Needle Coke is a rare petroleum coke that can be processed into a highly crystalline and pure carbon material using the delayed coking process. It is needle-like in appearance, hence the name. calcined coke is used predominantly in the production of graphite electrodes that are essential for steel, silicon and aluminum smelting in electric arc furnaces. Other key characteristics of calcined coke include its low electrical resistivity and high tensile strength, which are crucial for its role as a raw material in graphite electrodes.
Uses of calcined coke
Needle Coke finds its major application as a raw material in the manufacture of ultra-high power graphite electrodes that are extensively used in electric arc furnaces for steel making. Graphite electrodes must be highly conductive to efficiently transfer electric current into the melt. They also need to maintain their shape and strength at very high temperatures exceeding 3000°C. Only calcined coke has the unique properties to satisfy these stringent requirements of graphite electrodes.
Calcined coke derived graphite electrodes are also used in smelting of other metals like silicon and aluminum through the electric arc furnace route. The widespread adoption of electric arc furnaces instead of traditional fuel fired furnaces has significantly reduced greenhouse gas emissions from metal production industries over the past few decades. Continuous innovations to develop longer life graphite electrodes from superior grades of calcined coke will further help reduce environmental pollution.
Production and Refining of Needle Coke
Petroleum-based coke called sponge coke is used as the raw material for calcined coke production. In the delayed coking process, long chain alkyl aromatic hydrocarbons in the heavy residual oils undergo thermal cracking at high temperatures above 400°C in the absence of oxygen. This results in the deposition of a coke product with varying structure within the coking drums.
The coke deposited within the first few hours has a more random structure and less ordered arrangement of aromatic hydrocarbons. It makes conventional sponge coke. But the coke deposited towards the end of the coking cycle has a highly oriented molecular structure due to prolonged exposure to heat. This fraction, called needle coke, has the required properties for its usage as anode grade coke. Additional refining steps like calcination are carried out to enhance the crystallinity and purity levels of needle coke.
Needle Coke Manufacturers and Production Capacity
The global calcined coke production is estimated to be around 1.2 million tons per year currently. Due to the specific application requirements, only a few manufacturers globally possess the technology for calcined coke production. Major players in the global calcined coke market space include Indian Oil Corporation Limited (India), CNPC Jinzhou Petrochemical Co., Ltd. (China), Mitsubishi Chemical Corporation (Japan), Bao-steel Group (China), C-Chem Co., Ltd. (South Korea), Seadrift Coke L.P. (US), Shandong Yida New Material Co., Ltd. (China), Shanxi Hongte Coal Chemical Industry Co., Ltd (China), Sinosteel Anshan Research Institute of Thermo-Energy Co., Ltd. (China) etc.
Among them, Chinese producers dominate the current calcined coke manufacturing capacities with around 60% share of global capacity. However, Indian producers are fast expanding and investing in new calcined coke plants to cater to the rising domestic graphite electrode demand as well as export markets. Between 2015–20, global calcined coke capacity is projected to increase from 1.2 million tons to around 1.7 million tons to match the growing steel production through electric arc furnaces worldwide. New plants are coming up in the Middle East, India and Brazil as well to ensure energy security for these economies.
Future of Needle Coke Industry
Graphite electrodes derived from calcined coke have played a pivotal role in transitioning the steel industry from less energy efficient fuel fired furnaces to modern electric arc furnaces. This shift has led to enormous reductions in greenhouse gas emissions, helping the world progress towards climate change mitigation goals. Despite facing challenges from substitutes like carbon foam in certain niche applications, graphite electrodes are expected to continue dominating steel production in the foreseeable future.
With higher electric arc furnace steel capacity additions planned in emerging steel hubs of Asia and Africa, the calcined coke market demand is projected to grow steadily at 2-3% annually over the next decade. Sustained use of electric vehicles will further boost the demand for graphite electrodes from aluminum smelters. Innovation in graphite electrode technology including longer life and larger diameter grades requires continual improvements in calcined coke quality. Supply security and adequate availability of calcined coke matching stringent quality norms will thus be crucial to support the next phase of growth in green steel manufacturing worldwide.
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1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it.