The DMLZ ore body lies below the DOZ underground mine at the 2,590-meter elevation and represents the downward continuation of mineralization in the Ertsberg East Skarn system and neighboring Ertsberg porphyry.

The DMLZ ore body lies below the DOZ underground mine at the 2,590-meter elevation and represents the downward continuation of mineralization in the Ertsberg East Skarn system and neighboring Ertsberg porphyry.

The DMLZ has continued its ramp-up of production. Hydraulic fracturing operations have been effective in managing rock stresses and pre-conditioning the cave following mining-induced seismic activity experienced in 2017 and 2018. Ore extraction continues to exceed expectations, averaging 14,900 metric tons of ore per day in fourth-quarter 2019 and reached approximately 16,000 metric tons of ore per day at year-end 2019. Ongoing hydraulic fracturing operations combined with continued undercutting and drawbell openings in the two currently active production blocks are expected to expand the cave, supporting higher production rates that are expected to average 29,000 metric tons of ore per day in 2020, approach 60,000 metric tons of ore per day in 2021 and 80,000 metric tons of ore per day in 2022 from three production blocks.

The mill produces copper and gold concentrate from mined ore through a process to separate valuable minerals from the impurities covering them. The main steps in the process are crushing, grinding, flotation, and dewatering. Crushing and grinding transform ore size into fine sand in order to release particles containing copper and gold.

Flotation is a separation process to produce copper-gold concentrate. Concentrate slurry consisting of finely ground ore and water mixed with reagents is introduced into a series of mixing tanks called flotation cells, where air is pumped into the slurry.

The reagents used are lime, frothers and collectors. Frothers form stable bubbles that float to the surface of the flotation cell as froth. Collectors react with valuable metal sulfide mineral particle surfaces. rendering these surfaces hydrophobic. The hydrophobic sulfide mineral particles adhere to the air bubbles rising from the slurry zone into the froth floating on the surfac ........