Carburant Choose Appropriate To Reduce The Production Cost Of Castings
There are many kinds of raw materials of Carburant-adding agent, the production process is also different, there are wood Carburant, coal Carburant, coke, graphite and so on, and there are a lot of small kinds of classification. High-quality Carburant additive generally refers to the graphitization of Carburant agent, at high temperature, the arrangement of Carburant atoms in the microscopic form of graphite, so called graphitization. Graphitization can reduce the content of impurities in the Carburant additive, increase the Carburant content of Carburant additive and reduce the sulphur content.
The use of Carburant-adding agent in the foundry can significantly increase the amount of scrap steel, reduce the amount of pig iron or iron. Electric furnace melting of the feeding method, should be added to the Carburant agent with waste steel and other burden into the inside, the addition of small dosage can be selected on the surface of molten iron. However, to avoid large quantities of molten iron to feed, in order to prevent excessive oxidation and increase the effect of Carburant is not obvious and casting Carburant content is not enough. Adding the amount of Carburant agent, according to the proportion of other raw materials and Carburant content to be determined. Different types of cast iron, depending on the need to choose a different type of Carburant agent. The characteristics of Carburant-adding agent choose pure Carburant-containing graphite material, reduce the excessive impurities in pig iron, and the choice of Carburant-adding agent can reduce the production cost of castings.
Carburant in the form of Carburant, the melting temperature of 3,727 ℃, in the molten iron temperature can not be melted, so the Carburant in the Carburant agent in the main through dissolution and diffusion of two ways dissolved in iron liquid. When the iron liquid is wc=2.1%, graphite in the graphite Carburant-adding agent can dissolve directly in the molten iron. But the direct dissolution of non-graphite Carburant is basically non-existent, but over time, the Carburant in the molten iron gradually diffused dissolved. Therefore, the Carburant increasing rate of graphite Carburant is significantly higher than that of non-graphite Carburant.
It is shown that the dissolution of Carburant in molten iron is affected by the transfer of liquid boundary layer on the surface of solid particles. By comparing the results of coke and coal particles with those obtained from graphite, it is found that the diffusion dissolution rate of graphite Carburant-adding agent in molten iron is much faster than that of coke and coal particles. The partial dissolved coke and coal particle samples were observed by electron microscope, and a thin layer of viscous ash was formed on the surface of the sample, which was the main reason of the diffusion solubility in molten iron.
The Carburant-adding agent is suitable for smelting in induction furnaces, but it is different according to the process requirements.
(1) The use of Carburant-adding agent in the smelting of intermediate frequency electric furnace, can be in accordance with the proportion or Carburant equivalent of the furnace to add the middle and lower part, recovery rate of up to 95%;
(2) If Carburant is not enough to adjust the Carburant time-sharing, first clean furnace slag, and then add Carburant agent, through the iron liquid heating, electromagnetic stirring or artificial stirring to make the Carburant dissolved absorption, recovery rate can be around 90%, if the use of low-temperature Carburant technology, that is, the burden only melted part of the molten iron temperature is low, All the Carburant-adding agents are added to the molten iron, and the liquid is pressed into the molten iron to keep it from exposing the surface of the molten iron. This method increases the Carburant content of iron liquid up to 1%.