Today I will share with you the production process of graphite electrode.
1. Calcination: Carbon material undergoes heat treatment at high temperature to drain out the moisture and volatile components, improving the physical and chemical properties of the raw materials accordingly. Generally, the carbonaceous raw materials use gas and their own volatile components as the heat source for calcining. The maximum temperature is 1250-1350 ℃.
2. Grinding refers to the process of grinding carbon raw materials to small powder particles with particle size below 0.15mm or 0.075mm by hanging stick ring roller grinding machine, ball mill and other equipment.
3. Sieving is a process of dividing the broken materials with a wide range of dimensions into several kinds of particles with a narrower range through a series of sieves with uniform holes. The current electrode production usually requires 4-5 granule grades and 1-2 powder grades.
4. Compounding refers to the process of calculating, weighing and focusing aggregate, powder and binder of various sizes according to the requirements of the formula. The scientific nature, suitability of formulation and stability of batching operation are the most important factors affecting the product quality index and performance.
5. Kneading: The process of uniformly agitating and mixing quantitative carbonaceous granule and powder with various sizes and binders at certain temperature, as well as kneading into plastic paste is called kneading.
6. Molding: The molding of carbon material refers to the technological process of forming green-ware (or called raw products) with certain shape, size, density and strength of the mixed carbon paste under the external force exerted by the molding equipment to produce plastic deformation.
7. Calcination: It is a technological process in which green carbon product is put into a specially designed heating furnace for high temperature heat treatment under the protection of the filling material so as to carbonize the coal pitch in the raw material. The bituminous coke formed after carbonization consolidates carbonaceous aggregates and powder particles together. The calcinated carbon products have higher mechanical strength, lower electrical resistivity, better thermal stability and chemical stability.
8. Immersion treatment is a process in which the carbon material is placed in a pressure vessel and the liquid impregnant asphalt is immersed into the pores of the electrode of the product under certain temperature and pressure conditions. The aim is to reduce the porosity of the product, increase the volume density and mechanical strength of the product and improve the electrical and thermal conductivity.
9. Graphitization refers to the high-temperature heat treatment process in which carbon products are heated to more than 2300℃ in the protective medium in a high temperature electric furnace to transform amorphous disordered structure carbon into three-dimensional ordered stone inky structure.
10．Machining: the purpose of carbon and graphite material machining is to rely on cutting to reach the required size, shape, precision, etc., to make the electrode body and joint in line with the requirements of use.
11. Inspection of finished graphite electrode: inspecting accuracy, weight, length, diameter, volume density, resistivity, pre-installation precision, etc.