Iron is an essential element in many industries and represents an invaluable resource in the development of infrastructure and everyday products. Since the dawn of civilization, human beings have been looking for ways to acquire it and make use of its magnetic properties, mechanical strength and malleability. But how does it go from the mine to the factory, how is it extracted and processed?
Iron ore extraction
Iron comes principally from ores such as hematite, iron and magnetite. It is extracted from mines, either open pit or underground, using controlled detonations and excavations. The process varies according to the type of mine:
- In open-pit mining, excavations are usually made in the earth’s surface to extract the ore. First, the layer of soil and rock covering the ore body, known as overburden, is removed. Next, explosives are used to fragment the iron ore, which is then loaded onto trucks or conveyors and taken to the processing plant.
- In underground mines, galleries and tunnels are created to access the mineral deposit. Specialized equipment and machines, such as drills and loaders, are used to extract the ore and transport it to the surface. This method is only used when the deposit is at great depth or when the quality of the ore is high.
Preparation and processing of iron ore
Once the iron has been extracted, it has to be prepared and processed. Different techniques can be used to do this. It should also be noted that depending on the hardness and size of the pieces, the process may change, including further crushing or grinding steps. These are the main techniques used:
The iron ore is screened to separate out the smaller pieces. A fixed screen is used that the small particles fall through, keeping the machine from overloading and from consuming unnecessary power.
Shredding and stacking
The iron ore is then broken down into smaller sizes before being further crushed. When the ore has all been properly crushed, it is moved to a stockpile.
This stockpile is what allows a constant supply of material to the mill. This is important because it helps to ensure consistent results and stability in the iron recovery process. It is like a “warehouse” that ensures that there is always enough raw material available.
The mill grinds or mills the iron before it is separated. Efficient grinding is important as it minimizes the amount of recirculating material returning to the mill. This works by retaining the material inside the mill for a certain period of time.
Once the iron leaves the mill, it is classified using vibrating screens that isolate the fine particles from the coarse ones. The coarse particles are sent back to the crusher to be reground, while the fine particles are separated by gravity using spirals.
Gravity separation with spirals
In the spirals, the parts that are heavier or more volumimous are separated from the rest by centrifugal action. Larger particles concentrate in the lower parts and the smaller particles exit the system. This can be repeated several times.
What are the main uses of iron in forging?
Iron is a widely-used material in the forging industry. When subjected to high temperatures, it becomes malleable and can be molded into different shapes and sizes easily. This makes it ideal for the manufacture of a wide range of forged products.
One of its main uses is in manufacturing parts and components for heavy machinery, such as shafts, gears and sprockets. These require the high strength and durability that iron provides.
Iron is also used in the manufacture of hand tools and hammers, as its strength allows it to withstand repeated blows without deforming. It is also used in the production of metal structures, such as bridges and buildings, due to its ability to withstand heavy loads and tension.
Another common use of iron is in the manufacture of decorative elements, such as lampposts or other elements for public use. The reason is that iron makes it possible to create intricate and detailed designs, adding an aesthetic touch to different structures and spaces.