Recarburizers are used to adjust carbon levels: Materials that incorporate carbon into the steel in a liquid state. There are many types of materials with the possibility of being used as recarburizers, but the usual ones are:
- Petroleum coke.
- Natural graphite.
- Synthetic graphite.
The higher percentage carbon content in the recarburizer, the higher its effectivity. If the percentage of ash in the coal is high, the dissolution rate decreases due to the formation of a layer of impurities on the surface of the refueling agent, preventing the transfer of carbon to the molten bath, which increases production times and costs. Another aspect to consider is the negative influence of the acidic components of the ash on the basic refractory lining of the furnace.
The particle size plays an important role when the recarburizer is added to the surface of the bath. If the recarburizer is too fine:
- It floats on the surface of the molten bath.
- It burns prematurely.
- It is sucked in by the gas collection system.
- It is removed along with the slag.
If the material is too thick it penetrates deep into the bath, therefore, the reaction surface is too small, causing the recharging to be slow and ineffective.
The most important characteristics that a recarburizer must have are the following:
- It should be easy to introduce to the molten bath.
- Good solubility.
- Good performance.
- Adequate homogeneity.
- High percentage of fixed carbon.
- Low ash, volatile matter and moisture content.