Logistics of Mining and Base Industries: Overview

INITIAL NOTES
truthfully im unclear on how space economy would work at all still. on the one hand one can look at it in the sense of like theres all this stuff thats out there to be mined - well, metals certainly. volatiles are harder to get at it seems like since its all locked up in ices and probably contaminated with ammonia and such. and theres the infrastructural questions of how much does it take to maintain the infrastructure vs your production capabilities vs the maintenance stresses; hard radiation might not be that big of a problem if Shielding Good but idk, mining and earthmoving equipment will need to contend with regolith.
fusion requires tritium breeding, processing colossal amounts of he3 gas and building infrastructure to get stuff off of a gas giant, or churning tons of he3 regolith, or deuterium processing which requires a lot of water. either way means colossal refinery infrastructure for an interplanetary economy: 1 tonne deuterium requires processing about 4 million tonnes water.
that said, not all fusion needs are gonna take 1 tonne of deuterium but in a populous and industrial system building cool shit, i imagine, might. plus fusion propulsion pushes up power consumption, or you need to manufacture a lot of chemfuel or thermal / electric propellant.
so worked example: to fuel up a HOPE fusion ship you need a sphere of ice 0.94 km in diameter... on the plus side, this does mean you have a bunch of separated volatiles left over after the process. perhaps.
i imagine in okanverse they churn through ice like nobodys business. theyve actually decimated the outer system of various stars... though it might not be quite like that. volume goes up pretty fast with radius after all - still, its interesting to mull over.
i guess in the context of widespread fusion propulsion youd really want TNOs and KBOs because theres a bunch of huge ones. if my very back of the envelope rough reckoning on fusion consumption is right. i figured 4 million tonnes because deuterium heavy water processing requires 380000 tonnes iirc, from the figures for the deuterium water processing plant they had built for the CANDU reactors, because heavy water is good for neutron moderation or smth. and heavy water or deuterated water at least only has about 1/10 its mass being the deuterium you want, hence about 4 million.
see to be clear, i imagine everywhere in the solar system probably could be self sufficient though at a higher workload i guess. at least im sure you could carve out existence relative to what you can get with interplanetary "trade", whether it works like trade per se or not. i do think there would be definite benefits to interconnection though and like iunno. i will admit i'm uncertain how to write about a world where everything's fine... but also theres a lot of like transport and infrastructure that would be very worthwhile i think. like the asteroids would definitely make iron even cheaper than it already is on earth - cheaper than water, so to speak. i guess filtering out the platinum groups and nickel would be a thing but...
i would imagine bulk freighters never go out of style as long as theres plenty to ship tbh. and when youre talking tens and hundreds of millions of people living out in places...
rare earth elements give a particular reason to inhabit terrestrial bodies. asteroids in turn are probably also great for building solar. ofc, one thing that metal manufacturing requires a lot of is volatiles, and also heat. thats in part why smelters on earth use coal a lot and in brazil they use charcoal and not electric furnaces. apparently? i need to research that harder. but yea...
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History

At the point of the Abduction in the 2500s AD, spaceborne industry had been in development for over four centuries, a long and slow process that had nevertheless begun bearing fruit by the 2100s as the Anthropocene Climatic Collapse came into full swing. The promises of automated exponential growth never bore out; partly due to economic pressures from within the nations and corporate interests who sponsored initial development of the space economy, racked by the shocks of global economic collapse and pushing space mining as an eleventh-hour effort to staving off the rising tide of social uprising; partly due to inherent limitations, as the infrastructure of mining in space required significant upkeep and oversight, which in turn demanded further infrastructure to provide for the crew and interdependent needs of the mines and industries themselves. Nevertheless, early industries and stations grew with the trade in platinum metals and semiconductor elements, the demands of which necessitated the establishment of a network of volatiles refineries, agriculture and local electronics factories that began by the 2280s to lay the foundations for something like economic self-sufficiency for those spacers who chose to remain off Earth - if a very bare sufficiency.
Mining firms saw horizons for growth of the space industries in the late 21st and early 22nd centuries in five major areas:

1. the expanding Earth-orbit satellite economy,
2. semiconductor industries including the surging market for solar power from China and India,
3. as suppliers of industrial chemical catalysts,
4. the bullion market,
5. potential future demand for chalcophile / siderophile elements based on technological innovations made possible by increased availability, and declining ore grades of rare-earth + coltan + HFSE / LILE deposits required by many advanced electronics.

Crucial to the whole operation at every level, as it is today, was the volatiles industry: all kinds of industry, including metallurgy and certainly propellant manufacturing, depended on it. Separating out platinum group metals from iron and nickel, in particular - even at the significantly higher ore grades present in asteroid rock - requires great quantities of energy and/or solvents for use in electrometallurgical extraction or liquid-liquid extraction, which means volatiles production and/or solar panel production - which in turn requires industrial solvents, heavy Earth investment, or propellant shipment to Earth-orbit depots to take Earth-launched materiel the rest of the way, in turn consuming more volatiles. Skipping the on-site metallurgy phase and shipping the ore back to Earth in unmodified form would have exacerbated the problem, as vast pallets of iron-nickel would need to be lofted with chemical propellants, or vastly higher maintenance rates for mass drivers, iron being an already distinctly unprofitable industry.
Though volatiles are abundant in space given the right choice of environment - ice moons, TNOs / KBOs, comets and carbonaceous asteroids being particularly desirable - processing them is made more difficult than on Earth due to the need to boil them out, which requires significant power and boiler equipment across large volumes of ice, as well as due to the presence of significant hazardous impurities (ammonia, methane, etc) both to industry and to human health that are common in extraterrestrial ices.
Carbonaceous near-Earth asteroids had been early targets for mining firms seeking to supply the growing Earth-orbit satellite maintenance economy. These first mines and volatiles refineries saw early waves of expansion in the 2070s-2090s to process and purify bulk quantities of volatiles to manufacture purified water, chemical fuel, and industrial solvents at scale for the new siderophile refineries, which required heavy initial investments of equipment from Earth.


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The achievement of truly self-sustaining fusion power at the ITER facility in 2046 raised the possibility of another route to growth, though the challenge of realizing it remained formidable even as the first asteroid mining rigs took off in the 2050s and 2060s to establish rudimentary operations meant to supply Orbital ATK satellite maintenance platforms in Earth orbit. Even today, proton-proton fusion remains largely impractical, with a tremendous Lawson criterion (fusion initiation energy) requiring reactor conditions too harsh per unit power to be economical. ITER's history-making burn had been accomplished with tritium and deuterium, with the lowest Lawson of all possible fusion reactions. Deuterium could be separated out from water via the Girdler-sulphide process, but tritium would have to be bred via lithium target bombardment in existing fission reactors.
The demand for tritium posed a significant engineering challenge: D-T was the cheapest reaction in engineering terms, but D-D would mean that all reactants could be feasibly harvested at scale. However, D-D's Lawson criterion was 30 times higher.