DD273362A3 - Process for the production of resin-bonded, carbonaceous, basic, refractory products - Google Patents

Abstract

The invention relates to a production process of refractory products, which find their use in converters, pans, Elektroschmelzoefen and in high-temperature aggregates. The object of the invention is to exclude inhalation of toxic sulfur and Teergasen by a suitable energy-saving and effort minimizing production process and to ensure a high degree of flexibility in terms of product quality. According to the invention, the object is achieved by a production process in which 80-100% of a liquid synthetic resin is metered onto the premixed middle and coarse fractions of a refractory component and mixed so that a homogeneous mass results. To the mixture is added in particulate form a carbon carrier, a refractory fine component and a powdered synthetic resin, the mixture being homogenized after each addition.

Description

Field of application of the invention

The invention relates to a method for producing resin-bonded, carbon-containing, refractory products, their use in converters, pans, electric melting ovens and ^! n find high-temperature aggregates.

Characteristic of the known technical solutions

From the literature voischindene methods for the production of refractory bricks or other moldings are known.

These have so far been sufficient to obtain refractory products with certain property values.

With the introduction of carbon-bonded products, existing technologies were no longer sufficient to produce high-quality products. In order to achieve the required property values, a hot mixing process with coarse grain preheating in a separate unit and subsequent hot deformation was carried out.

A disadvantage of this method is the high energy consumption. In addition, there are problems with the press at carbon contents greater than 5%. The higher the carbon content, the lower the compressibility of the mass. Other disadvantages, such as the formation of toxic tar and sulfur vapors in the mixing and pressing process and the softening of the moldings in the heating process led to the transition to the synthetic resin bond.

Thus, DE-OS 3146866 describes a heat-resistant material with a phenol-formaldehyde resin binder which can be prepared by a conventional method as used for pitch-bonded refractory materials.

The disadvantage here is the addition of water to achieve a suitable consistency.

US Pat. No. 4,248,638 describes a method for the production of a magnesia carbon brick in which a novolak polymer is dissolved in a solvent in a complicated manner and then a curing agent is added.

A similar process is described in DE-OS 2806506, which also uses novolak phenol resin as binder solution. It is disadvantageous in products produced by these methods that the molded articles have a very low strength after molding, which makes further processing more difficult.

Improvements to these disadvantages are made in EP 0158895 df ι, which already shows ways of applying a mixture of phenol resins of Movolaktyp and the resol type. The production process is not discussed in detail, but it is said that this is of great importance for the optima'an property values of the products

A disadvantage of this solution is again the use of water to produce a compressible mass.

Object of the invention

The object of the invention is to provide a carbonaceous refractory production method which precludes inhalation of toxic sulfur and tar gases, minimizes energy and production costs and enables a wide range of products with improved product quality.

Explanation of the essence of the invention

The object of the invention is to exclude inhalation of toxic sulfur and tar gases by means of a suitable energy-saving and low-emission method of production, and to ensure a high level of flexibility with regard to product quality.

According to the invention the object is achieved by a manufacturing method in which 80 ... 100% of a liquid synthetic resin is metered onto the premixed middle and coarse grain fraction of a refractory component and mixed so that a

homogeneous mass arises. To this conglomerate of large refractory component and synthetic resin, a carbon support, a refractory fine component and a powdered synthetic resin are particulately added in series, wotoi after each addition is carried out homogenization.

This mixture of refractory raw materials and aggregates, the remaining liquid resin is then added and homogenized again.

The entire Doeier- and mixing process boi temperatures of a maximum of 3O ⁰ C, which is a work without

permeable to gases.

The mixture is molded at a specific pressure of greater than or equal to 100 MPa to give moldings. The molded articles are subjected to a curing process for a maximum of 20 hours.

Depending on the specificity of the molded products, the curing takes place, starting at 80 ° C to a maximum of 200 ⁰ C, wherein

either a one- or two-stage curing of the moldings is possible.

The single-stage hardening: ng takes place at temperatures of 160 ... 200 ⁰ C, the two-stage hardening in the 1st stage hot 80! 00 ⁰ C and in the second stage at 160 ... 200 ⁰ C instead ,

The occurring in this temperature range chemical reactions of the resin cause a complete

Curing of the product and give it corresponding properties. In the used for liquid

Resin is a resol type phenol-formaldehyde resin whose B time is at most 2.5 minutes, preferably 1 to 2 minutes.

The B time is understood to mean the time that a phonol resin requires to irreversibly change from a liquid state at a temperature of 150 ° C. to a gelatinous state. The powdered synthetic resin used is a novolak type phenol-formaldehyde resin whose flow distance is 20 to 70 mm, preferably 30 to 50 mm. Below the flow path, the route is to be understood that travels a compressed into tablets sample of a solid phenolic resins ^ on a 60 ° gensigten 12P plate at ⁰ C until cured.

The carbon content of the carbon support must be at least 80%.

Compared to the conventional technologies for the production of carbonaceous, refractory products, the one

Processing temperature of about 150 ⁰ C in the mixing and shaping process require, provides the inventive

Method is a minimization of production costs.

By applying the mixing technology according to the invention and the use of a low-viscosity synthetic resin, an extremely homogeneous molding compound is achieved, which has a positive effect on the one hand on the processing bit as well as on the quality of the end product.

embodiment

The invention will be explained in more detail below with reference to three exemplary embodiments.

I.Beispiel

This example relates to a Verfanren for producing resin-bonded, carbonaceous, refractory molded body with

a residual carbon content of 15%.

The metering and mixing process was carried out at room temperature and is tabulated for the sake of clarity.

Addition of mixing time

1. Medium and coarse fraction of a synthetic magnesite 30 s

2. 80% liquid resin 60s

3. solid carbon carrier 120 s

4. Fine fraction of a synthetic magnesite 180 s

5. 90s powdered synthetic resin

6. Remainder of the liquid synthetic resin 180 s

The middle and coarse fractions of the synthetic magnesite were in the range

0.1 ... 1.0mm, 1.0 ... 3.15mm, 3.15 ... 5.0mm.

The fine component of the synthetic magnesite is in the range of less than 0.1 mm. The liquid resin was a phenol-formaldehyde resin of the resol type whose B time was 2min at 15O ⁰ C.

scam.

The powdered synthetic resin used was a phenol-formaldehyde resin of novolactic acid, the oino flow path of

50mm possessed.

The solid carbon carrier contained 90% carbon. The molding compound produced was molded with a specific molding pressure of 140 MPa into refractory moldings, The refractory moldings were subsequently subjected to a two-stage firing regime in the 1st stage of 4 hours at 9O ⁰ C and

in the 2nd stage of 4 hours at 18O ⁰ C subjected.

Including heating and cooling, the entire curing process was 16 hours. The refractory shaped bodies produced have the following characteristic properties:

MflO content at least 96.5% (determined on annealed substance)

• Bulk density mlnd. 2.85 g / cm ³

Open porosity less than 5%

• Cold pressure strength at least 30 MPa

• rust carbon content min. 15%

2nd example

The example relates to a process for producing resin-bonded, carbon-containing, refractory molded articles with a residual carbon content of 6% based on a mixture of different sintered magnesites. The metering and mixing process was carried out at room temperature and is tabulated for the sake of clarity.

Addition of mixing time

1. Medium and coarse fraction of a sintered magnesite A 20 s

2. 100% liquid synthetic resin 120s

3. solid carbon carrier 120 s

4. Fine fraction of a sintered magnesite B 180 s

5. powdered synthetic resin 180 s

The medium and coarse fractions of the sintered magnesite A were in the range 0.1 ... 1.0 mm and 1.0 ... 3.15 mm. The fine fraction of sintered magnesite B was in the range of less than 0.1 mm. As the liquid resin, a phenol-formaldehyde resin of the resol type was used whose B time was 2 min at 15O ⁰ C. When

powdered synthetic resin, a phenol-formaldehyde resin of Novolaktvps was used, which had a flow distance of 50mm.

The solid carbon support contained 95% carbon. The produced Prebmasse was molded with a specific pressing pressure of 140 MPa to refractory moldings. The refractory moldings were subsequently one .- z 'iistufigen Aushärtregime in the 1 .Stufe of 4 hours at 80 ⁰ C and

in the 2nd stage of 4 hours at 170 ⁰ C subjected.

Including heating and cooling, the entire curing process amounted to 16 hours. The refractory shaped bodies produced have the following characteristic properties:

• MgO content at least 90% (determined on annealed substance)

• Raw density at least 2.90 g / cm ³

• open porosity smaller6%

• Cold pressure strength at least 80 MPa

• residual carbon content at least 6%

3rd example

The example relates to a process for producing Kunsthaizgebundener, carbonaceous, refractory moldings with a Residual carbon content of 10% based on synthetic magnesite and fused magnesite. The metering and mixing process was carried out at room temperature and is tabulated for the sake of clarity. Addition of mixing time

1. Medium and coarse fraction of a sintered magnesite A 20s

2. 100% liquid synthetic resin 120 s

3. solid carbon carrier 120 s

4. Fine fraction of a synthetic magnesite 160 s

5. powdered synthetic resin 150 s

The middle and coarse fractions of fused magnesite were in the range

0.1 ... 1.0mm

1.0., 3.16mm and

3.15 ... 5.0mm

The fine fraction of the synthetic magnosite was in the range of less than 0.1 mm.

The solid carbon support contained 90% carbon.

As a liquid synthetic resin is a phenol-formaldehyde resin dos resol type was used, the B-time was 2 min at 160 ^0C.

As the powdery synthetic resin, a novolak type phenol-formaldehyde resin having a flow distance of 50 mm was used. The molding compound produced was molded with a specific molding pressure of 160 MPu into refractory moldings. The refractory moldings were then subjected to a one-stage Ausharmsgime 6 hours boi 180 ⁰ C below.

Including heating and cooling, the curing process was 14 hours.

The refractory shaped bodies produced have the following characteristic properties:

MgO content (determined on annealed substance) min. 96%

Raw density at least 2.95 g / cm ³

Open porosity less than 4%

Cold pressure strength at least 50 MPa

Residual carbon content at least 10%

The comparison of Ausführungsbeispieie shows that can be prepared by the method resin-bonded, carbonaceous, refractory moldings of different raw material base and combinations with variable Restkchlenstoffgehalten.

Furthermore, this process, except for curing, enjoys the advantage that it can be implemented at room temperature and thus allows working without health-endangering gases and vapors.

Claims (6)

1. A process for the production of resin-bonded, carbonaceous, refractory products based on refractory raw materials, preferably sintered magnesites, synthetic magnesites, fused magnesites, dolomites, MgO-Al ₂ O ₃ spinel, recycled material and combinations of these raw materials, characterized in that 80 ... 100% of a liquid synthetic resin are metered onto the premixed middle and coarse grain fraction of a refractory component and homogeneously mixed, this conglomerate particulate in series a carbon support, a refractory fine component and a powdered synthetic resin is added, the mixture is homogenized after each addition and by addition of the remaining liquid synthetic resin (20... 0%) and subsequent homogeneous mixing, a compressible mass is obtained, the mass produced in the pressing process is pressed into shaped bodies at a specific pressing pressure of 100 MPa or more and the subsequent hardening process a maximum of 20 hours. 2. The method according to item 1, characterized in that the mixing process is carried out at temperatures of at most 30 ⁰ C. 3. The method according to item 1, characterized in that the hardening process of the moldings proceeds in a maximum of two stages, wherein the I.Stufe in the temperature range of 3O ⁰ C to 100 ⁰ C and the second stage in the temperature range of 16O ⁰ C to 200 ⁰ C is. 4. The method according to item 1, characterized in that the curing process of the shaped body takes place in one stage at temperatures of 1SO ⁰ C to 200 ⁰ C. 5. The method according to item 1, characterized in that the liquid resin used is a phenol-formaldehyde resin of Re3oltyp used whose B-time at 150 ⁰ C for a maximum of 2.5 minutes, preferably 1 to 2 minutes, and as a powdered synthetic resin Novolak-type phenol-formaldehyde resin is used whose Fextreckrecko is 20 to 70 mm, preferably 30 to 50 mm. 6. The method according to item 1, characterized in that the solid carbon support contains at least 80% carbon.