Cancelling ore pillars in large-scale coastal gold deposit: a case study in Sanshandao gold mine, China.

The Sanshandao gold mine was the first coastal metal mine in China, and the orebody is located along the coast and under the sea. The mining conditions are complex and a pillar and layer backfill mining method was adopted which resulted in a 22.6% per year loss of mined ore. The possibility of eliminating the pillars as mining progressed to deeper levels was investigated. Tests were conducted to determine the physical and mechanical properties of the rock mass and a rock quality classification system was developed applicable to coastal deposits. The depth at which the use of pillars could be eliminated was determined to be 555 m based on simulations using the finite element method. A novel room and pillar alternate layer backfill mining method was developed to reduce rock movement and ground settlement in the mining area and was applied to panel area 553 at the mine. Mining efficiency was increased by a factor of 4-5 and mining losses reduced by a factor of more than 5, while settlement of the roof strata was small.
The Sanshandao gold mine was the first coastal metal mine in China, and the orebody is located along the coast and under the sea. The mining conditions are complex and a pillar and layer backfill mining method was adopted which resulted in a 22.6% per year loss of mined ore. The possibility of eliminating the pillars as mining progressed to deeper levels was investigated. Tests were conducted to determine the physical and mechanical properties of the rock mass and a rock quality classification system was developed applicable to coastal deposits. The depth at which the use of pillars could be eliminated was determined to be 555 m based on simulations using the finite element method. A novel room and pillar alternate layer backfill mining method was developed to reduce rock movement and ground settlement in the mining area and was applied to panel area 553 at the mine. Mining efficiency was increased by a factor of 4-5 and mining losses reduced by a factor of more than 5, while settlement of the roof strata was small.