DE19629099A1 - Ceramic product production - Google Patents

Abstract

Obtaining a ceramic product comprises: (a) preparation of a mineral bonding agent; (b) preparation of a particulate material containing metal, preferably from residues of metalworking processes; (c) mixing of the bonding agent with the resultant particulate material, with the latter forming more than 30% by mass of the total; (d) production and drying of mouldings; and (e) baking of these mouldings to obtain a ceramic product. Also claimed are a resultant product and its application to blast furnace, melting and casting processes.

Description

The invention relates to a method for manufacturing a ceramic molded body, one after such Processed ceramic molded body according to the The preamble of claim 7 and the use of a such shaped body according to claim 10.

In the German Waste Act, there is a duty to waste recovery, the so-called waste recovery requirement wrote. Accordingly, waste recycling, i.e. H. the Ge then gain priority from substances or energy from waste before other disposal when recycling waste is technically possible, the resulting additional costs are not unreasonable compared to other methods and for the substances obtained or for the energy obtained there is a market. Waste recycling enables multiple use of fabrics while saving primary raw materials or the saving of primary energy sources gladly. Due to the considerable environmental problems, the com munen strives to dispose of waste through landfill avoid.

In the course of these efforts, for example, in German patent application 195 25 051.6 proposed in the Brick production clay and clay components of the raw material due to mineral-containing waste materials, such as Ha to replace fenschlamm and this one special Undergo drying process.

Experiments are also known in which asbestos when chopping and kneading the raw material for the goat Gel production were added, the asbestos fibers inerted during the firing process and into the kerami  cal matrix were included, so that they were created where brick is deposited without risk of environmental damage or another use, for example in Road construction can be fed.

Especially in the metalworking industry produce a large number of metal-containing waste materials that with comparatively energy-intensive and technological complicated procedures prepared and another Ver application.

For example, when rolling steel sheets, etc. so-called mill scale on the surface of the rolling stock. Under such a mill scale do you understand that during the rolling process on the steel Surface formed iron oxide, which before crossing certain rolling temperatures a multilayer structure from iron oxide (Fe₂O₃), iron oxide (Fe₃O₄) and iron has oxydul (FeO). The thickness of the mill scale layer increases with the rolling temperature and the rolling time as this Scale layer is permeable to oxygen. The mill scale is a porous, brittle and not firmly adhering layer that when rolling mostly by itself from the surface of the Rolled goods fall off. The scale-free areas of the rolling mill However, the areas scale immediately, so that in the Re gel after-treatment of the rolling stock after the rolling process is required. For this purpose, the rolled products are used many times undergo thermal treatment at the roll exit conditions so that the mill scale layer due to thermal expansion of the rolling stock flakes off and is thus removed.

As mentioned above, these contain layers of mill scale a high Fe content and are therefore high-quality waste substances that can be traced back to the manufacturing cycle.

So far, one has such mill scale waste with steel scrap mixed and in the blast furnace process as an addition to  Pig iron added. Such a return of the roll However, tinder has the problem that due to the undefined size and composition of the mill scale particle it is very difficult to find a predetermined Mi ratio with the steel scrap to be added to deliver, so that in unfavorable cases the Blast furnace process steel quality fluctuates.

Another problem is that in the rolling process rolling mill scale a comparatively high level Have part of rolling oil that during the rolling process is given to the surface quality of the rolling stock improve and minimize the wear of the rollers. There this oil content of the mill scale during steel production is not desired, only mill scale with an oil can Part of less than 1 mas% are used, so that often a costly post-treatment of the mill scale is required is such.

When grinding metal workpieces, preferably from Steel workpieces accumulate metallic grinding dust, which is mixed with cooling lubricant. Such industries cases are also from the above Reasons not directly with the steel production can be used, so that also a Post-treatment of the grinding dust mixed with oil required is such. A direct return of the processed Dust in the blast furnace is not possible, otherwise the Ge there is a dust explosion.

The object of the invention is to create a method fen, with such metal-containing metal residues processing processes, for example from forming processes or machining processes for further use can be led. Another object of the invention is to create a product from these residues for which there is a market and in one subsequent process step can be used.  

This task is related to the manufacturing process rens by the features of claim 1, with regard of the product through the characteristics of the subordinate Pa claim 7 and regarding the use of this pro duktes solved by the features of claim 10.

The invention proposes for the first time that metal-containing residues from a forming or spa process for producing a ceramic molded body to use, the metal-containing fraction a bandage substance is added, through which the dimensional stability of the ceramic molded body after the firing process is accomplished.

With the method according to the invention a Me tall - preferably iron - enriched intermediate created that due to its defined composition and geometric design in an advantageous manner in a blast furnace or foundry process can be used. The binding substance supports the formation of slag and thus the separation of impurities on the Melt surface. That means the binding substance acts as Slag generator and thus contributes to high steel quality act at.

Since in the method according to the invention after burning a geometrically defined shaped body is present, is the storage and transport of the moldings ge compared to the conventional solution in which irregular ge shaped mill scale parts had to be moved, essentially simplified.

The process can be started with particularly good success turn when the scale content exceeds 50 mas% preferably between 60 and 90 mas% of the molded body weight before the burning process.  

As an alternative to the mill scale, grinding dusts can also be used or chips from a machining process or others metallic residues from a production process Ver find application.

As a binding substance for binding the metal-containing frak tion can normally be used in brick manufacture turned clay or another mineral-containing waste fabric, such as the port mentioned at the beginning silt, bleaching earth or silty portions from a bo denwaschanlage or a mixture of such substances used will. It is essential that the mineral binding substance as a substitute for clay or clay for brick production can be used.

Leave the products made by the process use particularly well in steel mills when the egg content of the shaped body more than 40% by mass wearing.

Particularly advantageous for the burning process at the Shaped body production is when the metal-containing frac tion and / or the binding substance contain oil that at Burning process can be used as an energy source. By The high firing temperatures will make the bound oil so far burned that the limit desired by the steel mills values of less than one percent by mass of oil can be achieved are.

When used as an additive in the steel mill the melting point of the shaped body is adjusted such that it is approximately in the range of the melting point of the molten steel.

Other advantageous developments of the fiction method, the molded article according to the invention and the  Use of this molded article is the subject of the others Subclaims.

The following is a preferred embodiment he the invention with reference to the schematic drawing purifies.

The single figure shows a flow chart of a Ver driving for the production of a ceramic according to the invention Molded body.

An exemplary embodiment is described below, in which the mill scale occurring in a rolling mill, the an oil content of up to 15 mas% within the usual range has, is further processed.

As already mentioned at the beginning, the mill scale is after or by joining yourself during the rolling process replaced the descaling process. The descaling will carried out by various methods, mechani cal, chemical and the thermal Ver drive or combinations of these methods use fin the. Mechanical processes are very often used where blasting media made of ferrous materials are galvanized other rolling stock are spun. As a result, at like mechanical processes of the blasted and zer reduced mill scale with the blasting media made of iron materials are mixed.

This detached mill scale is operated by the operator of the he inventive method picked up at the steelworks and egg fed to a brick making process.

In this brick-making process, for example some Includes steps of the classic brick making process the delivered mill scale and a suitable binding sub stamping, such as used in brick manufacture  clay made of aluminum silicate or clay (with sand acc hardened clay) with constituents of iron hydroxide and counter if necessary, other admixtures (lean agents) mixed and crushed. This mixing / crushing process usually follows in a pan mill where the mixture against each other by rolling on slotted steel plates crushed and kneaded rotating pairs of rollers becomes. The mixing ratio is in the invention ß process set such that the proportion of bandage Substance (binding tone) is about 20 to 30 mas%, so that the Corresponding mill scale is approximately 70 to 80 mas%. Of course, uses are also possible for de the mill scale content in the range of 50 mas% or 90 Mas% is. The above Percentages refer to the Total amount of mixture before drying or firing gear. The preparation of the materials for the moldings manufacturing can be practically any wet or Include dry processing step as it has been done so far the production of heavy ceramics is known.

After crushing and mixing the components (Mill scale, binder clay) the mass is ver with H₂O steam sets and fed to an extrusion press (screw press), with a suitable design of the mouthpiece Strand with predetermined outer dimensions is formed.

This continuously pressed strand is at for example ge by a wire cutter cut and the resulting water-containing moldings fed to a drying process.

The preformed blanks are either stationary in Drying chambers or piled on a trolley in through tumble dryers at a temperature of around 100 ° C net, so that the deposited on the surface of the blanks Water is withdrawn, which is used to soften the raw  of mill scale and binder clay in the form of water vapor was fed during extrusion.

After the drying process, go through the piled up blanks a kiln, which is usually used as a tunnel or Ring furnace is formed. Be in this kiln the blanks at a temperature of 800 to 1200 ° C ge burns, from 800 ° C the water of hydration from the binding clay is expelled and the components at the same time Compaction of the mass can be sintered together.

Others in the binding substance or in the metallhalti existing residues, such as wise chrome or organic residues are left with the he process according to the invention in the ceramic matrix the so that this at least during the storage of the ge burned shaped bodies can not occur.

During the subsequent melting process in the steel mill these residues are preferably stored in the slag whose formation - as already mentioned - by the bandage Substance is supported so that the impurities cannot get into the steel.

After the firing process you get a form durable molded body that has a comparatively high egg Has sen fraction that is bound as iron oxide. The egg Senoxide components are integrated in the ceramic matrix the one that is essentially due to the added binding tone is formed.

During the burning process, this is usually done in Rolling mill contained burned rolling oil, so that by the released combustion energy the actual Brennvor is supported and the energy expenditure for the stove firing can be minimized.  

As already mentioned at the beginning, instead of the bandage tons also another mineral-containing waste or Mixture of such waste materials used with binding clay will.

When using such waste materials, it can Reduction in shrinkage when drying and burning be advantageous if the binder clay components or their Substitutes (harbor sludge, bleaching earth, silty parts from a floor washer, etc.) before mixing with the Mill scale can be pre-dried as shown in the beginning mentioned patent application 195 25 051.6 was described.

The dimensionally stable shape obtained after the firing process body is then stacked on pallets after cooling or packed in foils and for further use as Zu conveyed to the steelworks.

Since the manufactured with the inventive method ceramic body a defined composition and you te, is the dimensioning of the addition means for Blast furnace process compared to the conventional procedure much easier and more feasible, so that Steel quality can be increased. Another advantage is in it to see that no own or less slag formers must be added, since the binding substance shares even act as a slag generator.

In a preliminary test, it was usual Brick clay used in the brick industry with one Rolling mill originated mixed mill scale, the rolling mill scale content was 85 mas%. This mixture was made after The above-described process for a cuboid full body per processed, the drying temperature 110 ° C and the firing temperature was approx. 1000 ° C.  

The molded body obtained had an Fe content of 65 Mas%, a density of 3.7 kg / dm³ and a melting point in a range between 1230 ° C and 1310 ° C.

The molded body produced in this way was magnetizable and had a dimensional stability that was problem-free Transport to the steelworks guaranteed.

The processing parameters should be chosen so that a dimensionally stable molded body is obtained in which the iron content is as high as possible and its melting point in the range of the melting point processed in the steel mill ten melt or below, so that a homogeneous Melt composition is guaranteed.

Of course, instead of the above Iron mill scale also other metallic waste materials Manufacture of ceramic moldings are used which are reusable in a melting process.

A method for producing a kera is disclosed mix molded body, with the metal-containing waste materials a mineral binder and mixed in one Brick manufacturing process to be processed. The received Ceramic moldings are used as additives in a Me tallaufschmelzprocess used, the binding substance as Slag generator and the metal components act as an alloy tion components of the melt can be used.

Claims (10)

1. A method for producing a ceramic molded body, comprising the steps:

• - preparation of a mineral binding substance;
• - Processing a metal-containing fraction, preferably from residues of a metal processing process;
• - Mixing the binding substance with the metal-containing fraction, the proportion of the metal-containing fraction being more than 30% by mass;
• - Forming and drying a blank;
• - Firing the molded product to a ceramic molded body.

2. The method according to claim 1, characterized in that the fraction from residues containing iron eisenhal contains mill scale from a rolling process and the Malt scale content more than 60 mas%, preferably 70 to 90 Mas%, based on the weight of the molded body before Burning process. 3. The method according to claim 1, characterized in that the metal-containing fraction abrasion, grinding dust, Chips or other residues from a shaping process, preferably ent a machining process holds.   4. The method according to any one of claims 1 to 3, characterized ge indicates that the binding substance bind tone or a mineral waste, such as harbor silt, bleach earth or silty parts from a floor washer or contains a mixture of such substances. 5. The method according to any one of claims 1 to 4, characterized ge indicates that the Fe portion of the metal-containing Fraction is more than 40 Mas%. 6. The method according to any one of claims 1 to 5, characterized ge indicates that the binding substance and / or the me tall-containing fraction contain oil that the Brennvor gang burned so that the oil content in the molded body is less than 1 mas%. 7. Ceramic molded body with a mineral bin matrix containing the substance, characterized by a share of more than 60 mas% - based on the Ge importance of the preform before firing - metallhalti residues from a metalworking process. 8. Ceramic molded body according to claim 7, characterized records that the melting point of the molded body in Be is the melting point of the metal component. 9. Ceramic molded body according to one of claims 7 or 8, characterized by a metal content of more than 40 mass%.   10. Use of a metal-containing ceramic molded body as an additive in a blast furnace, smelting or casting esserie process.