Sorry I missed this for over a month.
THAT is the stuff, @Estokha!
@cyclopath That stuff also makes a damn fine Faraday cage when you line the walls and ground it… you know, just fyi. 
Actually, @midsfactory, you have met the problem well with various solutions. However, while powder can be faster (IF it is very clean and free of oxide), it can really only be used once with any simplicity. Cleaning oxides off of tiny copper dust particles can be an exercise in futility, since they might just be almost entirely composed of oxide, being so small! The same goes for the copper*sulfur reaction product… it may comprise the entire particle by the time it’s done reacting… so you cannot clean it up with citric acid and reuse it, the way you can reuse copper scrubby mesh. A likely more pernicious problem with copper dust is reacting it with anything can simply cause it to dissolve!
To speed up the reaction of sulfur compounds with metallic copper, heat and moisture help.
Why not just use an adsorbent for that pesky elemental sulfur you think remains after the copper?