DE1646834B1 - Process for the production of unfired, refractory bricks and masses from magnesite chromium and chromium magnesite - Google Patents

Description

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The invention relates to a method for producing 0.12 mm, preferably at most 0.10 mm, on

of unfired, refractory bricks and masses and

from magnesite chromium and chromium magnesite and aims at c) the sintered material a silica content of

above all, unfired stones of this type to a maximum of 5.5%, preferably a maximum of 4.5%

create the burned-up, d. H. at temperatures 5 and

of more than 1750 ⁰ C fired magnesite chromium bricks and d) a lime-silica ratio of at most chromium magnesite bricks are at least equivalent. 0.6, preferably at most 0.35.
Another aim of the invention is to produce unfired magnesite chromium and chromium magnesite bricks. between the resistance to slag attack and other chromium oxide-containing substances or the chrome ore and properties for the delivery of highly bean- magnesia, in itself, and this direct bond is also required industrial furnaces, in particular for the additional processing of the sintered material and the setting of walls and ceilings from Siemens-Martin-15 so in stones made from them are ideal for ovens. Finally intended to keep. This makes it possible, without the stones themselves to burn the invention, the production of refractory high temperatures and thus the after-masses on the basis of magnesite chromium and parts of a high-temperature fire of stones in chromium magnesite, which have to be taken through a good fire purchase, To obtain stones that are at least equivalent to high strength, pressure fire resistance, cold pressure resistance - 20 fired stones,
speed, abrasion resistance and resistance to slag- In the course of further research it was now possible to distinguish attack and in the unshaped state, it was found that very favorable properties such. B. as mortar, patch and gunning mixes, or in having unfired, refractory bricks and also in a shaped state in the form of ramming masses in masses of magnesite chromium and chromium magnesite then industrial furnaces and metallurgical vessels used 25 can be obtained if not all processes can be obtained. steps applied according to the older proposal

It is already known that one can become magnesite chromium, but only use the measures and become chromium magnesite stones with valuable properties that the chromium oxide-containing substances can essentially be obtained by combining them with the magnesia material before the special chromium ore high temperature firing case of temperature 30 deformed state together a sintering firing temperatures of over 1700 ⁰ C subjects. Such a subject and the set for the burning process is technically difficult to carry out due to the different position of the sintered material on a lime-silica reasons; It can be fired in a ratio of a maximum of 0.6 and a silica factories in which stones are set at normal temperatures of at most 5.5%, a high temperature firing only with 35 but the temperature during sinter firing is increased large investments in the production program and, if the granular sintered material is sintered, since in the case of a high temperature magnesia is added, this addition a certain brandes special measures are necessary in order not to exceed the maximum amount. Accordingly, it relates to preventing the stones from being crushed and the invention of which ensures a method for producing dimensional and dimensional stability at least approximately to 40 unfired, refractory stones and masses. Magnesite chrome and chrome magnesite with a direct

The inventor has already dealt with this problem earlier (German binding between the chromoxydhaltigsn materials legeschrift 1 257 655) and / or the chromium ore and the magnesia, from one of them found a possibility, the stone fire at a temperature of at least 1700 ⁰ C without avoiding high temperatures. According to this 45 melting obtained sintered material (simultaneous sintering), earlier proposal for the production of a silica content of at most 5.5%, burnt or unfired, refractory magnesite - preferably at most 4.5%, and a lime, silica chromium and chromium magnesite bricks containing chromium oxide -Ratio of at most 0.6, preferably substances, in particular chrome ore, with magnesite, at most 0.35, and this method is optionally characterized by sintered magnesite, or other natural 50, that a sintered material is used, borrowed or synthetic, when burning magnesium is that supplied at a temperature of minds least 1750 ° C oxyd magnesium compounds mixed burned, and the granular sinter Ge and, preferably after deformation into briquettes or where appropriate with a maximum of 35 percent by weight of sintered bricks, at temperatures of at least 1700 ⁰ C. magnesia mixed and this mixture ge in known without melting together sintert (simultaneous firing), 55 is formed into stones if desired, and the sintered material is then grained and, if after the addition of sintered magnesia, mixed into stones, the sintered material used for the production of the sintered material is shaped after previous deformation. In this process, the particular combination of briquettes or stones with the measures listed is used, that temperatures of at least 175O ⁰ C are burned.

60 It should be noted here that according to the above

a) For the production of the sintered material, the older proposal (German Auslegeschrift 1 257 655) containing oxide materials have a grain size of 0 to 6mm, preferably 0 to 4mm, for the production of fired stones, whereby e.g. 185O ⁰ C burnt sintered material used at least 65%, preferably at least 80%, but for the extraction of the sinter of the chromium oxide-containing substances in a grain material for the production of unfired stones of more than 0.12 mm, only firing temperatures of 1730 and 1740 ^{0 are available} C an-

b) whereas the magnesite or magnesium oxide is given. It couldn't be guessed at that time The material to be supplied has a grain size below that for the manufacture of unfired

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Stones in the case of using one at tempe- gives the best results. Magnesite instead of Rohraturen of at least 175O ⁰ C Simvltan- obtained others can optionally natuer inters over the use of a Liehe or temperature-synthetic, upon firing Magnesiumraturen obtained under 1750 ⁰ C Simultaminters oxide supplying magnesium compounds used werderfreak surprising and anticipate in any way 5 den, but the use of raw magnesite is achieved that the advantage is obtained from the at. Likewise, MgO-containing at least 1750 ° C fired simultaneous sintering materials, such as sintered magnesia, can be used for the simultaneous firing of unfired bricks in a considerably better way. But this is economically viable. In the case of the production of fired, unfavorable, since it requires two firing, th stones is the temperature at which the simultaneous production of larger moldings from the materials to be sintered is obtained, provided that this temperature is 1700 ° C sintering materials exceeding its purpose, practically more or less without being moderate, if the magnesia component is only in grosser concern; grain sizes are available for the production of unfired stones, which is particularly the case with the use of a temperature of sintered magnesia or a temperature of at least 1750 ^° C. by other methods compared to the use of magnesite processed as flotation. Temperature of 175O 17C0 to below ⁰ C during If the starting materials are in fine-grained form of simultaneous extraction linters essential, is also deformed into granules importance. into consideration, but with pressed moldings, also the further feature of the present invention such as briquettes or stone moldings, better properties, which consists in the fact that the grained sintered shafts, such as porosity and bulk density, are made from the material, optionally with sintered magnesia, however, products obtained in sintered material are achieved. Quantities of a maximum of 35%, based on the fire The chromium oxide-containing substances or the chromite solid constituents, is noteworthy. For the production of the sintered material, a grain size of 0 to 6 mm, preferably 0 to 4 mm, can have a grain size of 0 to 6 mm, preferably 0 to 4 mm, for stone production up to 75%> ² 5, whereby at least 65%, preferably at least preferably below 40% > Sintered magnesia is added at least 80% of the chromium oxide-containing substances in one, and z. B. for the build-up of grain sizes of over 0.12 mm. ^Unfired stones should be 60% simultaneous sintering and 40% aDer preferably the grain size should start at 0 mm, sintered magnesia should be used. On the other hand, fine grains of less than 0.12 mm are also present, in the case of the present invention there should be 30. When using a chromite fraction of the finding that for the production of un- 0 to 6 mm or 0 to 4 mm normally fired stones are not more than 35% sinter - at least about 10% of a grain size from 0 to magnesia added to the simultaneous sintering v / ground 0.12 mm in front.

to be allowed to. As already mentioned, there is a characteristic of the 35 invention used in the method according to the invention that for the structure of the unfired kept lime-silica ratio of less than 0.6 stones and masses the grained sintered material and the quantities of silica listed are (simultaneous sintering) with an addition of at most mainly in the form of forsterite, and it is 35% sintered magnesia, based on the refractory are not interfering amounts of low-melting components, is used. Here are allowed to Monticellite present. The silica-grained sintered material should preferably have a maximum of 8%, preferably acid content of the sintered material below 4.0% or still only 3 to 5%, based on the refractory better to be below 3.5%. When adhering to the components, fine-grain sintered magnesia of a grain guide Lime-silica ratios and a maximum size of 0.12 mm at most can be added. That content of silica is certainly a complete means that the sintered material in addition to at most Coating of the chromium oxide-containing components, ins- 45 8% sintered magnesia with a grain size of up to especially the chromite, prevented with silicates and 0.12 mm still up to 27% sintered magnesia one as a result, in the case of the applied grain size of over 0.12 mm are added Firing temperatures of at least 1750 ° C can be obtained, the grain size being the coarser a direct bond between the chromium oxide sintered magnesia is preferably greater than 0.5 mm containing constituents and which should be 50 during firing.

formed periclases guaranteed. Finally, it has also been found to be essential for the preservation of this direct bond and thus that, in the case of the production of stones from the majority of the favorable properties of the unfired stone material produced from grained sintered material, if this sintered stone material made from this sintered material has 13% or more Cr ₂ O ₃ contains, absolutely and masses are necessary compared to the lime-silica 55, the sintered material has a fine-grain Ma ratio and the silica content the grain size gnesia with a grain size of at most 0.12 mm and the materials to be sintered are not so essential in amounts up to a maximum of 8%, preferably 3 to 5%, of importance. Preferably, however, for the production of the sintered material, the magnesite should be added for the refractory constituents, or which otherwise the cold compressive strength of the bricks in the magnesium compound would not be sufficient in the case of deformation to the delivery condition. Briquettes in grain sizes from 0 to 0.2 mm, in the case of the unfired products according to the invention of forming into stones in a grain size of contain in addition to the listed refractory constituents up to 5 mm, preferably 0 to 3 mm, generally only share one additive be on. In these cases, therefore, there are coarser binders such as sulphite waste liquor or magnesium sulphate. Grain sizes of the magnesia component of over 65 should be appropriate in the finished products, also 0.12 mm. As a magnesium oxide supplying material like in the sintered material, the lime-silica mixture is preferably used raw magnesite or floated raw magnesite (molar ratio) not more than 0.6 and the silica magnesite (flotation magnesite), as this acid content is below 5.5%.

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The invention is based on the following examples of these stones was as follows:
explained in more detail. _si 0 ₂ 3 _j3 o _{/ o}

Fe ₂ O ₃ 8.7%

B ice ρ ie 1 1, Al ₂ O ₃ 7.4%

⁵ Cr ₂ O ₃ 20.3%

A mixture of chrome ore (0 to 4 mm) became ^ ₁ Q ₅₇ ' ₃ Ji ⁰

with flotation magnesite (0 to 0.2 mm) with the addition of niTilivpriiist Ί "> o / °

of about 10% magnesite fly ash and 4% ge uiunverrasc _{AZ / o}

saturated kieserite solution to form briquettes or stones. The stones showed in a comparison with pressed and fired at around 1820 ° C. The usual way from a mixture of chrome ore The sintered material was crushed and ground, and sintered magnesia obtained unfired stones and 67% of this material with a grain size of practically the same composition after firing 0.3 to 4 mm and 28% with a grain size of 0 to im Tunnel kilns at around 1550 ° C. were 0.12 mm, with the addition of 5% fine flour, values with regard to cold compressive strength, pressure fire-ground sintered magnesia with a grain size of resistance, torsional strength and bursting. The results of the comparison test under 0.10 mm with the addition of 1.5% dry results are shown in the following sulphite waste liquor and 1.5% saturated kieserite solution, the figures being processed in the stones that are applied to the stones at a temperature from the left column were dried according to the invention, in 18O ⁰ C. The composition 20 of the right column relates to the usual stones.

Volume weight

Apparent porosity

Apparent porosity (after fire in a tunnel furnace)

Cold compressive strength

Cold compressive strength (after a fire in a tunnel kiln)

Thermal shock resistance (deterrents)

Pressure fire resistance ts (after a fire in a tunnel furnace)

Torsional strength (rotation speed in degrees / h)

at HOO ⁰ C

at 1200 ° C

at 1300 ° C

Bursting

3.00 g / cm ³ 3.01 g / cm ³ 12.5% 12.5% 18.0% 19.5% 600 kg / cm ² 600 kg / cm ² 550 kg / cm ² 290 kg / cm ² over 50 over 50 above 1700 ° C above 1700 ° C (100% of the test values) (60% of the test values, 40% below 1700 ⁰ C) 0.02 0.08 0.08 0.24 0.30 0.69 2.0 6.0

Example 2

The following mixture was used to produce the sintered material:

72% raw magnesite (0 to 0.2 mm) 12% chrome ore (0.10 to 3 mm) 16% magnesite fly ash
21 saturated kieserite solution per 100 kg of the mixture

This mixture was compressed into briquettes, which were fired at 1750 ⁰ C. The sintered material obtained can be granulated and compressed using the formula given in Example 1, grain sizes and with the aid of conventional binder to stones which are ready for use after drying at 17O ⁰ C. However, the sintered material can also be used for the production of ramming compounds or other refractory compounds. In particular in the case of stone production, however, as already mentioned, due to the Cr ₂ O ₃ content of the sintered material, which exceeds 13%, it is necessary to add up to 8% sintered magnesia in the form of fine powder from 0 to 0.12 mm, since otherwise the cold compressive strength of the stones in the delivery condition would be unsatisfactory. However, an addition of more than 8% of this fine-grained sintered magnesia must not take place, since otherwise the other favorable properties caused by the high-temperature firing of the sintered material would be impaired again.

Example 3

92% of the sintered material according to Example 2 was powdered with a grain size of 0 to 0.2 mm with 3% Water glass and 5% clay (0 to 0.12 mm) mixed. The mixture obtained in this way can be sent dry and used as a spray compound at the point of use. to For this purpose, the mixture is more usual depending on the type of spraying machine (slurry or Torkret) Way in a tank or directly in the spray nozzle mixed with the required amount of water and splashed.

Claims (6)

Patent claims: 1. Process for the production of unfired, refractory bricks and masses from magnesite chromium and chromium magnesite with a direct bond between the chromium oxide-containing substances or the chromium ore and the magnesia, from a sintered material obtained at a temperature of at least 1700 ⁰ C without melting (simultaneous sintering), which has a silica content of at most 5.5%> preferably at most 4.5%, and a lime-silica ratio of at most 0.6, preferably at most 0.35, characterized in that a sintered material is used, which is fired at a temperature of at least 1750 ° C, and the granular Sintered material optionally mixed with a maximum of 35 weight percent sintered magnesia and this Mixture is deformed in a known manner, if desired, into stones. 2. The method according to claim 1, characterized in that for the production of the sintered material the magnesite or the magnesium compounds are used in the case of deformation into briquettes with grain sizes from 0 to 0.2 mm will. 3. The method according to claim 1, characterized in that for the production of the sintered material the magnesite or the magnesium compounds in the case of deformation to stones in a grain size of 0 to 5 mm, preferably 0 to 3 mm, can be used. 4. The method according to any one of claims 1 to 3, characterized in that for the production of the sintered material, the chromium oxide containing substances mm, a grain size of 0 to 6, preferably from 0 mm to 4, have, at least 65% preferably at least 80 ⁰ J _0, the chromium oxide containing substances mm are present in a grain size of about 0.12. 5. The method according to any one of claims 1 to 4, characterized in that the grained Sintered material at most 8%, preferably 3 to 5%> based on the refractory components, Fine-grain sintered magnesia with a grain size of 0.12 mm or less are added. 6. The method according to claim 5, characterized in that the grained sintered material in the case of a content of 13% ° the more Cr ₂ O ₃ always fine-grained sintered magnesia with a grain size of at most 0.12 mm and in amounts of at most 8%> preferably 3 to 5%> based on the refractory components, is added. 009547/318