1 Effect of carbonizer particle size
 
The carbon increase process using the carbon increase agent includes the dissolution diffusion process and the oxidation loss process. When the particle size of the carburizer is different, the dissolution diffusion rate and oxidation loss rate are also different. The absorption rate of the carburizer depends on the combined effect of the dissolution and diffusion speed of the carburizer and the oxidation loss rate: under normal circumstances, the carburizer particles are small, the dissolution rate is fast, and the loss rate is large; the carburizer particles are large, The dissolution rate is slow and the loss rate is small. The choice of carbonizer particle size is related to furnace diameter and capacity. In general, the diameter and capacity of the furnace are large, and the particle size of the carburizer is larger; on the contrary, the particle size of the carburizer is smaller. For the electric furnace smelting crystalline graphite below 1t, the particle size requires 0.5 ～ 2.5mm; the 1t ～ 3t electric furnace smelting crystal graphite requires the particle size 2.5 ～ 5mm; 3t ～ 10t electric furnace smelting crystal graphite requires the particle size 5.0 ～ 20mm; the crystal graphite particle size covered in the ladle requires 0.5 ~ 1mm.
 
2 Influence of the amount of carburizer(Low sulphurGraphite petroleum coke/calcined petroleum coke) added
 
Under a certain temperature and the same chemical composition, the saturation concentration of carbon in the molten iron is constant. The solubility limit of carbon in cast iron is ([C%] = 1.3 + 0.0257T－0.31 [Si%] － 0.33 [P%] － 0.45 [S%] + 0.028 [Mn%] (T is the temperature of molten iron). At a certain saturation, the more the amount of carburizer is added, the longer the time required for dissolution and diffusion, the greater the corresponding loss, and the absorption rate will decrease.
 
3 The effect of temperature on the absorption rate of carburant
 
From the point of view of kinetics and thermodynamics, the oxidizability of the molten iron is related to the equilibrium temperature of the C-Si-O system, that is, O in the molten iron will react with C and Si. The equilibrium temperature changes with the target C and Si content. When the molten iron is above the equilibrium temperature, carbon oxidation occurs preferentially, and C and O generate CO and CO2. In this way, the carbon oxidation loss in the molten iron increases. Therefore, when the carbonization temperature is above the equilibrium temperature, the absorption rate of the carburizing agent decreases; when the carbonization temperature is below the equilibrium temperature, the saturation solubility of carbon decreases due to the lower temperature, and the rate of carbon dissolution and diffusion decreases, so the yield is also lower Low; when the carburizing temperature is at the equilibrium temperature, the carburizing agent absorption rate is the highest.
 
4 The influence of molten iron stirring on the absorption rate of carburant
 
Stirring is conducive to the dissolution and diffusion of carbon, to avoid the carburizing agent floating on the surface of the molten iron and being burned. Before the carburizing agent is completely dissolved, the stirring time is long and the absorption rate is high. Stirring can also reduce the time of carbonization and heat preservation, shorten the production cycle, and avoid the burning of alloy elements in the molten iron. However, if the stirring time is too long, it will not only have a great impact on the service life of the furnace, but also after the carburizing agent is dissolved, the stirring will aggravate the loss of carbon in the molten iron. Therefore, the appropriate stirring time of molten iron should be appropriate to ensure that the carburizing agent is completely dissolved.
 
5 The influence of the chemical composition of molten iron on the absorption rate of carburant(Low sulphurGraphite petroleum coke/calcined petroleum coke) 
 
When the initial carbon content in the molten iron is high, under a certain solubility limit, the absorption rate of the carburizer(Low sulphurGraphite petroleum coke/calcined petroleum coke)  is slow, the absorption amount is small, the burning loss is relatively large, and the carburizer absorption rate is low. When the initial carbon content of the molten iron is low, the situation is reversed. In addition, silicon and sulfur in the molten iron hinder the absorption of carbon and reduce the absorption rate of the carburizer; while the manganese element contributes to the absorption of carbon and improves the absorption rate of the carburizer(Low sulphurGraphite petroleum coke/calcined petroleum coke) . In terms of the degree of influence, silicon is the largest, followed by manganese, and carbon and sulfur are less affected. Therefore, in the actual production process, manganese should be added first, then carbon, and then silicon