Refractory for cupola
Ehong cupola is a kind of refractory material used to build cupola body and related parts. Impact furnace, also known as molten iron protection furnace, is a thermal equipment for smelting pig iron between foundry industry and some steel-making cars. The working temperature of the protector is generally 1400 ~ 1 stone. . With the development of technology, the furnace type tends to be large, and the vigor of molten iron has been greatly improved. Therefore, the furnace lining works under the conditions of high temperature, sudden temperature change, charge impact, hot metal scouring and slag erosion, and the damage is aggravated. The refractories used in Tian Chong protection have also changed from ordinary refractories to advanced refractories, and from ordinary refractory bricks to unshaped refractories. The refractory furnace body for cupola furnace body consists of furnace bottom, furnace body, forehearth and bridge frame. (see figure), structural schematic diagram of cupola 1, furnace bottom plate and solid working layer at the bottom of the furnace; 3 a tuyere, 4 a furnace body, 5 a fan-shaped hollow iron brick, 6 a charging port and 7 a smoke exhaust port; 8. Spark catching guide. 9. A bridge. 10, a forehearth, 1 1, a slag outlet; 12 The refractory at the bottom of the taphole is the part that directly contacts with high-temperature molten iron, and bears all the burden quality. Therefore, it must have certain mechanical strength and chemical toughness to improve its service life. Firstly, laying clay insulating brick on the furnace bottom, and then laying clay bricks; Finally, according to the different requirements of molten iron, the working layer is rammed with metallurgical magnesia or quartz sand and sintered. -The working layer on the furnace body is made of refractory material. Due to the mechanical impact and wear of the burden during charging, fan-shaped hollow iron bricks are used for masonry, and quartz sand is filled outside; The working layer at the lower part of the furnace body, especially the tuyere area and slag area, is easy to be damaged due to the action of high temperature, slag and airflow, so magnesia-chrome bricks or magnesia bricks with good corrosion resistance or corundum bricks with high strength must be used. The working layer of the rest of the furnace body generally adopts high-strength clay bricks or semi-silicon bricks, or high-nitrogen bricks. The insulation layer of furnace body generally adopts clay insulating brick or floating bead brick. The working layer and tuyere in the lower part of cupola body are its weak links. Weng made several minor repairs during a furnace service. Too much flux, too much air supply or oxygen-enriched blast, and frequent intermittent work will directly affect the service life of furnace lining. The forehearth and the bridge are made of refractory materials and used to connect the cupola body with the forehearth. They are composed of vaults, walls and bottoms, and are generally made of clay bricks. In order to improve the service life of the lower part and bottom skin of the wall, dense high-alumina bricks can be used for masonry; The forehearth consists of a bottom, a wall and a top. The top of the stove is arched or hung with a flat roof. The front hearth is generally built with clay bricks and high alumina bricks, and the bottom working layer is rammed with ramming material, which is the same as the bottom of cupola. Due to the influence of high-temperature molten iron and slag erosion, the service life of the taphole and slag outlet of the bridge and the front guard plate is short, which requires frequent minor repairs. Large cupola is blown by hot air or oxygen-enriched air, with high temperature and large production capacity. Because of the bad working conditions, this part is damaged quickly, and it is difficult to maintain production with clay bricks or high-alumina bricks. Aluminum-carbon or corundum-silicon carbide refractory castable should be used for pouring or tamping to achieve good integrity, high strength and strong corrosion resistance, so the service life is obviously prolonged, generally up to about one year. Refractory materials of other parts of cupola include those of chimney and spark catcher. The chimney is directly connected with the cupola shaft, and its shell is made of steel plate, and its lining is built with ordinary clay bricks, or it can be poured with ordinary refractory castable. The chimney is equipped with a furnace liner heat exchanger, which can preheat the air to 300~500℃. Spark collectors are used to capture hot coke powder and dust particles brought out of flue gas. The reflector (cover) above the chimney mouth can be welded with steel plate or cast iron, and its lining is sprayed with refractory paint.