Electric Furnace Steelmaking Technology

author: Anna

2024-06-28

Electric Furnace Steelmaking Technology

New Generation Electric Furnace Steelmaking Technology Goals

Focusing on the goals of efficient production, simplified functions, environmental friendliness, intelligent control, and diversified raw materials, electric furnace steelmaking technology continues to develop. The goal pursued for high efficiency of electric furnace smelting is to shorten the smelting cycle and power-on time as much as possible and reduce the consumption of smelting electricity.

Efficient Electric Furnace Smelting

We Should Work Around the Following 6 Aspects to Achive Efficient Electric Furnace Smelting:

The method of increasing the input electric power per ton of steel is technically manifested in the enlargement and higher power of the equipment;
Increase the chemical heat of oxidation of elements in steel and the chemical heat provided by oxygen burners; increase the sensible heat of scrap steel after preheating by scrap steel;
Improve electrical efficiency and power factor, such as rationalizing the power supply system, adopting intelligent electric arc furnaces, optimizing the short network structure, etc.;
Shorten thermal shutdown time, such as scrap loading time, electrode connection time, steel tapping time, furnace repair time, etc.;
It is more efficient to organize the production of a single variety of the entire production line than to organize production of multiple varieties.
Choose an advanced furnace type to achieve the goals of full scrap preheating, continuous feeding, no lid opening, flat molten pool, low noise, less smoke, trace amounts of dioxin, dust removal ash recovery, etc.

The Development Process of Electric Furnace Steelmaking Technology

In the process of technological development, electric furnaces have experienced traditional open-cover electric furnaces, Fuchs electric furnaces (vertical preheating scrap steel), Consteel electric furnaces (horizontal continuous feeding), Quantum electric furnaces (quantum electric furnaces), Ecoarc electric furnaces (environmental protection and ecological electric arc furnaces), Sharc electric furnace (shaft electric arc furnace), CISDI-Green electric furnace (Saidi green intelligent electric furnace), CERI-s1-Arc electric furnace (MCC Jingcheng's new scrap steel preheating electric furnace) and other different types of developments.

Advantages and Disadvantages of Traditional Conventional Open-top Electric Furnaces

The Advantages of Traditional Conventional Open-top Electric Furnaces

The advantages of traditional conventional open-top electric furnaces are that they have fewer equipment failures and are stable and reliable. However, their disadvantages are that they are almost unable to achieve the above purposes well and have low production efficiency.

In the 1990s, Fuchs electric furnaces and Consteel electric furnaces were introduced to China almost at the same time. Because of the high failure rate of Fuchs electric furnace equipment, it was basically eliminated under the background that the cost of scrap steel cannot be offset.

After Consteel electric furnace equipment was localized, it developed rapidly due to its advantages of high efficiency, low cost, stability and reliability under the background of "China's transformation to electric power".

Before 2017, 95% of the electric furnaces in the country were open-top charging types; since 2017, more than 85% of the company's new electric furnace equipment were continuous horizontal charging systems.

Disadvantages of Consteel Electric Stove:

The main reason is that the design temperature of scrap steel for horizontal flue gas preheating is 400 degrees Celsius to 600 degrees Celsius, and the scrap steel temperature can generally only reach 200 degrees Celsius to 300 degrees Celsius;
The temperature of the waste gas in the preheated scrap steel channel is in the peak range where furans and dioxins are produced, and the problem of environmental pollution caused by harmful gases is difficult to solve;
A large amount of "wild wind" enters the preheating channel, which brings difficulties to dust removal and waste heat recovery.

Quantum Electric Furnace VS Ecoarc Electric Furnace VS Sharc Electric Furnace

Quantum electric furnaces, Ecoarc electric furnaces and Sharc electric furnaces hope to solve the above problems by preheating scrap steel with vertical flues.

Quantum Electric Furnace

The Quantum electric furnace uses a scrap trough lifting trolley to replace the basket feeding, and adopts a siphon-type slag-free tapping system. It still uses a finger-type system to maintain and preheat scrap steel, with high preheating temperature and less harmful gases. Currently, there are a total of 11 Quantum electric furnaces in production and under construction in the world, including 1 in Mexico, 1 in Turkey, 1 in Bangladesh, and 8 in China. At the end of 2020, two Quantum electric furnaces were put into production in China, and the comprehensive effect remains to be seen.

Ecoarc Electric Furnace

The main part of the Ecoarc electric furnace is composed of a melting chamber for melting scrap steel and a preheating shaft furnace directly connected to the melting chamber. The sealing of the furnace body and scrap steel preheating are combined. It operates in a flat molten pool and is highly automated. The scrap preheating temperature can be adjusted Reaching 800 degrees Celsius, the generation of pollutants can be avoided, and the dioxin emission is less than 0.1ng-TEQ/m3 (nanogram toxicity equivalent value per standard cubic meter, the same below).

Sharc Electric Furnace

There are currently 9 Ecoarc electric furnaces in production and under construction, including 5 in Japan, 1 in South Korea, 1 in Thailand, and 2 in China (under construction). Sharc electric furnaces are all DC electric furnaces with low noise and less dust. They are designed with double shafts to use exhaust gas to preheat scrap steel. Dioxins are less than 0.1ng-TEQ/m3. In terms of application, in addition to a 100-ton Sharc electric furnace in operation in Turkey, HBIS Shigang has introduced two 130-ton Sharc electric furnaces. In short, the number of applications of these three types of electric furnaces is small, and their prospects remain to be further observed.

The Development of Electric Furnaces in China

At present, domestic electric furnace equipment accounts for 85% of the domestic electric furnace production capacity, and imported electric furnaces account for 15%.
Although domestic manufacturers already have certain strengths in single equipment, and electric furnace equipment under 100 tons has basically been domestically produced, Chinese scientific and technological workers have also been committed to developing complete sets of electric furnace equipment with independent intellectual property rights.

CISDI-Green Electric Furnace

In an attempt to combine the advantages of horizontal charging and vertical electric furnaces, domestic equipment manufacturers launched CISDI-Green electric furnaces. This electric furnace uses the idea of step-shaped continuous closed scrap feeding, forming a unique patented technology for ladder feeding. It has obtained patent authorization in China and the European Union, and has formed a domestic group standard. The technical indicators are also relatively advanced, and several electric furnaces are put into use in China and Southeast Asia.

CERI-s1-Arc Electric Furnace

Another equipment manufacturer launched the CERI-s1-Arc electric furnace.
The scrap steel is added to the shaft through the trolley. The steel pushing mechanism below the shaft pushes the scrap steel into the horizontal channel. The horizontal channel vibrates the scrap steel into the flat molten pool, thereby realizing continuous feeding of scrap steel;

Reduce dioxin content and realize waste heat utilization through flue gas quenching, activated carbon adsorption and waste heat boiler.

This electric stove integrates many advanced technologies and is still in the promotion stage.

In general, domestic electric furnace manufacturers still need to work harder in many aspects in designing and manufacturing advanced furnace types.

The future development direction of electric furnace types will be electric furnaces that can achieve continuous feeding, scrap steel preheating, green environmental protection, low dioxin emissions, waste heat recovery and intelligent steelmaking.

Various high-efficiency production technologies are adopted in advanced furnace types. Currently, some domestic Consteel electric furnaces can achieve a 30-minute smelting cycle just like converters under the condition of all scrap steel.

Other technical and economic indicators can reach a metal recovery rate of 90% to 92%, total scrap steel power consumption is less than 300 kWh/ton, electrode consumption is less than 1.0 kg/ton, and the annual output per unit nominal capacity can reach 10,000 tons of steel/ton. above.

Process Management and Control of Low Production Cost of Electric Furnace Steel

At present, the cost of electric furnace steel is 500 yuan/ton of steel to 600 yuan/ton of steel higher than that of long-process. The difference mainly lies in raw materials (iron ore, coke, scrap steel), power consumption, electrode consumption, refractory consumption, etc. Short-process reduces the path of cost lies in the above factors.

Given that the costs of Chinese steel companies have remained high for a long time, expanding scrap steel imports and reducing dependence on iron ore are realistic options.

In addition, process management and control for low production costs of electric furnace steel also include:

Reduce raw material costs, strengthen the classification, processing and management of scrap steel and iron-containing raw materials, and widely use various iron-containing materials such as hot-pressed iron blocks, vanadium-extracted iron, etc.
Reduce energy consumption, carry out research on the optimization of electric furnace power supply technology, reduce power consumption and electrode consumption, and recover physical heat, such as hot charging of sponge iron and hot metal mixing;
Strengthen the recovery of chemical heat, such as scrap steel preheating technology and the implementation of continuous feeding devices;
Off-peak electricity consumption, use of off-peak electricity discounts, continuity and automation of the operation process, shortening of thermal shutdown time, etc.