WO2005001359A1 - Fire-resistant brickwork and fire-resistant bricks for producing the brickwork - Google Patents

Abstract

The invention relates to a fire-resistant brickwork in an industrial furnace, inside of which nonferrous metals such as copper, lead, zinc, nickel or the like are molten at temperatures higher than 700 DEG C, particularly higher than 900 DEG C, at least in part, in an oxidizing furnace atmosphere. The brickwork is made of unfired bricks made of a fire-resistant material, and carbon is contained in the fire-side or hot-side surface area of the bricks of the brickwork. The invention also relates to a fire-resistant brick for producing a brickwork.

Description

 Fireproof masonry and fireproof stones for the production of the masonry

The invention relates to fireproof masonry and refractory bricks for the refractory delivery of industrial furnaces in which non-ferrous metals (non-ferrous metals) such as copper, lead, zinc, nickel or the like. are melted in an essentially oxidizing atmosphere at temperatures above 700 ° C., in particular above 900 ° C.

Copper, lead, zinc, nickel or the like are melted on an industrial scale in various vessels (Pierce-Smith converter, QSL reactor, various shaft furnaces, etc.) The melting process is carried out both reducing and oxidizing.

The so-called running time of the ovens depends, among other things. also on the type of refractory brick lining, which on the one hand protects the metal jacket of the furnace from the effects of high melting material, flame and atmospheric temperatures and on the other hand reduces heat losses.

The furnace lining is usually exposed to high temperature changes, high mechanical and chemical stresses. The changes in temperature result from the batch mode and the blowing in of cold process materials. Mechanical stresses are caused by rotary movements of the furnace. The masonry is chemically stressed by the process slags and metal melts and by volatile connections in the furnace atmosphere.

These industrial furnaces are delivered or lined with fired refractory bricks, essentially with refractory bricks based on MgO-Cr ₂ 0 ₃ or MgO. The furnaces are divided into different zones in terms of brickwork, because the zones are subjected to different loads during operation. With the QSL reactor, a distinction is made, for example, between the reduction area, the oxidation area and the associated nozzle zones. The wear of the FF material is mainly due to chemical corrosion from slags and other process materials as well as flaking of infiltrated layers due to temperature changes.

While the majority of the furnace is lined with normal MgO or MgO Cr ₂ 0 ₃ stones, slag zones and, above all, the nozzle zones must be reinforced with very high-quality, high-fired, so-called direct-bonded magnesia chrome stones.

These refractory linings can be found in all types of non-ferrous metal production vessels, regardless of the design.

Naturally, these fired refractory products have an open porosity that is in the range between 13 and 20 vol. % lies. Process materials such as slags, melts or gases can infiltrate into these open pores and decompose the stone through chemical reactions and / or lead to completely changed thermomechanical properties of the structure than those of the original refractory material. Changing chemical attacks and changing thermal and thermomechanical loads lead to accelerated wear and damage.

In the past, attempts have been made to counter this problem by improving the material composition and the production parameters of the fired stones and thus adapting them to unfavorable operating conditions. This application-relevant optimization essentially includes a change in the chemical-mineralogical composition of the stones with the aim of, for example, increasing their corrosion resistance and optimizing the grain structure, the pressing pressures and the firing temperatures. An example are directly bonded MgO-Cr ₂ 0 ₃ stones based on simultaneous sintering or fused granules, which usually have a high Corrosion resistance and density guarantee as normal magnesite chromite stones. On the other hand, these measures often worsen the thermo-mechanical properties of the stones, because at the same time they become less flexible due to the higher density.

The object of the invention is to provide fireproof masonry for furnaces and / or furnace areas operated with an oxidizing furnace atmosphere, which is considerably less infiltrable, but at the same time also has a superior resistance to temperature changes due to high flexibility.

This object is solved by the features of claim 1. Advantageous developments of the invention are characterized in the subclaims.

According to the invention, unfired refractory bricks made of commonly used material, e.g. made of an above-mentioned refractory material with commonly used space frames, which are phosphate-bound or whose binder is a synthetic resin, tar or pitch, or which are bound by another suitable binder.

It is essential that carbon, in particular graphite, is contained in the stone material, in particular in the pores, on the side of the brick lining or the stones facing the furnace interior. The graphite can be a natural or an artificial graphite, for example flake graphite. It has been shown that the graphite under the typical conditions (slags, temperatures) apparently behaves differently than expected and does not oxidize prematurely or too quickly in a damaging manner. The result is surprisingly a very little infiltrated layer of slag, which prevents oxygen from entering the stone. The effect of graphite in combination with a carbon-based binder such as synthetic resin, tar or pitch is particularly effective, whereby the effect is particularly good when art resin is present. Phenolic resins (phenol resol) or phenolic resin novolak solutions are used in particular as synthetic resins.

The porosity in the graphite-containing zone, but preferably also in the whole unfired stone, is expediently less than 20% by volume, preferably less than 14% by volume, in particular the porosity is between 1 and 8% by volume.

The graphite content of the graphite-containing zone is preferably 2 to 30% by weight, in particular 5 to 20% by weight. In the case of carbon-containing binders, the carbon content from the binder plus graphite should be within the stated limits of 2 to 30% by weight, in particular 5 to 20% by weight. The carbon-containing binder is preferably used in amounts of 2 to 5% by weight, in particular 2.5 to 4% by weight.

According to a special embodiment of the invention, the graphite-containing zone additionally contains antioxidants, such as, for example, Al, Si, Mg, SiC, Si ₃ N ₄ , B ₄ C, A1N, BN, SiAlON, or metallic alloys. Through special reactions with the process materials, the antioxidants can support the formation of the sealing zone on the surface and protect against too deep penetration of the oxidation into the graphite-containing zone, so that carbon reserves remain for later replication of defective sealing areas.

It is within the scope of the invention to use stones which contain graphite completely or in their entirety or through and through. It is also within the scope of the invention to use, in particular, stones which contain completely graphite and are bound by carbon-containing binders such as synthetic resin, tar or pitch. In this respect, the invention provides for basic, carbon-containing refractory bricks, known per se, to be used for the masonry of oxidizing stoves or furnace areas, which are actually intended for use in reducing Atmosphere, for example for use in steel production. Such basic refractory bricks are used, for example, to line iron and steel producing vessels such as converters, steel ladles or electric arc furnaces. These likewise unfired carbon-containing stones, in particular magnesia stones or dolomite stones, ensure compatibility with most basic slags and the stability of the carbon, in particular also of the graphite, in the reducing atmosphere that prevails in the steel production. The stones are bound with synthetic resin, pitch or tar and shaped in the cold state (phenol resin-bound or phenol resin-novolak-bound stones) or in the hot state (phenol resin-novolak-bound or tar or pitch-bound stones). The stones also sometimes have ^{antioxidants',} which reduce the carbon loss due to their higher carbon against Sauerstoffäffinität. The effect of the antioxidants is mainly based on an increase in gas access and an increase in strength. Metals, carbides or nitrides, for example Al, Mg, Si, SiC, B ₄ C, Si ₃ N ₄ , A1N, BN or SiAlON, are typically used.

Within the scope of the invention, use is made of the known technology for producing such carbon-containing stones by producing stones used according to the invention with the corresponding technology.

Due to the surprisingly in-situ, thin sealing infiltration zone and in particular also due to a low porosity, the thermochemical resistance to attack by process materials in the manufacture of non-ferrous metals is largely guaranteed. Apparently, when oxygen enters, the first reaction products in situ block the pore channels in the stones and at least reduce the further access of oxygen and thus a further reaction of the latter with the carbon. In addition, the graphite content, particularly in combination with carbon-containing binders, brings about a desirably low modulus of elasticity E and, accordingly, a desirably low shear modulus G.

If MgO and carbon are used as raw material components, the graphite-containing zones or the stones are very thermally stable. A partial or complete exchange of the MgO for other refractory minerals such as spinels, corundum, bauxite, andalusite, mullite, flint clay, chamotte, zirconium oxide, zirconium silicate does not affect the protective infiltration zone.

The oxidizing atmosphere surprisingly produces only a minimal carbon burnout on the hot stone side of the masonry, whereby the ashing that occurs also surprisingly leads to a type of sealing zone on the stone surface, probably due to sintering processes on the stone surface, without other material properties Stones get lost. In the occupied furnace areas, the infiltration zone forms very quickly and relatively permanently during operation. Flaking is less common, even with overheating and alternating loads.

According to the invention, stones are used for the hot furnace zones such as the nozzle zone, for example a QSL reactor for melting lead, which can withstand the attack of the hot process materials, for example stones based on MgO and graphite. These expediently contain the antioxidants mentioned, which control the combustion of the carbon. The antioxidants also increase the strength of the stone on the insert side. In addition to magnesia (sintered magnesia or melted magnesia), the stones can also contain spinel, bauxite, zirconium oxide, zirconium silicate, or corundum, or magnesia can be completely replaced by these minerals, especially if the thermal conductivity is to be reduced. The stones used according to the invention are not only used for the nozzle teeth, but also expediently for all other zones. For example, the entire rest of the QSL reactor can be delivered with stones based on MgO and carbon. The carbon content of the stones should also be between 2 and 30% by weight in this case. These stones can also contain antioxidants for the stated purpose.

If the temperatures on the outside of the firing unit, the so-called furnace jacket, become too high during use, there is the possibility of delivery with so-called two-layer masonry. This masonry consists of the described carbonaceous stones on the hot side, characterized by their content of refractory minerals, graphite and possibly antioxidants and on the furnace shell side of an insulating masonry consisting, for example, of a commercially available firebrick or another thermally insulating material, for example one easy fireclay.

Stones used according to the invention contain zonal graphite on the hot side. The cold side of the stone can e.g. consist of the same material without graphite or a heat-insulating material.

1 shows such a structure, the two-layer brick 1 consisting of the graphite-containing hot zone 2 and the cold insulation zone 3.

These stones can be made in one step and have a permanent bond between the two zones. Of course, the insulating part and the carbon-containing part can also be glued to the carbon-containing part with an adhesive after each separate manufacture to facilitate installation.

Fig. 2 shows schematically a cross section through a QSL reactor and Fig. 3 by a Kaldo converter.

The nozzle zone 4, the oxidation part 5 and the reduction part 6 of the QSL reactor 9 as well as the upper and lower vessel 7, 8 of the Kaldo converter 10 are lined with carbon-containing magnesia stones.

The invention is explained in more detail below with the aid of the following delivery examples for refractory masonry.

Example 1: QSL reactor

The starting point is a tube furnace in which lead is smelted under typical operating conditions. The zone division according to FIG. 2 is as follows:

Nozzle areas 4 K and S reduction part 6 oxidation part 5

A delivery according to the invention results as follows:

Nozzle zone 4

It is delivered with a magnesia stone with a graphite content, with or without antioxidants; the composition of this stone is as follows:

Magnesia grit 0-4 mm 50 - - 80 wt. -% magnesia flour <0.1 mm 5 - - 25 wt. -% flake graphite 2 - - 25 wt. -% aluminum powder 0 - - 5 wt. -% B ₄ C powder 0 - - 5 wt. -%

Binder is phenol resol, which is added to the dry batch in an amount of 3.2% by weight. The stone is available in the usual formats for the non-ferrous industry with a pressure of 160 MPa pressed and then annealed at a temperature of 200 ° C.

The stones are installed using the installation tools and methods that are common in the non-ferrous industry.

The following composition is particularly advantageous

Enamel magnesia grain 0-4 mm 70 - - 74, preferably 72 wt. Melted magnesia flour <0.1 mm, 10 - - is, preferably 13 wt. Flake graphite 8 - - 12, preferably 10 wt. Aluminum powder 2 - - 4, preferably 3 wt. B ₄ C powder 1 - - 3, preferably 2 wt.

Reduction part 6

It is delivered with a magnesia stone with a graphite content, with or without antioxidants; the composition of this stone is as follows:

Magnesia grit 0-4 mm 50 - - 80% by weight magnesia flour <0.1 mm 5 - - 25% by weight flake graphite 2 - - 25% by weight aluminum powder 0 - - 5% by weight B ₄ C ulver 0 - - 5% by weight

Binder is phenol resol, which is added to the dry batch in an amount of 3.2% by weight. The stone is pressed in the usual formats for the non-ferrous industry with a pressure of 160 MPa and then annealed at a temperature of 200 ° C.

The stones are installed using the installation tools and methods that are common in the non-ferrous industry.

The following composition is particularly advantageous:

Sintered magnesia grain 0-4 mm 70 - 73, preferably 71% by weight sintered magnesia flour <0.1 mm 11-16, preferably 14% by weight of flake graphite 8-12, preferably 10% by weight Aluminum powder 5, preferably 5 wt.

Oxidation part 5

It is delivered with a magnesia stone with a graphite content, with or without antioxidants; the composition of this stone is as follows:

Magnesia grit 0-4 mm 50 - - 80 wt. -% magnesia flour <0.1 mm 5 - - 25 wt. -% flake graphite 2 - - 25 wt. -% aluminum powder 0 - - 5 wt. B ₄ C powder 0 - - 5 wt. -%

Binder is phenol resol, which is added to the dry batch in an amount of 3.2% by weight. The stone is pressed in the usual formats for the non-ferrous industry with a pressure of 160 MPa and then annealed at a temperature of 200 ° C.

The stones are installed using the installation tools and methods that are common in the non-ferrous industry.

The following composition is particularly advantageous:

Sintered magnesia grain 0-4 mm 74 78, preferably 76% by weight sintered magnesia flour <0.1 mm 11 16, preferably 14% by weight flake graphite 4 7, preferably 5% by weight aluminum powder 2 4, preferably 3% by weight of B _Λ C powder 1 3, preferably 2% by weight

Example 2: Kaldo converter 10

The starting point is a converter in which lead is melted and refined under typical operating conditions. The zone division according to FIG. 3 is as follows:

Upper vessel 7 Lower vessel 8

A delivery according to the invention results as follows:

Upper vessel 7

Delivery is made with a magnesia with a graphite phita ^'PROPORTION, with or without antioxidants; the composition of this stone is as follows:

Magnesia grain 0-4 mm 0 - - 80 wt.% Magnesia flour <0.1 mm 5 - - 25 wt.% Flake graphite 2 - - 25 Ge. -% aluminum powder 0 - - 5% by weight -% B ₄ C powder 0 - - 5% by weight

Binder is phenol resol, which is added to the dry batch in an amount of 3.2% by weight. The stone is pressed in the usual formats for the non-ferrous industry with a pressure of 160 MPa and then annealed at a temperature of 200 ° C.

The stones are installed using the installation tools and methods that are common in the non-ferrous industry.

The following composition is particularly advantageous

Enamel magnesia grain 0-4 mm 70 74, preferably 72% by weight of melted magnesium flour <0.1 mm 10 16, preferably 13% by weight flake graphite 8 12, preferably 10% by weight aluminum powder 2 4, preferably 3% by weight of B ₄ C powder 1 3, preferably. 2% by weight

Lower vessel 8

It is delivered with a magnesia stone with a graphite content, with or without antioxidants; the composition of this stone is as follows: Magnesia grit 0-4 mm 50 - - 80 wt. -% magnesia flour <0.1 mm 5 - - 25 Ge. -% flake graphite 2 - - 25 wt. -% aluminum powder 0 - - 5 wt. -% B ₄ C powder 0 - - 5 wt. -%

Binder is phenol resol, which is added to the dry batch in an amount of 3.2% by weight. The stone is pressed in the usual formats for the non-ferrous industry with a pressure of 160 MPa and then annealed at a temperature of 200 ° C.

The stones are installed using the installation tools and methods that are common in the non-ferrous industry:

The following composition is particularly advantageous:

Sintered magnesia grain 0-4 mm 69 - 73, preferably 71% by weight sintered magnesia flour <0.1 mm 16-22, preferably 19% by weight of flake graphite 8-12, preferably 10 gaw. - ^

The success of the invention is illustrated below using two model offsets for feeding the nozzle area of QSL reactors (reducing and oxidizing part) for the production of lead:

Offset 1:

MgO sinter 97.5% 84% flake graphite 10% AI powder 2% B ₄ C powder 1% phenolic resin binder 3%

Offset 2:

MgO sinter 97.5% 82% flake graphite 10% AI powder 5% phenolic resin binder 3% With stones from these offsets, the following results were achieved in the QSL reactor at two different nozzle positions compared to a high-quality, directly bound chromium magnesium stone:

The above comparison shows the superiority of the deliveries according to the invention over conventional deliveries. The operating hours could be increased considerably and the wear considerably reduced.

Claims

claims 1. Refractory masonry in an industrial furnace, in which at least partially non-ferrous metals such as copper, lead, zinc, nickel or the like are melted at temperatures above 700 ° C., in particular above 900 ° C., in an oxidizing furnace atmosphere, characterized in that the masonry is made of unfired bricks made of refractory material and carbon is contained in the fire-side or hot-sided surface area of the masonry bricks. 2. Masonry according to claim 1, g e k e n n z e i c h n e t d u r c h stones that have zonal carbon in the area of the surface provided for the fire side of the masonry, in particular in a 1 to 18 cm, preferably 2 to 15 cm thick zone. 3. Masonry according to claim 1 and / or 2, d a d u r c h g e k e n n z e i c h n e t, that the stones have the formats commonly used. , Masonry according to one or more of claims 1 to 3, d a d u r c h g e k e n n z e i c h n e t, that the stones contain the carbon in the form of graphite. 5. Masonry according to claim 4, characterized in that the stones contain flake graphite. 6. Masonry according to claim 4 and / or 5, d a d u r c h g e k e n n z e i c h n e t, that the stones also carbon in the form of carbon-containing binder, e.g. Contain tar and / or pitch. 7. Masonry according to claim 6, d a d u r c h g e k e n n z e i c h n e t, that the stones contain synthetic resin as a binder. 8. masonry according to claim 7, d a d u r c h g e k e n n z e i c h n e t, that the stones contain phenolic resin as a binder. 9. masonry according to claim 7, d a d u r c h g e k e n n z e i c h n e t, that the stones contain phenolic resin-novolak as a binder. 10. Masonry according to one or more of claims 4 to 9, d a d u r c h g e k e n n z e i c h n e t, that the stones in the carbon-containing zone contain 2 to 30 wt .-%, in particular 5 to 20 wt .-% carbon. 11. Masonry according to one or more of claims 4 to 9, d a d u r c h g e k e n n z e i c h n e t, that the stones contain a carbon-containing binder in amounts of 2 to 5 wt.%, In particular 2.5 to 4 wt.%. 12. Masonry according to claim 1 and one or more of claims 3 to 11, characterized in that the carbon is contained homogeneously distributed throughout the stone. 13. Masonry according to claim 12, d a d u r c h g e k e n n z e i c h n e t, that it is made of stones made of in particular basic refractory material, in particular based on MgO. 14. Masonry according to claim 13, characterized in that it is formed from stones in which MgO is at least partially replaced by spinel and / or corundum and / or bauxite and / or andalusite and / or mullite and / or flint clay and / or chamotte and / or zirconium oxide and / or zirconium silicate. 15. Masonry according to one or more of claims 1 to 14, characterized in that the stones have a porosity of less than 20 vol .-%, in particular less than 14 vol .-%, preferably a porosity between 1 and 8 vol .-% , 16. masonry according to one or more of claims 1 to 15, d a d u r c h g e k e n n z e i c h n e t, that the stones have known antioxidants, in particular in amounts of 1 to 10 wt .-%, preferably in amounts of 2 to 8 wt .-%. 17. Masonry according to one of claims 1 to 16, g e k e n n z e i c h n e t d u r c h carbonaceous stones based on spinel and / or bauxite and / or corundum and / or zirconium oxide and / or zirconium silicate. 18. Masonry according to one or more of claims 1 to 16 at least in an oxidation zone of an industrial furnace, in which a non-ferrous metal is melted, marked etchch carbonaceous stones based on andalusite and / or a mineral of the sillimanite group and / or bauxite and / or clay-rich chamotte such as Flintclay and / or zirconium oxide and / or zirconium silicate. 19. Masonry according to one or more of claims 1 to 16 in an oxidation zone and / or a reduction zone and / or a nozzle zone of a QSL reactor or in an upper and / or lower vessel of a Kaldo converter, characterized by carbon-containing stones based on MgO and / or MgO / spinel mineral and / or MgO / bauxite and / or MgO / corundum and / or MgO / zirconium oxide and / or MgO / zirconium silicate. 20. Masonry according to one or more of claims 1 to 16 and 19, in particular according to claim 19, characterized in that the stones have the following composition: fused magnesia 0-4 mm 70-74, preferably. 72% by weight of melted magnesium flour <0.1 mm, 10-16, preferably 13% by weight flake graphite 8-12, preferably 10 wt .-% aluminum powder 2-4, preferably 3% by weight of B ₄ C powder 1-3, preferably 2% by weight 21. Masonry according to claim 19 and / or 20 in an oxidation zone, characterized by stones of the following composition: sintered magnesia 0-4 mm 74 - - 78, preferably. 76% by weight sintered magnesia flour <0.1 mm 11 - - 16, preferably 14% by weight of flake graphite .4 - - 7, preferably 5% by weight aluminum powder 2 - - 4, preferably 3% by weight B ₄ C powder 1 - - 3, preferably 2% by weight 22. Masonry according to claim 18 and / or 19 and / or 20 in a reduction zone, characterized by stones of the following composition: sintered magnesia 0-4 mm 70 - - 73, preferably. 71 wt. Sintered magnesia flour <0.1 mm 11 - - 16, preferably 14 wt. Flake graphite 8 - - 12, preferably 10 wt. Aluminum powder 4 - - 5, preferably 5 wt. 23. Masonry according to claim 19 and / or 20 in an upper vessel of a Kaldo converter, characterized by the following composition: fused magnesia grain 0-4 mm 70 - - 74, preferably. 72 wt. Melted magnesia flour <0.1 mm 10 - - 16, preferably 13% by weight flake graphite 8 - - 12, preferably 10 wt. Or aluminum powder 2 - - 4, preferably 3% by weight B ₄ C powder 1 - - 3, preferably 2% by weight 24. Masonry according to claim 19 and / or 20 in a lower vessel of a Kaldo converter, g e k e n e z e i c h n e t d u r c h the following composition: sintered magnesia 0-4 mm 69 - 73, preferably. 71% by weight sintered magnesia flour <0.1 mm 16-22, preferably 19% by weight of flake graphite 8-12, preferably 10% by weight 25. Refractory stone for the production of masonry according to one or more of claims 1 to 11 and 13 to 24, g e k e n n e e c h n e t d u r c h a one-piece structure of a carbon-containing hot side zone 2 and a heat-insulating zone 3 made of a heat-insulating material. 26. Refractory stone for the production of masonry according to one or more of claims 1 to 24, g e k e n n z e i c h n e t d u r c h the composition of claims 20 or 21 or 22 or 23 or 24.