure: mouth is the mullite characteristic peak, and zero is the cristobalite characteristic peak, and △ is the corundum characteristic peak, and ▽ is quartzy characteristic peak.

Embodiment

In order to understand the present invention better, further illustrate content of the present invention below in conjunction with embodiment, but content of the present invention not only is confined to the following examples.

Embodiment one:

Get Yunnan kaolin powder (less than 200 orders) 3.00g, add the Repone K powder of kaolin powder weight 18 ‰, add the cerium oxide powder of kaolin powder weight 2 ‰, mix, put into corundum crucible, crucible is put in the Si-Mo rod chamber type electric resistance furnace, speed with 4 ℃ of per minutes is warming up to 1300 ℃, 1300 ℃ of calcining insulations 3 hours, obtains the mullite product, product is carried out X powder crystal diffraction analysis, obtain XRD figure spectrum 4.As can be seen from Figure 4 mullite is about 55-60% mutually, does not contain cristobalite, and other is an amorphous phase.

Embodiment two:

Get Yunnan kaolin powder (less than 200 orders) 3.00g, add the Repone K powder of kaolin powder weight 16 ‰, add the cerium oxide powder of kaolin powder weight 4 ‰, mix, put into corundum crucible, crucible is put in the Si-Mo rod chamber type electric resistance furnace, speed with 4 ℃ of per minutes is warming up to 1300 ℃, 1300 ℃ of calcining insulations 3 hours, obtains the mullite product, product is carried out X powder crystal diffraction analysis, obtain XRD figure spectrum 5.As can be seen from Figure 5 mullite is about 55-60% mutually, does not contain cristobalite, and other is an amorphous phase.

Embodiment three:

Get Yunnan kaolin powder (less than 200 orders) 3.00g, add the Repone K powder of kaolin powder weight 19 ‰, add the cerium oxide powder of kaolin powder weight 3 ‰, mix, put into corundum crucible, crucible is put in the Si-Mo rod chamber type electric resistance furnace, speed with 4 ℃ of per minutes is warming up to 1300 ℃, 1300 ℃ of calcining insulations 3 hours, obtains the mullite product, product is carried out X powder crystal diffraction analysis, obtain XRD figure spectrum 6.As can be seen from Figure 6 mullite is about 55-60% mutually, does not contain cristobalite, and other is an amorphous phase.

Embodiment four:

Get Yunnan kaolin powder (less than 200 orders) 3.00g, add the Repone K powder of kaolin powder weight 20 ‰, add the cerium oxide powder of kaolin powder weight 5 ‰, mix, put into corundum crucible, crucible is put in the Si-Mo rod chamber type electric resistance furnace, speed with 4 ℃ of per minutes is warming up to 1300 ℃, 1300 ℃ of calcining insulations 3 hours, obtains the mullite product, product is carried out X powder crystal diffraction analysis, obtain XRD figure spectrum 7.As can be seen from Figure 7 mullite is about 55-60% mutually, does not contain cristobalite, and other is an amorphous phase.

Embodiment five:

Get Yunnan kaolin powder (less than 200 orders) 3.00g, add the Repone K powder of kaolin powder weight 13 ‰, add the cerium oxide powder of kaolin powder weight 5 ‰, mix, put into corundum crucible, crucible is put in the Si-Mo rod chamber type electric resistance furnace, speed with 4 ℃ of per minutes is warming up to 1300 ℃, 1300 ℃ of calcining insulations 3 hours, obtains the mullite product, product is carried out X powder crystal diffraction analysis, obtain XRD figure spectrum 8.As can be seen from Figure 8 mullite is about 55-60% mutually, does not contain cristobalite, and other is an amorphous phase.

Embodiment six:

Get Yunnan kaolin powder (less than 200 orders) 3.00g, add the Repone K powder of kaolin powder weight 10 ‰, add the cerium oxide powder of kaolin powder weight 1 ‰, mix, put into corundum crucible, crucible is put in the Si-Mo rod chamber type electric resistance furnace, be warming up to 1300 ℃ with the speed of 10 ℃ of per minutes, 1300 ℃ of calcining insulations 3 hours, obtain the mullite product.

Embodiment seven:

Get Yunnan kaolin powder (less than 200 orders) 3.00g, add the Repone K powder of kaolin powder weight 20 ‰, add the cerium oxide powder of kaolin powder weight 5 ‰, mix, put into corundum crucible, crucible is put in the Si-Mo rod chamber type electric resistance furnace, be warming up to 1300 ℃ with the speed of 2 ℃ of per minutes, 1300 ℃ of calcining insulations 3 hours, obtain the mullite product.

The comparative example 1:

Get Yunnan kaolin powder (less than 200 orders) 5.00g and put into corundum crucible, crucible is put in the Si-Mo rod chamber type electric resistance furnace, speed with 4 ℃ of per minutes is warming up to 1300 ℃, 1300 ℃ of insulations 3 hours, obtain the mullite product, product is carried out X powder crystal diffraction analysis, obtain XRD figure spectrum 1.As can be seen from Figure 1 mullite is about 55%-60% mutually, and cristobalite content is about 10%, and other is an amorphous phase.This figure explanation is not when 1300 ℃ of calcined kaolins add additive, and unnecessary quartz has part and changes the cristobalite phase that diminishes the mullite performance into.

The comparative example 2:

Get Yunnan kaolin powder (less than 200 orders) 10.00g, add the aluminum oxide of kaolin powder weight 40%, mix, put into corundum crucible, crucible is put in the Si-Mo rod chamber type electric resistance furnace, be warming up to 1500 ℃ with the speed of 4 ℃ of per minutes, 1500 ℃ of calcining insulations 6 hours, obtain the mullite product, product is carried out X powder crystal diffraction analysis, obtain XRD figure spectrum 2.As can be seen from Figure 2 mullite is about 60% mutually, and corundum content is about 20%, and cristobalite content is about 10%, and other is an amorphous phase.Even this figure explanation also can't be eliminated the cristobalite phase fully at 1500 ℃ of calcined kaolins.

The comparative example 3:

Get Yunnan kaolin powder (less than 200 orders) 8.00g, add the Repone K of kaolin powder weight 15 ‰, add the cerium oxide of kaolin powder weight 5 ‰, mix, put into corundum crucible, crucible is put in the Si-Mo rod chamber type electric resistance furnace, speed with 4 ℃ of per minutes is warming up to 1300 ℃, 1300 ℃ of calcining insulations 3 hours, obtains the mullite product, product is carried out X powder crystal diffraction analysis, obtain XRD figure spectrum 3.As can be seen from Figure 3 mullite is about 55-60% mutually, does not contain cristobalite, and other is an amorphous phase.The product of preparing is gone up mutually from thing and do not contained the cristobalite phase that diminishes the mullite performance, and is approaching with the product Molochite sand of the ECC of Britain leading company on the composition.

Claims

1. the method for preparing mullite from kaoline is characterized in that it comprises the steps:

2), admixtion is warming up to 1300 ℃ with the speed of 2 ℃-10 ℃ of per minutes, 1300 ℃ of calcining insulations 3 hours, product.

2. the method for preparing mullite from kaoline according to claim 1, it is characterized in that: the particle diameter of described kaolin powder is less than 200 orders, and Al ₂O ₃Greater than 36%.