Ferrous Metals and Steel Production: A Comprehensive Overview
Ferrous Metals: An Introduction
Ferrous metals are those containing iron as a base element. They can also include small proportions of other elements.
Major Mineral Deposits
- Polanco
- Preserve Wagner
- Black Eyes
- Agrominsa
- Sherry Villafranca
- Alquife
- Riotinto
- Aznalcollar
- Tharsis
Types of Iron Ore
- Magnetite
- Hematite
- Limonite
- Siderite
Iron Ore Processing and the Blast Furnace
Gathering and Preparation
Iron ore undergoes crushing and grinding before entering the blast furnace. The useful ore is then separated from non-coking coal. Coking coal, essential for the process, can be artificially created.
Blast Furnace Operation
The blast furnace’s purpose is to melt the ore and generate the chemical reactions necessary to transform iron oxide into iron. The process also involves:
- Heating: The furnace reaches temperatures around 1650°C to melt the iron ore.
- Flux: Lime is introduced to react with impurities in the ore, forming slag.
- Slag Removal: The slag, containing impurities, is periodically removed from the furnace.
- Iron Extraction: Molten pig iron is extracted from the crucible at the bottom of the furnace.
The pig iron is then further processed into steel, often using a converter.
Steel Processing from Pig Iron
The Converter
Pig iron contains excess impurities that must be removed in refining furnaces, such as the LD converter. The process involves:
- Raw Materials: Liquid pig iron, flux, and alloys.
- Step 1: The converter is tilted to add pig iron and scrap.
- Step 2: The converter is upright, and oxygen is injected to burn impurities.
- Step 3: The converter is tilted to remove slag.
- Step 4: Steel is poured and alloys/carbon are added.
Steel Production from Scrap: The Electric Arc Furnace
Electric arc furnaces are used to process scrap steel. Key components include:
- Electrical Transformer
- Flexible Cables
- Electrode Arms
- Electrode Clamps
- Hydraulic Arm
- Smoke Vent
- Oscillating Structure
The process involves:
- Step 1: The lid is removed, and scrap is added.
- Step 2: The furnace is closed, and electrodes melt the scrap.
- Step 3: Oxygen is injected to remove impurities.
- Step 4: Slag is removed, and ferroalloys and carbon are added.
- Step 5: Steel is poured into a ladle.
Steel Casting
- Conventional Casting: Pouring liquid steel into a mold.
- Continuous Casting: Pouring liquid steel into a bottomless mold.
- Ingot Casting: Pouring liquid steel into molds, cooling, and storing.
Steel Rolling
Rolling involves passing the material between two rollers. There are two types:
- Hot Rolling: Performed at around 1000°C.
- Cold Rolling: Performed at room temperature.
Classification of Ferrous Alloys
- Irons: 0.01% to 0.03% carbon
- Steels: 0.03% to 1.76% carbon
- Cast Irons: 1.76% to 6.67% carbon
- Graphite: >6.67% carbon
Types of Steel
- Alloy Steels: Specific percentages of alloying elements.
- High-Alloy Steels: Higher proportions of alloying elements.
Commercial Presentation of Steel
- Sheets: 1×2 meters or 3×3 meters
- Bars: Long and massive
- Wire: Narrow diameter bars (less than 5mm)
- Strip: Thin and long plates
- Profiles: Hollow pieces with variable cross-sections (e.g., angular, IPN, tubular, square, T, rectangular)
Cast Irons
Cast irons are iron-carbon alloys that may contain other elements. They are classified by properties and composition.