A solar oven seems the obvious way to melt and separate Lunar ore. Beyond the initial Earth-built small equipment, Luna-built reflectors seem easy to manufacture, so at least that part of the system can be scaled easily.
The separating system might be more difficult to create on Luna. Don’t know the technology well enough to predict.
Lunar soil will yield lots of silicon and oxygen, and some metals and water.
The probable local deficit will be hydrogen, carbon, and nitrogen. Needed for organic processes and materials. Possibly enough hydrogen if surplus water is found.
Hydrazine will be hard to make locally because it is N2H4. At some point in the future it may be easiest to gather ammonia (NH4)and hydrocarbons in bulk from gas giant atmospheres to bring nitrogen and carbon to the moon.
Xenon: useful in ion engines because of its high atomic mass. Next-heavier noble gas is radon, which is not so good because it is radioactive. However, if thorium is used for nuclear power, I think radon is one of its fission byproducts; so it may be more easily available through other processes.
PAVERS: Even if major products will be glass mirrors, photovoltaic wafers, and semiconductor chips, it is likely that there will be surplus SiO2/SiO4 ‘waste’. This can be formed into pavers to lay onto the surface and cover the dusty natural surface in high-traffic areas. Tracking dust into habitats and other areas with mechanical working parts is potentially a serious problem, so glass paving may be needed in large quantities.
In addition, a prodigious quantity of mirrors should be produced which can be assembled into several in-crater telescopes of enormous size. The mirrors should be mounted on adjustable stands so that the overall reflector can be refocused north or south to view a band, rather than just a single thin track directly overhead.
The first telescope will probably be built near to the south polar base, perhaps as a prototype for the subsequent telescopes to be positioned at different latitudes.
MOBILE MIRROR-ARRAYS: 20m reflectors could be mounted on standard creeper-slabs, together with a solar array, so that they can creep northward under their own power. They can reposition themselves within craters or sloped terrain to point further northward or southward; multiple units could also synchronize as very large arrays.
So again, the first thing to refine and use in large quantities is metal, to make the roller-slabs and other structures. Sufficient glass will be produced incidentally.
Refined compounds will accumulate at a faster pace than it can be used, at least in some cases. Some things will be dangerous, like thorium, uranium, and nuclear waste shipped up from Earth. For long-term storage, these should be dissolved into molten silica, formed into blocks, and stored in piles covered with about a meter of plain soil (to pad against impacts).
Water-ice will also need to be shaded from sunlight so that it does not boil off. Sublimation may also be a problem, in which case ice may need to be stored in tanks.