Placer Mining
What is Placer Mining?
Placer mining is a form of surface mining that targets loose accumulations of valuable heavy minerals that have been naturally concentrated in streambeds, floodplains, beach sands, or other unconsolidated sediments by the action of water and gravity. In Alaska, placer mining has historically focused on gold, but placer operations may also recover other dense minerals such as platinum-group metals, cassiterite (tin), scheelite (tungsten), and other heavy accessory minerals that occur with gold in gravel deposits.
In addition to conventional surface mining of stream and bench gravels, Alaska also has underground “drift” placer mining, where miners tunnel into frozen (permafrost) gravel deposits to access buried pay streaks, then thaw and excavate the pay material for processing at the surface. Placer mining methods include mechanical excavation and water-based gravity separation (such as sluices, jigs, and other equipment) as well as suction dredging, in which a floating dredge uses a suction hose to vacuum gravel from the streambed and process it through onboard recovery systems; suction dredging is another form of placer mining that works directly in active channels rather than in exposed banks or benches. Because placer deposits consist of already weathered and eroded sediments that contain physically liberated minerals, placer mining generally does not generate Acid Rock Drainage and typically does not require chemical treatment to recover the valuable minerals.
Placer Mine Permitting
In Alaska, Placer Mining is permitted through the Application for Permits to Mine in Alaska (APMA) program.