Needle Coke: Excellent Technology Urgently Needs Development

By Lei Lijing, Guan Yunnan, Jilin Design Institute of CNPC Northeast Refining & Chemical Engineering Co., Ltd.

Needle coke is a carbonized product of petroleum bitumen or coal pitch. It has good crystallization degree, high mechanical strength, low thermal expansion coefficient and a good graphite property, and electrodes produced from needle coke have low resistivity, heat resistance and oxidation resistance, so needle coke is widely used to produce high power graphite electrodes and ultra high power graphite electrodes in aerospace equipment and steel making equipment.

Product quality needs to be improved

With the rapid development of electric furnace steel-making technology, the requirements on carbon materials are getting higher and higher, and the development and production of needle coke is constantly adapting to the requirements.
Needle coke is divided into oil-series and coal-series, the two different production processes. At present, PetroChina Jinzhou Petrochemical Co., Ltd. has China’s only industrial oil-series needle coke unit, using technology from Sinopec Research Institute of Petroleum Processing. China University of Petroleum has also been dedicated to the development of technology in this sector. In November 2015, technology for the production of high-quality needle coke using poor slurry oil, jointly conducted by SEI, Sinopec Shanghai Petrochemical Co., Ltd., Sinopec Research Institute of Petroleum Processing and Refining and Marketing Company was achieved.
The coal-series needle coke production and R&D enterprises mainly include Shanxi Hongte Coal Chemical Co., Ltd., Sinosteel Anshan Research Institute of Thermo-Energy Co., Ltd., Chemical Company of Baoshan Iron & Steel Co., Ltd., Shanxi Shuozhou Sanyuan Carbon Co., Ltd. and Shandong Minsheng Coal Chemical Company (formerly Shandong Yankuang Kelan Coal Tar Company). These production enterprises use process technology that is divided into three steps – pretreatment of raw material, delayed coking and sintering – however, the product quality needs to be improved.

Consumption is hoped to increase

In 2015, China’s total capacity to make needle coke reached 320 kt/a – coal-series needle coke capacity was 280 kt/a. Major coal-series needle coke producers were Shanxi Hongte Coal Chemical Co., Ltd., Sinosteel Anshan Research Institute of Thermo-Energy Co., Ltd. and Jiangsu C-Chem Company. PetroChina Jinzhou Petrochemical Co., Ltd. was China’s only oil-series needle coke producer with a capacity of 40 kt/a. Jiangsu C-Chem Company, a joint venture between Nippon Steel of Japan and Koppers of the United States, conducted trial production in August 2015. China’s major needle coke producers in 2015 are listed in Table 1.
Due to the small number of domestic needle coke producers, the downturn of iron and the steel industry downstream and the slowdown of demand growth, the domestic operating rate of needle coke was lower in 2015. In the first 10 months, output of needle coke reached 131 kt, the net import volume was 43 kt and the apparent consumption reached 174 kt. In the same 10 months, import volume of oil-series needle coke and coal-series needle coke reached 34 kt and 18 kt, respectively, and the export volume of needle coke was 9 kt.
In China, needle coke is mainly used to produce high power graphite electrodes and ultra high power graphite electrodes for electric furnace steel. The production of these electrodes is concentrated mainly in a few super-large graphite electrode enterprises. In the first 10 months of 2015, China’s total output of graphite electrodes reached 411 kt, including 153 kt of high power graphite electrodes and 137 kt of ultra high power graphite electrodes, and the consumption of needle coke reached 174 kt.
In developed countries, the output of electric furnace steel accounts for around 30%-40% of the total crude steel output, while the proportion of domestic electric furnace steel is less than 10%, and due to the decline of the domestic iron and steel industry, consumption of needle coke has decreased year-on-year in recent years. The domestic output of steel will not grow much; however, the steel-making technology and the adjustment of product portfolios still has great development space, especially electric furnace steel. It is expected that by 2025, China’s proportion of electric furnace steel among all steel produced will approach the world average level, and the consumption of needle coke will increase commensurately.

Table 1   China’s major needle coke producers in 2015

Producer    Product variety    Capacity
(kt/a)
Shanxi Hongte Coal Chemical Co., Ltd.    Coal-series needle coke    150
Jiangsu C-Chem Company    Coal-series needle coke    60
Sinosteel Anshan Research Institute of Thermo-Energy Co., Ltd.    Coal-series needle coke    40
Chemical Company of Baoshan?Iron &?Steel?Co., Ltd.    Coal-series needle coke    20
Shijiazhuang Deli Chemical Co., Ltd.    Coal-series needle coke    10
PetroChina Jinzhou Petrochemical Co., Ltd.    Oil-series needle coke    40
Total        320



Oil-series needle coke becomes an investment focus

At present, China cannot produce high-quality joint needle coke that is used in the production of graphite electrode joints.
China’s portfolio of needle coke products has been seriously out of balance. Coal-series needle coke is dominant in the production of needle coke. However, a voluminous by-products of the production of coal-series needle coke are difficult to deal with, so the operating rate is generally lower. The quality of oil-series needle coke is superior to that of coal-series needle coke. Because its component is suitable for the preparation of large ultra high power graphite electrode products, oil-series needle coke has become the development focus of graphite electrode sector. Oil-series needle coke will gradually replace coal-series needle coke to become an investment focus.