This is a descriptive term with some justification:
cccccccccccccccccccccccccccccccccccccccccccccccccccccc
Polscy górnicy pracujący w kopalni dostawali znacznie wyższe wynagrodzenia niż np. górnicy węgla kamiennego na Górnym Śląsku, pracując ok 2 lat pod ziemią. By jednak ograniczyć koszty, wydobycie urobku prowadzono metodą "suchą"
http://fotopolska.eu/Kowary/b19806,Kopalnia_rud_zelaza_i_ura...
------------------------------------------------------------------
Dry mining equipment and machinery (Dry Minerals Processing Plants) are designed and configured for classification, concentration, separation and recovery of metals and minerals concentrate in dry mode and without the use of water.
http://www.dovemining.com/dry_processing_mining_system.htm

--------------------------------------------------------------

Mineral sands mining involves both dry mining and wet (dredge mining) operations. In some countries, mineral sands products are also recovered from hard rock mining methods. All of Iluka’s mining operations entail dry mining, typically involving the extraction of heavy mineral ore from relatively shallow, unconsolidated and free flowing deposits.

Dry mining operations use trucks, excavators, scrapers, loaders or dozer push techniques to recover ore to a mining unit plant. This then conveys, usually by pipeline slurry, the ore to a wet concentrator plant. Dry mining is suitable where deposits are shallow, contain hard bands of rock, or are in a series of unconnected ore bodies. Dredge mining, or wet mining, is best suited to ore reserves below the water table. Dredges mine in artificial ponds, pumping ore in slurry form to a floating concentrator. The ore is washed through spirals that use specific gravity to separate the heavy mineral sands from the lighter quartz and clay.

http://www.iluka.com/company-overview/mining-processing