Toward Achieving Carbon Neutrality: Taking on the Challenge of 100% Aluminum Recycling by a Window Manufacturer

Aluminum is a lightweight, rust-resistant material used for various YKK AP products, which include windows, curtain walls, and exterior products such as carports and fences. At the point when it is refined from an ore called bauxite, aluminum uses large amounts of energy. In terms of CO₂ emissions across the entire YKK AP supply chain, material procurement creates the most CO₂ emissions, with aluminum accounting for more than 80% of that total (FY2022 results). On the other hand, aluminum is an easily recyclable material, and because it can be recycled by using a small amount of energy, recycling only creates about 3% of the CO₂ emitted when making new aluminum ingots (new ingots) from bauxite. Promoting aluminum recycling will lead to a significant reduction in CO₂ emissions throughout the supply chain, and will make a significant contribution to achieving carbon neutrality.

Aluminum recycling can be broadly divided into two methods. One method is internal recycling, in which scraps (return scraps) generated by the in-house manufacturing process are reused as materials. The other is external recycling, utilizing market-obtained recycled materials, such as used aluminum sashes and tire wheels. YKK AP has already achieved 100% internal recycling, and we are currently working to increase the external recycling rate. The goal set forth in the "Evolution 2030" Vision, which was announced in March 2023, is a 100% external recycling rate by FY2030. If this goal is achieved, we expect CO₂ emissions (Scope 1+2 and Scope 3) in FY2030 to be reduced by approximately 40% compared to FY2013. However, the external recycling rate in FY2022 was 27%. We would like to introduce the efforts YKK AP is making to achieve this lofty goal.

The aluminum material used in YKK AP products is made by taking certain amounts of metals, such as magnesium and silicon, and mixing them with externally purchased aluminum ingots, then melting them together in a melting furnace. The material is hardened into "billets," which are then extruded through a die to form aluminum bar profiles. After surface treatment to make the aluminum rust-resistant, the profiles are cut and processed according to the product, then assembled into curtain walls, carports, and other products.

As the first step of that initiative, the Shikoku Plant (Kagawa Prefecture) began restructuring its aluminum casting facilities in October 2021. Following the renewal of the aluminum melting and holding furnaces in the first phase of construction, YKK AP's first recycling furnace was introduced in the second phase of construction, and began operation in September 2023.

In truth, there were an abundance of issues to be addressed during the actual installation and operation of the equipment. Koji Hayashi, the General Manager of the Casting Technology Office, Profile Technology Department, who was in charge of equipment installation, said that "Although we had conducted tests prior to the introduction of the furnace, we discovered some issues that we had not anticipated when we started operating it at a practical scale for a long period of time. We are on track for continuous operation, and will work to further optimize conditions." Another major issue that needs to be addressed on-site is the problem of "storage space." Market-obtained recycled materials have three to four times the volume of new ingots, and in some cases, eight times the volume. Aki Taoka, Casting Line Manager of the Materials Production Department at the Shikoku Plant, who is in charge of the aluminum casting process, said that "Because of their large volume, we cannot stock large quantities. We need to procure materials in accordance with production plans, and we are also paying attention to truck dispatch. In addition, we are working on automating the material loading process, since the number of times materials are handled for loading into the recycling furnace will increase," as YKK AP works to address the unique challenges posed by market-obtained recycled materials.

With the recycling furnace that started operation in September, the Shikoku Plant’s external recycling rate increased from 33% in FY2022 to 50% in December 2023 as a single month. The goal is to achieve a rate of 76% by FY2024 and a rate of 100% by FY2030. In addition, with the Shikoku Plant as the starting point, we intend to restructure and introduce recycling furnaces at all of YKK AP’s locations in Japan with aluminum casting facilities, starting with the Kurobe Plant (Toyama Prefecture), Tohoku Plant (Miyagi Prefecture), and Kyushu Plant (Kumamoto Prefecture). On the other hand, Mr. Hayashi said, "Even now, we can achieve a 100% external recycling rate for specific lots. However, there are many technological challenges involved in achieving a 100% recycling rate for all lots." Bringing the challenges into view, he noted the need to remove impurities during the melting process, and move forward with quality assurance initiatives.

At present, YKK AP is focusing on the following research topics: "creating upgraded recycling technology (*2) to remove impurities," "establishing a production process for recycled aluminum (*3) by sorting market-obtained recycled materials," and "building a recycling system by reducing aluminum oxide and putting it to use." For example, procurement is one of the major challenges in external recycling. Until now, we have used market-obtained recycled materials which have clear origins and identifiable compositions of the original aluminum material. However, as external recycling intensifies, the price of market-obtained recycled materials has soared. It has become impossible to cover production volume simply by using market-obtained recycled materials that have clear origins and compositions. As a result, it is necessary to utilize mixed metals (*4), which do not have clear origins and compositions. Various technological developments are required, including technologies for analyzing these materials, separating them, and removing the impurities produced when mixed metals are melted. Regarding the purpose of YKK AP’s participation in this project, Hiroyuki Tanihata of the Technology Planning Office at the Profile Technology Department, serving as the secretariat for the project at YKK AP, said, "It is difficult for us at YKK AP to pursue these technological developments on our own. We hope that this project will serve as a space where we can gain a plethora of knowledge from industry, government, academia, and the private sector."

The plan is for seven engineers from YKK AP to participate in the various research themes being pursued in this project, promoting research and development on shared issues with universities and other companies. YKK AP will also establish a laboratory in Collaborative Research Building for Light Metals, University of Toyama, which opened in October 2023, to further accelerate technological innovation.