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Fabricación de acero
La fabricación de acero es un proceso de varias etapas que comienza con la fundición del mineral de hierro para convertirlo en hierro fundido en un al…
La fabricación de acero comienza con la fundición del mineral de hierro en hierro fundido en el alto horno. La fundición consiste en estratificar el mineral de hierro con un combustible llamado coque y piedra caliza triturada en el horno.
Primero, el coque se enciende con una ráfaga de aire, produciendo monóxido de carbono, que reduce el mineral a hierro fundido.
La piedra caliza forma una escoria, capturando las impurezas, y flota sobre el metal fundido. A continuación, este hierro fundido se drena para el procesamiento del acero.
El hierro fundido contiene exceso de carbono e impurezas. Se adopta un proceso básico de oxígeno para eliminarlos. Se trata de una lanza de oxígeno sumergida en hierro fundido y chatarra, utilizando un fundente de cal y fluorito, que forma escoria desechable al reaccionar con el fósforo.
Por último, se pueden introducir nuevos elementos metálicos para modificar la composición del acero según sea necesario.
Cuando el acero llega a la etapa de vertido desde el horno, se moldea en lingotes o se procesa a través de una máquina de fundición de hebras. Los moldes de lingotes pueden tener diámetros que abarcan varios pies y alturas que van de seis a ocho pies.
Además, el acero terminado se funde continuamente en formas gruesas y rugosas conocidas como piezas en bruto o florituras.
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Q1: What happens during the smelting stage of steel manufacturing?
Smelting occurs in a blast furnace where iron ore is layered with coke fuel and crushed limestone. Coke ignition produces carbon monoxide, which reduces the ore to molten iron. Limestone forms slag that captures impurities like silica and phosphorus, floating above the molten metal for easy separation before the purified iron drains for steel processing.
Q2: How does the basic oxygen process improve molten iron quality?
A water-cooled oxygen lance is dipped into molten iron mixed with scrap metal. Lime and fluorspar flux are added, reacting with phosphorus and other impurities to form discardable slag. This refining process removes excess carbon and contaminants, producing cleaner steel suitable for composition modification with new metallic elements.
Q3: What role does limestone play in the blast furnace?
Limestone is layered with iron ore and coke in the blast furnace. During smelting, it forms slag that captures impurities such as silica, phosphorus, and alumina from the molten iron. The slag floats above the molten metal, allowing easy separation and removal of contaminants before the purified iron is drained.
Q4: What are the two main methods for shaping steel after refining?
Refined steel is shaped through ingot molding or strand casting. Ingot molds are large containers with diameters and heights spanning several feet, producing individual ingots. Alternatively, strand-casting machines continuously cast refined steel into thick, rough shapes called beam blanks or blooms, ready for further processing into various steel products.
Q5: Why is carbon monoxide essential in iron ore reduction?
Carbon monoxide is produced when coke is ignited with a blast of air in the furnace. It acts as the reducing agent, chemically converting iron ore into molten iron by removing oxygen from the ore. This reduction process is fundamental to extracting pure iron from raw ore during the smelting stage.
Q6: What impurities does slag remove during steel manufacturing?
Slag captures impurities including silica, phosphorus, and alumina from molten iron during smelting. In the blast furnace, limestone reacts with these contaminants to form slag, which floats above the molten metal. During the basic oxygen process, lime and fluorspar flux also react with phosphorus to form additional slag for removal.
Q7: How can steel composition be customized after the basic oxygen process?
After refining removes excess carbon and impurities through the basic oxygen process, new metallic elements can be introduced to modify the steel's composition. This allows engineers to tailor the steel's properties to meet specific requirements for different applications before the material is shaped into ingots or beam blanks.