The generalized types of steel making electric furnaces include electric arc furnaces, induction electric furnaces, electroslag furnaces, and electron beam furnaces. The usual electric furnace steel refers to steel produced by an alkaline electric arc furnace. Therefore, this paper focuses on electric arc furnace (EAF). The electric arc furnace has two types: DC electric arc furnace (DC-EAF) and AC electric arc furnace (AC-EAF). Since the DC electric arc furnace can reduce the amount of refractory materials, it is more energy-saving and less noisy, and the flicker is halved, so the application is increased and rapidly developed. . For DC arc furnaces, new technologies such as eccentric bottom tapping, water-cooled furnace wall, water-cooled furnace cover, oxygen-burning nozzle, and scrap preheating are all suitable and the effect is good. The 1990s was the era of rapid development of DC-EAF, including industrialized countries with high scrap recycling rates, such as the United States, Japan, South Korea, and developing countries with insufficient power supply, such as China and Southeast Asian countries, which have built more than 50 tons in a few years. Electric arc furnace reaches 100
Above Taiwan, the representative ones are Japan’s 240tDC-EAF and the US’s 280tDC-EAF.
The DC arc furnace is provided with a graphite electrode at the top of the furnace. The arc is stable and concentrated, and has the characteristics of good agitation of the molten pool, uniform temperature distribution in the furnace, and improved melting efficiency. A typical feature of a DC arc furnace is that the top graphite electrode is the cathode and the anode is coupled to the furnace bottom. This requires that the bottom of the furnace must be electrically conductive, and the conductive materials available at the bottom of the furnace are mainly:
(1) Conductive refractory materials (ABB);
(2) Metal components: including iron bar electrodes (Irsid-Clecim), steel sheet electrodes (VAI), multiple steel needle electrodes (GHH), and copper-steel composite water-cooled bottom electrodes.
In addition to the special requirements of the refractory materials used in the bottom of the DC arc furnace, the refractory materials used in other parts have great similarities. Widely used in AC arc furnaces (AC-EAF) are ultra-high power electric furnaces (UHP-EAF), which have high production efficiency, slow furnace wall loss, shortened melting time, improved thermal efficiency, and reduced power consumption. The advantages of arc stabilization and the like. Therefore, ultra-high power electric furnaces have been widely used in the late 1970s. UHP technology has developed towards large capacity and high power in recent years. The power of individual UHP-EAF has reached 1000kVA/t or even higher, which is called ultra-high power arc furnace. In order to give full play to the advantages of UHP, technologies have been developed to match ultra-high power, including water-cooled furnace walls, water-cooled furnace covers and long-arc foam smelting technology. More than 30t electric arc furnaces in Europe have been equipped with water-cooled slag wall and water-cooled furnace cover. Japan’s electric arc furnace is equipped with water-cooled furnace wall, accounting for more than 70%. Western Europe and the United States have also adopted water-cooled slag wall. The use of water-cooled furnace wall technology can make the service life of the furnace wall reach 2000 or more, reduce the consumption of refractory materials by more than 60%, increase the productivity by 8% to 10%, reduce the electrode consumption by 0.5kg/t, and reduce the production cost by 5% to 10%. The use of a water-cooled furnace lid can achieve a life of 4,000 times.
According to the type of tapping, the electric furnace can be divided into a trough-type arc-discharging arc furnace and an eccentric bottom-out arc-discharging arc furnace (EBT). Due to the eccentric bottom (EBT) tapping port, the water-cooling area can be enlarged, the refractory cost is reduced, and the ladle is made. The amount of slag discharged is reduced, so the application is gradually increasing. Electric steel making uses scrap steel and metallized pellets as raw materials, mainly using arc heat. In the arc action zone, the temperature is as high as 4000 °C, and the scrap steel is refined into new steel through a series of metallurgical chemical reactions. The smelting process is generally divided into a melting period, an oxidation period and a reduction period. In the furnace, not only an oxidizing atmosphere but also a reducing atmosphere can be caused, so the efficiency of dephosphorization and desulfurization is high.
Chinese electric furnace steel making mainly smelts high-quality alloy steel. In recent years, with the continuous changes in the electric steel making process, including higher operating temperatures, increasing capacity of steel making electric furnaces, stronger temperature changes, and increasing alloy steel quality, higher refractory materials have been proposed.