Description of Refining Slag:Refining slag is a composite material primarily composed of metal ions such as CaAl2O4, Al2O3, SiO2, CaF2, and MgO. These ions combine to form groups like CaO-CaF2, CaO-Al2O3, and CaO-Al2O3-SiO2. Based on its form, refining slag can be categorized into sintered refining slag, premelted refining slag, and mixed refining slag.
Mixed Refining Slag: This type is created by manually or mechanically mixing raw materials in a certain proportion and particle size. It is characterized by a simple method and flexible operation but has a slow melting speed and uneven composition.
Sintered Refining Slag: Compared to the mixed type, sintered refining slag is more uniform and stable, with a faster melting speed. However, it has a higher cost, and due to its lower density and larger number of pores, it is prone to suction during the refining process.
Premelted Refining Slag: This is the refining slag used for steelmaking. After mixing raw materials in proportion and melting them at a temperature higher than the slag system's melting point, the slag is cooled and crushed to obtain the premelted refining slag. It has high purity, uniform chemical composition, stable phase, low melting point, and fast slag formation speed. It can significantly shorten the refining time and can be directly used in the slag washing process of the converter ladle tapping process to improve the cleanliness of the molten steel.
Characteristics of Refining Slag:
Rapid slag formation greatly improves the kinetic conditions of the chemical reaction in the molten pool during refining, accelerates the reduction reaction, and thus shortens the refining time.
It has strong reducibility, deoxidation, and desulfurization capabilities to remove harmful components in the molten steel and has the ability to trap non-metallic inclusions in the steel, achieving the purpose of smelting clean steel.
It can significantly reduce power consumption, electrode consumption, refractory consumption, and the consumption of some expensive reducing agents such as aluminum and silicon-calcium alloy, and can also reduce the overall production cost in the refining process to a certain extent.
Application of Refining Slag:Refining slag is put into the ladle before tapping. As the molten steel flows into the ladle from the upper layer, there is vigorous stirring between the molten steel and the refining slag. The refining slag quickly melts in the molten steel and then aggregates and floats. Due to its strong reducibility, it has a strong deoxidation and desulfurization ability, which can remove oxygen and sulfur impurities in the molten steel during the mixing process.
Improving steel cleanliness through slag refining
Serial No. | Chemical composition % | Physical properties | Application |
CaO | Al2O3 | CaF2 | SiO2 | MgO | Moisture % | Grain size mm |
RLP-1 | 45～50 | 41～46 | 4～6 | ≤4 | 2～4 | ≤0.5 | 1～30 | Medium carbon steel |
RLM-1 | 46～55 | 30～38 | — | ≤6 | 4～10 | ≤0.5 | 1～30 | High carbon steel |
