Pig Iron
Pig iron is a casting material extracted from iron ore that contains high levels of carbon, iron, and other impurities. Pig iron is the basis of
Steelmaking
Desulfurization outside the furnace of molten iron refers to a pretreatment process that desulfurizes the molten iron outside the furnace before entering the steelmaking furnace to reduce the sulfur content of pig iron, improve the quality of steel, and improve the comprehensive technical and economic indicators of the steel plant.
Steelmaking is the processing of pig iron into steel with certain chemical composition, mechanical properties and physical properties. The process goes through many steps, each requiring different operations and additives.
Blast furnace desulfurization is the process of removing sulfur in blast furnace ironmaking and is the most important desulfurization link in steel production. Sulfur is one of the most harmful elements in steel. In order to reduce its harm, the sulfur content in steel must be reduced as much as possible. Theoretically, desulfurization should be completed during ironmaking in the blast furnace. Chinese national standards stipulate that the maximum allowable sulfur content in pig iron shall not exceed 0.07%, and companies often use 0.03% sulfur content in pig iron as a quality assessment indicator. Therefore, blast furnace desulfurization is the primary issue in producing qualified pig iron.
Sulfur can be dissolved in liquid pig iron to form an infinite solution. Although the solubility of sulfur in solid iron is very small, it can be concentrated on the grain boundaries in the form of sulfides such as FeS to form a low melting point eutectic of Fe and FeS. When heated to a certain temperature, a liquid phase appears in iron. This leads to thermal brittleness of iron and steel, and the steel is prone to cracks during rolling and forging. Sulfur can also form sulfur oxides with oxygen in steel, causing hot embrittlement to occur at lower sulfur content and temperature. Various sulfide inclusions can also be formed in iron and steel. Together with other non-metallic inclusions, they have a great impact on the mechanics of steel, reduce the filling ability of molten iron, and cause bubbles in castings.
