DE3142021A1 - Refractory alumosilicate masonry brick - Google Patents

Abstract

Carbon-bonded refractory mouldings, in which the predominant refractory aggregate is andalusite, is characterised by the absence of significant shrinkage after degassing at 1100 DEG C.

Description

Refractory brick made of aluminosilicate

Natural aluminosilicate, which, among other things, clays, diaspore, cyanites and contain bauxite 'are the larger components of many refractory bricks, which are continuously produced. If the brick analysis is less than about 5 / o A1203 these are identified in technology as high-aluminum oxide bricks. Quite in general, the properties of aluminosilicate vary with the proportion of aluminum nium oxide. This may be due to the amount of type of mineral and with the large scope Glass phases are explained by the aluminosilicate substances when the brick is fired develop.

When the alumina content of refractory clay and high increases Alumina content tends to be resistant to stress at elevated temperatures to rise. The resistance also tries to peel off when the temperature changes rapidly to rise. These changes in properties are usually part of mitigation the amount of poorly refractory and fragile silicate glasses in the base mass of the brick. On the other hand, increasing the alumina tends to result in one Increase in porosity that physically resists chemical attack on the brick made vulnerable by metallurgical slag. In addition, the brick leans with higher alumina content results in less resistance to alkaline Vapors and against shrinkage when used after cooling down from high temperatures0 It Few words are suitable for what is meant by silicon dioxide-containing base material is.

Aluminum oxide and silicon dioxide in aluminosilicate refractories react when fired to form most of the mineral mullite.

Three moles of aluminum oxide react with two moles of silicon dioxide. if the ratio of alumina to silica exceeds 2 to 3, becomes the Burnt brick also contain corundum.

If the ratio is less than 3 to 2, the fired brick becomes practically mullite and one of the crystalline or glassy forms of silicon dioxide. Depending on the impurities and the heat treatment, the silicon dioxide will be to a certain extent Perimeter be in the shape of glass. The lower the ratio of alumina to silicon dioxide, the more SiO2 is in crystalline or glassy form.

The amount of glass then relates to the amount of shrinkage that occurs.

It is an object of the invention to provide refractory alumina-silica forms indicate that is characterized by the lack of shrinkage after firing at 11000C is. According to the invention, carbon-containing refractory fittings with of 1 to 35 weight percent carbon and the balance of a non-basic refractory Unit provided.

The refractory aggregate consists essentially of at least 75. Weight percent andalusite.

Preferably balancing the refractory aggregate, if not everything is andalusite, pure aluminum umoxide or another alumina-silica. The forms preferably contain 0 to 35 percent by weight layered graphite, you however, less than 7.5 percent by weight of amorphous graphite and / or carbon black can also be used contain. In general, the shapes are between 0.1 and 1 percent by volume Stretching with andalusite for at least 65% of the total weight of the load. These Stretching is important because it prevents the lining from becoming loose when an Cooling down from high temperatures takes place.

Andalusite is a mineral with the same chemical formula (Al2SiO5) like sillimanite and cyanite, but with different physical properties.

A better understanding and other features and benefits of implementation of the invention will become apparent to those skilled in the art upon studying the following description of the examples. Of course, these examples are only for explanation and do not represent any restrictions. All sizes correspond to the Tyler series, unless otherwise stated.

All chemical analyzes, except those specifically indicated, are based on an oxide analysis in accordance with standard chemical reporting practice Refractory material content. All analyzes should be considered typical and all parts and proportions are by weight.

The mixtures of the examples were made in the same for bricks Way made. The fireproof Aggregate was specified by size and mixed with a phenolic novolak resin. The cargo sorted by size are tempered in a mixing process in order to obtain compressible charges. the Charges were pressed into brick at about 1265 kg / cm2 and the brick was dried at 1200C for twelve hours. After cooling, the stone was tested subjected to its dry density and ability to change volume after Ent detect gases. Various alumina-silica borons were made which can be found in Table I.

Mixtures with predominantly different alumino-silicon dioxide grains has shrink properties between 0.4 and 1.5%. The brick at which a other refractory material has been added has somewhere in between Shrinkage. Mixture 3 example contains equal amounts of alumino-silicon dioxide grains and is stretched with pyrophyllite, but the stretching involved puffing.

Mixtures 9-14 in Table II were made with the following Ratios of andalusite to alumino-silicon dioxide graining of 50:50, 55:45, 60:40, 70:30 and 75:25.

All mixes except mix 14 with the 75:25 ratio from andalusite to alumino-silicon dioxide grain showed a shrinkage in volume degassing.

The mixtures according to Table III were with. Andalusite is the only one refractory aggregate manufactured.

Mixtures 15 to 18 contain up to 30% layered graphite. if the amount of layered graphite is increased from 0 to 30%, the volume expansion decreases degassing at 1100 ° C from 1.2% to 4%. Mix 15 only with the resin that is in the surcharge to andalusite, would contain about 1.3% carbon, which is derived entirely from the resin. Mixtures 19 and 20 with 2.5 and 5% respectively amorphous graphite expands after degassing. Additional tests have shown that stretching occurred when less than 7.5% amorphous graphite was used is. Mixture 21 with 5% carbon black and without graphite expanded after degassing, The classes of refractory aggregates used in the previous examples are the following: -3 + 10 stitches --3 to 40%; -10 + 28 stitches --15 to 25%; - 28 + 65 meshes --10 to 15%; and the balance -65 stitches. The usual chemical Analysis of the refractories used in the examples result from Table IV.

The others used in the exemplary refractory composition Materials not included in Table IV are calcined alumina and tabular alumina. These two substances contain around 99% Al2O3 and the, leveling trace impurities that are common in technology known are. Similarly, the crystallite and silicon dioxide are highly pure Silicon materials, i.e. 99% SiO2 and also well known.

Table I Mixture 1 2 3 4 5 6 7 8 aluminosilicate grain (50% AL2O3) 75.8% 75% 45% 80% - - - 90% aluminosilicate grain (60% Al2O3) - - - - 90% - - -Aluminosilicate grain (70% Al2O3) - - - - - 90% - - calcined bauxite - 10 - - - - - - tabulated Al oxide - - - - - - 90% refractory clay - 5 - - - - - -Cristobalite - - - 10 - - - -vaporized SiO2 4 - - - - - - -calcined Al2O3 10.2 - - - - - - -layered graphite 10 10 10 10 10 10 10 10 Pyrophillit - - 45 - - - - -plus additives Novlak resin 5 5 5 5 4.5 4.5 4.5 5 hexamethylenetetramine: 0.55 0.55 0.55 0.55 0.33 0.33 0.33 0.55 bulk density after drying at 96 ° C pef 152 153 148 142 154 156 186 146 volume change after Degassing at 1100 ° C% -0.5 -0.9 +2.6 -0.4 -1.5 -1.2 -0.4 -0.4 Bloated Tabel II mixture: 9 10 11 12 13 14 aluminosilicate grain (50% Al2O3) 45% 40.5% 36% 31.5% 17% 22.5% aluminosilicate grain (60% Al2O3) 45 49.5 54 58.5 63 67.5 layered graphite 10 10 10 10 10 10 Andalusite grain size - 50/50 55/45 60/40 65/35 70/30 75/25 ratio plus additives novolak resin 4.75 4.75 4.75 4.75 4.75 4.75 hexamethylenetetramine 0.35 0.35 0.35 0.35 0.35 0.35 bulk density after drying at 205 ° C pef 158 159 159 160 160 161 Change in volume after degassing at 1100 ° C - 0.55 -0.63 -0.67 -0.91 -0.46 +0.11 Table III Mixture 15 16 17 18 19 20 21 Andalusite 100% 90% 80% 70% 97.5% 95% 95% Layered graphite - 10 20 30 - - -amorphous graphite - - - - 2.5 5 carbon black - - - - - - 5 plus additives novolak resin 3.0 3.0 3.0 3.0 3.5 3.5 3.5 Bulk density after 166 164 163 159 167 166 165 @ heat treatment at 135 ° C pef +1.2 +0.6 +0.4 +0.4 +0.7 +0.4 +0.8 Table IV Alumo- Alumo- Alumo silicate silicate-silicate hot-calcined solid grain size grain size bauxite pyrophyllite Clay andalusite (50% AL203) (60% Al2O3) (70% Al2O2) SiO2 46.9% 39.6% 24.6% 5.9% 78.7% 62.9% 38.0% Al2O3 49.6 59.2 69.2 89.0 19.5 33.5 60.2 TiO2 2.4 2.6 3.2 3.2 0.4 2.1 0.20 Fe2O3 1.01 1.1 1.0 2.1 0.6 1.0 0.99 CaO 0.02 0.02 0.02 0.02 0.2 0.2 0.07 MgO 0.04 0.05 0.04 0.02 0.1 0.3 0.12 Total alkali 0.12 0.11 0.07 0.06 0.2 0.5 0.29 LOI Nile Nile Nile Nile 3.8 12.3 + 0.42 * (x) This is a weight gain

Claims (7)

P a t e n t a n s p r ü c h e 1. Carbon-bonded refractories Fittings with 1 to 35% weight percent carbon and the balance one not basic refractory aggregate consisting essentially of at least 75% by weight Abdalusit consists, that is not indicated, that after degassing no shrinkage occurs at a temperature of about 1100 ° C. 2. Fittings according to claim 1, d a d u r c h g e -k e n n z e i c Not that the balance of the non-basic refractory aggregate aluminum silicate or alumina. 3. Fittings according to claim 1, d a d u r c h g e k e n n z e i c h n e t that they consist of 0 to 39 percent by weight layered graphite. 4. fittings according to claim 1, d a d u r c h g e k e n n z e i c h n e t that at least 65% weight percent andalusite are included. 5. fittings according to claim 1, d a d u r c h g e k e n n z e i c h n e t that after degassing at about 110OOC a volume expansion between 0.1 and 1% takes place. 6. Fittings according to claim 1, d a d u r c h g g e k e n n z e i c Not that it contains up to 5 percent by weight of carbon black. 7. Fittings according to claim 1, d a d u r c h g e k e n n z e i c h n e t that less than 7.5% is amorphous graphite.