DK157456B - APPLICATION OF A HYDRAULIC BONDING HIGH-CONCRETE CONCRETE OF AL 203 FOR WORKING PARTS WHICH COME IN CONTACT WITH METAL MELT. - Google Patents

Description

DK 157456 B

The present invention relates to the use of a hydraulically bonding refractory concrete with high clay soil content for wear parts that come into contact with metal melts, such as plugs, casings, in particular closure plates for slides on containers containing steel smelt.

Wear parts are generally parts which, after reaching a wear limit, must always be renewed or replaced so as not to impair the safety of the assemblies. They are mostly exposed to 10 high thermal, chemical and possibly eroding attacks and in many cases must also be able to withstand considerable force loads. Thus, e.g. a prerequisite for sealing plates for slides on metal-containing containers; and eroding attacks from the flowing melt by adjustable cast-beam cross-section can hold at least one container discharge.

20

For such and similar loads, hitherto worn parts of valuable, dry, semi-dry and plastic refractory compositions have been produced by relatively complicated stomping, shaking and pressing methods with more or less costly finishing. Wear-25 parts with an adaptation-correct design require precisely adhered heat treatment methods over time and in addition, a careful chip-taking design. Eg. For example, those surfaces on slabs of sliding dolls which must be sealing together with other surfaces and at the same time be easily slidable or movable are extremely flat. But also bores and grooves and the like are often provided with chip-forming design, so that especially wear-correct wear parts that require mechanical machining cause considerable production costs.

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DK 157456B

From Neue HUtte 1965, Hefte 5, pages 275-279, use is made of hydraulically bonding refractory concrete with fillers such as corundum to temperatures of 1700 ° C in industrial furnaces and for pouring nozzles for iron pans subjected to relatively low corrosive and eroding loads. . According to Sprechsaal, 107, Jg. pages 904-913, it is proposed to use chemically bonding refractory concrete for casting bricks for boiler closures, utilizing precisely the low abrasion resistance of the refractory concrete to subject the through-hole opening to the casting stone a gradual expansion during casting so that the casting rate can be maintained at constant thrust state. . From Cement-Lime Plaster, no. 10, 1973, pages 457-463, use of hydraulically bonding refractory concrete in the cement industry is also known for low loads in a cement kiln. From H. Lehmann, 15 Scripture Series Stone and Earth, Volume 3, Fireproof Concrete

Tornerde-Schmelz-Zement, 1959, Hermann HUbner Verlag Goslar, pages 52-53, it is known that such slightly durable concrete can have a room resistance of approx. 0.2% at an unknown temperature and that the cold compressive strength depends on the cement mixture, the additives and the grain structure. In Koppers Merkblåtter, April 1971, is described a hydraulically bonded refractory concrete consisting of stamped mass which, with an A ^ Oø content of 95%, has a burning heat of -0.95 at 1800 ° C, a heat expansion of 1.60 at 1800 ° C and a cold compressive strength of the unburned product of 400 kp / cm2 and after burning at 1800 ° C of 720 kp / cm2.

German Publication No. 2,048,488 proposes refractory mixtures with hydraulic bonding for the production of refractory concrete, which with a content of 92% A1203 has a cold compressive strength of 400 bar measured on the dried crude product and 1200 bar 30 after burning at 1600 ° C. The dimension change after firing at 1600 ° C is -0.52. From The Refractory Journal Sept./Oct. 1975, pages 10-19, it is known that ceramic refractory material for wear parts of sliders can have a cold compressive strength between 175 and 245 kp / cm 2 and a mold resistance after firing at 35 1650 ° C of ± 0.2%. The known ceramic refractory materials from Transactions and Jorunal of the British Ceramic Society, Vol. 74, 1975, pages 41-47, have e.g. a cold compressive strength at one

DK 157456 B

3 not mentioned temperature between 56, 80 and 118, 88 MN / m 2 and a molding capacity after burning at 1650 ° C of -1,259 to + 0.453.

It is the object of the present invention to simplify the manufacture of refractory wear parts.

The object is achieved according to the invention by using a high-clay hydraulic bonding concrete with a high content of clay soil with a cold compressive strength of at least 400 kp / cm2 measured on the dried raw product, which after burning at 1400 ° C is at least 700 kp / cm2 and a mold resistance at 1400 ° C of at least ± 0,2% for wear parts that come into contact with metal melt, especially for firing plates and / or bottom plates in sliding closures on containers containing 15 steel melt.

In this way, especially the manufacture of slab pairs for sliding shutters can be greatly simplified, as concrete cast in a mold closely matches the mold surfaces and smooth clean surfaces on the mold also provide smooth clean counter surfaces on the mold body. Accordingly, it is possible to obtain the sliding surfaces 20 of sliding plates with great accuracy already during the shaping of the slab, so that prolonged mechanical post-machining fades away. Also, the flow openings can be formed directly therein and thus the plates are removed in the finished state. 1 2 3 4 5 6 7 8 9 10 2

The clay-rich concrete with the physical properties described above gives the reliability of the abrasive material produced therefrom 3 times due to high stresses due to heat stresses as well as 4 chemical and eroding attacks. This is of considerable advantage when the refractory concrete has corundum and active clay soils as additives 6 and exhibits less than 15% clay soil cement with a maximum of 22% lime, and optionally a flux is introduced and the analysis preferably shows at least 96% less than 3% CaO and less than 0.5% SiO. The 8 high proportion of AlgO ^ is advantageous for the durability of the concrete mold body against varying temperature. In addition, a possible overall porosity of between 23 and 27% by volume of exclusively open pores, which may, for example, be favorable for temperature exchange, is advantageous. is best oak 10 down to a tar impregnation.

4

DK 157456B

With the additives corundum and active clay soil, the amount of clay soil is conveniently between 5 and 15%, since in a further embodiment of the invention for certain applications it may be particularly convenient to replace 1 to 5% of the additives 5 with a spinel forming substance, preferably MgO or compounds giving MgO. The magnesia contained in the concrete reacts at approx. 1000 ° C with the decay products resulting from dehydration of the binder for spinel MgO 2 Al 2 O 2. The structure of the concrete thereby becomes firmer and denser and, consequently, also more durable against infiltration of steel-melt and against impact, if the appearance of the steel bath has already been formed. Instead of MgO, NiO, CoO and ZnO as well as compounds which form these oxides can also be used.

If a further increase of the impact resistance of the mold body is desired, this can conveniently be done by adding up to 5% soot or graphite.

In many cases, it is recommended to replace up to 7% of the additives with chromium oxide to counteract the wetting of the mold body with the liquid melt and slag. In addition, the additives below 0.5 mm are conveniently available as round grains, which gives a further positive effect on the strength of the mold body.

The preparation of a refractory slurry is described below in connection with a table containing mixtures, grain sizes and properties of five refractory concrete which are within the scope of the invention.

In a mold similar to the shape of a sliding plate, 30 were cast and vibrated concrete according to positions 1 to 5. The subsequent bonding and curing lasted 12 hours. After molding, the plate was set at room temperature for 48 hours, then subjected to drying at 110 ° C, which finished the preparation. 1

To test the strength values at higher temperatures, the plate was first heat treated at 600 ° C and the cold compressive strength measured after cooling. The process has been repeated at 1400 ° C.

5

DK 157456 B

The firing rate shown in the table after firing at 1400 ° C in% is identical to the mold resistance of the refractory concrete required by the invention.

5 Information on the applicability of a refractory concrete for wear parts, especially for slab pairs for sliders also provides the peeling test. The following conditions are attached:

A 100 x 100 mm plate with a smooth (abrasive) surface stays on a 10 zone with a diameter of approx. 30 mm heated by means of an autogenous welding torch suitable for piercing 20 to 30 mm thick. plate. The oxygen pressure is hereby 2.5 ato and the pressure of the acetylene gas 0.5 ato. The distance from the nozzle in the burner with a rack to the plate is 50 mm and the test time is 15 seconds.

15

If no breakdown occurs, the material is well suited for the production of plate pairs for sliding shutter. The material is useful if, after subsequent scraping of the test body, particles become detached, but it is useless as soon as rinses occur during the test.

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DK 157456 B

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Claims (8)

1. Use of a hydraulically bonding refractory concrete with high Al 2 Al3 content with a cold compressive strength of at least 400 kp / cm2 measured on the dried raw product, which after burning at 1400 ° C is at least 700 kp / cm2 and a mold resistance at 1400 ° C of at least ± 0.2% for wear parts that come into contact with metal melt. Use of a refractory concrete according to claim 1, characterized in that it contains corundum and active clay soil as additives, a clay soil cement containing less than 15 22% lime and optionally a fluxing agent and provides an analysis of at least 96% A ^ O, less than 3% CaO and less than 0.5% SiO2 · Use of refractory concrete according to claim 2, characterized in that up to 5% of the additives are replaced with a spinel = 20 forming substance, preferably MgO or compounds giving MgO. Use of refractory concrete according to claim 2, characterized in that up to 5% of the additives are replaced with soot, pitch or graphite. 25 Use of refractory concrete according to claim 2, characterized in that up to 7% of the additives are replaced with chromium oxide. Use of refractory concrete according to claims 1 to 5, characterized in that the additives below 0.5 mm are in the form of round grains. Use of refractory concrete according to claims 1 to 6 for slides and / or slabs in sliding shutters on containers containing steel melt. 35 Use of refractory concrete according to claims 1 to 7, characterized in that the shaped wear parts are tar-impregnated.