What are the differences in the three stages of electrode paste sintering?

The three stages of electrode paste sintering will result in different states of electrode paste at different temperatures, as follows:

Dissolution stage: At this stage, the coal tar in the electrode paste begins to gradually melt, and the electrode paste changes from solid to semi-solid. The heat source for dissolution mainly comes from the resistance heat generated by the current passing through the electrode shell, as well as the heat generated by the electrode heating element. At this stage, it is necessary to adjust the current and voltage appropriately according to the speed of electrode consumption.

Curing stage: As the temperature further increases, the coal tar pitch in the electrode paste continues to decompose and discharge, while undergoing carbonization reaction, gradually transforming the electrode paste from a semi-solid state to a harder carbon electrode. At this stage, the adhesive performance of the electrode paste is enhanced, and the strength and conductivity of the electrode are gradually improved.

High temperature sintering stage: After reaching a higher temperature, the electrode paste enters the high temperature sintering stage. At this stage, the coal tar pitch in the electrode is almost completely decomposed and discharged, and the carbon particles in the electrode paste will combine more tightly through chemical reactions and physical interactions at high temperatures, forming a dense carbon structure. The electrodes at this stage have high mechanical strength and conductivity, and can withstand high temperatures and intense chemical reactions inside the electric furnace.

These three stages are the different sintering processes that electrode paste undergoes in a submerged arc furnace as the temperature increases, each stage having its own specific temperature range and physical and chemical changes. Understanding and mastering these stages correctly is crucial for optimizing electrode management, improving production efficiency and stability of calcium carbide furnaces.