Refractory products used in electric arc furnaces

Source: | Author:ChangXing Refractory | Published time: 1598 days ago | 976 Views | Share:

Electric furnaces mainly use scrap steel as the main raw material for steelmaking. Put scrap steel, lime, etc. into the furnace. When the electricity is turned on, an electric arc is generated between the electrode and the scrap to heat the charge. The metallurgical spare parts undergo a series of chemical reactions, and the scrap is made into steel. Electric furnaces mainly include DC electric arc furnace, AC electric arc furnace and induction furnace.

A.Refractories for DC electric arc furnace

There are three types of DC electric arc furnaces, namely ABB, Clecim and GHH. Different types of DC electric arc furnaces are classified according to the structure of the bottom electrode, which illustrates the importance of the bottom electrode. The bottom electrode of the ABB type DC electric arc furnace is electrically conductive with a conductive refractory material, and the bottom surface is cooled; while GHH has many small steel needles (thin steel rods with a diameter of 20-50mm) buried in the bottom, and the bottom surface of metallurgical spare parts is also cooled by wind ; The bottom electrode of Clecim is 1-4 thick steel rods, and the lower end is cooled with a copper water cooling jacket. On the basis of these three types, various forms have been developed, such as the steel sheet type, the water-cooled bottom electrode rod type, and the steel rod and copper rod composite bottom electrode type.

The life of the bottom electrode of the DC electric arc furnace is essentially the life of the refractory material. For the Clecim bottom electrode, the electrode cover bricks are made of iron, magnesia-carbon, magnesia-aluminum, and iron-based refractories. The repair materials currently used are mainly magnesium dry ramming materials. For DC arc furnaces with conductive steel needles or steel sheet bottom electrodes, dry materials are often used between the steel needles or steel sheets, and some are made into preforms, mainly magnesium refractories. In order to improve the life span, NMe0-C materials are now available. It is impossible to greatly increase the life of the bottom electrode by improving the performance of refractory materials. Therefore, metallurgical spare parts have carried out hot repair work abroad in recent years. The hot repair materials used are required to be conductive refractory materials (the conductive steel needles and steel sheets are arranged), mainly including magnesium-iron conductive ramming materials, magnesium-carbon conductive ramming materials, magnesium-calcium carbon conductive ramming material.

B.Refractories for AC arc furnace

The refractory used for the AC arc furnace bottom was rammed into the furnace bottom with asphalt tar iron sand or brucite knotting material in the early days, and then more iron bricks and low-grade magnesia carbon bricks were used to build the furnace bottom. By the 1990s In the 1940s, my country began to use dry vibrating ramming materials of furnace bottom magnesium-calcium-iron series. The construction of various metallurgical parts is simple and convenient, without baking, after the construction is completed, it can be directly used in steelmaking. Refractory materials for small electric arc furnace walls mainly use asphalt magnesia bricks, iron-carbon bricks, and iron sand to fill the furnace charge. For ultra-high-power large electric furnaces, high-quality magnesia-carbon bricks are used for electric furnace walls, especially high-quality magnesia-carbon bricks with very high performance for slag lines and hot spots. Magnesium gunning materials are mainly used for furnace wall repair.

Small electric arc furnace roofs generally use high alumina bricks, high power and ultra-high power electric arc furnace top electrode triangles with corundum, metallurgical spare parts, chromium steel jade and corundum magnesia castables and preforms. The outer roof generally uses fired high alumina brick or unfired high alumina brick, magnesia brick and magnesia chrome brick. The tapping tip generally adopts side tapping troughs.

In our country, we generally use high-aluminum, magnesium and other non-shaped ramming materials or castables prefabricated integral tapping troughs. The taphole bricks are magnesia bricks, magnesia carbon bricks, and coarse sand with forsterite as the matrix is often used as drainage sand.