What does it take to get from raw materials, to molten iron, to beautifully-finished flat-rolled steel?
The life cycle of steel production is an important and extensive one. For those of us in the industry who deal with (or monitor) the process at every step, it’s our duty to understand the ins and outs of steel production. This way, we can confidently ensure the products we’re manufacturing and selling are of the utmost quality.
The following is an outline of how steel is made and what this life cycle means to the industry.
1. Iron ore and coal coking
Steel is an alloy primarily based on iron, but iron only occurs naturally as iron oxide in the earth’s crust. Because of this, the ores must be “converted” or “reduced” using carbon. Carbon is produced after coal is coked and heated.
The coal coking process involves heating metallurgical, or coking, coal to 1000-1100 degrees Celsius in the absence of oxygen, creating hard, porous lumps called coke. The absence of air succeeds in driving off impurities so the remaining carbon is pure. The entire process occurs over 12-36 hours in coke ovens.
The coke is either quenched immediately for storage or transferred directly into a blast furnace for iron-making. In the blast furnace, the coke is combined with iron ore and flux (small quantities of minerals like limestone), which collect more impurities. Heated air (about 1200 degrees Celsius) is blown to burn the coke and produce carbon monoxide, which reacts with the ore and melts the iron. The impurities are then drained, and voila, you have hot metal ready for steelmaking.
2. Steel production
The most common steelmaking process occurs in a Basic Oxygen Furnace and accounts for about 70% of the world’s steel production . There, molten iron ore is combined with steel scrap and more flux. The scrap melts, the flux purifies, and the carbon content is reduced by 90%, resulting in liquid steel. Secondary processes may be applied afterwards, like the addition of elements such as boron or chromium.
Another 29% of the world’s steel production is produced using Electric Arc Furnaces. This process does not involve actual ironmaking; only the re-use of existing steel. These mini-mills run an electrical charge which is supplied when electrodes are placed within the furnace, producing an arc of electricity that melts recycled steel scrap directly into new steel. Fluxes may be used to drain out impurities.
The additional 1% of steelmaking can be accounted for by less common methods like Pulverized Coal Injection.
3. Finished products
Molten iron from production furnaces typically runs through continuous casters and is formed into slabs, blooms, and billets. These basic products are further processed to create even more steel products through various operations such as hot rolling, cold rolling, and hot dip galvanizing
Pacesetter processes flat rolled steel from domestic and offshore mills to provide our customers with galvanized steel, cold rolled steel, galvannealed steel, aluminized steel, stainless steel, and galvanized bonderized steel products.
We provide in-house services including high-speed precision slitting, precision blanking, cut-to-length sheets, along with finishing touches such as pre-painting, embossing, perforating, and fabricating.
Our steel products are used in a large number of industries, and their life cycle does not end there. Since steel is 100% recyclable, many of our products will someday return to the furnace, where they will be melted, produced, and finished all over again. The great beauty of steel is that it is the eternally reincarnated backbone of industry.