At present, the industry has basically formed a consensus, China's iron and steel industry in the carbon peak, carbon neutral process, BF - converter long process and electric furnace short process in the first half of the role and carbon reduction contribution is different, the first half of the carbon peak depends on the long process, the second half of the carbon neutral depends on the scientific and orderly development of the short process.

On August 25, the "Iron and Steel Industry steady growth work Plan" (hereinafter referred to as the "Plan") issued by the Ministry of Industry and Information Technology and other seven departments also highlighted the importance of the short process of electric furnace, especially the whole scrap electric furnace process. The "Plan" proposes to accelerate the implementation of the high-quality development of electric furnace short process steelmaking project, implement differentiated capacity replacement, environmental management and other policies for all scrap electric furnace steelmaking projects, and create the world's advanced electric furnace steel industrial cluster

"The development of all scrap electric furnace short process can simplify the production process, achieve energy saving and emission reduction, is an important way to achieve decarbonization in the steel industry, but also the trend of high-quality development." On September 11, Yin Ruiyu, academician of the Chinese Academy of Engineering, shared his thoughts on promoting the whole scrap electric furnace process in an exclusive interview with the reporter of China Metallurgical News.

He analyzed that China will increasingly have the conditions for the development of the whole scrap furnace process, it is expected that around 2045 the amount of scrap steel will exceed 400 million tons/year, and some years can even reach 500 million tons, at the same time, the proportion of non-fossil energy applications will gradually expand, rich power resources, cost reduction.

According to incomplete statistics, there are more than 250 short process electric furnace enterprises in China, of which nearly 200 are all scrap electric furnace process enterprises. There are many, but the development of all scrap electric furnace process still faces many practical challenges.

From the economic point of view, the electric furnace used for the production of wire and profiles is appropriate to about 70 tons

Yin Ruiyu told the "China Metallurgical News" reporter that the short process of the electric furnace includes four main processes of steelmaking, refining, continuous casting and steel rolling, and the processes rely on different interface technologies to connect and match, forming a complete steel production process.

"From a process point of view, the tonnage of the furnace depends on the capacity of the mill, which in turn varies according to the type of steel produced and its market capacity." Yin Ruiyu stressed, "In the metallurgical process, the ability of each process equipment is the best only if it matches each other."

He explained in detail that in the whole scrap electric furnace process, the capacity of the rolling mill used to produce different steel products and the tonnage of the electric furnace are different, and there are generally the following categories:

First, the production of long materials and steel for construction around the city. The production capacity of rolling mills used in different construction steel production plants is different. The production capacity of rolling mills for producing rebar is about 1 million tons, and the suitable electric furnace capacity is 100 tons to 120 tons. The production capacity of the high line mill is 600,000 tons to 700,000 tons, and the appropriate electric furnace capacity is about 70 tons; The production capacity of the rolling mill is 500,000 tons to 700,000 tons, and the suitable electric furnace capacity is about 70 tons.

The second is the production of alloy steel long materials. Generally, the annual output level of a single operation line (diameter 16 mm to diameter 90 mm rods) is 600,000 tons to 700,000 tons, and the appropriate electric furnace capacity is 70 tons to 100 tons.

Third, it is combined with thin slab continuous casting and continuous rolling to produce hot rolled coil or pickling plate. The general annual output of 1.8 million tons to 2 million tons, usually with 2 electric furnace production, the appropriate electric furnace capacity of 100 tons to 150 tons.

Fourth, the production of ordinary medium and thick plates. Yin Ruiyu said that the rolling mill and electric furnace equipment used in the production of medium and thick plates are closely related to the width of the plates, so it is not easy to generalize.

"From the economic point of view, the production of rebar and thin slab continuous casting - continuous rolling products, the furnace tonnage should not be less than 100 tons, and the production of wire, profiles used in the furnace to about 70 tons is appropriate." Yin Ruiyu summarized and pointed out that combined with international experience, the entry point of China's development of all scrap electric furnace process should be based on rebar and wire production plants, replacing small and medium blast furnace - converter process to produce rod and wire products.

Yin Ruiyu pointed out in particular: "Starting from 100 tons will affect the entry threshold of the development of the whole scrap electric furnace process to some extent, which is not conducive to the promotion of the whole scrap electric furnace process in different regions according to local conditions." At the same time, from the perspective of process structure, the ability matching between the electric furnace - refining - casting machine - rolling mill is very important, and the 70-ton electric furnace is more reasonable to match the high line rolling mill, which is convenient for the whole process to cooperate and the casting billet high temperature hot charging, which is conducive to energy saving, emission reduction and carbon reduction, otherwise some cold billets will fall."

The electric furnace is not the bigger the more advanced, the process ability to connect and match is crucial

Yin Ruiyu repeatedly stressed: "Electric furnace is not the bigger the more advanced, the process ability to match is crucial."

In recent years, large-scale transformation of main equipment has become a trend in the steel industry. According to incomplete statistics, the average furnace capacity of blast furnaces in China has increased from 770 cubic meters in 2015 to more than 1,400 cubic meters in 2021; Since the implementation of the "Implementation Measures for Capacity Replacement of the Steel Industry" on June 1, 2021 to the end of July 2023, a total of 66 electric furnace steelmaking equipment have been built, new or to be built in China, with an average nominal capacity of 97.4 tons/seat, close to 100 tons/seat, which indicates that China's electric furnace steelmaking equipment is rapidly advancing on the road to large-scale development.

"Large-scale is not the only indicator to evaluate whether the electric furnace steelmaking technology is advanced, there are many more important dimensions, there are several key technologies of electric furnace steelmaking should be concerned about and promoted by the industry and enterprises." Yin Ruiyu reminded. These technologies include no cover, scrap preheating continuous feeding, flat melting pool smelting, eccentric furnace bottom steel, multi-furnace continuous pouring, etc., can effectively reduce energy consumption, so it should become the future development direction of enterprises. Yin Ruiyu took the scrap preheating continuous charging process as an example: "Compared with the electric furnace using traditional technology or other technology, because the scrap preheating continuous charging process does not need to open the furnace cover, not only saves the basket charging time, but also avoids the radiation loss caused by the exposure of the molten steel pool to the air environment, reduces the power consumption, and reduces the power time."

Yin Ruiyu also pointed out: "From the current domestic electric furnace operation indicators, the technical and economic indicators of about 70 tons of electric furnaces are not worse than 100 tons of electric furnaces." If 100 tons is used as the limit threshold, it will cause some steel mills to expand and increase production."

Research data show that the average smelting cycle of 70 tons to 80 tons horizontal preheating continuous charging electric furnace is about 32 minutes, the average daily output of 45 furnace steel under full load production, the average smelting power consumption is 335 KWH/ton of molten steel, and the electrode consumption is 0.75 kg/ton of molten steel. The average smelting cycle of 100 tons to 120 tons of electric furnace equipment is about 36 minutes, the average daily output of 40 furnace steel under full load production, the average smelting power consumption is 355 KWH/ton of molten steel, and the electrode consumption is 0.8 kg/ton of molten steel.

"On the whole, the 70 tons to 80 tons of electric furnace process (scrap smelting) energy consumption is not high, the smelting cycle is short, and from the perspective of realistic realization of steelmaking - continuous casting - wire rod, steel mill and other processes reasonable connection and matching, the furnace capacity of 70 tons to 80 tons is reasonable." Yin Ruiyu pointed out.

Research data show that at present, the average furnace capacity of China's electric furnaces is only 68 tons, the proportion of limited equipment is relatively high, and the number of electric furnaces below 100 tons accounts for 79%. "At present, domestic electric furnaces below 100 tons are mainstream equipment, and if enterprises implement capacity expansion and transformation under the guidance of policies, taking into account the scarcity of indicators, it is easy to cause expansion risks, resulting in an increase in actual production capacity and energy consumption and emissions, which is not conducive to low-carbon development." Yin Ruiyu pointed out.

In addition, he said that from the perspective of mechanical equipment level and electronic control level, the 70-ton electric furnace has a high degree of localization, and the average level of production indicators is better than that of imported electric furnaces, which is conducive to reducing investment and promoting the development of domestic equipment manufacturing industry.

Finally, Yin Ruiyu said that the above views are personal opinions and are only for the reference of relevant parties.