Within them are a treasure-trove of idle junk that could be transformed into high-value metal. The gold alone adds up to more than $80 million.

Enter Veena Sahajwalla​, professor of engineering at the University of NSW, who already has an impressive track record of turning waste into productive capacity. Her invention to recycle car tyres into useable steel was successfully commercialised and has already saved more than two million tyres from entering Australian landfill.

"Mining our waste stockpiles makes sense for the economy and the environment," Professor Sahajwalla said.

At present obsolete mobile phones and other e-waste are taken to what she calls "mega-smelters" for recycling. Some of it has to be shipped overseas.

Her solution? She has built a prototype mini-factory at UNSW's Centre for Sustainable Materials Research and Technology (SMaRT).

The aim is for these micro-smelters to be taken to waste sites, reducing transport costs and emissions from trucking and shipping.

"They also promise a safe way for poor communities in developing nations to generate income from the production of metal alloys," she said.

UNSW's SMaRT centre estimates that a tonne of mobile phones (about 6000 handsets) contains 130 kilograms of copper, 3.5 kilograms of silver, 340 grams of gold and 140 grams of palladium. That adds up to tens of thousands of dollars worth of metal alloy.

Professor Sahajwalla's prototype uses precision high-temperature reactions to produce alloys from the waste circuit boards, while also destroying toxins. Then a drone identifies the target metals from crushed e-waste and a robot extracts them before they are taken to the furnace.

She said that the micro-factories could be run regionally in Australia, uniting networks of local councils with not-for-profit recycling companies and local businesses.

Mobile phone recycler, MobileMuster, estimates 25.5 million obsolete phones are littering Australian homes and workplaces.

Worldwide, the United Nations Environment Program estimates the trillion-dollar electronics industry generated 42 million tonnes of obsolete equipment in 2014. It said this e-waste contained nearly $70 billion worth of embedded resources.

"The world urgently needs a safe, low-cost recycling solution for e-waste," Professor Sahajwalla said. "Our approach is to enable local communities to transform e-waste into valuable metal alloys."

She doesn't know when this latest invention of hers will go commercial but said there is already one interested industry partner.

MobileMuster is the recycling program of Australia's mobile phone industry. It estimates more than 95 per cent of materials in mobile phones can be recovered and returned to the supply chain.

It has more than 3300 public drop off points around the country including all major mobile phone retailers. They can also be posted for free by picking up a reply-paid satchel from Australia Post outlets.

Spyro Kalos, the manager of MobileMuster's recycling program, said: "It is great to see that UNSW is researching and investigating micro-recycling factories. There is great potential here for this technology to be used in developing markets where there is a lack of recycling infrastructure."

Professor Sahajwalla said: "We already understand the value of sourcing energy from the sun. Similarly we can source valuable materials from our waste."

Find out more:

Mobile Muster www.mobilemuster.com.au

UNSW SMaRT centre www.smart.unsw.edu.au