DE1571411A1 - Process for the production of refractory moldings, especially for steel furnaces - Google Patents

Description

Process for the production of refractory moldings, in particular for steel melting furnaces

For the refractory lining of steel melting furnaces and Moldings made from fired, sintered or molten dolomite, magnesite, lime or any other solution of these substances and tar or tar-like substances as binders by pressing, tamping, shaking and the like. Manufactured.

Since the softening point of tar, measured according to the Cremer-Sarnow (DIN 1995) method, is around 30-60 ° C., depending on the composition, there is a known risk of softening with such shaped bodies. This can occur in particular when the lining in the converter is first heated, but it can also take place when such shaped bodies are stacked in stacks at higher outside temperatures, e.g. ³ . be stored in countries with a warmer climate, or in the overheated halls of the steelworks.

The consequence of this is that the moldings are already deformed during storage or later in the lining during heating. This can even lead to a collapse of the converter wall. to lead. This danger is intensified by the loading of the overlying moldings in the I.'auerv / Erk of the converter

2 ter, which is up to 2 kg / cm for large units.

In practice, this difficulty is countered by the fact that during the first heating and "burning of the Ilonver brickwork, the V / and temperature, in particular in the range up to about 500 ⁰ G, is possible.

009809/0702 ^^ -2-

Dr.Jlz / Lr jj

157HT1

can be passed through quickly. With such a fast one When heated, the volatile components of the tar evaporate and the remaining part of the tar solidifies through Polymerization and formation of a graphite structure. Despite this rapid upsurge and the associated rapid "m'var- 'lu-ig and partial solidification of the tar. can the nachtoili; o not softening and deforming with consistency avoided "/ ground. Therefore, the durability of these linings in the '3tahlöfen are even with the same smelting Programmable and completely identical chemical composition and the same ratio of tar and the basic ones refractory materials, same building structure and condition, as well as the same compression of the moldings fluctuates quite a bit and therefore unsatisfactory, because minor deformations can k-ium be avoided. 'Is the result of formation and increased slag infiltration.

With the modern larger converters, especially the oxygen inflation converters for services of more than 100 tons per batch, is due to the even higher. andun ^ on and the greater ..andstyle strength the risk of misery and the with it associated consequences are particularly acute.

Js, several methods are developed and known whose aim it is the heating of the newly lined converter without To achieve deformation of the refractory lining. These methods for achieving a Pormstabilitnt are based essentially ensure that the molded bodies are individually installed before they are installed in the converter stored, i.e. not stacked, to burn. Js various temperature ranges have been proposed for this, between approx. 150 and 1000 G or at which Work is also carried out in this area in several temperature intervals. .However, the conditions of this separation process and specifically the duration of the temperature treatment in none of the known processes is more precisely defined. Without exception this firing process is carried out in the absence of air or in such a way that the shaped bodies are embedded in coke breeze,

009809/0702 ^

157H11

Graphite, among other things, must be protected against oxygen and the effects of air.

Ee eats understood and it has also been shown that by this little precisely defined method, the shape stability is not ensured with certainty, whereby the food shelf life still fluctuate in the steel furnaces and do not reach the optimum, or _o the temperature treatment of the stones characterized uneconomical will.

The present invention provides the teaching, burning the tar-based tar- moldings of calcined dolomite, magnesite, lime or a mixture of these substances under precisely DEFINE · ten TemperaturbedinfTingen conduct so that all moldings abi an always uniform and largely optimal formst ^lit: get it and linings these moldings treated according to the invention do not suffer any deformation during heating, for example of the converter.

It has been shown that the dimensional stability and also the durability, which can best be achieved by heating the moldings, depend not only on the level of the temperature at which the treatment is carried out, but that it essentially depends on the duration of the temperature treatment arrives, and one must, if one wants to achieve optimal results, take into account the individual temperatures to which the molded body was exposed and the corresponding times.

It has been found that the best results are obtained if the shaped bodies, which consist essentially of burnt or sintered or molten dolomite, magnesite, lime or a mixture thereof, as well as tar or tar-like substances, prior to installation in are heated, the steel melting furnaces to "temperatures between 200 and 4-5O ⁰ C, the heating time in dependence on the temperature, according to Figure 1, is within the range of the characteristic lines A and C.

009809/0702

BAD RlQSNAt

The results are particularly favorable if the heating time is within the range of the characteristic curves Λ and B as a function of the temperature as shown in Figure 1. It was also found that the process can be carried out not only at one temperature, but advantageously also in two or any number of temperature stages. Thus, a molded body made of tar dolomite, which was initially tempered at a lower temperature for 50 % of the time required at this temperature, according to Figure 1, can then be tempered again at a higher temperature for 50 % of the time required here. In an analogous way, the treatment can take place according to any temperature curve in the range described, and the treatment times can be set or varied for individual temperatures on this temperature curve.

The required treatment times are determined by the code ' Lines A and G, according to Figure 1, as high and low values set. Appropriately, one chooses {but a treatment time, which lies in the area between the characteristic curves A and B. In this way you can use for each treatment furnace the residence times can be determined for any temperature profile

The strengths of the untreated moldings can vary greatly depending on the tar, grain structure and type of shaping, but the increase in strength as a result of the treatment is always around 50 - 70 % ·

Pitch, bitumen, residues from petroleum distillation and asphalt can also be used as binders for lifting or instead of tar can be used in amounts of about 3 to 12%.

Furthermore, you can use the binders or mixtures thereof, advantageously carbon in a finely divided state, e.g. in the form of coal, coke, graphite, soot, activated carbon or add such a thing. Such an addition increases the moldings and thus the converter lining. Amount of carbon added, which causes the slag attack to deteriorate *

009809/0702;

- 5 - '

BAD iGWAL

can be wrestled »

If a tar or a tar-like substance which contains carbon in a finely divided state is used for the molded body mixture, it is possible to increase the amount of tar to more than 12%. This is particularly important when a refractory brick is desired that has an increased carbon content. .

It is advisable to use all of these binders absolutely free of water, especially when processing dolomite or Lime. For this purpose, they can be treated with air in the liquid, molten state, i.e. at a sufficiently high temperature, partly through tin nozzles into the liquid until the foam formation has ended. ■

This results in even a slight hydration of the refractory materials prevented during mixing and eating.

For the same reason, it is expedient to protect the molded body from moisture in the surrounding area during the temperature treatment Protect gas atmosphere. Therefore, humidity is to be kept away from the corner.

The basic refractory raw materials can contain mineral additives such as chrome ore, zirconium oxide or sintering facilitators Contains agents such as sisenoxide, kanganoxide. Also can these substances are mixed in.

It is also possible to use the volatile constituents of the tar to be removed from the shaped bodies in a known manner by flushing gas or by vacuum and, if necessary, condensed.

You can also see the volatiles leak out the moldings by draining inserts, v / ie melting ones or promote gasifying fibers, threads, öt-llbe or the like, as well as through channels intentionally created during molding.

The escape of the

009809/0702 - 6 -

volatile constituents are slowed down if an increased carbon content is desired in the molding

An increase in the carbon content in the outer layers of the molding can expediently be achieved by spraying or brushing with liquid tar or by dipping, the tar ζ.B ₀ containing a higher proportion of anthracene oil or creosote oil. This coating must be applied before the heat treatment

Catalysts which accelerate the solidification can also be added to the binders. As such catalysts It is well known that oxides of metals, especially iron, hangan, nickel, lead, and rare earths are preferred or nitrogen oxides for use

It is also possible, as known per se, the inventively treated molded body to obtain a smooth and dense surface with an organic layer, ζ · _Β ο of paraffin, tar, pitch, bitumen, asphalt, wax, to cover Kunsthara etc ·. This coating is expediently carried out by dipping the shaped bodies into the molten organic mass or by spraying immediately after the heat treatment.

009809/0702 - 7 -

/ I * ♦ ι ι

example

To produce the shaped bodies, a sintered dope , half of which consisted of 0.3-1.5 mm grain sizes and half of 1.5-3 mm grain sizes, was prepared by pressing to form shaped bodies with the addition of 5-5% tar . These moldings were prepared according .Schaubild 1 · treated at a temperature of 280 ⁰ G in the determination of the treatment period the Aufheiszeit of 200 ° to 280 ° C was taken into account · It required 3 hours so that it was heated at 260 ° € 15 hours.

The stones had a compressive strength of 125 kg / cm. While an untreated molding clearly deformed at a temperature of 100 ^° C. and a load of 2 kg / cm ", this phenomenon was not found in the heat-treated moldings. The achievable final strengths were always about 50%, mostly 70% above the strength of the untreated molding.

The same results * can be achieved if one instead of dolomite, magnesite or lime or a mixture of used these substances

Pat ent claims

- 8 009809/0702

BATH

Claims (13)

1'67H11 t claims 1) Process for the production of moldings for brickwork, which are optimally dimensionally stable when heated in steel melting furnaces and _t essentially consist of burned or sintered or molten dolomite, magnesite, lime or a mixture thereof, as well as tar or tar-like substances, characterized in that the shaped bodies are heated before installation in the steel melting furnaces to temperatures of between 200 ° and 4-5O ⁰ C, said. The heating time as a function of the temperature according to Figure 1 lies within the range of the characteristic curves A and C. 2) Method according to .Anspruch 1, characterized in that the Heating;: time depending on the temperature accordingly Sclviubild 1 within the range of the characteristic curves A and B lies. 3) Method according to claim 1 and?, Characterized in that the heating successively at different temperatures, takes place at a fraction of the required time, in such a way that the fractions add up to 1 4) ancestors according to don claims 1-3 »characterized in that Than the tar through or through to the toilet. Pitch, bitumen, Liiickfitände of oil distillation, asphalt and the like. replaced. 5) Method according to claims 1-4, characterized in that the Fouerfestmaterial and / or the tar carbon in a finely divided state as coal, coca, graphite, soot, activated charcoal or the like. be added _o 6) Method according to .Ansprüche 1-5, characterized in that 009809/0702 _m . 9. tit / A 1 571 All that the tar contains polymerization and / or condensation catalysts. 7) Process according to claims 1-5, characterized in that the tar is condensing and / or polymesizing Contains substances. 8) Method according to claims 1-6, characterized in that that an anhydrous tar or tarry tar is used. 9) Method according to claims 1 - ß, thereby gekennzeioh- ; net that before or during the Vii heat treatment for the Formation of channels or drainages in the molded body fusible or volatile to fibers, threads, otäbon or Ribbons shaped otoffe brings into the exit ommisehung. 10) Method according to claims 1-9, characterized in that that to increase the carbon content in the Molded bodies carrying out the heat treatment under excess pressure. 11) Process according to claims 1-9, characterized in that for better removal of the tar vapors from the interior the molded body carries out the heat treatment under negative pressure. 1P) Process according to claims 1-11, characterized in that one for .Crhöhunn; the carbon content in the outer "" layers of the shaped body before the heat treatment the molded body is sprayed with liquid tar, which contains a higher proportion of anthracene oil or creosote oil, brushed or immersed in it. 13) The method according to the 'jinprüchen 1 - 1 °, characterized in that the shaped bodies are coated with an outer protective layer following the ^ heat treatment, _o BATH 009809/0702 -AQ- L e r s e i t e