There are, but a lot of them can't be reconstituted without other resources. Take, like, rebar, which is the post-apocalyptic author's favorite source of "chunky metal"--it's low-grade steel that melts north of 1200 deg C. If you don't have access to fossil fuels (or an electric arc furnace, and then how are you going to power it?) you're probably looking at a charcoal forge. Charcoal forges require a ton of airflow (relatively easy, if potentially work-intensive) and a ton of fuel to get hot enough to melt even iron, let alone steel (and remember that modern shitty steel is still pretty good by historical standards!).

You can absolutely do it, but you're crawling by your fingernails. And then you have to multiply that by thousands of different factors and different problems. I've thought about this a bunch through the lens of building a game in a world like this and done quite a bit of research, and I tend to think that most of what you might consider "ready resources" in such a world require a pretty significant amount of re-bootstrapping that become really, really hard without easy hydrocarbons.

Maybe doable! Probably really really hard.

Thought provoking. Thanks!

Something like this is part of the background of Gene Wolfe’s “Book of the New Sun” series, totally wild books that are set in a far future earth. Mineral wealth is totally exhausted, and “mining” just means digging up the detritus of forgotten civilizations.

I’m really tempted to post spoilers by way of example, but part of the fun of the book is putting the pieces together and realizing what’s going unsaid because the narrator either takes it for granted or doesn’t understand it himself. Very strong recommend if you have any interest in sci fi/fantasy.