Pyrites Plant

Ownership: 100% Fresnillo plc
Location: Zacatecas, Fresnillo District
Facilities: Leaching plant (Saucito mine), flotation plants (Saucito, Fresnillo mines)
Commercial Production: 2Q18 (phase I), 2H20 (phase II)
Anticipated Production: Annual average 3.5 moz silver and 13.0 koz gold
Capex: US$ 155 million

The Pyrites plant is expected to improve overall recoveries of gold and silver, and therefore maximise production in the Fresnillo district; expected to total an average of 3.5 moz silver and 13 koz gold per year once both phases are operating at full capacity.

This project was divided into two phases, the first phase consisted of the iron flotation circuit and pyrites leaching plant at the Saucito mine, which was commissioned mid-2018. The second phase, a 14,000 tpd tailings flotation plant at the Fresnillo mine, is under construction and is expected to be concluded in 2H20. 

The second phase, a flotation circuit, will treat the ongoing and historical tailings from the Fresnillo mine to produce a pyrites concentrate which will be sent to a filtration plant and then on to the leaching plant at Saucito, the final part of the process to produce the precipitates. Commissioning of phase II of the Pyrites plant set for 2H 2020.

Pyrites Plant (Phase I)


  2Q22 1Q22 % change 2Q21
Iron concentrates processed (t) 33,326 32,364 2.8 48,523
Silver (oz) 126 150 (16.0) 167
Gold (koz) 422 510 (17.3) 721
Ore grades        
Silver (g/t) 160 193 (17.2) 147
Gold (g/t) 1.21 1.59 (23.8) 1.56


  • Quarterly silver and gold production decreased 16.0% and 17.3% vs. 1Q22 due to lower ore grades.
  • Quarterly silver production decreased 24.5% vs. 2Q21 due to a lower volume of pyrite concentrates processed which was mitigated by the higher ore grade.

  • Quarterly and first half gold production decreased 41.5% and 33.3% vs. 2Q21 and 1H21 respectively, due to a decrease in the volume of pyrite concentrates processed from Saucito’s flotation plant and a lower ore grade.

  • First half silver production decreased 9.0% vs. 1H21 primarily due to a lower volume of pyrite concentrates processed, mitigated by a higher ore grade and recovery rate.
  • In 2022, we continue to estimate silver production from the Pyrites plant at Saucito to be in the range of 700 to 750 koz while gold production is estimated to remain in the range of 1.5 to 2.5 koz.
  • We expect to complete the tie-in of the plant to the national electricity grid in the coming weeks followed by the ramp up of the plant soon after.