Ihe ngwọta nke mmiri pan igwe ihe ndọda mmiri na-ewu ewu nke ukwuu n'ọtụtụ mba Africa dị ka Zimbabwe, Egypt na Sudan, Usoro ọrụ na-akụpịa → egweri → knelson centrifugal concentrator nhọrọ (iji nweta nnukwu size free gold) → na-ama jijiji table (ịhọrọ ezi gold si ore ọdụ). 20 ton kwa elekere. Mgbe e gwepịasịrị ya, a na-agbaji nkume ahụ n'ime ihe na-erughị 20mm. A na-etinye irighiri ihe ndị ahụ n'ime igwe nri mmiri na-acha ọla edo, a na-awụsa ha na ntụ ntụ ihe dịka 100 ruo 150 ntupu (site na 80 ruo 150 micron). Mgbe ahụ, a na-ebufe slurry a na-emepụta n'ime igwe ihe igwe mmiri na-ekpo ọkụ na ebe nchekwa centrifugal nke ọla edo, nke a na-anakọta ụfọdụ ájá ojii na-etinye ọla edo. Mgbe ahụ, ọdụdụ ahụ na-aga na tebụl na-ama jijiji maka mgbake ọzọ nke ọla edo fọdụrụnụ.
A ga-ebunye akụrụngwa ndọda ọla edo n'ime akpa 20ft ma ọ bụ 40ft dịka oghere na ịdị arọ siri dị. Ruo ugbu a, anyị ezipụla akụrụngwa ike ndọda n'ọtụtụ mba, gụnyere Sudan, Zimbabwe, Mauritania na Egypt.