Professional knowledge sharing of anthracite recarburizer

There are many kinds of raw materials for recarburizers, and the production process is also different. There are wooden carbon, raw coal carbon, coke, high-purity graphite, etc., and there are many under various categories. Small type. Recarburizers generally refer to recarburizers that have undergone graphitization. Under high temperature standards, the order of oxygen atoms is the external economic shape of high-purity graphite, so it is called graphitization. Graphitization can reduce the content of residue in the recarburizer, the carbon content of the recarburizer, and reduce the sulfur content.

The recarburizer is applied during forging, which can greatly reduce the amount of used steel and reduce the amount of cast iron or eliminate the need for cast iron. The feeding method of heating furnace smelting should promote the recarburizer along with the recycled waste materials such as waste steel, and the dosage can be selected and added to the surface of the molten steel. However, it is necessary to prevent a large amount of material being added to the molten steel to avoid excessive air oxidation and the actual effect of carburization is not significant and the carbon content of castings is insufficient. The amount of recarburizer added depends on the formulation and carbon content of other raw materials. Different types of pig iron are selected according to different models and specifications of recarburizers. The characteristics of the recarburizer itself selects pure carbon content graphitized chemicals to reduce excessive residues in the cast iron. The selection of suitable recarburizers can reduce the cost of casting products.

In the entire process of the smelter, due to poor seasoning or discharging and excessive carburization, sometimes the carbon content in the steel does not meet the top-period regulations. At this time, it is necessary to increase the carbon in the desolubilization. Common recarburizers include recarburizing cast iron, electrical grade powder, petroleum coke powder, charcoal powder and coke powder. In steelmaking furnaces and smelting plants of medium and medium carbon steel, petroleum coke with very little residue is used as a recarburizer. The requirements for the recarburizer for top-blowing converter steelmaking are that the fixed carbon should be high, the ash, volatile, and sulfur, phosphorus, nitrogen and other residues should be low, and it should be dry, tidy, and have a moderate particle size distribution.

Its fixed carbon composition is:

w(C)>96%, volatile matter≤1.0%, w(S)≤0.5%, w(moisture)≤0.55%, particle size distribution is 1 to 5 mm.

If the particle size distribution is too fine, it is easy to ablate, and if it is too coarse, it will float on the surface of the desolubilization and cannot be digested and absorbed by the molten steel. For the induction furnace, the particle size is 0.2-6 mm, in which steel and other light metals are 1.4-9.5 mm, and the medium carbon steel is specified for low nitrogen, and the particle size is 0.5-5 mm. These are actually based on the actual furnace type smelting These key points are actually distinguished and adopted by the types of factory product artifacts.

1. Furnace capital investment method:

The recarburizer is suitable for smelting applications in induction heating furnaces, but the actual applications are also different according to the processing technology regulations.

(1) The recarburizer is used in the smelting of the intermediate frequency electric furnace, which can be added to the lower part of the heating furnace according to the preparation or carbon equivalent regulations, and the utilization rate reaches 95%;

(2) If the amount of carbon is not enough to adjust the carbon time-sharing chart, first use the slag in the clean furnace, and then add a recarburizer. According to the temperature of the molten iron, electromagnetic induction mixing or manual mixing, the carbon can be melted, digested and absorbed, and the utilization rate can be 90%. Up and down, if the warm recarburization process is selected, that is, only part of the recycled waste is melted. When the molten iron temperature is low, the recarburizer is added to the molten iron at one time, and the solid recycled waste is used to press it into the molten iron. It is not allowed to expose the surface of the molten iron. In this way, the carbon increase of molten iron reaches 1.0%.

2. Carbon increase outside the furnace:

(1) Spray graphite powder in the bag

Graphite powder is used as a recarburizer, and the blowing rate is 40kg/t, which is estimated to increase the carbon content of the molten iron from 2% to 3%. As the carbon content of the molten iron slowly rises, the carbon usage rate decreases. The temperature of the molten iron before recarburization is 1600°C, and the average value after recarburization is 1299°C. Injecting graphite powder to increase carbon, generally uses N2 as the medium, but under the industrial production standard, it is more convenient to use air compression, and the oxygen in the air compression causes CO. The chemical change heat can compensate for a part of the temperature drop, and the CO recovery atmosphere has Conducive to improving the actual effect of carbon increase.

(2) Apply recarburizer when tapping iron

You can put the 100-300 mesh graphite powder recarburizer into the bag, or rush into it from the tapping trough. After the molten iron is filled, the molten iron can be fully mixed, and the carbon can be melted and digested as much as possible. The carbon utilization rate is around 50%.