Apple has unveiled a robotic system called Liam to take apart iPhones and recover valuable materials that can be recycled, such as silver and tungsten. The move is an attempt to address criticism that Apple's products, while sleek and seamless in design, are so tightly constructed that their components can be difficult to disassemble, refurbish and reuse.

Liam, which has been under development for nearly three years, will initially focus on the iPhone 6. Apple plans to modify and expand the system to handle different devices and recover more resources, the company said. The system started to operate at full capacity in February and can take apart one iPhone 6 every 11 seconds to recover aluminium, copper, tin, tungsten, cobalt, gold and silver parts, according to Apple.

At that rate and working uninterrupted, Liam likely can handle no more than a few million phones per year, a small fraction of the more than 231m phones Apple sold in 2015.

Lisa Jackson, Apple's vice president of environment, policy and social initiatives, said the robotic system is meant to push the technology sector toward more recycling, both by manufacturers and consumers. As research continues on larger-scale recycling, Jackson, who was US Environmental Protection Agency administrator from 2009 to 2013, said Apple hopes to reuse more materials in future products.

"Ultimately, our goal is to create breakthroughs that allow us to use those high quality materials in our own products, because reuse and recycling is so important. And that's where you can come in. With Apple Renew, you can recycle your devices easily and quickly and in a way that's safe for your data and safe for the planet. All you have to do is take them into an Apple retail store," Jackson told the audience at a launch event held at Apple's Cupertino, California headquarters.

The recycling system consists of 29 robotic modules on a single site near Apple's headquarters in Cupertino, California. It will focus initially on iPhone 6 phones sold in the United States, where Apple gets about 40% of its revenue. A second Liam is being installed in Europe, Apple said.

The world is awash in discarded electronic equipment, with the United States and China accounting for nearly a third of it. Less than a sixth of global e-waste is properly recycled or made available for reuse, according to an April 2015 United Nations University report.

Apple does not disclose how many of its devices are turned in for recycling every year. Under its existing program, the company offers customers store credit for recycling certain devices and will recycle old products for free.