alluvial mining

基本解释

Placer mining: Oldest method of recovering gold from alluvial deposits.
砂鑛古河牀裡的金砂鑛牀。
Mechanized placer mining, with special devices for washing and separating waste from valuable minerals, is used in productive alluvial deposits.
機械化砂鑛開採用於含鑛量豐富的砂鑛牀．利用專門設備來淘洗、分離廢物與有用鑛物。
Gravel cemented geological body, called solid formation, has been found in the fluvial sediment of Quaternary system in the exploration and mining of alluvial gold deposit in recent years.
近年來在砂金鑛牀的勘探和開採中，發現在第四系河流沖積物中存在砂礫石膠結地質躰，被稱爲膠結層。

He is one of many who have flocked to the Kangari hills in southern Sierra Leone to find small fortunes in the hard graft of alluvial gold mining.

De Beers is active in every category of industrial diamond mining: open-pit, underground, large-scale alluvial, coastal and deep sea.
FORBES: Anglo American Receives Final Regulatory Approval for De Beers Acquisition