(1) The nitrogen content of coal carburizer is different according to the quality of coal, generally in the range of 2000 —— 7000ppm, that is 0.2% —— 0.7%.

(2) Ordinary calcined petroleum coke carburizer, because it has not been calcined at high temperature, may be calcined at low temperature and short time. Generally, the nitrogen content is about 1000ppm, and the sulfur content is also high. You can't draw a clear mark on white paper.

(3) The content of nitrogen is 300-500 ppm and the sulfur is much lower than the former. You can leave clear marks on white paper.