According to the quality requirements, raw materials, and process conditions of the products, the cathode carbon blocks in China are basically divided into three categories: ordinary cathode carbon block, semi graphite carbon block, and graphite carbon block.
Anthracite calcined at 1250 ~ 1350 ℃ is the main raw material of common cathode carbon block. The semi graphite carbon block can be divided into two types according to different production processes. One is to use high-quality high-temperature electric calcined anthracite or to use more graphite fragments or even all graphite fragments as aggregate. The formed green products are only roasted (the roasting temperature does not exceed 1200 ℃) and no longer enter the graphitization furnace for heat treatment. This kind of carbon block is called semi graphite carbon block. The other uses more easily graphitized coke as aggregate, raw products are roasted and then put into graphitization furnace for heat treatment at 1800 ~ 2000 ℃. This kind of carbon block is called semi graphitized carbon block. The former has higher strength and hardness, while the latter has better conductivity and integrity. The graphitization temperature of graphite carbon block should reach about 2500 ℃ with easily graphitized coke as raw material.
The difference between semi graphite carbon block and graphite carbon block lies in the different degrees of ordered lattice arrangement of products, that is, the different degrees of graphitization. The degree of graphitization can be expressed by the resistivity of the product. The lattice of the graphite carbon block is basically in an ordered arrangement state, and the resistivity is less than 15 μ Ω· m. The graphitization degree of semi-graphite carbon block is low or only partial, and the resistivity is 15 ~ 45 μΩ· m. The highest heat treatment temperature of semi-graphite carbon block is about 2000 ℃, and the graphitization temperature of graphite carbon block is 2500 ~ 2800 ℃. Common cathode carbon block, resistivity 50 ~ 60 μΩ.m. There is no application of graphite cathode carbon block in China.