ZHENGSHAN TECHNOLOGY

Carbon electrodes can be divided into three types based on their applications and manufacturing processes: carbon electrodes, graphite electrodes, and self baking electrodes.

Carbon electrodes are made from low ash anthracite, metallurgical coke, asphalt coke, and petroleum coke as raw materials, with a certain proportion and particle size composition. When mixed, binders asphalt and tar are added, stirred evenly at an appropriate temperature, and pressed into shape. Finally, they are slowly roasted in a roasting furnace. It can be divided into four categories: natural graphite electrodes, artificial graphite electrodes, carbon electrodes, and special carbon electrodes.

Graphite electrodes are made of petroleum coke and asphalt coke as raw materials to produce carbon electrodes, which are then placed in a graphitization resistance furnace at a temperature of 2273-2773K and undergo graphitization to produce graphite electrodes. Graphite electrodes are divided into the following types.

① Ordinary power graphite electrodes allow the use of graphite electrodes with current densities below 17A/cm2, mainly used in ordinary power electric furnaces for steelmaking, silicon refining, yellow phosphorus refining, etc.

② The surface of the graphite electrode is coated with a protective layer (graphite electrode antioxidant) that is both conductive and resistant to high temperature oxidation, reducing electrode consumption during steelmaking (19% to 50%), extending the service life of the electrode (22% to 60%), and reducing electrode energy consumption.

③ High power graphite electrodes allow the use of graphite electrodes with a current density of 18-25A/cm2, mainly used in high-power electric arc furnaces for steelmaking.

④ Ultra high power graphite electrodes allow the use of graphite electrodes with current densities greater than 25A/cm2. Mainly used for ultra-high power steelmaking electric arc furnaces.

Self baking electrodes use smokeless coal, coke, asphalt, and tar as raw materials to make electrode paste at a certain temperature. Then, the electrode paste is loaded into the electrode shell installed on the electric furnace. During the production process of the electric furnace, it relies on the Joule heat generated by the current passing through it and conducts heat inside the furnace to self sinter and coke. This type of electrode can be used continuously, extended and shaped while being used, and can be fired into large diameters. Self baking electrodes are widely used in the production of ferroalloys due to their simple process and low cost.

Main technical performance of electrodes

The electrode material should have the following physical and chemical properties:

① Good conductivity and low resistivity are required to reduce energy loss, minimize short network voltage drop, increase effective voltage, and enhance melt pool power;

② The melting point should be high;

③ The coefficient of thermal expansion should be small. When the temperature changes rapidly, it is not easy to deform and should not cause small cracks to increase resistance due to internal stress caused by temperature changes;

④ Sufficient mechanical strength is required at high temperatures;

⑤ The impurities should be low and not contaminate the variety being smelted.

Selection of electrodes in the ferroalloy industry

Self baking electrodes are widely used in ferroalloy smelting, refining ferrosilicon, silicon chromium alloys, manganese silicon alloys, high carbon manganese iron, high carbon chromium iron, medium low carbon manganese iron, medium low carbon chromium iron, silicon calcium alloys, tungsten iron, etc. Self baking electrodes are prone to adding carbon to the production alloy and introducing carbon into the iron sheet, resulting in the production of low carbon iron alloys and pure metals. If carbon chromium iron, industrial silicon, and metallic manganese are used, carbon electrodes or graphite electrodes should be used.