skillissuer

depends on manufacturer, some state it's just 50%

hydrogen is the easy one, because you can burn it off on catalytic bed, then pass through bed of 3A MS to trap water. done

separating excess oxygen and nitrogen is easier and there's already some nitrogen (as much as 50%) in crude helium

yeah it's distilled off from nitrogen-heavy natural gas, like you could do with nitrogen-heavy gas without helium, or even air. all three processes are done commercially. the issue is that helium bearing natural gas is limited in supply and getting low enough temperature at latter stages of helium refining and liquefying requires bespoke facility. this part is hard

energy expenditure would be similar to purifying it from helium concentrate, so not much difference. considering small volume of balloon helium this wouldn't probably mean large increase. i also don't know what this guy is about

balloon helium has some air in it, it's still 90%+ helium, probably

it's pretty fucking hard. only six countries in the world produce helium, and you get engineering challenges that don't exist anywhere else. for example you can't use any grease on helium turbine bearings in the lower temperature stages because all of them freeze, so the solution is to use gas lubricated bearings. this is some serious precision engineering that has to work in extreme conditions

it's also hard because the simpler way of liquefying gases, like the one used for nitrogen that uses no moving parts in the coldest part, fails for helium, this makes liquefying helium harder than any other gas. it's also hard because of limited availability. it's hard because of massive capital costs and lots of custom machinery. it's hard because of scale required. about any other compound can be manufactured without at least some of these problems

technology is there, the issue is to run it cheaply, reliably and on scale. this is the actual problem

edit: i mean it's a problem that responds well to throwing money at it. if there was extra need for helium that would be met by diverting balloon gas, then it would work at some price, but we're nowhere close to it

it's much more complicated than that, and the most useful property of helium is its low boiling point. it goes like this:

first, you start with natural gas that has some nitrogen, some water, some helium, some carbon dioxide, heavier hydrocarbons, thiols, dust, and such. mechanical filtering gets rid of dust and mist, water, carbon dioxide and thiols are removed chemically, heavier hydrocarbons are removed on active carbon. now we have mix of methane, ethane, hydrogen, helium, nitrogen, traces of carbon monoxide, dioxide and water. this all is cooled down, first just to freeze out these trace amounts of water and carbon dioxide, then to liquefy what is left.

next this liquid mixture is put through massive distillation tower, allowing for separation of mainly nitrogen and methane. this nitrogen and methane are end products, some are sold as liquids but most are regasified in order to cool down incoming gas and save some energy. another product is helium concentrate, at this point it can be 50% to 80% with rest being nitrogen but this depends on exact facility.

then, some extra air is added to helium concentrate, it's heated up and passed over catalyst bed. this is done in order to burn out hydrogen and any hydrocarbons, because separating oxygen from helium is much easier than separating hydrogen from helium. products of this burn are water and carbon dioxide that can be separated chemically. then again it's all cooled down, nitrogen and oxygen are liquefied, then it's all cooled down further and from some 30K on it's just helium being circulated as gas because you can't liquefy it like any other gases, it needs a special process. on every pass, with extensive recycling of heat some part of it is liquified and this is the final output, 5N liquid helium.

at least that's how it works in a facility built in 70s in then eastern block. now it supplies half of europe and a research facility situated nearby. i suspect it was built with at least some military applications in mind during this time, namely helium is used for pressurizing hydrogen tanks of rockets, but also soviets toyed with an idea of using gas lasers militarily. this requires a supply of helium, and a supply of neon is also a nice thing to have in this situation. neon was produced in Azovstal cryogenic oxygen factory serving nearby steelworks, as it can be separated from air. it ended up providing virtually all neon for semiconductor manufacturing in the world, but from what i understand there are alternative suppliers by now

wdym by "low purity" helium, helium that has been purified cryogenically is easily 99.999% if not better, and this is the main process used worldwide iirc

helium just boils off in MRI/NMR machines, this is the major use of helium i think. if you could recycle that in machines that already are out there, that would solve lots of problems. there are newer systems that do not require cryogens or just require liquid nitrogen which is much cheaper and less energy intensive. these things use closed loop refrigeration, but in turn you need to supply them with power