How Aluminum Scrap Becomes Aluminum Profiles

Introduction

Driven by global carbon reduction targets and the growth of green buildings, aluminum recycling has become a key issue in the sustainable transformation of the building materials industry. As one of the most widely used and highly recyclable materials in the world, aluminum can theoretically be recycled repeatedly without losing its properties.
So how do discarded aluminum windows and doors, beverage cans, and automotive aluminum components from daily life  "reborn" into high-quality aluminum profiles through a series of processes?
This article introduces the complete production process of recycled aluminum profiles and explains how this “urban mine” creates both environmental and economic value.

What Are Recycled Aluminum Profiles?

Recycled aluminum profiles refer to aluminum alloy profiles produced mainly from recycled aluminum scrap through processes such as pretreatment, melting, refining, billet casting, extrusion, and surface treatment.
Unlike primary aluminum produced through electrolysis, recycled aluminum avoids energy-intensive and high-emission processes such as alumina refining and electrolytic reduction. Instead, it allows already extracted aluminum resources to enter a circular recycling process.

Sources of Recycled Aluminum Scrap

Recycled aluminum raw materials mainly come from two categories:

• New scrap: Generated during aluminum processing, including extrusion cut-offs, edge scraps, and defective products. This type of scrap has high aluminum content and fewer impurities, making it an ideal source for producing premium recycled aluminum. 
• Old scrap: Recovered after consumer use, including discarded aluminum windows and doors, curtain wall profiles, automotive components, and beverage cans.

A significant statistic is that the overall global aluminum recycling efficiency is approximately 76%, and the global aluminium scrap market was valued at US$53.67 billion in 2025.  This means that aluminum scrap has transformed from a production byproduct into a strategic raw material closely related to circular economy goals and decarbonization strategies.

Production Process of Recycled Aluminum Profiles

The transformation from aluminum scrap into high-quality aluminum profiles is a standardized closed-loop process consisting mainly of three stages: material pretreatment, aluminum alloy melting, and aluminum extrusion with surface treatment.

Material Pretreatment– Purify Substrate

The first step in the production of recycled aluminum profiles is to conduct rigorous pretreatment of the recycled aluminum scrap. This is the first checkpoint to ensure the quality of recycled aluminum and directly determines the quality of the final aluminum profiles.

Dismantling and Sorting

Qualified aluminum scrap materials are disassembled and sorted via manual and automated dual modes, and classified into pure aluminum, wrought aluminum alloy, cast aluminum alloy and mixed materials to remove large non-aluminum impurities. 
The steps are as follows:

• For scrap aluminum products, dismantling should be performed to remove steel and other non-ferrous metal parts connected to the aluminum.
• For thin, loose, sheet-like scrap aluminum parts, such as locking arms, speed gear bushings, and aluminum shavings from automobiles, they should be compressed into bales using a hydraulic metal baler.
• For steel-cored aluminum stranded wire, the steel core should be separated first, and then the aluminum wire should be wound into coils.
• Highly pure sorted aluminum materials can be directly fed into furnaces for smelting.

Mechanical Crushing and Screening

Larger scrap aluminum (greater than 50-80cm) or materials containing coatings or paint need to be crushed. The crushed material is then automatically screened, with those meeting size requirements proceeding to the next process.

Magnetic Separation and Eddy Current Separation

• Magnetic Separation Device: Removes magnetic waste materials such as iron and steel from scrap aluminum. Iron is a harmful substance in aluminum and its alloys, having the greatest impact on the mechanical properties of aluminum alloys, causing the material to become brittle and prone to breakage. 
• Eddy Current Separation Equipment: Further separates non-ferrous metals such as copper and zinc, improving the purity of aluminum alloys.

Flotation and Cleaning

Lightweight materials such as waste plastics, waste wood, and waste rubber are removed using a spiral propeller, and impurities such as dirt and ash are cleaned away.

High-temperature Baking and Roasting

Most aluminum scrap surfaces are attached with oil stains, paint and carbonized coatings, especially aluminum scrap cans.  High-temperature baking and roasting completely eliminate surface attachments, avoiding bubble defects in recycled aluminum ingots caused by residual impurities during smelting.

After the above processes, scattered scrap aluminum is transformed into "pure aluminum blocks" with clearly defined compositions and uniform dimensions.
According to industry standards for recycled aluminum production, the purity of the pre-treated scrap must reach at least 99.8%. Specifically, the total amount of non-aluminum metal impurities (such as zinc, copper, iron, and magnesium) in the recycled aluminum raw materials must typically be less than 1.0% to 2.0%, and the content of organic impurities (paint, oil, and plastic) is typically limited to between 0.5% and 2% by weight. 

Aluminum Alloy Smelting and Refining: Formation of High-Purity Alloy Matrix

Pre-treated aluminum scrap cannot be directly used for profile production. It must undergo smelting and refining to be converted into aluminum alloys with precise compositions.
The main steps include:
Batching → Charging → Melting → Dross removal → Stirring → Sampling → Composition adjustment → Refining → Degassing → Filtration → Casting

Precise Batching

Scientific batching is the key to quality control. According to the standards of target aluminum alloys (e.g., 6000-series Al-Mg-Si alloys with high magnesium oxidation loss), different aluminum scrap materials and intermediate alloys are proportioned to compensate for smelting burn loss, making the molten alloy close to the target component, This reduces the difficulty of subsequent adjustments and increases the metal recovery rate.

Furnace Loading and Melting

The sorted scrap aluminum is added to the smelting furnace and heated (650℃～750℃) to melt it into a liquid state. 
The smelting process requires strict control of smelting temperature and time to ensure that the scrap aluminum can be completely melted and retain the required alloy components to the greatest extent. 

Slag Skimming and Stirring

Regular slag skimming and sufficient stirring are conducted during melting to remove oxides and impurities. 
Targeted impurity removal technologies (beryllium iron removal, oxidative magnesium removal, sedimentation zinc and lead removal) are adopted according to impurity types to enhance alloy purity.

Adjusting Alloy Composition

During the smelting process, the content of certain elements in the alloy's chemical composition increases or decreases due to factors such as temperature and oxidation. Generally speaking, elements with a strong affinity for oxygen suffer greater losses. For example, aluminum, magnesium, boron, and titanium have a very strong affinity for oxygen, and therefore suffer greater losses; while iron, cobalt, nickel, copper, and lead have a weaker affinity for oxygen, and therefore suffer less losses.
Real-time sampling and testing of the composition are performed, and appropriate element supplements are added to meet the standards of the target aluminum alloy (e.g., 6063 or 6061 aluminum alloy).

Converter Refining

After the metal composition is adjusted, the melt is transferred to a refining furnace for further refining. The purpose of aluminum molten metal refining is to obtain a high-cleanliness alloy molten metal with low gas content through degassing and impurity removal measures.

Degassing

The core purpose of degassing in recycled aluminum production is to remove gases such as hydrogen dissolved in the aluminum molten metal, preventing defects such as porosity and looseness in the castings, and ensuring mechanical properties and density. 
By introducing inert gases or adding refining agents, the tiny bubbles generated in the aluminum molten metal simultaneously adsorb and carry away oxide inclusions, improving the purity of the molten metal.

Ingot Casting

After the melt is purified and standardized, it is transferred to a holding furnace and then poured into casting machines. The molten aluminum is cast into solid forms such as rolling ingots, extrusion billets, or foundry alloys for new product manufacturing.

This process completes the transformation from scrap aluminum to high-quality aluminum alloy substrate.

Profile Forming –Aluminum Extrusion and Surface Treatment

Whether using recycled or virgin aluminum alloys, the production process for aluminum profiles is basically the same. Generally, extrusion and surface treatment are used.

Aluminum Profile Extrusion Process

Aluminum extrusion uses the plasticity of aluminum alloy. Heated aluminum billets, usually at 400–500°C, are pushed through specially designed extrusion dies under high pressure to create continuous profiles with specific cross-sectional shapes. 
The extrusion process includes:

• Billet heating and cutting.
• Die extrusion.
• Cooling and straightening.
• Cutting to required length.
• Aging treatment for strength improvement.

Similar to squeezing toothpaste, this process features high material utilization and flexible cross-sectional design, enabling the manufacture of solid, hollow, and complex irregularly shaped profiles, meeting the diverse custom aluminum profile needs of fields such as construction, transportation, aerospace, electronics, and new energy.

Common surface treatments

• Anodizing: Forms a dense aluminum oxide (Al₂O₃) protective layer to improve corrosion resistance and wear resistance.
• Electrophoretic coating: Deposits an organic coating on the anodized surface to enhance weather resistance.
• Powder coating: Uses electrostatic spraying and high-temperature curing to create a durable protective coating.
• PVDF coating: Suitable for high-rise building curtain walls due to excellent weather resistance and self-cleaning performance.
• Wood grain transfer: Creates decorative wood-like finishes through thermal transfer technology.

Finally, the profiles are finished through quality inspection, polishing and packaging to become qualified recycled aluminum profile products.

Advantages of Recycled Aluminum Profiles

Recycled aluminum profiles provide significant advantages in low-carbon development, resource conservation, and cost efficiency. 

Energy Saving and Carbon Reduction

Primary aluminum production involves bauxite mining and high-energy electrolysis, generating 14.8-15.1 tons of CO₂e per ton. In contrast, recycled aluminum only produces 0.3-0.6 tons of CO₂e per ton, with carbon emissions reduced by more than 95%. It effectively helps the construction industry achieve full-life-cycle carbon reduction.

Resource Circularity

Aluminum can be recycled infinitely with a recycling rate of 80%-90%. Driven by building decarbonization and new energy vehicle lightweighting, the global aluminum demand will reach 106.8-107.3 million tons in 2026. Using recycled aluminum reduces dependence on mineral extraction and supports sustainable resource management.

Cost Advantage

With increasingly stringent global carbon emission regulations and the full implementation of the EU's Carbon Border Adjustment Mechanism (CBAM), the low-carbon value of recycled aluminum will directly translate into economic benefits in the era of carbon tariffs.
Compared to primary aluminum production, each ton of recycled aluminum can reduce CO₂ equivalent emissions by approximately 14.5 tons. For the same quality of aluminum profiles, the lower the carbon emissions during the production process, the higher the economic benefits.

The Impact of Future Building Development on Recycled Aluminum Profiles

Since the built environment accounts for nearly 40% of global energy-related emissions, countries are taking mandatory measures to reduce carbon emissions from buildings, such as:

• The EU's revised Energy Performance Directive for Buildings (EPBD) mandates that all new buildings achieve zero emissions by 2030 and requires solar-ready designs.
• The Singapore government, through its green building master plan, aims to make 80% of its building stock green by 2030.
• The US is implementing stringent LEED green building certification.

Stricter carbon emission limits are driving market demand for ultra-low carbon recycled aluminum profiles. The economic value and market competitiveness of low-carbon aluminum products are continuously increasing.

Conclusion

Recycling aluminum scrap into aluminum profiles is a mature, scientific, and low-carbon resource utilization technology that effectively reuses waste resources. With the continuous advancement of the dual-carbon strategy and the widespread application of green buildings, the market size and application scenarios of recycled aluminum profiles will continue to expand.
Through continuous technological upgrades and the optimization of quality systems, recycled aluminum profiles will achieve higher performance breakthroughs, promoting the green, low-carbon, and sustainable development of the building materials industry and supporting the achievement of global dual-carbon goals.