500mm Graphite Electrodes

 

Petroleum coke/Needle coke: Premium low-sulfur, low-ash coke as aggregate

Coal tar pitch: Medium-temperature or modified pitch as binder (softening point 80-90℃)

Additives: Optional graphite scraps or anti-oxidants

Key Controls:: Ash content ≤0.5%; Volatile matter 8-12%; True density ≥2.10g/cm³

 

 

Multi-stage crushing process: Primary crushing (50-80mm) via jaw crusher

Secondary crushing (10-20mm) via roller crusher

Fine grinding (0.075-0.5mm/200 mesh) via ball mill

Screening System: Vibrating screens (4-6 particle size grades)

Optimized aggregate/fine powder ratio (3:7~4:6)

 

Process Flow: Dry mixing: Preheat aggregates at 150-180℃ for 2-3 hours

Wet mixing: Add liquid pitch (180-200℃), knead for 40-60 mins

Cooling: Cool to 110-130℃ before forming

Forming Methods: Extrusion (vertical/horizontal ramming)

Vibration forming (for large electrodes)

Molding (special shapes)

 

 

Temperature Profile: Room temp→300℃ (5-7 days, volatile removal)

300→800℃ (3-5 days, binder coking)

800→1200℃ (2-3 days, pre-graphitization)

Key Parameters: Baking cycle: 25-35 days

Peak temperature: 1100-1250℃

Packing material: Metallurgical coke (anti-oxidation)

 

 

(High-density electrodes require 2-3 cycles)

Preheating: 200-300℃ under vacuum (≤10kPa)

Pressure impregnation: 0.5-1.5MPa for 2-4 hours

Re-baking: Follow baking process

Weight Gain: 1st impregnation: 8-12%

2nd impregnation: 5-8%

 

 

Acheson Furnace Process

Loading capacity: 50-80 tons/furnace

Heating curve: 0-24h: Slow ramp to 800℃

24-72h: Rapid heating to 2600-2800℃

Soaking: 12-24 hours

Cooling cycle: 7-10 days

Quality Controls:

Post-graphitization resistivity ≤6.5μΩ·m

Temperature uniformity ±50℃

 

 

Processing Steps: Turning: Diameter tolerance ±1mm

Threading: ISO/NPT standards (pitch 8-12mm)

End finishing: Flatness ≤0.1mm/m

Surface treatment: Optional anti-oxidation coating

Precision Standards:

Straightness ≤1mm/m

Concentricity ≤0.5mm

Thread clearance ≤0.2mm

 

 

Test Items: Physical properties: Density, resistivity, flexural strength

Dimensional inspection: CMM verification

Ultrasonic testing: Internal defect detection

Joint test: Torque resistance ≥3000N·m

Certifications:

Complies with GB/T 3072-2018

ISO 9001 certified

 

 

Moisture-proof: PE film + desiccants

Transportation: Dedicated steel frames

Storage: Humidity ≤60%, max 3-layer stacking

Process Highlights:

"Low-Temperature Prolonged Baking" minimizes cracks

Multi-grade particle optimization enhances density

Precise graphitization ensures uniform properties

Full-process MES traceability

(HP/UHP grades available per customer requirements)