Steel, one of the most widely recycled materials, plays a crucial role in reducing environmental impact. In fact, an impressive 80% of the UK’s scrap steel is recycled, making it a global leader in sustainable steel practices, in stark contrast to the US, where only 50% is recycled. However, beneath these promising statistics lies a less encouraging reality.
To truly grasp the sustainability of steel recycling, it’s essential to understand the manufacturing process that transforms iron ore into steel. This process, which employs virgin materials like iron ore, is known as primary production.
Blast Furnace: The initial step involves converting iron ore into iron. In a blast furnace, coke, iron ore, and limestone are combined, and a hot blast of air, heated to 1,000 degrees Celsius, ignites the coke. This intense heat raises the furnace’s interior temperature to over 2,000 degrees Celsius, creating molten iron, which settles at the furnace’s bottom due to its higher density compared to molten limestone and coke.
Turning Iron into Steel: The second step is transporting the iron to a steel plant for further processing. To reduce the carbon content in iron and transform it into steel, two methods are commonly used: basic oxygen steelmaking (BOS) and electric arc furnace (EAF). In 2019, global crude steel production reached 1.87 billion tonnes, with approximately 70% from BOS and 30% from EAF, the latter being predominant in recycling scrap steel.
Refining the Steel: The final stage involves various processes to refine the steel further, depending on the desired composition. For instance, alloying steel with chromium produces stainless steel.
The global steel industry is responsible for a significant share, approximately 5-8%, of greenhouse gas emissions worldwide, making it one of the most polluting industrial sectors. To put it in perspective, producing 1 ton of steel results in around 1.8 tons of carbon dioxide emissions.
Recycling steel has been practiced primarily for economic reasons due to its inherent magnetism, making it easy to separate from other materials. Moreover, steel doesn’t undergo significant chemical property changes during recycling, enabling endless recycling possibilities. In theory, your car could be made from steel initially manufactured in 1950.
The real economic value of recycling steel lies in substantial cost savings in primary production. By recycling steel, you skip the energy-intensive blast furnace stage, leading to a remarkable 70% energy savings. For every 1 kg of recycled steel, you save 1.5 kg of CO2 emissions and 1.4 kg of iron ore. This is partly attributed to the higher efficiency of electric arc furnaces compared to blast furnaces. As a result, steel recycling is gaining popularity for its environmental benefits, in addition to economic incentives.
The electric arc furnace (EAF) method is the primary choice when recycling old steel, as it can incorporate more than 80% recycled steel in a single furnace load. In contrast, the basic oxygen steelmaking (BOF) process typically uses only 25% to 35% scrap steel in its total load.
It’s estimated that a whopping 93% of waste steel can be recycled, offering significant room for improvement in reducing the steel industry’s environmental impact. The good news is that steel is highly recyclable, and a substantial portion of it already undergoes recycling.
In fact, we can guarantee that our steel raised planter edging systems include a proportion of recycled steel. Since all recycled steel is melted down and reformed, it’s challenging to specify the exact proportion. Nonetheless, ensuring steel is recycled at the end of its lifespan is a promising step toward a more sustainable future.