Principles of the Smelting Process in a Closed Calcium Carbide Furnace

Principles of the Smelting Process in a Closed Calcium Carbide Furnace

Based on the aforementioned analysis of the reaction process in the closed calcium carbide furnace (submerged arc furnace) and the distribution of materials within it, quicklime and carbon sources transition from a solid to a molten state due to the heat generated by electrical resistance and arcing. This transition significantly enhances the kinetic energy within the molecules. 

The heat promotes the mutual movement and contact of molecules, particularly near the electrode ends. Under high-temperature conditions, the more reactive calcium oxide comes into contact with carbon, forming intermediate products. 

This process subsequently leads to the separation of calcium, producing calcium vapor. When the calcium vapor comes into contact with carbon, calcium carbide is formed, completing the preparation process of calcium carbide.

With the continuous preparation and synthesis of calcium carbide material, its content is steadily increasing, further elevating the temperature of the molten material.

The co-generated carbon monoxide species disturb the molten material, enhancing the contact area and the likelihood of reactions, thereby facilitating the rapid progression of the reduction and reaction processes.

The smelting process within the calcium carbide furnace can be subdivided into six distinct phases based on varying states, as follows:

Upon entering the carbide furnace, the material is initially preheated in the preheating layer. During this phase, the temperature is relatively low, and the lime and coke primarily exhibit a phase separation stage:

A. As the material sinks progressively into the diffusion and reaction zones, the temperature at the end adjacent to the electrode increases, leading to the onset of melting of calcium oxide. The molten calcium carbide reacts with the surrounding carbon to form an intermediate substance, CaOC;

B. As the position continues to descend, the temperature increases further, causing the intermediate substance CaOC to dissociate into calcium vapor. Upon contact with the carbon source, the calcium vapor generates calcium carbide;

C. During the generation of calcium carbide, the reaction produces one molecule of carbon monoxide, which initiates a perturbation in the system. Under this influence, further production of calcium oxide melt occurs;

D. At this point, the aforementioned process will be repeated, continuously generating calcium carbide and carbon monoxide;

E. Until the reaction stabilizes, a eutectic mixture of calcium oxide and calcium carbide is formed;

F. Deposition occurs within the molten pool, resulting in the formation of a molten layer.