# US 7,744,811 B2 · Furnace expansion joint with compressible graphite joint filler and manufacturing method

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- Number: US 7,744,811 B2
- Document ID: US7744811B2
- Status: Granted
- Kind: B2
- Application number: 11/825,080
- Filed: 2007-07-02
- Published: 2007-11-22
- Granted: 2010-06-29
- Earliest claimed: 2004-12-30
- Assignees: Sgl Carbon SE
- Inventors: Jörg Mittag; Oswin Öttinger
- Web page: https://patentgrep.com/patent/US7744811B2

## CPC

- C21B 7/06: Linings for furnaces
- C04B 37/006: {consisting of metals or metal salts}
- C04B 37/008: {by means of an interlayer consisting of an organic adhesive, e.g. phenol resin or pitch}
- C04B 2237/086: Carbon interlayers
- C21B: MANUFACTURE OF IRON OR STEEL (preliminary treatment of ferrous ores or scrap C22B1/00)
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE

## Abstract

Expansion joints located in the upper part of the hearth walls of a reduction furnace are filled with a plate-shaped compressible graphite filler having a density of 0.1 to 0.2 g/cm3. A method of manufacturing such a joint filler is also provided.

## Claims

### Claim 1

An expansion joint located in an upper part of hearth walls of a reduction furnace, the expansion joint consisting of:
two lining blocks forming two horizontal gaps each having a height of 25 to 45 mm and a vertical seamless joint therebetween; and
a plate-shaped compressible graphite filler having a density of 0.1 to 0.2 g/cm3 obtained by compacting expanded graphite precursor material, said filler filling said horizontal gaps.

### Claim 2 (depends on 1)

The expansion joint according to claim 1, wherein said compressible graphite filler includes a stack of up to five plates having a thickness of 0.5 to 1.5 cm.

### Claim 3 (depends on 2)

The expansion joint according to claim 2, wherein said compressible graphite filler stack is cut to a required size and glued together by suitable high-temperature glues.

### Claim 4 (depends on 3)

The expansion joint according to claim 3, wherein said high-temperature glues are phenolic resin.

### Claim 5 (depends on 1)

A method of assembling an expansion joint, the method consisting of the following steps:
gluing the compressible graphite filler according to claim 1 to the respective lining blocks with suitable high-temperature glues; and
subsequently forming the expansion joint with the lining blocks.

### Claim 6 (depends on 5)

The method according to claim 5, wherein the high-temperature glues are phenolic resin.

### Claim 7 (depends on 1)

A method of manufacturing a compressible graphite filler, the method consisting of the following steps:
compacting a conventional expanded graphite precursor material having a density of 2 to 7 mg/cm3 to a desired density, by at least one of pressing in a conventional press or calandering; and
trimming to final dimensions following the compacting step to form the compressible graphite filler according to claim 1.

### Claim 8 (depends on 7)

The method of manufacturing a compressible graphite filler according to claim 7, which further comprises implementing reinforcing carbon fibers or carbon fiber non-woven or woven mats into the conventional expanded graphite precursor material before compressing.

### Claim 9 (depends on 7)

The method of manufacturing a compressible graphite filler according to claim 7, which further comprises further treating the graphite filler with oxidation retarding agents.

### Claim 10 (depends on 8)

The method of manufacturing a compressible graphite filler according to claim 8, which further comprises further treating the graphite filler with oxidation retarding agents.

### Claim 11 (depends on 7)

The method of manufacturing a compressible graphite filler according to claim 7, which further comprises further treating the expanded graphite precursor material with polyphosphoric acid before compressing.

### Claim 12 (depends on 8)

The method of manufacturing a compressible graphite filler according to claim 8, which further comprises further treating the expanded graphite precursor material with polyphosphoric acid before compressing.