In the production process of graphite electrode, graphite anode and high density and high strength graphite products, in order to reduce the porosity and improve the density and strength of the products, it is necessary to impregnate the semi-finished products after baking. If the impregnated products are directly sent into the graphitization furnace, the production efficiency of the graphite chemical process will be reduced, the power consumption will be increased, the environment will be polluted and the working conditions will be deteriorated. Therefore, it is necessary to put the impregnated product into the calciner again, so that the impregnant can be carbonized under mild conditions. Practice has proved that the secondary roasting of the impregnated products is beneficial to improve the quality of graphitized products and the economic benefits of enterprises.

The main difference between the second roasting and the first roasting is that the products after the second roasting are impregnated after one-time roasting. The geometric shape of the products has been fixed, and the overall deformation will not occur during the second roasting. In addition, the thermal conductivity of the impregnated product is higher than that of the original product, so the heat treatment process of the second calcination is faster than that of the first roasting, and the final temperature is only 700 ℃. Therefore, if the first roasting curve is 320h, the second roasting curve is generally 138h. Another characteristic is that the filler is not needed in the second roasting.

The main technical feature of the secondary baking of the impregnated electrode is that when the calcined product reaches 400-500 ℃, some asphalt will be heated and melted out of the impregnated electrode. If the ordinary tunnel kiln is used for roasting, it will flow to the kiln car surface, and the other part will be released as combustible gas. Therefore, it is necessary to adopt the roasting device which can make the combustible materials escaping from the electrode burn directly in the kiln.