Aluminium is one of the most easily recycled materials. In fact, one estimate suggests that 75% of all the aluminium ever produced is still in use.
Even so, huge quantities go to waste. Mostly, it’s the stuff that ends up on the factory floor: can trimmings, grinder dust, turnings and chopped wire. And often, a large factory will produce tons of it every day.
“It’s the final waste. It’s like a dust. And it does contain some aluminium but it’s no longer valuable to recycle,” said Khalid Bahsoon, an independent recycling and waste management consultant.
But a company based out of a farm shed in the UK hopes to change all that. NetZeroChem Ltd, led by retired engineer Alan Smith, has come up with a process to turn this previously mostly worthless waste into valuable industrial materials.
Smith has a touch of the alchemist about him. He rattles off numbers, and explains in detail how his reactor can take shavings and dust – which he says mostly ends up in landfill – and turn it into hydrogen and aluminium hydroxide.
“The real neat trick is not really the hydrogen, but the residue in the reactor. Because when you use the aluminium like this, you make aluminum hydroxide,” he said.
Aluminium hydroxide is used in thousands of industrial processes, and it can also be used to make aluminium oxide, which is potentially even more valuable. The latter is found in everything from toothpaste to glass, but it fetches the most money when it’s used in ceramics for microprocessors.
The reactor also creates a significant amount of energy. Aluminium smelters are among the world’s most energy-hungry industrial facilities. A large one can consume as much electricity as a small city. But Smith’s reactor is a little like running the process in reverse, generating as much as forty times the energy required to power it.
“The reason it’s so good, of course, is that you’re stealing the energy that was locked up in the aluminium,” he said.
There are potential environmental benefits too. At present, most aluminium oxides are produced during the process of making aluminium itself. Typically, that means digging up patches of rainforest to get at the bauxite underneath.
The highly-alkaline mine tailings are also a problem. On a number of occasions, so-called ‘red mud’ dams have burst, causing environmental damage to nearby waterways, and in some cases killing people who were unfortunate enough to be in the way. Smith hopes an alternative process might reduce the environmental impact.
“If we could make our own in England, where we have no source at all, it would save a lot of shipping, a lot of mining, and so on, as well as the energy bonus we would get from the scrap that pollutes when it’s re-smelted,” he said.
Path to market
Ultimately, though, he hopes the reactor will make good commercial sense. So far he’s built a proof-of-concept version. The next step is to upgrade to a small, commercial version that could fit in a shipping container.
The target market is local government authorities (which usually oversee waste collection), aluminium recyclers, engineering companies and beverage packers. Tobacco companies are potentially a market too, as the foil in cigarette packs generates aluminium trimmings.
“In the beginning what we’d like to do is lease the plant to people. And we’ll find them energy customers if they don’t need the energy themselves. But we want to take away the hydroxide at the end and process it centrally, and then profit share with the lessees,” Smith said.
He claims that the waste, which sells for around US$200, could ultimately yield products worth ten times that much.
Now that would be a neat trick.