When you look at Taipei’s narrow alleys and rising skyscrapers, you might not immediately see the many opportunities to extract valuable materials from them. But that’s exactly what two companies in Taiwan are looking to the island’s cities and industries for. With growing concern over the sustainable supply of resources such as nickel and cobalt for the green energy transition, Taiwan’s oldest precious and rare metals refinery and largest recycled steel manufacturer are eliminating the need for new mineral extraction by transforming the island into an urban mine.

Urban mining—reclaiming materials from anthropogenic sources like infrastructure and waste products—is a recycling approach that goes beyond plastic bottles and aluminum cans. Materials like copper and zinc from demolished buildings, and gold and silver from old smartphones are recovered, recycled, and can be refined to industrial-grade quality for reuse.

From electronics to construction, material extraction is essential to the function of modern industry. But mining is a carbon-intensive process and earth’s raw minerals and metals are finite. Global material extraction has surged from 30 billion metric tons in 1970 to a projected 106.6 billion metric tons in 2024. And the clean energy transition—which requires lithium for batteries and silver for solar panels—will require an estimated total 3 billion metric tons of energy metals and materials.

As one of the world’s leading manufacturers of semiconductors and parts for communication devices, Taiwan is a critical part of the global supply chain, yet has few natural resources. But Taiwan’s Solar Applied Materials Technology Corporation and Tung Ho Steel Enterprise Corporation have each created their own partnership system by working directly with customers and competitors to “cycle” resources in a circular process where materials are collected, recycled, refined, and then resold back into the industrial environment. “Around 80% of our own raw materials are coming from our recycling process,” Solar Tech chairman C.F. Huang says. “That’s also why we call ourselves a circular economy company.”

Read more: Companies Are Trying to Offset Their Plastic Waste. Some Experts Are Skeptical

As one of the world’s leading manufacturers of sputtering targets—thin films of magnetic materials used for digital displays, semiconductors, and data storage—Solar Tech is also known for refining recycled gold and silver to 99.99% purity.

“One of our key capabilities is that we can do high-purity refining. In Taiwan, it’s not just Solar that can do the recycling,” Huang explains; in fact, Taiwan has over 1,700 companies that recycle industrial waste. “But when you want to put it back into industrial application, you need to be able to purify to high purity. And each different element is a specific technology and process line. You cannot mix it.”

Over the last 40 years, the company has developed an in-house recycling and refining process for eight major elements—including gallium, used in WiFi and bluetooth devices, and indium for touch screens and solar panels—that was largely driven by a need for a stable source of raw materials.

“Taiwan is a tiny island. We don’t have sizable mines at all. So all of these materials we had to import,” says Ben Hong, Solar Tech vice president. “If we cannot recycle it, everything comes from a mine somewhere.”

In 2022, the company recycled 247 metric tons of material and cut carbon emissions by more than 440,000 metric tons in that year. Most of their raw materials come in the form of waste—including semiconductor wafers, spent targets, and printed circuit boards—directly from the same customers it sells its products to. “The material flow is always between Solar Tech and our customers,” Huang says. “When this urban mining concept came out, we said this could be one of our routes, or foundation to get our materials.”

But receiving industrial and electronic waste from its customers means Solar Tech has not developed the capacity to gather resources on its own, and Huang is aware its business is reliant on its partners—an error or backup in the supply chain, a shortage or change in demand can cause problems elsewhere.

“Nowadays in the world, there’s not a single company that can do this recycling job under one roof,” Huang says. “There’s so many different elements in it, so people really have to work together.”

Read more: This Company Uses Recycled Metals to Make Steel

Elsewhere on the island, Taiwan’s largest recycled steel manufacturer, Tung Ho Steel, has developed a different system of cycling resources—not with its customers, but with its competitors. The company’s partnership with the industry’s other major steelmakers is collectively known as Taiwan Steel Union (TSU).

Having them join together was not an easy task, but we did it,” says TSU’s general manager Sean Lin.

Known for its earthquake-resistant steel, more than 90% of Tung Ho Steel’s primary raw materials come from scrap. Like glass and other metals, steel can be recycled indefinitely without losing quality.

But manufacturing steel creates hazardous waste—the process of melting base materials releases dust containing heavy metals. That dust can pollute water and soil resources. In the mid-90s, the issue attracted attention when Taiwan’s Environmental Protection Administration discovered contaminated duck eggs near a steel manufacturing site. In response, the then CEO of Tung Ho Steel reached out to his competitors, and in 1999 they pooled their resources to build a joint recycling plant to treat the waste in order to reduce pollution. “TSU is one of biggest urban mines in the world,” says TSU’s Lin, “with a license to treat up to 200,000 tons of waste per year.”

The process not only eliminates hazardous materials from the environment, but yields a useful resource: zinc oxide. Commonly used for preventing rust, zinc can also be an alternative battery material for electric vehicles. As the fourth most used metal on earth, global production of zinc was over 13 million metric tons in 2022, but only 30% of the zinc produced worldwide is recycled. The zinc oxide TSU recycles is sold to global zinc smelters and refined for industrial-grade use before being resold to Taiwan’s steel industry.

According to TSU’s 2021 sustainability report, its plant recycled over 51,000 U.S. tons of zinc oxide and reduced carbon emissions by over 47,000 U.S. tons in that year. Although the numbers represent only a fraction of global totals, they come from a partnership whose primary business lies outside the zinc industry itself–a group of competitors working to generate additional revenue by managing their waste and recycling resources.

As the global community looks for scalable climate solutions, businesses and policymakers may have to look for unexpected partnerships. While the urban mining practices in Taiwan may not be entirely closed-loop, they present a suggestion; they are a live case study in an environment already facing finite resources and the immediate effects of pollution—because after current global resources reach their limit, the earth itself may become a single urban mine.

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