What is graphitized petroleum coke?

Graphitized Petroleum Coke: A High-Performance Carbon Material Derived from Petroleum Coke

Graphitized petroleum coke is a carbon material produced by subjecting petroleum coke to high-temperature graphitization treatment (typically 2,800°C–3,000°C). Its core feature lies in the high-temperature-induced reorganization of carbon atoms in petroleum coke into a layered crystalline structure closer to natural graphite, significantly enhancing its physical and chemical properties. Below is a detailed analysis:

I. Core Characteristics: Performance Enhancement via Graphitization

1. High Carbon Content & Low Impurities
   • Carbon content exceeds 98%, sulfur content as low as <0.05%, with ash and volatile matter significantly lower than ordinary petroleum coke. This high purity makes it ideal for metallurgy, chemicals, and other industries.
2. Excellent Electrical & Thermal Conductivity
   • Graphitization creates a regular layered structure, reducing electron migration resistance. Resistivity drops to 5–7 μΩ·m (vs. 8–12 μΩ·m for ordinary coke), approaching the conductivity of natural graphite.
3. High Thermal Stability & Chemical Inertness
   • Maintains structural stability at elevated temperatures (e.g., >1,600°C in steel-making electric furnaces) and resists reactions with acids/alkalis. Suitable for refractory materials and high-temperature reactors.
4. High Absorption Rate & Low Coefficient of Thermal Expansion (CTE)
   • Porous structure (30–50% porosity) and low CTE (~1.5–2.5×10⁻⁶/°C) excel in applications like carburizers and lubricants.

II. Production Process: Key Steps in High-Temperature Graphitization

1. Raw Material Pretreatment
   • Select low-sulfur, low-ash premium petroleum coke (e.g., needle coke or sponge coke from delayed coking). Crush, screen, and homogenize particle size (e.g., 0–1 mm, 1–3 mm).
2. High-Temperature Graphitization
   • Traditional Acheson Furnace Method: Mix petroleum coke with graphitizing agents (e.g., quartz sand) and heat to 2,800–3,000°C in a resistance furnace for 20–50 hours. High energy consumption (6,000–8,000 kWh/ton) but mature equipment.
   • Modern Continuous Furnace Method: Use inert gas (N₂/Ar)-protected vertical or rotary tube furnaces for faster heating/cooling (cycle time: 24–48 hours). Energy consumption reduced to 3,500 kWh/ton, with higher purity (ash <0.1%).
3. Post-Processing
   • Cool, crush, and screen graphitized coke. Apply surface coatings (e.g., pitch) or chemical vapor deposition (CVD) to enhance performance per customer requirements.

III. Applications: A “Versatile Material” for Metallurgy & Chemicals

1. Metallurgical Industry
   • Graphite Electrodes: Core material for electric furnace steel-making, withstanding high temperatures and currents to improve efficiency.
   • Carburizer: Rapidly elevates carbon content (>90% absorption) in ductile/gray iron casting while reducing sulfur (<0.05%) to enhance casting quality.
   • Refractory Materials: Used in carbon bricks or ramming mixes for high-temperature furnace linings to extend service life.
2. Chemical Industry
   • Silicon Carbide Production: Acts as a carbon source reacting with SiO₂ to produce high-hardness, wear-resistant silicon carbide abrasives.
   • Battery Materials: Nano-sized graphitized coke improves lithium-ion battery anode charge/discharge performance.
3. Other Applications
   • Lubricants: Layered structure and low friction coefficient enable use as solid lubricants in machinery.
   • Plastic/Rubber Additives: Enhances conductivity or antistatic properties.

IV. Comparison with Ordinary Petroleum Coke

V. Market Value & Trends

Driven by the growth of electric furnace steel-making and new-energy vehicles, demand for graphitized petroleum coke continues to rise. Modern continuous furnace technology reduces production costs by 40–50% compared to traditional methods, enabling expansion into mid-tier applications. Future advancements, such as hydrogen reduction and microwave heating, promise greener, more efficient production processes.