Presentation on Electric Arc Furnace (A)

The electric arc furnace is an electric furnace that uses high temperature produced by electrode arc to smelt ore and metal. When the arc is formed by gas discharge, the energy is concentrated and the temperature of the arc zone is above 3000 ℃. For smelting metals, EAF is more flexible than other steelmaking furnaces, which can effectively remove sulfur, phosphorus and other impurities. The furnace temperature is easy to control, and the equipment covers a small area. It is suitable for smelting high-quality alloy steel.

Introduction

Through the metal electrode or nonmetal electrode to produce electric arc heating industrial furnace is called electric arc furnace. According to the form of arc, EAF can be divided into three-phase EAF, consumable EAF, single-phase EAF and resistance EAF. The furnace body of EAF is composed of furnace cover, furnace door, tapping tank and furnace body. The furnace bottom and wall are built with basic refractory or acid refractory.

According to the transformer capacity per ton of furnace capacity, EAF can be divided into ordinary power EAF, high power EAF and ultra-high power EAF. EAF steelmaking is to input electric energy into EAF through graphite electrode, and take the arc between electrode end and charge as heat source for steelmaking. Electric energy is used as the heat source in EAF, and the atmosphere in EAF can be adjusted, which is very beneficial to the smelting of steel grades with more oxidizable elements.

Shortly after the invention of EAF steelmaking, it was used to smelt alloy steel and developed greatly. With the improvement of EAF equipment and smelting technology, the development of electric power industry, the cost of EAF steelmaking is decreasing. Now EAF steelmaking is not only used for the production of alloy steel, but also for the production of ordinary carbon steel. The proportion of its output in the total steel output of major industrial countries is rising.

Development History

In 1888-1892, p.l.t.h é roult developed coal instead of energy by using a high temperature of electrode arc, and invented an arc furnace for direct smelting. At first, the EAF was only used for the production of calcium carbide and ferroalloy, and it was developed to make steel in 1906, and thus the scrap steel could be recycled economically and in scale. The electric energy is converted into heat energy by the arc between the end of the graphite electrode and the charge, and then the furnace charge is melted and the subsequent high-temperature metallurgical reaction is completed. Because it uses electric energy and is easy to adjust the atmosphere in the furnace, it can smelt various kinds of alloy steel including the oxidizable elements.

With the development of power industry, the continuous improvement of process equipment and the improvement of smelting technology, arc furnace is widely used and its production capacity and scale are increasing. The maximum capacity of EAF was 100t in 1930s, 200t in 1950s and 400t in the early 1970s. Especially in the past 50 years, the technical performance of EAF has been gradually improved, and the production cost has decreased significantly. The proportion of EAF steel in developed countries in Europe and America has exceeded 50%. The development of modern EAF smelting technology advances with the times. 

In the 1960s-1970s, the development of ultra-high power supply and related technologies is mainly carried out. HP and UHP are compared with the general power arc furnace (RP). They are mainly divided according to the capacity of transformer per ton of furnace capacity, and there is a trend of higher and higher in recent years. This means that the heat energy of the electric arc furnace is greatly increased in unit time, which makes the melting time significantly shortened, thus improving the production capacity, reducing electrode consumption, reducing heat loss and reducing the power consumption. The result is that the production capacity is increased again, and the cost also decreases greatly. High voltage long arc operation, water-cooled furnace wall, water-cooled furnace cover, foam slag technology, and external heat source melting have been widely used in conjunction with ultra-high power electric arc furnace. Ladle refining and intensified oxygen utilization have also been adopted.

In the 1980s, the development of LF and EBT technology made the modern EAF steelmaking process of EAF smelting and refining outside the furnace mature. It is worth noting that since then, people have paid more attention to the use of secondary combustion and flue gas sensible heat, namely, the preheating of scrap steel. Different preheating methods of scrap produce different types of modern EAFs, including ordinary arc furnaces preheating with basket scrap, flue shaft furnace with supporting claws, double shell arc furnace and Consteel arc furnace. At present, the equipment and production technology of EAF are still in the process of continuous development.

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