DE2405712A1 - COMPOSITION FOR THE MANUFACTURING OF THERMAL INSULATING FIRE-RESISTANT OBJECTS AND METHOD FOR MANUFACTURING THIS COMPOSITION - Google Patents

Description

Composition for the manufacture of thermally insulating refractory articles and methods of manufacture this composition

The invention relates to an improved composition for making thermally insulating refractories Items such as those used in metal foundries, such as items for lining the tops of ingot molds and foundry cavities. The invention is also directed to a method for Manufacture of the composition and thermally insulating refractory articles from the composition.

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The application of heat insulating refractory linings in bottoms of ingot molds and in foundry cavities has been known for many years. In the form of bricks and edge parts, one-piece hollow hot floors, hollow cylinders and the like they serve to delay the solidification of the molten material in the bottom of the ingot mold or in the Rise cavity and thus reduce the loss of metal due to shrinkage and segregation during cooling and solidification.

In particular, such linings with significantly improved compositions based on the incorporation of a proportion of organic and / or inorganic fiber material into the refractory mixture have been known for the past 10 years. The installation of these _Fa fibers used both to improve the thermal insulation properties of the liners and the improvement of their mechanical properties. Since most inorganic fibers are either too expensive or unacceptable by modern standards for health reasons, their use in such blends is limited and the main type of fiber material that is actually used in practice is paper pulp or cardboard pulp, both of which are effective and are cheap.

The majority of thermally insulating refractory linings that are currently in use consist of mixtures that contain between 60 and 95% powdered refractory material, between 1 and 20 % paper and cardboard fibers and up to 20% other components, for example organic or

there inorganic binders and sintering agents, with / being at all percentages are percentages by weight and these percentages refer to the finished composition or the lining are related in the dry state if the entire

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Water or all other liquid contained therein is extracted.

The known methods for producing such heat insulating refractory linings with a content of Paper pulp fibers or cardboard pulp fibers comprise the preparation of a very fluid pulp from paper, fibers or Cardboard fibers and a substantial proportion of. Water and / or another liquid that is refractory or other ingredients are added to form a slurry, in any embodiment one mechanical pulping device, for example a hydropulper. This slurry is then poured into molds, which have the shape of the desired lining, where the greater proportion of the water from the mixture through Applying pressure and / or vacuum is removed until the material is sufficiently firm to be out of the mold for oven drying can be removed. The material is then dried in an oven until essentially all of it residual water has been driven off and a hardenable resin in the original mixture has hardened.

The important common feature of the known manufacturing processes is the creation of a complete mixture in the form of a liquid slurry for shaping which contains a substantial proportion of water and is of a flowable or pourable consistency. For example, according to a typical procedure, one part by weight dry paper or cardboard containing 20 or more parts by weight of water and / or other liquid added in a hydropulper and after converting this mixture into a thin pulp the refractory material and

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other ingredients added to make a liquid slurry. The use of such a liquid slurry has serious flaws. There are complicated arrangements for stirring the mixture at the various stages of the manufacturing process Required before the molding process to keep the ratio of solids to liquid as consistent or as constant as possible. On the other hand, the amount of solid in a finished brick or body changes other object compared to the desired amount with subsequent damage to the strength of the finished object and its ability to withstand the ingress of molten material in use. this applies regardless of whether the amount of sludge introduced into a mold is measured in volume or weight, da consistency is essential in each case. Even the widespread use of stirrers prevents it not the undesirable change in the consistency of the sludge and in the subsequent appearance and behavior of the finished item.

Another disadvantage of using liquid slurries is that complicated molding equipment is required to extract the portion of liquid and retain the solids during the molding process. A relatively large volume of slurry must be introduced into the mold, which covers a substantial area contains fine sieve material so that the greater part of the liquid can be removed without it being excessive Loss of solids comes. Since the removal is carried out by the rapid application of pressure and / or vacuum must be, the screen areas must be mechanically strong and the presses used are complicated as a result and expensive.

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Another disadvantage of using liquid slurries
is that the particle size of the refractory
Materials must be carefully chosen and mixed in order
an obstruction to the extraction of the liquid fraction
to avoid during the molding process. If the size of the particles is too large or too small, the strength will be
adversely affects the objects made from the slurry.

It has now been found that it is possible to satisfactorily manufacture heat-insulating, refractory articles, the physical properties of which are comparable to those of similar articles made by known processes described above,
however, the use of mixtures in the form of
liquid slurries is not required.

According to a feature of the present invention, a composition for the manufacture of heat insulating refractory articles has a plastic consistency
and contains fibrous organic material and comminuted refractory material, the fibrous material constituting from 1 to 20 percent by weight of the composition. The composition usually contains one or more other ingredients, for example a binder, a sintering agent, a light filler and possibly inorganic fibrous material.

The composition according to the invention gives a stiff paste with a consistency similar to that of mortar, like him for. Brick walls is used. If so, put a pile of the composition on a flat surface

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is deposited, for example a floor, it only sinks in without showing any inclination over the Surface to flow out.

Such a composition, which can also be called a plastic solid, is a stable mixture, that does not show a tendency to separate after manufacture. It can be handled easily and easily be measured in parts by weight or volume in amounts that have a consistent solid content for the Have shaping. Because of the small amount of liquid, the mixture can be easily converted into a shape with a Use a small number of openings for liquid extraction and can be exposed to pressure in the simplest form to extract enough liquid that the mixture is firm enough to dry out of the mold to be removed.

The fibrous organic material of the composition preferably consists of paper fibers and / or cardboard fibers. The crushed refractory material can be of any one heretofore used in the manufacture of refractory linings for metal molds refractory material used, for example crushed fireclay with a particle size not over 10 meshes (B.S.S. sieve) ..

The composition according to the present invention can be prepared in one of three different ways. In the first method, the composition is created by adding dry organic fiber material, for example based on paper or cardboard, on water and / or another liquid in general in any In the form of a mechanical mixer, preferably one

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with paddles or blades, whereupon the mixture is subjected to the mechanical agitation of the mixer until the fiber material is comminuted so far that the pulp is formed. Then one passes the refractory and the others Ingredients and mixes them with the pulp to produce a mixture of plastic consistency, in which the fibrous material is sufficiently comminuted and intimately mixed.

According to the second method, the dry organic fiber material can be introduced into a similar suitable mechanical mixer at the same time as the required amount of water and / or other liquid * refractory material and other ingredients, whereupon the entire mixture is mixed "until it takes on a plastic consistency and the organic fiber material is sufficiently comminuted and intimately mixed.

According to the third method, the dry organic Fiber material together with the appropriate amount of water and / or another liquid in any conventional pulp equipment, e.g. a hydropulper introduced and mixed into a thick liquid pulp. This pulp is then transferred to another mixer in which the refractory material and the be mixed with other ingredients to produce a mixture of plastic consistency.

Regardless of which of the three specified methods is used, the choice is broadest made by the convenience of manufacture and for economic reasons, the water and / or the other

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Liquid must be kept to the minimum required, refractory and others To moisten components and still produce a plastic solid. All three procedures lead as such for the production of heat-insulating refractories Objects made from the desired mixture of organic fiber material, refractory material and other ingredients and the choice of particular particle sizes for the refractory and other ingredients is unnecessary.

The exact amount of required for the mixed composition The liquid needed to achieve the desired plastic consistency for shaping changes with it the proportion of organic fibrous material in the mixture and with the moisture-absorbing properties of the other components and must be determined by experiment. However, it has been found that the weight of the required Liquid ten times the weight of the dry organic used in the finished mixture fibrous material plus a supplement such as that used to moisten the refractory material and the other components required should not exceed. This last-mentioned amount of liquid for moistening of the refractory and other components should typically not be a quarter of the weight of the refractory Material and other components.

For example, it has been found that a heat insulating refractory lining is made up of a finished composition 10 parts by weight of paper or cardboard fibers, 80 parts by weight of refractory material and 10 parts by weight of binding agent

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and sintering agents, according to one of the above described three methods with the addition of only 90 to 120 parts by weight of water and / or other liquid can be produced.

In general, a composition according to the present invention, a consistency or apparent viscosity of at least 200,000 centipoises at a temperature of 35 ⁰ C.

Contrary to expectations, it has been shown that refractories Linings made from the compositions according to the invention have mechanical and physical properties, which are comparable to those of similar linings made by the previously known methods using liquid slurries. The use of a composition in the form of a plastic solid allows the use of a much simpler apparatus and the entire production is much easier to implement and requires less trained personnel. In addition, show in the finished Objects the fibers of the organic material have similar orientation patterns as in the case of objects, which are prepared by the previously known processes in which the compositions are absorbed in the form of liquid has brought slurries to use.

In addition, since the molding composition can be handled so easily without disintegration, it is possible to use it appropriately To introduce changes in the items made from the composition, what not was the case when liquid slurries were combined

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Had used subsidence. For example, it is extraordinary easy to manufacture lining articles, such as bricks, made up of two or more layers of different types Compositions are made by putting a layer of one composition in the mold, raw them spread into place and then one or more additional layers of different composition before pressing added. It is also possible to provide lining items with mechanical devices for hanging or fastening Manufacture in ingot molds or other casting molds by incorporating these devices into the rigid composition starts in the mold just before pressing. In addition, it is possible to use lining items Reinforce by adding reinforcing materials, e.g. steel rods or a wire mesh, to the rigid composition in the mold before pressing.

The invention is to be explained in more detail below with reference to exemplary embodiments in which the specified Parts are parts by weight.

example 1

A pulp is made by mixing 10 parts of dry newsprint with 110 parts of water in a Z-blade stirrer or mixer mixed. After a mixing time of 60 minutes, newspaper and water form a fiber pulp, to the in the mixer 85 parts of ground chamotte with a particle size not exceeding 10 mesh (B.S.S. sieve) and 5 parts of a phenol-formaldehyde novolak resin are added as a binder. Then the mixing is done for continued for another 20 minutes, after which the mixture was a

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has plastic consistency. A measured amount of this mixture is placed in an open-topped brick mold using a trowel and roughly spread within the hollow mold. The compression plate is then placed in the mold over the mixture and a pressure of about 50 psi (0.35 atmospheres) is applied to squeeze out most of the water and compress the mixture into the desired shape. The water was pressed out through a number of fine holes in the mold side walls and also through the fine gaps between the mold pressure plate and the mold side walls. The pressed composition was then removed from the mold cavity and placed in a drying oven, in which it was allowed to dry for a period of 3 1/2 hours at a temperature of 150 ^° C. in order to remove the remaining water and to cure the resin. The finished brick had satisfactory insulating, refractory and mechanical properties when used as part of an insulating lining for the top of an ingot mold. The dimensional and surface accuracy were excellent. If the brick-making process was repeated, then a large number of bricks could be made with very constant and consistent dimensions and mechanical properties, as well as very even weight and density.

Example 2

A mixture of 5 parts of dry shredded material was obtained Paper, 65 parts of crushed fireclay (IO mesh), 25 parts of calcined aluminum oxide, 2 parts of binding clay, 3 parts Textrin and 60 parts water introduced into a rotary mixer with tumbling action and mixed for 2 1/2 hours, according to which this composition has the plastic consistency

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assumed a stiff paste in which the paper fibers were evenly dispersed.

The mixture was then poured into a brick mold and roughly spread inside the mold cavity. Then were two suitably pre-formed metal components are lightly pressed into the mixture by hand before the pressure plate is in the mold has been pressed in. The mixture was then pressed and oven-baked under similar conditions as after Example 1 dried.

The finished brick had excellent properties like that of Example 1. The preformed metal components Formed a one-piece part of the brick and served as a base to which pre-formed metal hangers could be connected, providing a simple but effective means of hanging the brick from the The ceiling of the bar shape was created.

Example 5

A pulp was prepared in which 2 1/2 parts dry cardboard to 45 parts water in a hydropulper were admitted. This mixture was whipped at high speed for 10 minutes and formed then a fiber pulp. This pulp was then transferred to a Z-blade stirrer, where 60 parts of a refractory Aluminum silicate powder (10 mesh), 30 parts of calcined aluminum oxide, 2 1/2 parts of aluminum silicate fibers and 5 parts of phenol-formaldehyde novolak resin was added. The finished mixture was then mixed for 20 minutes and then had a plastic consistency.

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A second pulp was then made by adding 20 parts of dry paper to 200 parts of water in a hydropulper added and the mixture was whipped at high speed for 10 minutes, Ms a fiber pulp originated. This pulp was then transferred to a Z-blade stirrer, where 72 parts of crushed chamotte (10 mesh), 5 parts of vermiculite powder and 3 parts of binding clay were added. This second mixture would then last for 20 minutes mixed, whereupon it also had a plastic consistency.

A measured amount of the fiber mixture was then poured into an open-topped brick mold and uniform distributed over the lower part of this mold. A measured amount of the second mixture was then placed in the mold introduced and evenly distributed over the first mixture. The proportions of the two mixtures were adjusted so that that there is a layer of the first mixture of approximately one third of the thickness of the layer from the second mixture resulted.

The mold pressure plate was then inserted into the mold cavity and the ingredients were pressed and in the oven dried as described in Example 1.

The finished molded ingot brick for steel making had satisfactory mechanical properties and was dimensionally accurate. Pressing the two mixtures together to form a one-piece brick enables that Manufacture of a brick in which the side facing the steel filled in the "ingot mold", i.e. the Layer from the first mixture, much improved

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had refractory properties and was better fitted to withstand the penetration of the molten steel, while the side facing away from the molten steel and lying on the wall of the ingot mold from a thicker layer the second mixture has substantially improved thermal insulation properties and greater "mechanical strengths" exhibited. This combination of properties resulted in an improved overall behavior of the bricks.

Claims: - 15 -

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Claims (14)

Claims (1 · composition for the manufacture of thermally insulating refractory articles containing comminuted refractory material and between 1 and 20 wt -.% Organic fiber material, characterized in that the composition is made with plastic consistency. 2. Composition according to claim 1, characterized in that it comprises at least one material from the Group contains binders, sintering agents, light fillers and inorganic fiber material. 3. Composition according to claim 1 or 2, characterized in that the fibrous organic material consists of paper and / or cardboard fibers. 4. Composition according to one or more of the preceding claims, characterized in that the particle size of the crushed refractory material does not exceed 10 meshes (B.S.S. sieve). 5. Composition according to claim 4, characterized in that the crushed refractory material consists of crushed chamotte. 6. Composition according to one or more of the preceding claims, characterized in that that it has a consistency or apparent viscosity of at least 200,000 centipoises at 25 ° C. 409834/10 11 -16- 7. The method for producing the composition according to one or more of claims 1 to 6, characterized in that "organic fiber material and a portion of water and / or another liquid is poured into a mixer, the mixture until broken the fibrous material mixed to form a pulp and then the crushed refractory material and any other ingredients of the composition are mixed into the pulp. 8. A method for preparing a composition according to one or more of claims 1 to 6, characterized in that in a mixer at the same time the organic fiber material, a proportion of water and / or another liquid, the shredded refractory Material and other components of the composition are mixed. 9. The method according to claim 7 or 8, characterized in that g e k e η η ζ e i c h et that the organic fiber material is added to the mixer in the dry state. 10. A method for producing a composition according to one or more of claims 1 to 6, characterized by introducing the organic fiber material together with an amount of water and / or others Liquid in a pulp device, mixing the mixture in the pulp device into a thick liquid pulp, transferring the liquid pulp in a mixer and mixing in the shredded refractory and other ingredients the composition into the liquid pulp. 409834/1011 - 17 - 11. The method according to claim 10, characterized in that the organic fiber material of Pulp equipment is added in the dry state. 12. The method according to one or more of claims 7 to 11, characterized in that the weight of the amount of water and / or other liquid is not ten times the weight of the organic Fibrous material when dry plus a quarter of the total weight of the refractory material and others Components of the composition exceeds. 13. A method for making a heat insulating refractory article from a composition according to one or more of claims 1 to 6, characterized in that the composition molded into the desired shape and the molded paste to remove substantially all of the contained therein Liquid is heated. 14. The method according to claim 13, characterized that the composition contains a curable binder and the heating of the molded paste serves to harden the binder. 409834/101 1