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Ten characteristics of cupola melting
Dec 12, 2018

Cupola is a kind of shaft furnace for continuous smelting of cast iron. Most of them use coke as fuel. The cupola furnace smelting generally has three basic processes: coke combustion, heat transfer and composition change of molten iron.

The ten characteristics of cupola melting are as follows:


1. Cupola smelting is the simultaneous combustion of carbon in the cupola, the heat absorption of iron, the superheating of molten iron and the metallurgical reaction process. The three processes affect each other and cause each other. Changing any of these processes will affect other processes. This results in different results.


2. The smelting process is a physicochemical reaction process at high temperatures. Factors affecting the reaction process and results include temperature, material properties and state, material content, environmental pressure, and the like. The smelting process is carried out in a regular flow of matter, so that the parameters of the reaction and the reaction results are relatively stable within a certain range.


3. High temperature provides thermodynamic conditions for the smelting process, and also strongly influences the kinetic conditions, so it is the basic condition of the smelting process. The temperature and the distribution in the furnace have a very important influence on the stability of the smelting process, the quality and cost of the molten iron, as well as the labor intensity and production safety. Therefore, the smelting environment in which the high temperature and reasonable temperature distribution are created in the cupola is The primary task of cupola melting technology.


4. The smelting products of cupola are mainly cast iron, which can smelt from malleable cast iron with carbon content as low as 2.2% to high carbon cast iron with hypereutectic composition. The production of different grades of cast iron can also be achieved by reasonable selection of furnace structural parameters, charge types, and smelting process parameters.


5. Due to too many factors affecting the smelting process and the uncertainty of some factors, the stability of the molten iron quality is poor. Therefore, in the smelting of high-grade cast iron, especially in the production of large-scale castings, it is still necessary to treat the molten iron outside the furnace, such as desulfurization, gestation, purification, spheroidization, creeping, heat preservation and heating, as the smelting in the furnace. It is necessary to add.


6. In the cupola, the preheating and melting efficiency of the iron material is high and the iron liquid superheating efficiency is relatively low. From the reasonable use of heat, the cupola should not smelt high-temperature molten iron. However, from the perspective of improving the quality of molten iron, the melting temperature should be increased. Therefore, the molten iron from the cupola should not be lower than 1450 °C.


7. Cupola smelting is continuous, and the molten iron flows out from the cupola at a relatively stable flow rate. Therefore, the production capacity of the cupola is expressed by the melting rate, and the time of continuous smelting depends on the production schedule and the life of the charge. Hours to months.


8. Adaptability to equipment systems and production capacity. From the scoop furnace with only the furnace body, hearth and fan, three furnaces, to the configuration of the ingredients feeding equipment, preheating air supply equipment, water cooling equipment, slag and slag granulation equipment, soot purification equipment, automatic inspection and control operating system modernization The external hot air cupola can melt qualified iron liquid to meet different product requirements. The melting rate ranges from less than one ton per hour to hundreds of tons per hour, which can be adapted to different production scales. However, the technical and economic benefits of the furnace increase with the increase of capacity, so the development of large-capacity cupolas and the large-scale reduction of the number of small cupolas are inevitable requirements for China to become a casting power.


9. Compared with the induction furnace, the metallurgical performance of the cupola is much stronger, so the adaptability to the charge is wider.


10. Although the emission of soot and slag can pollute the environment, modern environmental protection technology can achieve standard treatment, and the recycling technology of emissions, soot and flue gas has been practically applied and gradually improved. With the development of large-capacity, external hot air and long furnace age, the harmless treatment and recycling of emissions will also be popularized.


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