Is zakat obligatory on mining companies immediately upon the extraction of gold from the earth, with the entirety of the produced quantity being accounted for at once, or is it not obligatory until a full year has passed, like trade, taking into consideration costs and obligations?

Scholars have differed on the permissibility of selling mineral dust. The Shafi'is prohibited it absolutely due to ignorance (of its contents), while the Malikis and Hanbalis permitted it when exchanged for something other than its own kind, but not for its own kind.

Mining companies pay zakat on mineral dust as trade goods. The zakat year for it is tied to the year of the money with which it was purchased. Zakat is paid according to its value, not its physical substance, and all its types are combined. No specific year (hawl) is stipulated for it, unlike the zakat on the mineral itself, for which no hawl is stipulated, and which is paid on the gold itself, not its value.