Where It All Begins – Iron Ore Mining ProcessIf we’re going to break down the logistics in the steel industry from start to finish, then we have to go to the origin, which is iron ore. Iron ore are rocks and minerals from which metallic iron can be extracted, so step one in the mining process is to find large iron ore deposits in the earth. When an ore deposit is initially discovered, the ground cover of surface vegetation, soil, and rock material is removed to reach the ore deposits. The overburden is continually removed throughout the iron ore mining process, and this continual cutting creates ore benches that resemble steps in the side of the pits.
BlastingAs the benches are formed, they become the site for blasting. Machinery is used to drill holes of suitable diameter, depth, and direction for explosives to be placed for what’s called “blasting.” This is where the process of converting iron to steel begins. Blasting is critical to the iron ore mining process and is used to expose the ore body and break it up for extraction. Blasting must create combustion without an external oxygen supply, and the most common explosives used to do so are a mixture of ammonium nitrate and fuel oil (ANFO).
TransportationFollowing blasting, the broken ore is ready for transport and loaded onto mine haul roads. Depending on the distance from the open pits to the blast furnaces, large dump trucks or belt conveyors may be used to transport the ore materials to the next phase of the iron ore mining process.
CrushingSince mined iron ore contains lumps of varied sizes, the biggest being more than 40 inches across and the smallest about 0.04 inches, it typically undergoes a crushing process to prepare it for the blast furnace which can handle lumps 0.27 – 0.98 inches in size.
SeparationOnce crushed, the separation process begins and the iron ore particles are divided into various sections by passing over sieves through which undersized material (or fines) will fall. During this process, the fines will be reformed into lumps of suitable size by a process called sintering.
Making pelletsFinally, the iron ore is made into pellets by combining iron ore with other products to create easily transportable materials. The range of additional ingredients used in pellet-making varies. However, it is not unusual for each pellet to contain some type of clay or limestone and elements such as dolostone and olivine as part of the mix.
The Steelmaking Process Begins With Smelting Iron OreNow that the iron ore is in pellet form ready for processing, the steel-making process begins. The first step is iron smelting, which is an industrial process used to extract usable iron from raw ore with heat and chemical agents. Iron smelting takes place in a blast furnace for intense heating, along with limestone and coke, and converted to molten iron. The molten iron is then tapped from the bottom of the furnace into molds known as pigs and allowed to solidify into pig iron. After smelting, the iron can be further processed and alloyed with other materials to produce steel. Here are some of the different methods of steel production.
Shaping SteelBefore steel transport and use can happen, the steel needs shaping. Several different methods for shaping steel are available in steel making, and they largely depend on the desired steel application.
Roll formingRoll forming involves gradually bending flat sheet metal into a long, uniform shape by passing it through a series of tool dies. It is highly economical for mass production of angles, channels, long components with holes, and complex shapes with multiple bends. Some common applications of roll-formed steel are:
- Construction Equipment
- Door Components
ExtrusionExtrusion is a process in which metal is confined in a closed cavity and then allowed to flow through only one opening so that the metal takes the form of the opening, much like squeezing toothpaste out of a tube. Some common applications of extrusion are:
- Aluminum Cans
- Fuel Supply Lines
Press brakingWhen a piece of sheet metal is formed along a straight axis, this is press braking. This process can be accomplished by a v-shaped, u-shaped, or channel-shaped punch and die set. Although press braking appears to be a simple concept, maintaining accuracy can often be quite difficult. This process is most commonly used for:
- Decorative or Functional Trim
- Electronics Enclosures
- Safety Features
StampingMetal stamping converts flat metal sheets into specific shapes or cuts out a piece of metal. This complex process can include several metal forming techniques, such as blanking, punching, bending, or piercing. Common applications of stamping include:
- Aircraft Components
- Power Tools
ForgingSteel forging shapes metal using localized compressive forces, or blows, delivered with a hammer or a die. The temperature at which it is performed determines the classification: cold forging, warm forging, or hot forging. Forged steel is commonly used to create:
- Axle Beams
- Ball Joints
- Drill Bits
CastingSteel casting involves pouring liquid metal into a mold that contains a hollow cavity of the desired shape. These items are typically made with forged steel:
- Art items
- Camera Bodies
- Casings, Covers