The amount of practical metallurgy knowledge we have under microgravity conditions falls in the "Not A Number" section of a floating-point unit calculation result.
Assuming you have some "dust' - you have to purify it, and then convert the refined ore into a chemically neutral granular material that is compatible with electron-beam or infared laser spot heating/sintering. On earth, buy the refined metal from Grainger in whatever format its available (screws, bar stock, etc.) - reformulate it as a powder (preferably something very chemically stable, uniform, and with particle sizes compatible with the resolution of the final use). None of these have been performed on-orbit that I am aware of.
Second, its a leaky system, volatile chemicals (water and Nitrogen come to mind) are needed for many of these stages for buffering and chemical conversion (reduction/oxidation), transport, lubrication, mixing, heat-treating and quenching, etc. etc.
Also, we don't yet know the true relative abundance of the important ores vs. locations for collection, Lunar surface? Lunar drilling? Trojan "asteroids"? NEO objects? Or do we have to go beyond Mars to get any decent quantities of these raw materials.
One more item - if you do have a perfect NEO rock with a nice mix of Iron, Aluminum, Titanium, Cobolt, Copper, and Silicon, first you will need to break this up into manageable chunks. A hand pick and a canvas bag won't work. Jackhammer and auger drills will also fail if they cannot be anchored to something in order to generate force on an ore vein. Once its in small chunks, how do you refine it? Chemical refining, gas/vapor distillation, electric arc furnaces, and other standard tools for metallurgy are used in the presence of 1 standard G. Will the use of a centrifuge to approximate 1G conditions work - think tidal forces, shear forces, and other non-linear effects that will pop up to create inconsistencies in the local environment around the refining process.
All of the above can and should be solved, but won't unless we are _there_ and there to stay.