A world idea I'm playing with for a sci-fi idea I'm working on has an atmosphere similar to the composition of Earth's atmosphere during the Carboniferous Period: Lots of oxygen, so while a human or a creature with similar breathing needs could probably breathe fine, that also means everything is extremely flammable. As this world is also relatively similar to Carboniferous Earth in that a large percentage of its overall landmass is covered in fairly dense forests, and while it's fairly damp and even downright swampy in many of these places, the higher oxygen content means that even damp things can sometimes Ignite.
The major sapient species on this world, as a result, are obviously fairly wary of fire hazards and fire in general; as a result, contrary to the evolution of technological progression in humans (which most sources say began in earnest with early man learning to harness fire), they likely wouldn't be able to harness and utilize Fire safely until much later in their civilization's development, when they would have the means to contain it and prevent its spread on a large scale. Even then, if they developed a means of harnessing fire at all after so long without it, it would probably be used sparingly and Very Carefully, limiting or at least slowing experimentation.
I have worked out a potential alternative: natural hot springs and other geothermal activity can be used in things like cooking and other complex food preparation, and the steam could probably be funneled or channeled to heat dwellings and power relatively simple machines, which in turn could probably open up new options for developing other technologies. They also behave and structure themselves in a fashion similar to an ant colony, and as a result already practice various forms of agriculture (similar to the practice of many in-real-life ant species that cultivate edible fungus and raise/"pasture" aphids for both nutrient-rich secretions and, eventually, meat) that would likely be aided by, and be an evolutionary pressure in favor of, the development of tools.
The one dilemma I have is this: while they can compensate for/find different paths to the development of various other technologies that seem to have shaped the development of human civilization, their aversion to/difficulty working with fire is going to make things like metallurgy difficult. While they were not initially a space-faring race, and only became aware of interplanetary travel when briefly invaded and occupied by a military power from another world before fighting them off and regaining independence later, they have likely seen the benefit of joining the intergalactic community on their own terms and are going to try and turn their hand to creating spacecraft, which will likely involve manufacturing things like metal and glass and plastic components (or, you know, rough equivalents) on a large scale. While it's possible that they borrowed new technology and ideas from their former oppressors, I was wondering how far along they could get in terms of Smelting Technology without outside influence, and how big of a jump that's going to be for them to make.
So, my question is this: if they have some means of funneling and redistributing steam for things like heating their nests and warming water (probably by digging tunnels or boring out large tree trunks for makeshift piping), could they somehow... Collect that heat, and use it to heat up something akin to a kiln or forge in function? Or is this something that, as far as we know, can only be accomplished with fire? Alternatively, what methods could be used to control the spread of fire enough to allow them a little more experimentation, given the higher amount of oxygen and increased likelihood and danger of accidental fire-starting?