User blog comment:JadenLan/New information about Remnant from WoR Vytal Tournament Festival/@comment-410526-20151010161931/@comment-4010415-20151010213151

Okay, I skimmed this conversation, buuuut... It's possible that freshly-mined Dust gets shipped to factories in Atlas. The factories do their thing (purify it, grind some of the crystals into powder, mix Dust into other colors, make Dust bullets, package everything up) and then the now-processed Dust is shipped from Atlas to other kingdoms.

That is why the Dust shipment was from Atlas, when it's possible that the SDC has quarries all over the world, considering it's known as one of the biggest/most successful Dust companies in the world.