Raw material and classification and performance of electrode paste
Raw material for preparing electrode paste
The raw material for making electrode paste is composed of solid carbon material and binding material. The quality of the electrode paste is closely related to the raw material formula and preparation process. Solid materials include calcined anthracite, metallurgical coke, petroleum coke and graphite electrode scraps. Anthracite is dense and has a high carbon content, which can improve the thermal stability, conductivity and mechanical strength of the electrode; the binder of the electrode paste includes pitch and coal tar, and 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 the electrode forms a hard whole. The formula of electrode paste should consider various factors such as the ratio of various aggregates, particle size composition, softening point of the binder, and the amount of addition.
Classification and performance of electrode paste
The quality of electrode paste is divided into standard paste and airtight paste due to different uses. The former is mostly used in semi-closed submerged arc furnaces; the latter is often used in closed electric furnaces and large-capacity semi-closed electric furnaces due to its low roasting temperature and easy sintering. The aggregates in the standard paste are mostly anthracite and metallurgical coke, while the aggregates in the closed paste are mixed with graphite and petroleum coke in large quantities. The binder of the standard paste is mostly medium temperature pitch, and the binder in the closed paste uses a lot of tar while also using more graphite chips. Due to the high prices of graphite shreds and tar, this is the reason for the high price of airtight pastes, especially high-standard airtight pastes.
The latest national standards for the physical and chemical indicators of electrode paste have not yet been announced, the original metallurgical industry standard YBT5215-1996 electrode paste physical and chemical indicators.