DD298632A5 - FIRE-RESISTANT MOERTEL - Google Patents

Abstract

The invention relates to a versatile refractory mortar for temperatures up to 1 600C, which is suitable for firing refractory bricks or as giesz- or spritzfaehige mass. The mortar consists of 20 to 80 * mill scales up to 6 mm, 20 to 60 * filter dust of the core up to 0.2 mm from the emission control of electric steel melting furnaces, 0 to 40 * refractory aggregates and 0 to 10% chemical and / or ceramic binders {Moertel, refractory to 1 600C; Walling, pourable, spritzfaehig; Mill scale; Fly ash; refractory aggregates; Binder}

Description

Field of application of the invention

The invention relates to refractory mortars for firing refractory bricks, especially periclase bricks or periclase-chromite bricks, as for example in the black metallurgy or non-ferrous metallurgy for the delivery of smelting furnaces or in the cement industry for the delivery of rotary kilns, preferably for the sintering zone , be used. The mortar is applicable for temperatures up to 1600 ⁰ C; its use as a pourable or sprayable mass is also possible when setting the appropriate consistency.

Characteristic of the known technical solutions

Refractory mortar is subject to various requirements regarding its processing properties and properties after processing, i. H. under conditions of use. These properties are directed partly opposite and therefore hardly together in a mortar available. For good processability, refractory mortar should be easy spreadable, d. H. To achieve the desired joint strength excess mortar should be squeezed out by pressure application from the joint. On the other hand, the mortar should have sufficient rigidity, so as not to be squeezed out of the joint in the continuous walls by the increasing weight of the overlying masonry, reducing the joint thickness. Furthermore, the brought with water in the appropriate consistency mortar should be processed for a long time without settling or untie prematurely. After processing, the mortar should have a good fire resistance or achieve and cause a perfect support from stone to stone. Nevertheless, the mortar should absorb in the joints occurring during heating volume expansion of the refractory bricks, without causing excessive pressure conditions or compressive stresses or edge pressures in the stones. On the other hand, the joints should be tight in any operating condition, the shrinkage in the processed mortar by the expulsion of the water must not be too large to allow any loosening of the masonry. Refractory mortars for firing refractory alkaline stones, such as periclase or periclase-chromite stones, are known to have the same base material as the refractory bricks. This base material is, for example, sintered magnesite, chrome ore, basic secondary material prepared from old stones or the like, which is used in comminuted form with a maximum grain size of 1-3 mm and with a corresponding fine grain fraction of less than 90 μm. Such mortars usually contain clay as a binder and dextrin or the like as a plasticizer. They are brought to the desired consistency with water. To achieve higher strengths, the addition of other binders such as water glass, magnesium sulfate, magnesium chloride, phosphates or the like is known.

To sine good spreadability of the mortar by good water retention capacity, the mortar must contain large amounts ^ binder. The high water content causes an undesirably large shrinkage of the joints, the refractoriness is reduced. A further disadvantage is that the high quality and with energy and processing costs significantly preloaded base material makes the mortar very expensive.

In order to obtain gas-tight joints, as are required in particular in furnace systems operated in high temperature ranges or in large vessels, the mortarless laying of the refractory bricks is variously carried out in order to exclude the disadvantageous properties or behavior of the mortar joints. However, this mortarless installation is particularly costly. Precise cutting work on the stone surfaces is required. This as well as the laying of the cut stones places high demands regarding qualification and experience bzv /. Skill of the relevant workforce.

It is also known to lay sheet-metal coated bricks mortarless. In the production of these stones are also very high requirements in terms of dimensional accuracy to meet. In addition, the sheet metal casing requires a considerable use of materials and production costs. The cost of such stones are correspondingly high.

In DE-OS 1671212, a mortar for firing refractory bricks is proposed, which is characterized by a particularly good spreadability and therefore particularly for the production of very thin, ie down to 0.1 mm, joints is suitable. This mortar consists of finely ground basic to neutral refractory material as well as binder and plastification agent. The refractory material has a total grain size below 60μΓη and thereby at least 90% below 10 \ im on. As binders 3 to 20% water-soluble sulfates or sulfites and as plasticizer 0.5 to 5% carboxymethyl cellulose, gelatin, bentonite or clay are proposed.

A mortar of this fineness has a very large water-retaining surface due to the fine grain. In addition, for rapid setting during processing, d. H. for sufficient support function of the joint, required binder content, the water retention capacity and thus the water content of the mortar to be processed is further increased. As already explained, this results in the disadvantage of a large volume shrinkage and the porosity of the mortar in the joint when expelling the water. In addition, making and sifting the refractory material in this fineness is very complicated and costly.

In DE-PS 925340 a mortar for firing refractory bricks is described, which contains in addition to fine flour, finely ground sintered magnesia and plasticizer or binder mineral spacer grain, which decomposes in the heat with release of water. The spacer grain is used to produce larger joint thicknesses. It is solid during the continuous building of the stones and ensures a good support from stone to stone. In the heat, the distance grain breaks down, whereby the Fugo can compensate for the volume expansion of the stones during heating.

A disadvantage is the unavoidable porosity due to the expulsion of the water and the decomposition of the spacer grain. As a result, the possibility of infiltration by aggressive slags and dusts is given in strengthening dimensions, which in turn endangers the stability of the Mt. jerwerkes.

In DE-PS 2755298 also a mortar for burying refractory bricks is described. This mortar consists of the known components refractory base material, binder and plasticizer. In order to be able to paint well in continuous walling, pressing it out for a long time, d. H. of mushy consistency, permanent mortar from the joints and thus to prevent a reduction in the joint thickness below the desired level, the mortar admixed metal admixtures of approximately spherical shape whose diameter corresponds to the desired joint thickness. These spacer grains take over until the setting of the mortar in the joint, the support function. When heating the furnace, the distance grains melt in the corresponding temperature range under Volumenverringeruny, whereby a compensation of the increase in volume of the stones through the joint is made possible. As advantageous spacers made of steel or gray cast iron or aluminum in amounts of 1 to 20 wt .-% proposed.

In order to counteract premature settling of the metallic admixtures which are heavier than the base material, an increased use of plasticizer or water glass is required, which is known to have a negative effect on the refractoriness of the mortar. On the other hand, the proportion of metallic admixtures required for a proper distribution in the mortar, especially in steel or cast iron, should be at the upper limit of the proposed range or above. This in turn results in a high uneconomical use of metals. In addition, the spacer grains for their production already require a considerable amount of technical and technological including energy costs and thus additional cost.

Object of the invention

The aim of the invention is to increase the service life of such refractory industrial furnaces or systems whose re-delivery has been required because of Verschlolßes the mortar joints already at a time at which the refractory stone material has not reached its wear limit or in which a mortar with mangle to premature wear of the Masonry leads.

By using inexpensive and sufficiently available starting materials and low processing costs, the invention provides a cost-effective and in many variations extremely versatile refractory mortar.

Explanation of the essence of the invention

The object of the invention is to develop a mortar for application temperatures up to 1600 ° C for firing refractory bricks, especially periclase or periclase-chromite bricks, which during its processing long time good spreadability but at the same time a good supportability and good adhesion on Stone, which is characterized under operating conditions of the relevant refractory plant by low porosity and at the same time by good elasticity in pressure strokes under the influence of temperature and developed at the fire-hit hottest zone of the refractory plant high resistance to attacking aggressive dusts and slags.

The mortar should also be suitable for processing by spraying or potting. According to the invention there is a refractory 'Jel that meets the requirements mentioned from 20 to 80Ma .-% Walzzundor the Grain size up to 6mm, 20 to 80Ma. ·% Filter dust from the flue gas cleaning of electric steel melting furnaces with grain size up to 0.2 mm -

in the context of this description of the invention further also referred to as Elektroofenfilterstaub-, 0 to 40Ma .-% refractory

Aggregates and 0 to 10Ma .-% chemical and / or ceramic binders. Depending on the intended type.

its processing, the mortar is brought by adding water in the desired processing consistency.

It already meets a mortar, only from the components mill scale and electric furnace filter dust in the amounts mentioned

exists, the required conditions. Economically advantageous is that the Walzzund coming for use may be contaminated with moisture and / or oil or fat. So it's millet grain of 6mm, like it is in one

Profile rolling mill in the technological process as a waste product, usable without any additional treatment measure. Analogous to this, the waste product resulting from the electric jet generation is filter dust from the exhaust gas purification of Electric steel melting furnaces usable without additional treatment. The essential components of the electric furnace filter dust

Among others, 45-70Ma% Fe ₂ O ₃ , 3-10Ma% FeO, 2-5Ma% MgO, 3-8Ma% CaO, 3-8Ma% SiO ₂ , 0.2 -1.0 Ma .-% C and 4-9 Ma .-% MnO.

The addition of further refractory additives and / or further known chemical and / or ceramic binders in

The quantities mentioned serve the further refinement or adaptation of the mortar to special processing or

Operating conditions by reinforcing or stressing for the particular application of particularly required properties

of the mortar.

In addition, the mortar according to the invention offers the possibility of economic recovery of anyway accumulating

valuable refractory waste material as aggregate, which is treated accordingly, i. crushed and classified, in one

Amount up to 40Ma .-% may be included in the mortar. According to various advantageous embodiments can as a refractory aggregate with a proportion of 0 to

40Ma .-% sintered magnesite grain size to 90μιη to increase the initial strength in the temperature range up to 100 ⁰ C or

Grain size up to 3mm to further increase the support of the mortar joint or treated periclase or periclase Chromite waste material are used. As a binder in a proportion of 0 to 10Ma .-% are clay, water glass or Epsom salt can be advantageously used to specific processing properties or properties for specific applications

especially to modify under conditions of use.

Made with water in the appropriate consistency, the mortar is processable by building, by potting or by Splashing. Mixing the solid components of the mortar and mixing the mortar with water to the desired consistency

carried out by known methods or in known facilities or facilities.

Another advantage in addition to the almost universal processability and applicability of the mortar according to the invention consists

in its uncomplicated manufacturability. Its production can be carried out either by a manufacturer, supplied by the metallurgical enterprises with the starting materials, or directly in the metallurgical plant in question

Companies in which the essential starting materials are produced as waste. embodiments The invention is explained in more detail below with reference to 3 examples. example 1

The refractory mortar of the invention consists of 50Ma .-% mill scale of the grain size to 6mm 50Ma .-% electric furnace filter dust. The mill scale to be used is used in the form as obtained in a Feinstahlwaizwerk as waste, ie the mill scale is already afflicted with water and also lubricating oil shares, and he falls in a grain size to 6mm. Any processing, such as drying or classification, eliminated. As electric furnace filter dust, dry filter dust from the exhaust gas purification of electric steel melting furnaces is used. This dust falls as a product in the grain size up to 0.2 mm and is also usable without any treatment. The mixing of these starting materials takes place in bekannton mixers by known methods, wherein the moisture contained in the rolling sinter prevents a greater dust during mixing. The essential components of the electric furnace filter dust are, among others, 45-70 mass% Fe ₂ Oa, 3-10 mass% FeO, 2-5 mass% MgO, 3-8 mass% CaO, 3-8 mass% SiO ₂ , 0.2-1.0 Ma .-% C and 4 - 9 Ma .-% MnO. The physical and chemical properties of the electric furnace filter dust in connection with those of the mill scale; allow, without any addition of binder or plasticizer, ie their proportion is in each case 0 wt .-%, ei ien manufacture versatile refractory mortar, which, even after prolonged storage, for its processing by adding water is brought to the desired consistency , This mortar has a good spreadability, a high water retention capacity and an intense bonding behavior to the stone.

The mill scale has platelet structure, with its largest length 6 mm and its thickness is less than 0.5 mm. Within the mortar layer, a toothing of the platelet structure, whereby a good initial strength and thus a good support ability, especially when rapidly progressively bricking refractory bricks, are achieved. The interlocking rolled-up mill scale tiles act as a sort of distance grain. Because of the good brushability due to the electric furnace filter dust thin joints are easily and because of the good support effect by the Walzzunderplättchen are easily produced even thicker joints to 5mm with rapidly progressing constructions.

Even under operating conditions, the mortar has the desired properties. He is able to make changes in volume depending on the thermal expansion of the stone material in different temperature ranges. As a result, a good gas-tightness of the joints is achieved in all temperature conditions of Ofenaniagen, while critical edge pressures are avoided on the stones. Shrink cracks, as they usually occur when using clay as a binder in previously known mortars, were not found when using this mortar according to the invention.

The unusually or above average high iron oxide content and the low porosity give the mortar a good thermal conductivity. As a result, a good heat distribution in the lining is effected, which contributes to an improvement in the thermal shock resistance of the entire lining and thus to a longer durability of the refractory industrial plant.

Finally, the excessively high iron oxide content of the raw materials and the other chemical constituents of the electric furnace filter dust create favorable conditions for the formation of refractory spinels with high resistance to aggressive dusts and slags at high temperatures.

Example 2 The refractory mortar according to the invention consists of 20Ma .-% mill scale of grain size up to 6mm, 40Ma .-% Electro-furnace filter dust of grain size up to 0.2mm and 40Ma .-% recycled periclase-chromite waste of grain size up to 3mm,

preferably up to 1 mm.

This mortar is particularly geared to the economic use of valuable refractory raw materials, which in the

resulting basic stone material are included. The properties of this mortar are substantially similar to those of Example 1. This mortar is well suited for use in the construction of deep furnaces for the steel industry.

Example 3

The refractory mortar consists of 40Ma .-% mill scale of grain size up to 6mm, 37% by weight of electric furnace filter dust of grain size up to 0.2 mm, 20Ma .-% sintered magnesite of grain size to S0 \ im and 3 wt .-% Epsom salt. After intensive mixing of these ingredients, the desired consistency is adjusted by appropriate addition of water and thereby mixed well again. The mortar so prepared can be stored for several hours at temperatures up to 30 ° C. At temperatures above 80 ° C, the mortar undergoes after processing an additional solidification beyond the otherwise normal dry strength. This additional solidification has an advantageous effect for rapid bricking of refractory bricks in complicated linings, e.g. B. in rotary kilns, from.

Claims (8)

1. Refractory mortar for application temperatures up to 1600 ⁰ C for firing refractory bricks, especially periclase or periclase-chromite bricks, or for casting or for the production of protective coatings, eg. By syringes, characterized by the following composition: - 20 to 80% by weight of mill scale of grain size up to 6mm ", - 20 to 60Ma .-% filter dust of grain size up to 0.2 mm from the emission control of electric steel melting furnaces, 0 to 40% by weight refractory aggregates, 0 to 10% by mass of chemical and / or ceramic binders. 2. Refractory mortar according to claim 1, characterized in that the «· refractory aggregate Sintermagnesit the grain size is up to 90 pm. 3. Refractory mortar according to claim !, characterized in that the refractory aggregate sintered magnesite grain size is up to 3 mm. 4. Refractory mortar according to claim 1, characterized in that the refractory aggregate is recycled periclase or periclase-chromite waste material. 5. Refractory mortar according to claim 1,3 or4, characterized in that the binder is clay. 6. Refractory mortar according to claim 1,3 or 4, characterized in that the binder is water glass. 7. Refractory mortar according to claim 1 or 2, characterized in that the binder is Epsom salt. 8. Refractory mortar according to claim 1, characterized in that the mill scale is subject to moisture and / or oil or fat.