The usage method of petroleum coke carbon additive and the importance of detailed calibration of nitrogen composition

Carbon additive is a non-ferrous metal product used to make up for the loss of carbon elements in smelters. The application of carbon additives in the foundry industry is also very common. At present, there are no standards for the application of carbon additives in forging non-ferrous metals in China. Forging carbon additives can be divided into high-nitrogen, medium-nitrogen and low-nitrogen carbon additives. It is necessary to pay attention to the amount of nitrogen in the carbon additive!

Many carbon additive distributors also do not calibrate the nitrogen content in detail. Recently, I inquired with a well-known carbon additive distributor in China, and the results are as follows

Of course, when calcining petroleum coke carburizer, since it has not undergone high-temperature calcination, the calcination temperature will be slightly lower and the calcination time will not be long enough. The nitrogen content is generally around 1000PPm, and the sulfur content is also high. It is impossible to draw clear marks on thin paper.

(2) The high-temperature calcined petroleum coke carburizer has a nitrogen content of 300 to 500PPm and a sulfur content much lower than the previous one. It can leave clear marks on thin paper.

(3) Coal carbon additive, the nitrogen content varies depending on the quality of the coal, generally ranging from 2000 to 7000PPm, that is, 0.2% to 0.7%. Is it estimated to be bituminous coal? Anthracite? Difference?

(4) It is very important to remind everyone that the graphite column particle carburizer is a carburizer made by extruding graphite powder with a binder into cylindrical particles. This type of carbon additive, as the carbon appears in the form of high-purity graphite, has excellent digestion and absorption in the furnace. It is basically the same as the high-temperature calcined petroleum coke mentioned above, and its price is around 5,000 yuan. The staff of the smelting plant all think that this type of carburizer is very good, with low sulfur content and low nitrogen content. Actually, it's not!! This type of carbon additive has a very high nitrogen content!! It is generally around 2000PPm. We hope everyone will pay attention!!

(5) The most effective high-temperature calcined petroleum coke carburizer with a nitrogen content of 100PPm. The sulfur content is lower than the previous one. It can leave clear marks on thin paper and has a comfortable touch, just like a 6B signature pen.

The quality of the carburizer is not good, with a high nitrogen content. It can easily cause N2 hole defects in the castings. It is said that nitrogen can enhance the strength of the pig iron substrate and update the compressive strength. However, due to the addition of a large amount of scrap steel during the production of pig iron, the nitrogen content in the steelmaking furnace has already been limited. At this time, if the nitrogen content of the carburizer is again very high, it can easily cause N2 hole waste in the castings.