srpski term (edited): zapunjavanje taložnice

Ova investicija je bila neophodna u cilju održavanja osnovne proizvodnje uglji, jer je zapunjavanje taložnice srazmerno toj proizvodnji.

"zapunjavanje taložnice je srazmerno proizvodnje uglja"

this indicates clearly that "taložnica" is a separate part of the coal mine, used for decantation of sludge after separation of coal, it's not the part where any coal was taken out of the ground.

Progressively filling a decantation basin as the mining of coal is going on is not the same as "backfilling" the hole left in the ground from extracting coal.