A Brief Discussion on the Differences Between Converter and Electric Arc Furnace Steelmaking

There are many methods of steelmaking, with the basic principle being the same; the differences lie in the sources of oxygen and heat energy required during the smelting process, as well as the equipment and operating methods used. Currently, the steelmaking methods adopted by various countries include converter steelmaking, electric furnace steelmaking, and open-hearth furnace steelmaking, with the main development trend being pure oxygen top-blown converter steelmaking. By 1976, converter steel accounted for 70% of the world's total steel production. (1) Pure oxygen top-blown converter steelmaking method
This method is a new technology developed after 1952 and is currently one of the more widely used and advanced methods in the world. Pure oxygen top-blown converter steelmaking has the following advantages:
(i) Fast production speed: Because pure oxygen is blown during smelting, carbon reduction occurs rapidly, and temperature rises quickly, greatly shortening the smelting time. A 300-ton converter takes less than 20 minutes for blowing, and including auxiliary work time, the total does not exceed 1 hour.

(ii) Wide variety and good quality: Pure oxygen top-blown converters can produce both ordinary steel and ordinary low-carbon steel. For example, the Capital Steel Plant has successfully trial-produced more than one hundred types of steel using this method. Because pure oxygen is used for blowing, the content of harmful gases such as nitrogen and hydrogen in the steel is relatively low.

(iii) Low infrastructure investment and production costs: The infrastructure investment for pure oxygen top-blown converters is equivalent to 60~70% of that for open-hearth furnace workshops with the same production capacity,
and production costs are also lower than those of open-hearth furnaces. Currently, with the successful development of multi-hole oxygen lance nozzles for pure oxygen top-blown converters, the oxygen supply per unit time has been greatly increased. Due to innovations in operating technology (for example, using electronic computing technology to adjust and control the smelting process), regardless of the converter capacity, the blowing time is basically similar. Even for a 300-ton converter, the net oxygen blowing time can be shortened to about 12 minutes. Within certain limits, the larger the furnace capacity, the better the economic effect, so top-blown converters are rapidly moving towards larger sizes. The world's largest converter now is 350 tons, and research is underway to build 400~450 ton converters.

(2) Electric furnace steelmaking method
The electric furnace steelmaking method mainly uses electric arc heat, where the temperature in the arc zone reaches up to 4000°C. The smelting process is generally divided into melting, oxidation, and reduction phases. Inside the furnace, both oxidizing and reducing atmospheres can be created, resulting in high efficiency for dephosphorization and desulfurization.

Electric furnace steelmaking using scrap steel as raw material requires less infrastructure investment compared to blast furnace-converter methods. At the same time, with the development of direct reduction, metallized pellets are provided to the electric furnace to replace most scrap steel, greatly promoting electric furnace steelmaking. There are currently about 1,400 relatively large electric furnaces worldwide. Electric furnaces are developing towards larger sizes, ultra-high power, and computer automatic control, with the largest electric furnace capacity being 400 tons.