by What is calcined coke?
Calcined coke is a highly purified petroleum coke used in the manufacture of graphite electrodes in electric arc furnaces used in steelmaking. It is valued for its ability to maintain its strength at high temperatures required during the steelmaking process. Calcined coke has a very low content of metals like calcium, silicon and sulfur in order to avoid contamination in the electrodes during their use in electric arc furnaces.
Its Unique Properties
Needle Coke derived its name from its physical properties which enables it to be formed into long, thin fibers or “needles”. It has high electrical conductivity and mechanical strength properties to withstand high temperatures in excess of 3000 degrees Celsius without softening or fusing together. These properties allow the electrodes made from calcined coke to efficiently transfer electric current through the steel scraps and provide heating in the furnace for melting.
Calcined coke also has a low coefficient of thermal expansion which prevents the electrodes from cracking or shattering during operation. Additionally, it has low reactivity with oxygen and does not rapidly oxidize or burn off in air. This property increases the longevity of electrodes and reduces replacement costs in steel production.
Usage in Electrodes and Steelmaking
Needle Coke finds its primary application in manufacturing graphite electrodes used in electric arc furnace steelmaking. Around 80% of the world’s steel is produced using electric arc furnaces which requires continuous graphite electrodes to generate the electric arc heat required for melting scrap steel.
The electrodes are hollow cylinders made of calcined coke agglomerated together with coal tar pitch to form a coke paste that is graphitized at high temperatures. They are lowered into the furnace and electric current is passed through them to generate temperatures up to 2000 degrees Celsius. During the process, the electrodes slowly burn off and new electrodes must regularly replace them. Proper physical and chemical properties of calcined coke used in electrodes lead to higher furnace efficiency and productivity.
Role of Needle Coke in Global SteelÂ
With nearly two billion tons of steel produced worldwide annually, the demand for calcined coke from the global steel industry has grown significantly. The unique properties of calcined coke make it irreplaceable in manufacturing electrodes and it accounts for approximately 40% of the input costs of electric arc furnace steelmaking.
Currently, China is the largest steel producer accounting for over 50% of global output. However, domestic calcined coke production is unable to match demand, forcing Chinese steel mills to import the material from other countries like Japan and the United States. Energy security concerns and lack of self-sufficiency in calcined coke prompted Chinese firms to invest heavily in new calcined coke projects both locally and overseas in recent years.
Supply Constraints and Tight Balance
The industry that produces calcined coke is capital intensive in nature with entry barriers due to requisite technical know-how and feedstock availability. Global production is concentrated among just a handful of companies mostly located in the United States, Japan and China. Total world capacity is estimated to be around 1.2 million tons annually against current consumption of 1 million tons.
Tight balance and inelastic supply response to demand growth has led to cyclic spikes in calcined coke prices over the years. Unplanned outages or delays in commissioned projects can severely strain supplies. Geopolitical tensions can also disrupt trade flows and exports to key consuming regions like China. All these factors contribute to calcined coke status as a critical material for the global electric arc furnace steel industry.
Rising global crude steel production driven by expanding economies is one of the key factors underpinning future Needle Coke demand growth. Steel producers are investing billions to modernize older furnaces and expand capacity using the latest electric arc furnace technologies. This transition from basic oxygen furnaces will further raise the proportion of steel manufactured using graphite electrodes.
On the supply side, major producers have announced capacity additions to come online after 2023 which should help address the current tight market conditions. However, uncertainties remain around project schedules and sustainability of supply increases. Ensuring energy and raw material security will remain a key priority for steel producing nations to avoid disruptions in this critical industrial material. calcined coke is poised to retain its importance as the foundation for graphite electrodes and electric arc furnace steelmaking well into the future.
*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it.
