CASE2

Lime powder plays an important role in steelmaking plants, mainly including the following aspects:

1、 Slagging effect

1. Removing impurities: During the steelmaking process, pig iron contains a large amount of impurities such as silicon, manganese, phosphorus, sulfur, etc. Lime powder reacts with these impurities to form slag with a lower melting point. For example, quicklime powder reacts with silicon to produce calcium silicate, and reacts with phosphorus to produce calcium phosphate. These slag can float on the surface of the molten steel for easy discharge, thereby reducing the impurity content in the steel and improving its quality.

2. Adjusting the fluidity and alkalinity of slag: Appropriate slag fluidity is crucial for the steelmaking process. Lime powder can adjust the alkalinity of slag and make it have appropriate fluidity. When the alkalinity of slag is moderate, the viscosity of slag is low and the flowability is good, which is conducive to the separation of molten steel and slag and improves steelmaking efficiency. Meanwhile, appropriate alkalinity can also promote the removal of impurities and improve the purity of steel.

2、 Desulfurization effect

1. Reaction with sulfur in pig iron: Sulfur is a harmful element in steel that can reduce its toughness and weldability. Calcium oxide in quicklime powder reacts with sulfur in pig iron to form calcium sulfide, thereby removing sulfur from steel. For example, in the steelmaking process, adding an appropriate amount of quicklime powder can reduce the sulfur content in the steel to the specified range and improve the quality of the steel.

2. Formation of stable sulfides: The generated sulfides such as calcium sulfide are relatively stable in the slag and are not easily re entered into the molten steel. This can ensure the stability of desulfurization effect and guarantee the quality of steel.

3、 Protective function of furnace lining

1. Formation of slag protective layer: During the steelmaking process, slag forms a protective layer on the surface of the furnace lining, reducing the erosion of the furnace lining by molten steel and furnace gas. Lime powder, as a slag forming agent, helps to form a stable slag protective layer. For example, when the content of calcium oxide in the slag is high, the melting point and viscosity of the slag are high, which can better adhere to the surface of the furnace lining and protect it.

2. Reduce the temperature of the furnace lining: The reaction between quicklime powder and impurities in the molten steel releases a large amount of heat, which can be absorbed by the slag, thereby reducing the temperature of the furnace lining. Lower furnace lining temperature can extend the service life of the furnace lining and reduce steelmaking costs.

4、 Improving thermal efficiency

1. Heat absorption: The reaction between quicklime powder and water will absorb a large amount of heat, which can play a certain cooling role in the steelmaking process and regulate the furnace temperature. At the same time, the quicklime powder that absorbs heat will be converted into calcium hydroxide, which further participates in slagging and other reactions, releasing more heat and improving the thermal efficiency of the steelmaking process.

2. Promote combustion: In the steelmaking process, a large amount of fuel needs to be burned to provide heat. Calcium oxide in quicklime powder can react with sulfur in fuel to produce substances such as calcium sulfate, reducing the adverse effects of sulfur on combustion, promoting full combustion of fuel, and improving thermal efficiency.

In summary, quicklime powder plays an important role in steelmaking plants by improving the quality of steel, reducing production costs, and extending the service life of furnace linings through slag making, desulfurization, furnace lining protection, and increasing thermal efficiency.