Introduction to semi-coke and Its Industry Chain

Semi-coke is produced from high-quality Jurassic coal blocks abundant in the Shenfu (Shenmu + Fugu) coalfield. As a new type of carbon material, it is widely used in various fields such as calcium carbide, ferroalloys, blast furnace injection, boiler fuel, civilian fuel, and industrial gas production.

The production of semi-coke primarily relies on low-temperature carbonization, with the carbonization temperature generally controlled between 600℃ and 750℃. During the production process of semi-coke, by-products such as coal gas and coal tar are also generated.

The production capacity of semi-coke in China is mainly distributed in Shaanxi, Xinjiang, Inner Mongolia, Ningxia, and Hebei. Among these, Shaanxi (with a production capacity share of approximately 48%) and Xinjiang (with a production capacity share of approximately 37.5%) are the two regions with the largest production capacity of semi-coke in China. In Shaanxi, the capacity is mainly concentrated in the Shenmu (approximately 27% of production capacity) and Fugu areas (approximately 19% of production capacity). In Xinjiang, the capacity is mainly concentrated in the Hami area (approximately 20% of production capacity).

Calcium carbide is the largest consumption field for semi-coke; semi-coke is primarily used in the smelting of ferrosilicon in ferroalloy production; as a new type of blast furnace injection fuel, semi-coke is considered a potential area for significant future consumption growth in the field of blast furnace injection, replacing traditional injection coal.

Introduction to Semi-coke and Its Industry Chain

Semi-coke, also known as semi-coke, is produced from high-quality Jurassic coal blocks abundant in the Shenfu (Shenmu + Fugu) coalfield. As a new type of carbon material, it is widely used in various fields such as calcium carbide, ferroalloys, blast furnace injection, and industrial gas production due to its characteristics of high fixed carbon, high resistivity, high chemical activity, low ash content, low aluminum, low sulfur, and low phosphorus, making it an irreplaceable carbon material.

The structure of semi-coke is blocky, with a particle size generally between 0-80mm, and its color is light black. Depending on the particle size, semi-coke can be classified into large material (>40mm), medium material (18-40mm), small material (8-18mm), and coke dust (<8mm).

Production Process of Semi-coke

The production of semi-coke primarily relies on low-temperature dry distillation (the process of coal pyrolysis under conditions of air isolation at low temperatures), with the dry distillation temperature generally controlled between 600℃ and 750℃. During the production of semi-coke, by-products such as coal gas and coal tar are also generated. The main types of coal used for producing semi-coke include long flame coal, non-caking coal, and weakly caking coal, which are non-caking or weakly caking coals with medium to high volatile matter content.

Introduction to semi-coke and its industrial chain

Traditional semi-coke furnaces include external heating and internal heating types. The external heating type uses a fire channel heating method for dry distillation, which has a complex furnace design, low thermal efficiency, and an investment cost approximately three times that of the internal heating type. The internal heating semi-coke furnaces are mainly the upright three-section type developed by Anshan Thermal Energy Institute, Shaanxi Metallurgical Design Institute, and Shenmu Sanjiang, among which the SJ-V type semi-coke furnace developed by Shenmu Sanjiang has a single furnace capacity of 200,000 tons per year, with a lower limit of raw coal particle size reaching 3mm. (China Ferroalloy Network "Analysis of the Current Situation and High-Quality Development of the Yulin Semi-coke Industry")

Currently, the main type of semi-coke furnace used in the market is the upright three-section type (internal heating), primarily the SJ low-temperature dry distillation furnace. The semi-coke facility mainly consists of sections for coal preparation, carbonization, screening and transportation, and coal gas purification.

As of 2021, the annual production capacity of semi-coke in China is approximately 131 million tons, with the capacity primarily distributed in the regions of Shaanxi, Xinjiang, Inner Mongolia, Ningxia, and Hebei. Among these, Shaanxi (with a capacity share of about 48%) and Xinjiang (with a capacity share of about 37.5%) are the two regions with the largest production capacity of semi-coke in the country. The capacity in Shaanxi is mainly concentrated in the regions of Shenmu (with a capacity share of about 27%) and Fugu (with a capacity share of about 19%). In Xinjiang, the capacity is mainly concentrated in the Hami region (with a capacity share of about 20%).

The main production areas of semi-coke in China, namely Yulin in Shaanxi and Hami in Xinjiang, utilize long flame coal as their raw material. However, due to the unique differences in coal quality and variations in pyrolysis processes, there are significant differences in the quality of semi-coke products.

The main characteristics of semi-coke products from Yulin are: 1) a high comprehensive yield of oil and gas, with 1 ton of raw coal yielding approximately 0.6 tons of semi-coke, along with by-products of 0.06 tons of coal tar and 600 m³ of coal gas; 2) excellent product quality, with good particle size, suitable mechanical properties, a fixed carbon content exceeding 80%, and superior reduction performance. Yulin semi-coke also exhibits high chemical reactivity, very low ash content, and very low sulfur content, making it suitable for fields such as ferroalloys, calcium carbide, and chemicals, and it meets the current production process requirements of the metallurgical industry. It has already been exported to countries such as Russia and Japan.

The main characteristics of semi-coke products from Hami are: 1) a high yield of oil and gas, with 1 ton of coal yielding approximately 0.5 tons of semi-coke, along with by-products of 0.1 tons of coal tar and 900 m³ of coal gas; 2) relatively poor product quality, with higher ash content and a higher powder rate, where the ≤6mm coke foam exceeds 70%. It is primarily used as thermal coal for combustion, with only a small amount of lump semi-coke mixed with coke being used for the production of calcium carbide and ferroalloys.

Introduction to the Semi-coke Industry Chain

At the raw material end, Semi-coke primarily uses raw coal (long flame coal, non-caking coal, weak caking coal, etc.) for production, with an average consumption of 1.6-1.7 tons of raw coal required to produce 1 ton of Semi-coke. Additionally, by-products such as coal tar and coal gas can be obtained (approximately 0.1-0.16 tons of coal tar and around 900-1500 m³ of coal gas).

At the end-user consumption side, Semi-coke is widely applied in various fields including calcium carbide production, ferroalloy smelting, blast furnace injection (as a substitute for anthracite), boiler fuel, civilian fuel, and industrial gas production.

Among these, calcium carbide (calcium carbide, an important basic chemical raw material, mainly used for producing acetylene gas, and also for organic synthesis, oxy-acetylene welding, etc.) is the largest consumption area for Semi-coke downstream, with an average consumption of about 0.85 tons of Semi-coke required to produce 1 ton of calcium carbide. In 2021, China's calcium carbide production totaled approximately 13.922 million tons, equivalent to a consumption of about 11.83 million tons of Semi-coke, accounting for 22.3% of the total Semi-coke production in 2021. According to MYSTEEL data, as of 2022, China's calcium carbide production capacity was approximately 40.145 million tons, an increase of 1.645 million tons compared to 2021.

Furthermore, Semi-coke is primarily used in the smelting of ferrosilicon in ferroalloy smelting (Note: China's metallurgical standards (YB/T034-92) specify the technical requirements for ferroalloy coke, requiring particle sizes of 2-8mm, 8-20mm, and 8-25mm. Therefore, the Semi-coke used for smelting ferrosilicon is Semi-coke small material), with an average consumption of about 11.5-12 tons of Semi-coke required for each ton of ferrosilicon. According to ferroalloy online data, in 2021, China's ferrosilicon production totaled approximately 8.56 million tons, equivalent to a consumption of about 6.74 million tons of Semi-coke, accounting for 12.7% of the total Semi-coke production in 2021. As of 2021, China's ferrosilicon production capacity was approximately 10.2 million tons.

Finally, as a new type of blast furnace injection fuel, Semi-coke is considered a potential area for significant future consumption growth in the field of blast furnace injection, replacing traditional injection coal. With a national pig iron production of approximately 870 million tons in 2021 and an injection coal ratio of 145 kg/t (the average level of key steel enterprises nationwide), it is estimated that about 126 million tons of injection coal is needed annually in China. If Semi-coke replaces 30% of the injection coal, approximately 37.8 million tons of Semi-coke would be required, representing a vast consumption area. Currently, research and experimental analysis on the use of Semi-coke for blast furnace injection have been conducted by companies such as Shougang Group, Panzhihua Steel, Jiugang, Ansteel, Baosteel, and Xinxing Ductile Iron Pipes.

The by-products generated in the Semi-coke production process (low-temperature dry distillation), coal gas and coal tar, can also be fully utilized: