Ever been to the rainforest where they are digging for bauxite to ship to the US to be processed into aluminum.
The amount of energy saved in recycling aluminum is 95%, plus saving the rainforest.
Steel might not be as high – some have it at about 60% – but it is well worth to recycle, not only in terms of saving energy but also in saving resources.
Glass is the one thing that is borderline re recycling – some estimates showing only 5% energy saved and some showing somewhat more than that.
If 95% of aluminum used in the U.S. is recycled, it’s because aluminum doesn’t deteriorate particularly in the environment and is near to hand. However, aluminum recycling is a pretty marginal thing, cost-wise. It’s a pretty good business when aluminum prices are high and utility costs are low. But it can go negative on a recycler, and sometimes does. I have known several aluminum recyclers and that’s just a fact of the business.
It can be pointed out too that a lot of aluminum goes “up the chimney” in recycling. A lot of recycled aluminum is thin (like cans) and a lot of it burns up in the process of recycling. A lot of it has paint or oil on it, which also encourages burning of some of the aluminum itself as well as the foreign material. Among the most profitable things to recycle are transmission housings. Lots of aluminum in them and the alloy is exactly what transmission manufacturers want. But they always have transmission fluid and oil on them, which gets burned off.
A lot of other stuff gets burned in the process too. Aluminum windows and doors often have insulating material stuck to them. It burns off, creating cyanide gas in the process. Some aluminum products have bits of iron or other things bolted in or adhering. A lot of organic material goes into the furnace with the aluminum.
Importantly, there is the change of alloys. One of the main alloy materials for aluminum products is silicon. But others require copper or other metals. Not hard to add, but to take them out, they have to oxidize them with other additives or an “oxygen lance”. It’s truly awe-inspiring to see the belch of flame, smoke and fumes arising out of an aluminum furnace when they add the oxidizer. That’s burned copper, zinc, silicon or other materials going right up the chimney.
And, of course, a lot of aluminum oxide is generated. There are uses for it, including your toothpaste. (yup, your toothpaste) But a lot of it is simply dumped because recycling generates so much of it.
Oh yes, aluminum recycling is usually a three-step process of melting. Most of the initial recycling is done by entrepreneurs who collect the scrap and melt it willy-nilly without regard to content, creating a big block they call a “sow”. The “sow”, then is sold to an alloys processor that melts it again and recasts it into ingots of the desired alloy. The manufacturer of the end product then melts it again.
Recycling is a long way from being a clean or energy-lean process. It might help the rain forest, but it sure doesn’t save much energy (if any) and creates a lot of pollution itself.
I have never visited a steel recycling plant, but I am reasonably confident steel recycling is even dirtier than aluminum recycling because of all the stuff that goes into the furnaces. Imagine what all is in a crushed car that isn’t steel. I have seen how they crush scrap into those big cubes that go into the furnaces, and it’s a long way from being pure steel.
