Title of Invention

A FIRED CERAMIC MOULDED BODY AND A PROCESS FOR ITS PRODUCTION

Abstract The invention relates to a composition for the production of a refractory ceramic moulded body, a non-fired or fired moulded body formed from the composition and a possibility for use.
Full Text

COMPOSITION FOR THE PRODUCTION OF A REFRACTORY CERAMIC MOULDED BODY, MOULDED DODIES FORMED THEREFROM AND USE
DESCRIPTION
The invention relates to a composition for the production of a refractory ceramic moulded body, a non-fired or fired moulded body formed from the composition and a possibilty for use.
Refractory ceramic products are subdivided into basic and non-basic products, for example. The basic products include those based on MgO (magnesia) such as magnesia products or magnesia-chromite products.
Such, in particularly purely magnesitic, types exhibit an excellent abrasion resistance, frequently however, an unsatisfactory infiltration behaviour viscosity is metallurgical slag such as those typical in processes for the production of stainless steel, for example. Such processes are known as AOD (= argon-oxygen decarb processes) or VOD {- vacuum-oxygen decarburisation processes) . The detaching behaviour, too, is unsatisfactory.
Apart from these purely magnesitic types, fired (including carbon-bound) bricks are known which contain at least a considerable proportion of dolomite [CaMg{CO3) 2] in the fired form. Depending on the deposit, the content of MgO or CaO of the dolomite varies, in terms of order of magnitude i. t amounts to 60 % by weight CaO and 40 % by weight MgO. SiO:,r Fe20:,, AI.O3, MnO (
Fe2O3-contenL of 0.5 to 1.0 % by weight and a typical AI2O3 content of 0.2 to 0.8 % by weight.
Depending on whether the compositions consist exclusively of dolomite or predominantly of dolomite (apart from additions of magnesia), the moulded parts formed therefrom are referred to as dolomite products or magdol products. Dolomite as a component of the composition means calcined dolomite or sintered dolomite, i.e. components containing CaO The wear of a dolomite or magdol brick is considerably greater than in the case of s pure magnesia brick:. Such moulded parts containing CaO + MgO, however, have a substantially lower infiltration tendency and detach themselves less easily*
In Dh: ICO 10 918 Al, a composition for the production of a refractory ceramic moulded body is disclosed which comprises the following i ndependent components:
a) 80 to 97 % by weight of fused magnesite, sintered magnesite cr mixtures of these wi th an MgO content of > 93 % by weighs and a grain size of b) 3 to 20 % by weight of CaO in a grain fraction of An essential aspect is that calcium oxide is added as an independent component of the magnesitic main component.
The moulded perts formed from this composition represent a quasi compromise between the known magnesia and magdol products', When using corresponding products, the expected improvement in the resistance to abrasion and the lower infiltration tendency is achieved; however, detachments can al3o take place,

The invention is based on the task of improving the moulded bodies known from DK 100 10 918 regarding their tendency to detach themselves without having to forego the good abrasion and corrosion resistance properties (as in the case of purely magnesitic moulded bodies) and the resistance to infiltration.
The invention is based, in this connection, on the following considerations: the side of a refractory ceramic moulded body which is facing the fire (the melt) is at a particular risk of detaching itself. This side is exposed to the highest temperatures (partially of more than 1,700 °C). Consequently, it was the aim of the development to improve the properties of the product regarding its softening under pressure (according to DIN-EN 993-8, 1997) and to make the structure more flexible. This is achieved by the following means. Small proportions of molten phase are admitted without negatively influencing the refractory properties. In this way, the thermal expansion, in particular, of HgO can be compensated. Thermomechanical tensions are avoided. Detachments (so called wspa1ling") can be prevented or at least reduced.
Consequently, the invention deviates from the teaching of DE 100 10 9] 8 Al of adding CaO as an independent component in maximum purity to the composition. Instead, a CaO-containing component is used in the composition in a controlled manner, which component is capable of introducing different foreign oxides, such as Fe203, into the composition. In this way, dicalcium ferrite, among other rhinos, is formed as secondary phase during firing of moulded body produced from the composition. Dicalcium ferrite provides the moulded body at elevated temperatures (application temperature) with a certain structural elasticity such that stresses can be better absorbed and/or reduced. Moreover, iron oxide acts as a mineraliser - when firing brick.

According to the invention, the iron oxide content (of the composition) can be between 1 and 8 % by weight.
Consequently, the i nvention deviates deliberately from the requirement of the state of the art of taking into account as 1ittle Fe2O3, in any case One possibility of adjusting the Fe2O3 content consists of using dolomite rich in iron oxide, for example. In this way, a proportion of MgO is introduced into the composition simultaneously. A further proportion of MgO is provided by a purely magres it component, e.g. fused magnesia or sintered magnesia.
A lurther essential differentiation criterion with respect to the composition according to DE 100 10 918 Al consists of the selacti on of the grain sizes for the individual components. Whereas, in the state o£ the art, the CaO-containing component is to be used in a grain fraction of 2 mm and/or 2 mm).
For the MgO-containing component, insofar as it has not already been taken into account as dolomite, the grain sizes are in particular in the region of 0.3 mm,

In its most general embodiment, the invention relates to a composition for the production of a refractory ceramic moulded body which comprises at least one component containing MgO and CaO in a grain size of a) 50 to 90 % by weight of MgC
b) 8 ro 40 % by weight of CaO,
c) 1 to 8 % by weight of Fe2C2,
d) up to 10 % by weight of others.
The sum total of a) to d) should be 100% by weight. Any binder, water etc is calculated separately.
The moulded parts formed from this composition can be classified as magnesia products comprising additions containing CaO and Fe2O3 from the composition, these
additions prociding the fired product with properties that
have previously been obntained only with products having a
high CaO conttent. Moreover. it ios possible to achieve
excellent corrosion propertiues with moulded parts made from
this composition, as in the case of pure magnesia bricks.
These properties are combined with a gopod infiltration
resistance andimproved structural elasticity such as they
have been known previously only in the case of purely
dolomitic moulded bodies. All mopulded parts such as bricks,
panels, rings etc. arfe moulded bodies
The attached illustration shows a polished face of a brick
according to the invention in the indicated magnification
The syructure of the brick determined by coarse
dolomitic grains (1) with an Fe2O2 content of approximately
3 % vby weight. Between these coarse (in the polished face;
dark) grain, comparatively smaller Mgo grains(2) can be
discerned between which Mgo-CaO melt additions (3) can be discerned.


The product: illustrated which was fired aL 1,550°C has the following characteristic va1ues ;

11 with 96 % by weight of MgO
2) with 41 % by weight of CaO and 3.8 % by weight of
Fe203.
The toral MgO content is approximately 71 % by weight, the total CaO content: approximately 26 % by weight, the total Fe203 content approximately 1.6 % by weight.
The bricks fired from this working material mixture (composition) at 1,400 °C have a value of T0t5 of 1,520 °C and an excellent resistance to detaching.
As detailed above, the MgO-containing component can consist of sintered magnesia, for example, with a grain fraction of
The proportion of MqO and CaO can also be introduced into the composition, via a so called MgQ+CaO molten material (co-smelter) [(3) in the illustration of the polished phase].
Insofar as no sintered dolomite is available in order to achieve the required proportion of Pe^G^in the composition, the iron oxide can be admixed by foreign components, e.g. in the form of scale.
As a rule, the iron oxide content wi11 be > 1.4 % by weight, e.g. 1.5 to 2 % by weight, however, if. can also be adjusted ~o values of > 2 % by weight, e.g. 2 to 4 % by weight, an upper limit of 3 % by weight being frequently sufficient to achieve the desired structural flexibility. The structural flexibility can also be characterised as fol]ows;
The test for softening under pleasure according to DIN EN 9 93-8 (1997) provided T0.5 values of between 1, 400 °C and 1,700 'c, values between 1,500 °C and 1, 650 UC being
advantageous.
The other foreign oxides such as ZU2O3, MnO and SiGz can be adjusted to values of The MgO-ccntaining component, insofar as it is introduced as pure magnesitic component, should have a degree of purity of > 90 % by weight, in particular > 95 % by weight.
The mean grain size (dbo) of the CaO-containing component can be selected to be larger than the mean grain size (dso) of the MgO-containing component, the MgO containing component being intended to have a degree of purity of > 90 % by weight, in particular > 95 % by weight.

According to one embodiment, the above-mentioned ratio also applied regarding a grain size of "dos" in each case.
Within the oxide analysis indicated, non-fired ceramic moulded bodies can be produced using the above-mentioned components containing MgO and CaO, a binder being usually admixed to the composition. The binder can be d carbon-containing temporary binder such as paraffin, for example.
from this non-fired product, a fired moulded body can be produced directly, the firing process taking place in a standard oven at temperatures above 1,400 °C.
The components of the composition, their grain size and the firing temperature can be selected in such a way that the fired moulded body has a raw density of > 3 g/cmj. The raw density leads to a relatively low open porosity which, according to one embodiment, is indicated as being The porosity and raw (apparent) density is responsible for the required infiltration resistance. The products have a good resistance to detaching and a high resistance to corrosion. They are also sui table for difficult fields of application in steel manufacture and in rotary ovens, e.g. for the production of cement. The content of Fe203 can also be above 4 % by weight, e.g. 6 or 8 % by weight, the structural flexibility being further increased at low application temperatures.

































(amended) PATENT CLAIMS
A fired ceramic moulded body, made of a composition which comprises at least one purely magnesitic component and at least one component containing CaO, all in a grain size a) 50 to 90 % by weight MgO,
b) 8 to 40 by weight CaO,
c) 1 to 8 by weight Fe2O3,
d) up to 10 % by weight others,
the sum total of a) to d) being 100 % by weight, providing, after firing, a test, value To.5 according to DIN EN 593-8 (1997) of between 1,400 and 1,700oC.
Moulded body according to claim 1 with a raw density of > 3 g/cm3.
Moulded, body according to claim 1 with an open porosity of Moulded body according to claim 1 in which the purely magnesitic component has a degree of purity of > 90 %
by weight. MgO.
Process for the production of a fired ceramic, FO2O3 comprising moulded body, with a test value TU/b according to OTN EN 993-8 (1997) of between 1400 °C and 1700 °C, according to which a composition is used, comprising at least one purely magnesitic and at least one component 'containing CaO, all in a grain size of a) 50 to 90 % by weight of MgO,
b) 8 to 40 % by weight of CaO,
c) 1 to 8 1 by weight of Fe2O3,

the total sum of a) to d) being 100 %, and forming dicalcium ferrate as a secondary phase after firing at a temperature > 1400oC.
Process according to claim 5 in which at least one CaO-containine; component ox the composition has a
grain size of > 2 mm.
Process according to claim 5 in which at least one CaO-cor.tainmg component of the composition has a size of Process according to claim. 5 in which the MgO-containir.g component of the composition with a decree of purity of > 90 % by weight has a grain size of mm.
Process according to claim 5 in which the MgO-eenco"' mg component of the composition with a degree of purity of > 90 % by weight has 'a grain size of process according to claim 5 in which the MgO-containing component of the composition with a degree of purity of > 90 % by weight has a grain size of
Process according to claim 5 in which the mean grain size (d50) of the CaO-containing component of the composition is greater than the mean grain size (d50) of the MgO-containing component of the composition with a degree of purity > 90 % by weight.

12. Process according to claim 5 in which the grain size
(d85) of the CaO-containing component of the
composition is greater than the grain size (d95) of
the MgO-containing component of the composition with a
degree of purity of > 90 % by weight.
13. Process according to claim 5 in which at least one
CaO-containing component, of the composition has a
grain size of 14. Process according to claim 5 in which at least one
CaO-contaning companent of the composition has a
grain size of 15. Process according to claim 5 with a Fe2O3 content of
the composition of > 1.5 % by weight.
16. Process according to claim 5 with a Fe20_3 content of
"Che composition of > 2 % by weight.
17. Process according to claim 5 with a proportion of an
MgO-CaO fused grain component in the composition.
18. Process according no claim 5 in which the oxdic
analysis of the composition exhibits at least one oi
the following oxides: MnO, TiO2, ZrOS, SiO2.
19. process according to claim 5, in which the purely
magnesitic component has a degree of purity of > 90 %
by weight.
20. Use of a moulded body according to claim 1 for lining
of a rotary kiln.



Documents:

1617-chenp-2005-abstract.pdf

1617-chenp-2005-claims.pdf

1617-chenp-2005-correspondnece-others.pdf

1617-chenp-2005-correspondnece-po.pdf

1617-chenp-2005-description(complete).pdf

1617-chenp-2005-drawings.pdf

1617-chenp-2005-form 1.pdf

1617-chenp-2005-form 18.pdf

1617-chenp-2005-form 26.pdf

1617-chenp-2005-form 3.pdf

1617-chenp-2005-form 5.pdf

1617-chenp-2005-pct.pdf


Patent Number 212952
Indian Patent Application Number 1617/CHENP/2005
PG Journal Number 13/2008
Publication Date 28-Mar-2008
Grant Date 17-Dec-2007
Date of Filing 15-Jul-2005
Name of Patentee REFRACTORY INTELLECTUAL PROPERTY GMBH & CO. KG
Applicant Address WIENERBERGSTRASSE 11, AT-1100 WIEN,
Inventors:
# Inventor's Name Inventor's Address
1 EDER JOHANN FERDINAND-HANUSCHSTRASSE 45, A-8700 LEOBEN,
2 NEUBOCK, RAINER RAIMUNDGASSE 6, A-8010 GRAZ,
PCT International Classification Number C04B 35/043
PCT International Application Number PCT/EP03/13823
PCT International Filing date 2003-12-06
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 103 01 881.6 2003-01-17 Germany