alluvial mining

基本解释

Placer mining: Oldest method of recovering gold from alluvial deposits.
砂矿古河床里的金砂矿床。
Mechanized placer mining, with special devices for washing and separating waste from valuable minerals, is used in productive alluvial deposits.
机械化砂矿开采用于含矿量丰富的砂矿床．利用专门设备来淘洗、分离废物与有用矿物。
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.
近年来在砂金矿床的勘探和开采中，发现在第四系河流冲积物中存在砂砾石胶结地质体，被称为胶结层。

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