Recycled steel is a much more sustainable building material than virgin steel because it eliminates waste, emissions, and the enormous energy used to extract coal, iron ore, and limestone.
However, its sustainability depends on the recycling process — it must be recycled under carefully controlled conditions to minimize its environmental impact. You can achieve this by adhering to the best practices for recycled steel production and use.
Scrap metal recycling poses potential hazards like bruises, cuts, more severe injuries, and even death. Failure to adhere to best practices like sorting and segregation results in impure feedstock for recycled steel, meaning additional processing costs to ensure the final steel leaving the production process is good quality.
Upholding the best practices for recycled steel enhances employee safety and the quality of the recycled steel to be used for green building.
In this article, I’ll discuss the best practices for recycled steel to ensure safety and sustainability. You’ll know what is expected of you, from properly segregating the different waste types to sustainability modifications like using green process energy. Keep reading!
First, it’s essential to understand the steel recycling process before we cover the best practices. So, in case you’re not up to speed, let’s take a look at the procedure for producing sustainable, high-quality recycled steel that doesn’t compromise structural integrity.
You can recycle steel through the following steps:
The first step is collecting steel scrap for recycling and sorting it into different categories to ensure the purity of the final product.
Scrap metal dealers and local authorities collect steel scrap in person or from designated drop-off points. The primary sources of steel scrap for recycling include:
- Prompt (industrial) scrap: Residual scrap from off-cuts discarded during large-scale manufacturing processes like electronics, sheet metals, and automobiles. The manufacturer can’t keep the residue for reuse because they don’t have a milling plant for reprocessing, so it’s taken to a recycling facility.
- Home scrap: Like its prompt counterpart, home scrap is residual in-house leftovers of manufacturing processes. It can’t be marketed because it could be from trimmings or have manufacturing defects. However, unlike prompt scrap, home scrap is recycled and reused where it is manufactured. So, there is no need for collection and transportation.
- Obsolete scrap: This includes scrap appliances, household items, used automotive parts, and other products that are no longer in use. They’re collected for recycling or reuse as raw materials.
The scraps are then sorted magnetically based on their type — ferrous or non-ferrous.
The sorted scrap is then taken to a reprocessing mill to produce recycled steel.
Once in the milling facility, the scrap is taken into a mechanical shredder that crushes it into smaller pieces.
Shredding is necessary to make the recycling process more efficient in terms of energy consumption and to ensure the pieces are small enough to fit into the smelting furnace.
The shredded scrap is transferred into a large electric arc furnace for smelting.
The furnace operates at approximately 3,500°C (6,332°F) to turn the scrap into molten steel. The process involves the injection of oxygen and carbon and creates an insulating slag layer over the molten steel, which helps to prevent solidification.
The molten scrap undergoes purification to remove impurities that can affect the final product’s quality.
Purification is one of the most important best practices for recycled steel that ensures high-quality products.
Steel recycling firms often purify the steel produced by using magnetism and electrolysis. These techniques remove impurities like tin, lead, and zinc.
This is the final step, where the molten steel is cast into the desired shapes and sizes. Casting involves pouring the molten steel into molds to form ingots.
Quality control tests like tension and hardness value testing are then conducted to check the metal’s quality.
The metal will only proceed for sale and reuse as recycled steel if it passes quality control tests. Otherwise, it undergoes another round of melting and purification.
Safety and sustainability are critical elements that should not be compromised when recycling steel scrap.
Even though you can’t control the scrap’s origin, you can improve safety and sustainability by adhering to these best practices for recycled steel:
Personal safety is paramount when handling steel scrap in the milling facility. Although steel recycling has many environmental benefits, it poses serious risks, especially during handling.
So, what are the risks of scrap metal?
The main risks associated with scrap metal recycling include:
- Injuries: From bruises and cuts to more severe injuries, steel recycling is a risky process that requires utmost care and protection.
- Exposure to toxins: Steel scrap may contain toxic substances like mercury, lead, and zinc that can cause poisoning if mishandled. Exposure to hazardous gases and fumes from the melting furnace is also possible.
- Machinery malfunction: Any misalignment or failure in machinery when processing the metal can cause accidents.
- Fire hazards: Fire outbreaks are possible when smelting and welding.
- Heavy lifting: Employees may have to lift heavy scrap metal items, which can cause strain and injuries.
By incorporating personal safety practices, you can avoid these risks and improve workforce safety.
But what are the safety precautions for recycling you should be following? Let’s go through them.
Personal Protective Equipment (PPE) is essential in steel recycling. This equipment, when used appropriately, protects workers from recycling hazards.
So, what PPE is required for scrapyard? It includes the following:
- Hard hats: To provide head protection against falling items.
- Protective glasses: To prevent eye injuries from flying debris.
- Heavy-duty gloves: To protect hands against punctures and cuts.
- Steel-toed boots: To protect feet against crushing and falling objects.
- Face masks: To prevent dust inhalation.
All steel scrap recycling employees require comprehensive training on safety and recycling procedures.
The training should include:
- Safety protocol: Training on safety guidelines for their job, including the associated hazards and mitigation.
- How to use PPE correctly: Training on the appropriate use of personal protective equipment.
- Safe lifting and manual handling: Training on proper manual handling and lifting techniques to prevent back and limb strain.
- Emergency protocols: Instructions on how to respond in case of accidents or fires.
- Waste management: Training on the proper waste segregation and handling to promote sustainability.
The crucial material handling and storage practices for recycling safety include:
- Organization: All scrap metals should be organized at a designated point to prevent tripping that can cause injuries.
- Incorporate healthy lifting techniques: Use the recommended manual handling techniques like squatting and pushing instead of twisting to prevent strain and injuries.
- Use machinery appropriately: Ensure the use of the right machinery for the right task to prevent machine faults and malfunctions.
- Storage of hazardous materials: Store flammable and corrosive materials safely away from fire. It’s advisable to store them in sealed containers.
- Mechanical tools for heavy lifting: Employees should lift heavy scrap metals using equipment like cranes and forklifts to prevent lifting injuries.
Steel retains its structural properties like tensile strength even when recycled many times. However, this is only possible if quality control standards are met.
The standard quality control practices to observe when recycling steel include:
The homogeneity and purity of steel scrap help ensure recycled steel’s quality and can be achieved by careful sorting and segregation.
Sorting and segregation involve separating steel scrap by type, size, and grade to prevent contamination. It makes it easier to identify recyclables from non-recyclables, which can alter the final product’s quality.
The commonly used sorting and segregation methods in steel recycling include:
- Magnetic sorting: This uses magnetic fields to separate ferrous materials from their non-ferrous counterparts, like aluminum.
- Manual sorting: Sorting and segregating the scrap manually into categories based on size, shape, and type.
- X-ray Fluorescence (XRF): The scrap metal can be analyzed to determine its composition and other elements for segregation.
- Laser-Induced Breakdown Spectroscopy (LIBS): Assessing the composition of steel scrap through optical and low-level methods. These methods use a highly focused laser beam to generate a spectroscopic signal for analysis and segregation.
QC tests are essential for grading and assessing recycled steel.
The commonly used QC tests in scrap metal recycling include:
- Metallurgical testing: This involves evaluating the properties of the recycled steel by subjecting it to chemical, mechanical, and thermal tests.
- Hardenability testing: Heating a long sample of recycled steel uniformly and exposing it to water. This tests the depth of hardenability distribution.
- Tension test: Determines the recycled steel’s ductility, yield strength, and tension levels.
- Compression test: Evaluate if the material can withstand plastic deformations.
- Eddy inspection: This inspects the scrap metal’s surface for flaws and cracks through electromagnetic induction.
- Ultrasonic test: This determines the internal structure of recycled steel by transmitting sound waves through it.
Construction and demolition services account for about 600 million tons of landfill waste in the U.S. annually.
According to Science Direct, steel is among the leading construction and demolition wastes that get into landfills, polluting the environment.
However, you can make recycled steel a more sustainable construction material by incorporating the following practices:
Steel recycling uses high-voltage electric arcs to maintain the furnace at 3,500°C (6,332°F), which requires a huge amount of electricity, increasing CO2 emissions.
You can make steel recycling more sustainable by incorporating green process energy generated from natural sources like sun, wind, geothermal, and hydropower.
Powering the recycling plant with green energy reduces reliance on fossil fuels, decreasing the company’s carbon footprint.
Moreover, green energy eliminates the generation of greenhouse gases like carbon dioxide and sulfur dioxide. These gases are the leading causes of global warming because they contribute to the greenhouse effect.
While power is necessary for steel recycling, reducing energy consumption can make the process more eco-friendly, not to mention more efficient and cheaper to run.
Some energy conservation techniques for sustainable recycling include:
- Furnace insulation: Insulate the furnace walls and doors to retain heat. This reduces the time taken to preheat the furnace before melting steel scrap and the overall energy consumed by the furnace.
- Use regenerative burners: Regenerative burners use the hot flue gases from the furnace to preheat the incoming fuel. This recycles more energy for reuse.
- Heat recovery systems: Capture and recycle the heat generated during steel recycling for other processes like drying and tempering.
- Install LED lighting: Replace conventional lighting systems with energy-efficient LED lamps to reduce energy consumption. Although this energy saving is small compared to the amount the entire process uses, every little helps.
Feedstock refers to input materials for the manufacture of recycled steel. They include scrap metal, water, oxygen, and gas.
The fewer raw materials required for the process, the more sustainable it can be.
Consequently, you should make feedstock adjustments to conserve these essential resources. The best ways to achieve that include:
- Optimizing the recycling process for efficiency: Streamline the process to reduce waste and maximize scrap metal recovery. For instance, automate the sorting process to improve efficiency.
- Using recycled scrap metal for feedstock: Reduce reliance on virgin materials and use recycled steel scraps instead. This conserves non-renewable resources like coal, limestone, and iron ore.
- Shifting to more efficient recycling furnaces: Upgrade older furnaces with modern, energy-efficient options to reduce power consumption. According to the International Journal of Engineering Sciences and Research Technology, the latest electric arc furnaces incorporate heat integration techniques that save energy.
- Identify areas of improvement: Document the entire production process and identify areas of improvement for optimization to reduce feedstock input.
Carbon capture techniques make steel recycling more environmentally friendly by capturing the emitted carbon dioxide and sequestering it in underground geological formations.
Alternatively, switch to hydrogen-based fuel sources or renewable energy systems to reduce carbon emissions.
Metal scrap could potentially contain contaminants like oil, plastic, and rubber. The metal itself is not usually hazardous but might be contaminated with toxic materials due to the environment in which it was used.
You can handle scrap metal manually or by using lift cranes and trucks. Each method has drawbacks — while manual handling exposes employees to strains and sprains, using cranes and trucks generates carbon emissions.
Following best practices for recycled steel is crucial to ensure workforce safety and improve sustainability. These two components are essential for steel recycling success.
Two things stand out from this discussion: implementing personal safety practices and fostering eco-friendly recycling.
Always ensure employee safety by providing appropriate PPE and providing sufficient training.
Finally, incorporate environmentally friendly techniques by optimizing raw material use and using green energy sources.