The materials needed by the military (steel in tanks, aluminum in airplanes, etc.) often has to be very high quality, so recycled scrap would not be good enough. But the recycled material was good enough for less demanding, civilian uses. So metals that would have been needed for these civilian uses could be replaced with recycled metals, thus leaving ‘virgin’ metals for military uses.
So the recycled metals were useful in the overall war effort, even though it mostly did not go directly into military purposes.
P.S. While rubber is quite difficult to recycle, at least some of it was reused in WWII. I remember relatives talking about a big floor mat made of reused rubber that was installed on the concrete floor at a factory. They laughed about it, saying that it looked like an oversized braided rug made out of rubber scraps. But it turned out to be very helpful to the legs of the people working long hours there, and productivity went up while worker sick time went down.
Also, I expect that the fuss about collecting even the smallest amount of rubber (Mom’s office even had a container where all the secretaries put broken rubber binders) emphasized the importance of rubber & other vital materials, and led to people being more careful about using it. (And it stuck. Sixty years later, my mother would never throw away aluminum foil until it had been used at least 2 times.)
My experience with recycling scrap for my own amusement/profit is that if you can provide metal of all one type you get more than if you bring in mixed alloys. For example, I get paid MUCH more for a quantity of just aluminum pop cans than I do for random bits of aluminum. Clearly, having a pile that’s of just one type of metal is more profitable down the line, otherwise I wouldn’t be seeing greater profit on my end. I’d expect the situation to be the same in the past.
As for aircraft aluminum - airplanes are, ideally, made with just enough structure but no more, in order to keep weight down. That principle applied back in WWII, even if airplanes of that era are overbuilt by today’s standards. In order to do that successfully, the materials used in aircraft had to be (and still need to be) of high and consistent quality. It seem to me that starting with “virgin” stock, rather than a mish-mash of recycled scrap, would be better in several ways to achieve that goal.
Both are possible. But while I don’t have any specific knowledge (despite growing up in a region that was involved in aluminum production) it seems unlikely to me that rocks are more standardized in their content than manufactured products or easier to transport.
But the rocks are “more standardized” - in that they are Aluminum oxides, without alloys. Aluminum from recycling can have added titanium, for example. In fact, there are pages and pages of different Aluminum alloys. These are all items that started as molten Aluminum, with some alloying metal(s) added.
For many applications, you can use this just fine, even when mixed with other Aluminum alloys, and much of the Aluminum you use every day comes from these items remelted. But for certain applications, the correct alloying is critical.
While theoretically it’s possible to remove a lot of these alloys, in practice it isn’t economical.
So planes are likely made from Aluminum from ore ( with some Aluminum from scrap recycling from air-plane manufacturing, say), Beer cans are predominantly (57%) melted scrap - but specifically scrap cans. Aluminum in certain toys can be pretty much any recycled scrap.
The energy to re-melt aluminum is a fraction of the energy needed to extract it from ore. But the alloys mean we will still extract significant quantities from ore for a while yet.
So If I’m understanding you correctly, you’re saying it’s easier to seperate aluminum from the other materials it’s found with in ore (primarily oxygen) than it is to seperate aluminum from the other materials it’s found with in manufactured products (like copper, magnesium, manganese, silicon, or zinc).
At the risk of highjacking the thread, I will point out this is a general problem-and a general result. Scrap metal drives during WWII, clothing drives after major disasters, in general any time the public is asked to contribute goods, are more for the PR among the public than help to the effort. After major hurricanes for instance, the many of the donated supplies are trucked to landfills. But it makes the public feel good-and that makes it worth it. We just need to be aware of the reality of the process.
It’s not that the process is more or less difficult. It’s that scrap is highly variable in its content, especially when compared to virgin ore. The scrap you get one day may contain a lot of iron. Then the next load contains iron and a little vanadium. the next has a no iron but some titanium and copper. It may be that the methods for removing iron versus vanadium and copper are very different. It takes time to switch to the copper process and then switch to the titanium process. Now compare this to the bauxite you’re bringing in from Jamaica. It has aluminum plus some other stuff which has to be removed. BUT…all of the ore from that mine has the same mix of materials. So you never have to switch processes. So your smelter can just keep on cranking out product without having to stop, determine the mix of materials in the latest batch and switch processes for it.
While this may be true for clothing drives, the scrap drives were on commodities (scrap steel, scrap aluminum) that had intrinsic value, regardless of the state of war. In other words, if you had a dollar-bill drive, it might be annoying to have a stack of ones, but they would have value.
Having said all this, it is possible for the economics to change enough to make certain metal recycling worthwhile. If chromium becomes rare enough due to war or high demand, then it might become economical for some metal processors to seek out chromium-laden scrap metal. But this is completely hypothetical. I have no idea how expensive any particular metal would have to become to make this type of recovery profitable.
“Pot metal” usually refers to low melting point zinc based die casting alloys, not scrap steel. This is indeed what is often used for automotive door handles and such.It is much stronger than cast aluminum, and the temperature is low enough that permanent molds can be used. But the alloy content needs to be well controlled to capture good mold detail and avoid weak spots etc.