Strong and resilient, steel is among the most widely-used materials globally. However, as the world grapples with the devastating consequences of climate change, builders are turning toward recycled steel for more sustainable construction.
Besides its sustainability benefits, there are many recycled steel facts you need to know before deciding if it’s the best material for your project.
Recycling steel conserves energy and natural resources like iron ore, coal, and limestone used to produce virgin steel. Moreover, the process promotes green building by eliminating the environmental degradation associated with opencast mining to extract iron ore.
Should we embrace recycled steel to mitigate the effects of climate change?
In this article, I’ll discuss the 14 important steel facts you need to know to make the right decision.
From its effect on environmental conservation and cost-efficiency to durability, recycled steel has many benefits for modern builders. Keep reading!
1. Steel Is 100% Recyclable
Steel is 100% recyclable due to its composition.
As an iron alloy, steel contains only trace amounts of other elements like carbon, silicon, manganese, and phosphorus. These non-metallic elements make it tougher and stronger.
Steel’s magnetic properties make it possible to easily separate it from other materials like paper, plastic, rubber, and other (non-ferrous) metals.
The recycling process takes advantage of steel’s magnetic properties in the separation process, where strong magnets are used to automate the process of separating the steel scrap from the rest of the material in the feedstock. This improves the incoming material’s quality, which helps produce pure, high-quality recycled steel.
After separation, the recycling process melts the steel scrap to form a liquid, which is poured into molds, where it cools, solidifies, and is cast into new products.
During solidification, atoms combine to form the crystalline structure of recycled steel. Careful control of the process, especially the composition of the steel and its rate of cooling, ensures the finished product has the same chemical and physical properties as virgin steel and can be used in exactly the same way.
2. End-of-Life Steel Scrap Availability Is on the Rise
The rate of steel production grew tremendously at the start of the 21st century. The growth was mainly due to the development and expansion of China’s construction industry.
The consequence of the high steel production rate is an increase in the quantity of end-of-life steel structures for demolition.
While the average lifespan of steel products ranges from a few weeks to over 100 years, the availability of end-of-life scrap steel is growing rapidly.
Consequently, building and construction projects have access to more recycled steel than ever. As a result, builders and homeowners can enjoy reduced costs for steel in their construction projects.
The graph below illustrates the growth trend of end-of-life steel availability and its projection into the future:
3. The Steel Scrap Price Is on the Rise
The demand for recycled steel is on the rise as more and more people realize the benefits of this material. As with anything else, the higher the demand, the higher the cost.
Steel recycling firms need more steel scrap to sustain the high demand for recycled steel. However, the availability of steel scrap depends on end-of-life steel structures for demolition.
Due to the limited number of end-of-life structures to demolish and the ever-increasing demand for steel scrap, the price of recycled steel has increased over the last ten years.
According to Statista, the price of steel scrap per metric ton (2,205 lb) rose significantly between 2010 and 2022, albeit with a slight drop in price during the middle of that period and a lot of general volatility. 2021 and 2022 both saw the price go above $400 per metric ton, and this increase is attributed to the material’s limited supply.
The table below shows steel scrap price variations in the U.S. between 2010 and 2022:
|Year||Price in U.S. Dollars Per Metric Ton|
Table 1: U.S. steel and Iron scrap prices per metric ton from 2010 to 2022. Source: Statista
4. Global Steel Scrap Consumption Is on the Rise
More people are becoming aware of the environmental benefits of recycled steel. As a result, steel has become one of the best sustainable building materials as more builders are using it.
Approximately 32% of the steel produced in 2019 came from scrap to meet the rising demand for recycled steel. The trend is expected to continue, meaning more steel scrap will be recycled.
The graph below illustrates the world’s crude steel production vs. steel scrap consumption:
5. Steel Is the Most Recycled Material
Steel is the most recycled material globally. This is because it can be recycled repeatedly without losing any of its properties, such as strength and surability.
According to the World Steel Association, 680 million metric tons of steel were recycled in 2021.
The high steel recycling rate is attributed to the material’s wide application scope. Steel is necessary for the operation of many industries. From automotive and machine tools to construction and shipbuilding, steel is essential for everyday activities.
Unfortunately, producing virgin steel is costly and unsustainable. Therefore, the solution is shifting to its cheaper recycled variant.
6. Steel Recycling Is Essential for a Circular Economy
A circular economy promotes continuous material production in an eco-friendly way.
Steel recycling is essential for a circular economy since it conserves natural resources like coal, iron ore, and limestone.
Moreover, recycling steel prevents valuable materials from getting into landfills and, instead, allows them to be used to manufacture other products.
7. All Steel Contains Recycled Content
Did you know that almost any steel product you use contains recycled content? This is because, even in the manufacture of virgin steel, steel scrap is added to the furnace charge to improve efficiency, sustainability, and sometimes for the purposes of alloying and quality control.
The amount of recycled steel in different steel products ranges from 25 to 100 percent.
According to the American Institute of Steel Construction, structural steel products have the highest recycled content, ranging between 90 and 100%.
Salvaged steel would be even better, and could be reused without being remelted, provided it meets strict quality control standards. Provided it passes the necessary quality control tests, you can demolish a structure and use its structural steel components in a new project.
8. Recycled Steel Conserves Energy
Virgin steel production is an energy-intensive process. Producing a ton (2,000 lb) of primary steel requires approximately 6.0 MJ of energy.
Using such a high amount of energy in steel production means high consumption of natural resources to generate power. These resources include coal, crude oil, and natural gas.
Fortunately, recycling steel is less energy intensive. According to the United States Environmental Protection Agency, recycling steel conserves between 60 and 74 percent of the energy used to produce virgin steel.
To put that into perspective, recycling a tiny steel product like a steel “food can” saves enough energy to power a 10-watt LED bulb for over a day.
9. Recycled Steel Is Highly Durable
Thanks to its high strength-to-weight ratio, steel is renowned for its superior strength and durability, and recycled steel is just as strong and durable as virgin steel.
A high strength-to-weight ratio means recycled steel can withstand heavy loads without deformation. Thus, it can be used in high-stress environments without losing its properties. This explains why the material is widely used in bridge and highway construction to support heavy loads.
High ductility is another feature that makes recycled steel useful in construction. Ductility refers to the ability to draw a material into thin wires without snapping. This is useful in the production of wires and cables used in construction.
Recycled steel’s high ductility means it can be bent and formed into different shapes without sacrificing strength or rupturing, something that’s very important for structural beams and metal cables.
Finally, recycled steel undergoes wear and tear tests before being released for use. This provides confidence that it’s manufactured to withstand wear and tear, making it suitable for long-term use.
10. Recycled Steel Reduces Carbon Emissions
Steel production is among the processes that generate very high carbon emissions.
Manufacturing a ton (2,000 lb) of virgin steel generates about 1.89 tons (3,780 lb) of carbon. This high carbon emission results from the following processes:
- Opencast mining and quarrying: These processes require heavy machinery like bulldozers, diggers, and trucks that burn fuel, emitting carbon dioxide.
- Transportation: Iron ore, coal, and limestone are transported by trucks to the manufacturing facilities, emitting more carbon dioxide.
- Burning of coal: Coal is burned to produce coke, the fuel for converting iron ore to pig iron. The burning process generates a high amount of carbon dioxide.
- Basic oxygen furnace operation: These furnaces use a high amount of energy, contributing to the generation of carbon dioxide from energy production.
Recycling steel reduces carbon emissions significantly because it doesn’t incorporate processes like opencast mining and coking coal production.
However, that doesn’t mean recycling steel is free of carbon emissions. The process emits some carbon dioxide because it involves transporting and melting steel scraps at high temperatures.
However, recycling a ton (2,000 lb) of steel prevents the emission of about 1.67 tons (3,340 lb) of carbon.
Therefore, recycled steel is a more eco-friendly material that helps to combat global warming and climate change.
11. Recycled Steel Conserves Natural Resources
As mentioned, manufacturing primary steel consumes more natural resources. Unfortunately, most of these resources are non-renewable and finite, and will eventually run out.
Producing virgin steel requires the following natural resources:
- Coal: It is used to make coke which is used in a blast furnace to generate high temperatures and carbon monoxide to smelt iron ore.
- Iron ore: It’s smelted in a furnace to produce pig iron, the primary material for steel production.
- Limestone: It’s used to absorb impurities from pig iron during smelting.
Recycling doesn’t need these natural resources — it only requires steel scrap.
Preserving these natural resources by recycling steel makes them available for future generations while promoting sustainable development.
In terms of numbers, here is how much of these resources recycling a ton (2,000 lb) of steel conserves:
- Coal: 0.8 tons (1,600 lb).
- Iron ore: 1.4 tons (2,800 lb).
- Limestone: 0.3 tons (600 lb).
12. Steel Is Stronger Than Iron
Strength is essential, especially for building materials. One of the main steel facts that makes it suitable for construction is its excellent strength.
Steel is stronger than iron, based on their relative tensile and yield strengths.
The main reason that steel has higher tensile and yield strength than iron is its lower carbon content.
Increasing carbon content in steel generally increases the strength and hardness of the steel because the carbon atoms sit in the spaces between the bigger iron atoms, which improves the strength of the metal’s lattice structure by distorting it.
However, pig iron has a much higher carbon content (3.5-4.5%) than even high carbon steel (0.60-2.00%). Such an elevated carbon content causes the pig iron to be very brittle and unsuitable for construction because it tends to form martensite, a brittle, hard phase of steel.
The table below summarizes the tensile and yield strength of iron, steel, and other metals:
|Metal||Yield Strength (MegaPascals)||Tensile Strength (MegaPascals)|
Table 2: Yield and tensile strengths of different metals
13. All Steel Is Made From Iron
Steel is manufactured from iron ore, a material extracted from the earth’s crust.
Iron is the fourth most abundant component in the earth’s crust, and you might already know that the core of the earth is made of a molten iron-nickel alloy.
Iron is also the primary component for producing steel through the intermediate material, pig iron, a high-carbon content form of iron.
During steel production, the carbon content is reduced by blowing oxygen into the molten metal, which reacts with the carbon to form carbon monoxide gas. Other components are often added to the furnace to increase steel’s strength and hardness. These components include manganese, phosphorus, silicon, and chromium.
14. Blast Furnace-Basic Oxygen Furnace (BF-OF) Route Accounts for 71% of Steel Production
A blast furnace is used to extract pig iron from iron ore. Pig iron is then used to manufacture steel in two ways:
- Basic Oxygen Furnace (BOF): A BOF uses the Basic Oxygen Process, combining steel scrap (25-30%) with pig iron (70-75%) in a furnace. Oxygen is blown into the mixture to raise its temperature to melt the furnace charge. The high temperatures oxidize and evaporate iron impurities, reducing the carbon content to the optimum level for steel.
- Electric Arc Furnaces: Electrodes operating at high currents are used to melt steel scrap, which is sometimes mixed with small amounts of pig iron (5-10%). While melting, small amounts of other metals, such as nickel and chromium, are added into the furnace to attain the desired ratio for making the desired ferroalloy.
The Blast Furnace-Basic Oxygen Furnace (BF-OF) Route accounts for the highest steel production at 71%. The Electric Arc Furnace method accounts for only 29%.
BF-OF is the primary method because it’s economical, well-suited to large-scale production, and produces excellent-quality steel.
Steel Facts – Our Final Thoughts On Recycled Steel
From these 14 recycled steel facts, it’s evident that the material has numerous benefits for use in construction.
It’s an eco-conscious material that reduces carbon emissions, conserves natural resources like coal and iron ore, and is stronger and lighter than other materials like timber.
Many eco-conscious builders are turning to recycled steel for its sustainability and to help combat climate change.
The key point to remember is that, when recycled, steel doesn’t lose its valuable properties like strength and durability, so it’s an excellent construction material – every bit as good as virgin steel.