DE102007048105A1 - Method for the production of refractory material useful as filter, black wash, feeder, adhesive or form part for foundry technology, comprises hardening a slurry through a temperature treatment - Google Patents

Abstract

The method for the production of refractory material useful as filter, black wash, feeder, adhesive/form part for foundry technology, comprises hardening a slurry through a temperature treatment. The flue ash of the slurry is added as binding agent and the slurry is quickly heated so that the flue ash functions as binding agent and remains in the form of slurry. During the temperature treatment at 300-700[deg] C, the temperature increase is greater than 30[deg] C/min. The slurry is added to no further binding agent/a binding agent that evaporates or burns before binding phase- or sintering process. The method for the production of refractory material useful as filter, black wash, feeder, adhesive or form part for foundry technology, comprises hardening a slurry through a temperature treatment. The flue ash of the slurry is added as binding agent and the slurry is quickly heated so that the flue ash functions as binding agent and remains in the form of slurry. During the temperature treatment at 300-700[deg] C, the temperature increase is greater than 30[deg] C/min. The slurry is added to no further binding agent or a binding agent that evaporates or burns before carrying out binding phase- or sintering process. During hardening or sintering, the temperature increase is greater than 200[deg] C/h. A maximum temperature is held between 10-20 min. The slurry consists of more than 60% of flue ash related to the mass. The binding phase and/or the sintering process is carried out in less than 2 hours. The temperature treatment is carried out between 900-1200[deg] C. An independent claim is included for a refractory material useful as filter, black wash, feeder, adhesive or form part for foundry technology.

Description

Field of the invention

The The invention relates to a method for producing a refractory material and a refractory material.

Background of the invention

Refractory materials especially in foundry technology as molded parts such as casting troughs, Crucible, spout nozzles etc. used.

there For example, these are fused silica or alumina or cement-bound materials.

It is also known that the fly ash, ie incineration waste blast furnaces as aggregates, mainly for the Construction industry but also for Refractory materials is used.

fly ash has the advantage of being a relatively cheaper waste product Raw material is. Next is fly ash, as an additive for heat insulation quite well suited.

at known refractory materials limited the use of Fly ash but on a filler. So it's additional at least one more binder such as cement and / or a Phosphate-containing binder needed, to hold the other particles together in a fired state.

such On the one hand, binders are expensive and do not make it possible to provide them of refractory materials consisting essentially of fly ash. Rather, to achieve sufficient strength are right high levels of binder needed.

Further takes the burning process in conventional Refractory materials, especially in moldings often many hours. Due to the low system throughput and the expensive raw materials Therefore, known refractory materials are quite expensive.

Further Known refractory materials, especially as moldings designed, susceptible to cracking wherein crack gaps in the channel surface contaminate the melt can.

Object of the invention

Of the Invention is in contrast the object of a method for producing a refractory material, and to provide a refractory material, wherein said Disadvantages of the prior art are at least reduced.

Especially It is an object of the invention to a binder in the conventional Senses, such as cement and / or a phosphate-containing binder, waive to be able to.

A Another object of the invention is the system throughput in the Increase production of refractory materials.

A Another object of the invention is to additional coatings To be able to do without moldings.

It is further object of the invention, the use of a possible high proportion of fly ash in refractory materials.

Summary of the invention

The Invention is already known by a method for producing a Refractory material, a refractory material, as well as by use of fly ash as a binder according to one of the independent claims.

preferred embodiments and further developments of the invention are the respective dependent claims remove.

After that is a process for producing a refractory material for foundry technology intended.

The Inventors have found that it is surprisingly suitable Process parameters possible is to use a binder in the conventional To renounce meaning.

Previously it was assumed that flyash when burning, in particular after the burning of organic raw materials without the addition of a suitable binder disintegrates.

The However, inventors have now found that in particular when the temperature increase, at least after the burning out of organic Raw materials or after volatilization a greenbinder is sufficiently fast, the material does not decompose, but the fly ash acts as a binder.

It is to assume that it is at least not mainly is a sintering process, but that through a binding phase the fly ash stability obtained.

Preferably no binder is added to the slip or a binder, which only as a green binder works, ie before the onset of solidification, in particular before using a binding phase or a sintering process itself evaporates or burns.

such Additives, which are green binders are used, are preferably organic substances, in particular Styrenes, acrylates and / or acrylic esters. The as greenbinder used additive serves only the better dimensional stability of the slurry essentially cold condition.

During the Temperature treatment is the temperature rise between a temperature of 300 ° C and 700 ° C at least temporarily more than 3 ° C / min., preferably more than 7 ° C / min. and more preferably more than 10 ° C / min. Preferably, at least the average temperature rise between a temperature of 300 ° C and 700 ° C over the above values. It turned out that in particular Temperature gradient of 300 ° C up to 400 ° C lead per hour that a slurry containing substantially fly ash becomes stable it stays and not for cracking and decay phenomena comes. The necessary increase in temperature depends, among others, on the size of the burning component from. Preferably, with the method according to the invention Components made of refractory materials with a thickness of over 1 cm be burned. The mentioned temperature gradients relate in the meaning of the application to the temperature in an oven or similar Device in which the slurry is heated for solidification.

Especially for larger components are even higher Temperturgradienten provided, for example, more than 20 ° C / min.

It has been found to be particularly small components even in an already substantially heated to the maximum temperature Furnace, possibly after drying, can be introduced without it comes to a cracking.

Preferably, especially for components larger than 5 cm, the Temperature treatment but carried out such that between a temperature of 300 ° C and 700 ° C at least temporarily, the temperature increase less than 50 ° C / min, preferably less than 40 ° C / min and more preferably more than 30 ° C / min.

Within The temperature gradient defined in this way meets the fly ash used optimum bovine properties without the fly ash breaking down or it comes to stress cracks.

to Control of this temperature profile can be both batch and roller kilns be used.

at a preferred embodiment of the invention the temperature rise above a temperature of 750 ° C at least temporarily, preferably during Consolidation or sintering only 200 ° C per hour. Depending on the application, a hold time at the maximum temperature is preferable between 5 and 60 minutes, more preferably between 10 and 20 minutes. intended.

By a temperature treatment, in particular a burning process, is the slip solidifies, wherein before or during solidification the Burning out additives. According to the invention the fly ash is used as a binder.

Of the Contains slip in a preferred embodiment of the invention more than 30%, preferably more than 50% and especially preferably more than 60% (in each case in percent by weight) fly ash. It leaves to produce a refractory material, which in the fired state consists essentially of fly ash, in particular more than 80%.

With The method makes it possible the temperature treatment in a process time of less than 15 hours, even in isolated cases less than 5 hours

Of the Plant throughput can be significantly increased, at the same time decreases also the energy requirement in the production of appropriate components.

there it is particularly advantageous that because of the short temperature treatment at the same time high temperature gradient the energy, which through the combustion of a foam during manufacture released by filters, for solidification and for rapid temperature increase in much higher share on the whole for needed the burning process Energy can be used.

ever according to the recipe, a temperature treatment with at least 650 ° C, is preferred with at least 850 ° C and particularly preferably carried out with at least 900 ° C.

The Inventors have further found that by adding of aggregates the melting point, and thus the necessary temperature reduce or increase leaves.

The Refractory material according to the invention can in a development of the invention even more particular as pure fillers containing aggregates. Suitable additives are for example, zirconium silicate, carbon, coke, quartz powder, sand, Talc, soapstone, silicon silicate, silicates, bentonite, clay, boron silicates, Boron carbides, nitrides, kaolin chamotte, chamotte kaolinite, alumina, Alumina porcelain flour etc.

One preferred range for a temperature treatment is 850 to 1400 ° C.

The Inventors have found that it is at higher temperatures, in particular cracking above 1300 ° C can come. It is suspected that such cracking off a loss of material due to an increasingly incipient sintering process results.

When Fly ash is preferably used as hard coal fly ash. The mean particle size of the fly ash is less than 1000 μm, preferably less than 500 microns and more preferably less than 250 microns.

Fly ash with a grain density of between 1400 and 2800 kg / m ³ , preferably between 1800 and 2200 kg / m ³ , is preferably used.

Further The invention relates to a refractory material, in particular a Filter, a sizing, a feeder, an adhesive, a molding or another refractory component for the foundry industry, wherein the refractory material Fly ash as a binder comprises.

Preferably the refractory material has no other binder or one further binder only in low concentration, in particular less than 20 weight percent, preferably less than 5 weight percent In one embodiment the refractory material may consist essentially of fly ash, So have a fly ash content of more than 70%.

there the fly ash serves as a combination of binder and filler, more fillers and binders are not required.

Alternatively, especially for High temperature applications, the fly ash can also essentially only be used as a binder. For this at least 5 weight percent, preferably 10 percent by weight fraction of fly ash.

Especially can essentially fused silica or alumina containing refractory components Binder fly ash have.

The refractory material preferably has a true density between 2 g / cm ³ and 4 g / cm ³ .

Further The invention relates to the use of fly ash as a binder in the manufacture of filters, sizes, feeders, adhesives and / or Moldings for the foundry technology.

A Plain, which applied to components in the unfired state is, is therefore also as a refractory material in the context of the invention Understood.

at the production of a slip used is more than 5 percent by weight, preferably added more than 10 weight percent fly ash.

In a preferred embodiment of the invention, fly ash of the following composition is used (percentages by weight): SiO ₂ 40 to 60% Al ₂ O ₃ 15 to 30% iron oxide 0 to 10% calcium oxide 0 to 10% sulfur oxides 0 to 1% potassium oxide 0 to 5% soda 0 to 1%

A preferred formulation for a filter, a sizing agent, a feeder or an adhesive contains at least one of the following constituents in the following amount (parts by weight): fly ash 60 to 90% Alumina porcelain flour 5 to 20% kaolinite 5 to 20% aluminum oxide 5 to 20% defoamers 0.2 to 1% wetting agent 0.2 to 1% Additive to green bond, preferably on an organic basis, eg B. wallpaper paste or types of acronite from BASF 2 to 12%.

Another preferred formulation, in particular for molded parts, contains at least one of the following constituents in the following amount (proportions by weight): fly ash 3 to 70% Alumina porcelain flour 10 to 30% Glass bubbles, in particular Q-Cel of the company Omega Minerals Germany GmbH 5 to 30% fluorspar 2 to 10% barite 2 to 10% defoamers 0.2 to 1% wetting agent 0.2 to 1% Additive as green binder 2 to 12% in particular silica sol L300 / 30%, 5 to 20% Acrylated silica sol etc.

at a preferred embodiment the invention is dispensed silica sol as an additive.

1 shows an exemplary temperature guide in the manufacture of a refractory material, wherein the temperature is plotted against time. For example, a gas-heated tunnel oven is used.

Within The first 30 minutes, the oven is heated to about 800 ° C. Through this fast temperature increase of about 25 ° C / min is enabled Fly ash to use as a binder.

at about 1100 ° C the temperature is maintained for about 10 minutes, then it is the oven in about a heating process corresponding speed cooled.

It can be in the production of refractory materials according to the invention Reach process times of 90 min. It is understood that the invention is not limited to a combination of the features described above, but that the expert all Features of the invention, where appropriate, will combine.

Claims (23)

A method for producing a refractory material, wherein a slurry is solidified by a temperature treatment, characterized in that fly ash is added to the slurry as a binder. Process for producing a refractory material according to claim 1, characterized in that during the temperature treatment between a temperature of 300 ° C and 700 ° C at least temporarily, the temperature increase more than 3 ° C / min, preferably more than 7 ° C / min and more preferably more than 10 ° C / min. Process for producing a refractory material according to one of the preceding claims, characterized that while the temperature treatment between a temperature of 300 ° C and 700 ° C at least temporarily the temperature increase less than 50 ° C / min, preferably less than 40 ° C / min and more preferably less than 30 ° C / min. Process for producing a refractory material according to one of the preceding claims, characterized that the slip is placed in an oven, which in less as 180 min, preferably in less than 60 min, particularly preferred in less than 50 minutes to over 800 ° C is heated. Process for producing a refractory material according to one of the preceding claims, characterized that the slip no binder or a binder that before the onset of solidification, especially before the onset of a Bindephase- and / or sintering process, volatilizes or burns added becomes. Method for producing a refractory material, in particular of casting troughs, according to one of the preceding claims, characterized that while the temperature treatment above a temperature of 750 ° C, preferably while a consolidation or a sintering, the temperature rise more than 100 ° C / h, preferably more than 200 ° C / h is. Process for producing a refractory material according to one of the preceding claims, characterized that a maximum temperature is substantially between 5 and 60 minutes, preferably between 10 and 20 min is maintained. Process for producing a refractory material according to one of the preceding claims, characterized that the slip, based on the mass, more than 30%, preferably contains more than 50% and more preferably more than 60% fly ash. Process for producing a refractory material according to one of the preceding claims, characterized that an additive is added to the slip as a green binder. Process for producing a refractory material according to one of the preceding claims, characterized that step of the temperature treatment, in particular a binding phase and / or a sintering process, less than 5 hours, preferably less 3 hours and more preferably less than 2 hours. Process for producing a refractory material according to one of the preceding claims, characterized that the temperature treatment with more than 680 ° C, preferably with more than 850 ° C and especially preferably more than 900 ° C carried out becomes. Process for producing a refractory material according to one of the preceding claims, characterized that the temperature treatment at less than 1400 ° C, preferred with less than 1200 ° C is performed. Process for producing a refractory material according to one of the preceding claims, characterized that as fly ash hard coal fly ash is used. Process for producing a refractory material according to one of the preceding claims, characterized that fly ash having an average particle size of less than 1000 microns, preferably less than 500 μm and more preferably less than 250 microns is used. Process for producing a refractory material according to one of the preceding claims, characterized that the slip a substance of reduction of the melting point, in particular alumina porcelain flour and / or kaolinite is added. A method for producing a refractory material according to any one of the preceding claims, characterized in that fly ash with a grain density between 1400 and 2800 kg / m ³ , preferably used between 1800 and 2200 kg / m ³ . Refractory material, in particular layer, feeder, Glue or molded parts for the foundry technology, and in particular produced by a method according to any one of previous claims, characterized in that the refractory fly ash than Binder includes. Refractory material according to the preceding claim, characterized in that the refractory material is less than 20% (Percent by weight), preferably less than 5%, more preferably has no further binder. Refractory material according to one of the preceding claims, characterized characterized in that the refractory material more than 5%, preferably has more than 10% fly ash as binder. Refractory material according to one of the preceding claims, characterized characterized in that the refractory material is silicon carbide, Zirkonoyxd, Kaolin, mullite, alumina, zirconium silicate and / or alumina porcelain contains. Refractory material according to one of the preceding claims, characterized in that the refractory material has a true density between 2 g / cm ³ and 4 g / cm ³ Use of fly ash as a binder in the Production of filters, sizes, feeders, adhesives and / or Moldings for the foundry technology. Use according to the preceding claim, characterized characterized in that a slip used in the manufacture more than 5%, preferably more than 10% fly ash is added.