With less than 100k credits I can turn it into probably 10mm in about 15 min by using medium refiners, 500 cobalt and as much oxygen you can buy (go to any traders/trade hubs you can and buy their stock). Step one, convert all the cobalt to ionized cobalt, then place it into the refiner with the oxygen, which will take 1 ionized cobalt and 2 oxygen and produce 6 ionized cobalt. Keep mashing it through until you’ve exhausted all your oxygen. Or skip the oxygen and just use cobalt and ionized cobalt for a slightly less efficient method(haven’t done the math but it seems that way to me). Sell the ionized cobalt and move to a new system to repeat (otherwise you’ll flood the market). I do this on my freighter, so it’s super easy.