The raw material used to make the electrode paste is a combination of solid carbonaceous material and binder.
The raw material formula and preparation process are closely related to the quality of the electrode paste. The solid materials include calcined anthracite, metallurgical coke, petroleum coke and graphite surface debris. Anthracite is dense and has a high carbon content. It can be used to improve the thermal stability, electrical conductivity and mechanical strength of the electrode. The binder of the electrode paste includes pitch and coal tar. Tar is added to adjust the softening point. The binder is decomposed during the sintering process of the electrode paste, and the volatiles are discharged and then converted into coke, so that a hard whole is formed between the electrodes.
The formulation of the electrode slurry should consider various factors such as the proportion of aggregates, the composition of the particle size, the softening point of the binder and the amount of addition. The quality of electrode paste is divided into standard type paste and closed paste due to different purposes. The former is mostly used in semi-closed submerged arc furnaces; the latter is mainly used in a closed electric furnace and large-capacity semi-closed electric furnace mainly due to its low temperature and easy sintering during the roasting process.
In general, mostly metallurgical coke and anthracite, and the total amount of airtight paste will have to adapt to a large amount of graphite and petroleum coke works. The binder of the standard paste can be mostly medium temperature pitch, and the binder in the closed paste uses tar in the process of using a large amount of funds, but also uses more graphite chips. Due to the high prices of graphite shreds and tar, this is the reason why the airtight paste, especially the high-standard airtight paste, is at a high price.