The casting industry is a typical high energy consumption and high pollution enterprise, and the task of energy conservation and emission reduction is very difficult. The service life of the furnace lining has a significant impact on whether the normal production of the electric furnace can be guaranteed. Through production practice, Annaijie has realized that based on the characteristics of the electric furnace binding materials, it is necessary to master the material selection, batching, knotting, baking and sintering processes, as well as daily maintenance and upkeep of the furnace lining during the smelting process, It is crucial to improve its service life.
The working conditions of the acid furnace lining material induction furnace lining are very harsh. In the process of use, it works under a series of complicated physical and chemical changes interwoven, and bears the high temperature effect of 1550~1580 ℃ in the smelting process, the severe impact and collision of pig iron, scrap steel and alloy material on the furnace lining during charging, the strong scouring effect of metal liquid on the furnace lining caused by electromagnetic stirring during smelting, the chemical erosion effect of slag on the furnace lining, and the sudden cooling and heating changes of furnace lining temperature caused by intermittent operation, As a result, cracks, local erosion, peeling, etc. occur in the furnace lining, and the acidic lining material causes the penetration of metal liquid, leading to the failure of the furnace lining. It can be seen that the refractory material of the furnace lining should have the following properties:
(1) High enough fire resistance. The working temperature of the induction furnace lining is generally lower than the temperature of the molten metal. However, considering the requirements for the service life of the furnace lining, it is also necessary to consider occasional or frequent overheating of the molten pool and groove. The fluidity of cast iron is good, and it is often unsafe to use materials with low refractory and softening temperatures in cast iron induction furnaces. As refractory materials for producing cast iron products in electric furnaces, their refractory should reach 1650-1700 ℃, and the softening temperature should be higher than 1700 ℃.
(2) The coefficient of thermal expansion is small, and the volume should be relatively stable with the change of temperature, without sharp expansion and contraction.
(3) Good chemical stability. The chemical stability of the material is closely related to the service life of the furnace lining. The furnace lining material should not be hydrolyzed and differentiated at low temperatures, not be easy to decompose and reduce at high temperatures, and not be easy to form low melting point substances with the slag during smelting. Not easily react with metal solutions, solvents, and slag.
(4) Acid furnace lining materials have high mechanical properties. When the temperature inside the furnace is low, it should be able to withstand the impact of the furnace material. When the metal is in a high-temperature molten state, it should be able to withstand the static pressure of the metal liquid and strong electromagnetic stirring. It should be wear-resistant and corrosion-resistant under the long-term erosion of the metal liquid.
(5) Good insulation performance. The furnace lining must not conduct electricity under high temperature conditions, otherwise there may be electric leakage and short circuit, causing safety and equipment accidents.
(6) The material has good construction performance, good repair and sintering performance, and is convenient for furnace construction and maintenance.
(7) Free from harmful impurities such as iron oxide and low melting point minerals.
Silica sand is an acidic furnace lining material with low price and a wide range of sources. It can basically complete its expansion changes at 600-800 ℃, and has small volume changes above this temperature. It has good thermal stability and resistance to molten iron leakage, and can adapt to intermittent operations. In addition, the load softening temperature of silica sand is close to its fire resistance, and its high-temperature mechanical strength is higher. The main technical conditions for using silica sand for furnace lining tying: The main component of silica sand is silicon oxide, and the higher its content, the higher the refractory degree of the furnace lining. Therefore, it is currently widely used as an acidic furnace lining tying material.
