Classification & Function of Submerged Arc Furnace Electrodes

The main function of the submerged arc furnace electrodes is to conduct electricity and convert electrical energy into thermal energy, thereby realizing the smelting of ore.

The electrode of the submerged arc furnaces (such as ferroalloy furnace, calcium carbide furnace, ferrosilicon furnace, etc.) is the core conductive component, which is responsible for converting electrical energy into thermal energy, so that the material in the furnace undergoes a reduction reaction or melts. Its performance directly affects the smelting efficiency, energy consumption and product quality.

Electrodes are usually divided into carbon electrodes, graphite electrodes and self-baking electrodes.

Self-baking electrodes are often used in SAF because of their low cost. The electrode holder is a key device for controlling the electrode, including conductive, clamping, pressing and releasing devices to ensure the stable operation of the electrode in the furnace.

The quality and operating status of industrial furnace electrodes directly affect the production efficiency and product quality of the submerged arc furnace.

Types of Submerged Arc Furnace Electrodes

SAF mainly uses two types of self-baking electrodes and pre-baked electrodes:

1). Self-baking electrode (Söderberg electrode)

Composition: The electrode shell (steel plate) is filled with electrode paste (asphalt coke + anthracite + binder), which is sintered and formed at high temperature in the furnace.

Features:

• It can be continuously extended without stopping for replacement, suitable for large-scale submerged arc furnaces (such as calcium carbide furnaces and ferrosilicon furnaces).

• Low cost, but the sintering process is complicated and prone to soft and hard break accidents.

• Sintering process produces smoke (a purification system is required).

2. Pre-baked electrodes

Composition: Carbon or graphite electrodes (such as graphitized electrodes) pre-baked in a special furnace.

Features:

• High strength, good conductivity, low resistivity, suitable for high-power SAF (such as yellow phosphorus furnaces and industrial silicon furnaces).

• It needs to be stopped for replacement, which is more expensive, but the stability is better than self-baked electrodes.

Characteristics of Submerged Arc Furnace Electrodes

1. High conductivity: It needs to withstand large currents (several thousand to tens of thousands of amperes), and the resistivity is low to reduce power loss.

2. High temperature resistance: The end temperature can reach more than 2000℃, and it needs to be resistant to oxidation and thermal shock.

3. High mechanical strength: avoid collapse of charge or fracture due to thermal stress.

4. Chemical stability: resist erosion by gases such as CO and SiO in the furnace.

5. Self-sintering (only self-baking electrodes): the electrode paste gradually cokes at high temperature to form a dense structure.

The Main Functions of Electrode

1. Power transfer: the high voltage current output by the transformer is introduced into the furnace to form an arc or resistance heat.

2. Thermal energy conversion: Arc heat (such as calcium carbide furnace): an arc is generated at the end of the electrode to directly heat the charge.

3. Resistance heat (such as ferrosilicon furnace): the current passes through the charge (such as coke + ore) to generate Joule heat.

4. Maintain the reaction zone: the electrode insertion depth affects the temperature distribution in the furnace and the efficiency of the reduction reaction.

5. Adjust the furnace condition: control the input power by raising and lowering the electrode to stabilize the smelting process.

The submerged arc furnace electrodes is a key component in a high temperature and high current environment. Its type and performance directly affect the smelting efficiency. Self-baked electrodes have low cost but complex maintenance, while pre-baked electrodes have good stability but high price. Reasonable selection and management of electrodes are crucial to reducing energy consumption and increasing production.