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)


  3Q22 2Q22 % change 3Q21
Iron concentrates processed (t) 37,142 33,326 11.5 37,376
Silver (oz) 142 126 12.7 143
Gold (koz) 653 422 54.7 441
Ore grades        
Silver (g/t) 159 160 (0.6) 157
Gold (g/t) 1.71 1.21 41.3 1.35


  • Quarterly silver production increased 12.7% vs. 2Q22 due to a higher volume of pyrites concentrates processed.
  • Quarterly gold production increased 54.7% vs. 2Q22 due to a higher ore grade and increased volume of pyrites concentrates processed.

  • Quarterly gold production increased 48.1% vs. 3Q21 due to a higher ore grade.

  • Year to date silver and gold production decreased 6.3% and 13.9% vs. YTD 21 respectively, mainly due to a decrease in the volume of pyrite concentrates processed from Saucito’s flotation plant.
  • Anticipate silver production from the Pyrites plant at Saucito to be in the range of 550 to 600 koz, reflecting the lower volumes processed (previously 700 to 750 koz), while gold production is estimated to remain in the range of 1.5 to 2.5 koz.
  • The tie in of the Pyrites plant to the national electricity grid has been delayed a few weeks as we are prioritising the process at Juanicipio. Nonetheless, we will continue working toward achieving this milestone and will update the market in due course.