# US 2018/0023004 A1 · Method of producing needle coke for low cte graphite electrodes

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- Number: US 2018/0023004 A1
- Document ID: US20180023004A1
- Status: Published application
- Kind: A1
- Application number: 15/721,926
- Filed: 2017-10-01
- Published: 2018-01-25
- Earliest claimed: 2006-06-29
- Assignees: GrafTech International Holdings Inc.
- Applicants: GrafTech International Holdings Inc.
- Inventors: Douglas J. Miller; Irwin C. Lewis; Ching-Feng Chang; Richard Thomas Lewis
- Web page: https://patentgrep.com/patent/US20180023004A1

## CPC

- C10B 55/00: Coking mineral oils, bitumen, tar, and the like or mixtures thereof with solid carbonaceous material (cracking oils C10G)
- C04B 35/522: {Graphite (C04B35/536 takes precedence)}
- C04B 35/532: containing a carbonisable binder
- C04B 35/6267: {Pyrolysis, carbonisation or auto-combustion reactions}
- C04B 35/83: Carbon fibres in a carbon matrix
- C10B 57/045: {containing mineral oils, bitumen, tar or the like or mixtures thereof}
- C10C 1/04: by distillation
- C10L 9/08: by heat treatments, e.g. calcining
- F27D 11/08: Heating by electric discharge, e.g. arc discharge
- C04B 2235/5248: Carbon, e.g. graphite
- C04B 2235/5276: Whiskers, spindles, needles or pins
- C04B 2235/6021: Extrusion moulding
- C04B 2235/656: characterised by specific heating conditions during heat treatment
- C04B 2235/722: Nitrogen content
- C04B 2235/726: Sulfur content
- C04B 2235/9607: Thermal properties, e.g. thermal expansion coefficient
- C10B: DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS (cracking oils C10G; underground gasification of minerals E21B43/295)
- 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
- C10C: WORKING-UP PITCH, ASPHALT, BITUMEN, TAR; PYROLIGNEOUS ACID (compositions of bituminous materials C08L95/00; carbon filaments by decomposition of organic filaments D01F9/14)
- C10L: FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS
- F27D: DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE

## Abstract

A method of producing low CTE graphite electrodes from needle coke formed from a coal tar distillate material having a relatively high initial boiling point.

## Claims

### Claim 1

A method of creating a low coefficient of thermal expansion graphite electrode, comprising:
(a) heating a needle coke precursor comprising at least 80% coal tar distillate having a boiling point of greater than 280° C. under pressure, thereby converting 60-90% of the coal tar distillate into raw coke;
(b) calcining the raw coke to create low coefficient of thermal expansion needle coke;
(c) milling the needle coke;
(d) mixing the milled needle coke with coal tar binder pitch to create a mix;
(e) extruding the mix to form a green electrode;
(f) baking the green electrode to create a baked electrode; and
(g) graphitizing the baked electrode to create a low coefficient of thermal expansion graphite electrode.

### Claim 2 (depends on 1)

The method of claim 1 wherein the mixing step contains from about 15% by weight to about 35% by weight coal tar binder pitch.

### Claim 3 (depends on 1)

The method of claim 1 wherein the low coefficient of thermal expansion graphite electrode has a coefficient of thermal expansion of from about 0.005 ppm/° C. to about 0.150 ppm/° C.

### Claim 4 (depends on 1)

The method of claim 1 further comprising crushing the raw coke of step (a) prior to the calcining of step (b).

### Claim 5 (depends on 1)

The method of claim 1 wherein the coal tar distillate has a modified Conradson carbon value of at least about 1%.

### Claim 6 (depends on 1)

The method of claim 1 wherein the pressure of step (a) is of from about 20 psig to about 100 psig.

### Claim 7 (depends on 5)

The method of claim 5 wherein the pressure is about 50 psig.

### Claim 8 (depends on 1)

The method of claim 1 further comprising heating the coal tar distillate of step (a) at a rate of from about 35° C. per hour to about 65° C. per hour.

### Claim 9 (depends on 7)

The method of claim 7 further comprising holding the temperature of step (a) for from about 16 hours to about 25 hours.

### Claim 10 (depends on 2)

The method of claim 2 wherein the crushed raw coke of step (b) is calcined to a temperature of from about 1300° C. to about 1500° C.

### Claim 11 (depends on 10)

The method of claim 10 further comprising calcining the coal tar distillate of step (b) at a rate of temperature change of about 300° C. per hour to about 400° C. per hour.

### Claim 12 (depends on 11)

The method of claim 11 further comprising holding the temperature of step (b) for from about 20 minutes to about 40 minutes.

### Claim 13 (depends on 1)

The method of claim 1 further comprising a needle coke yield wherein the yield of needle coke of step (b) is of from about 80% to about 95% of the raw coke.

### Claim 14 (depends on 1)

The method of claim 1 further comprising a final production yield wherein the yield of needle coke of step (b) is of from about 55% to about 85% of the coal tar distillate.

### Claim 15 (depends on 1)

The method of claim 1 wherein the coke precursor is substantially free of crushed coal.

### Claim 16 (depends on 1)

The method of claim 1 wherein the method does not include a hydrogenation step.