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. 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.

Pyrites Plant (Phase I)


  1Q23 4Q22 % change 1Q22
Iron concentrates processed (t) 27,952 32,211 13.0 32,364
Silver (oz) 111 111 0.2 150
Gold (koz) 270 374 (27.7) 510
Ore grades        
Silver (g/t) 177 145 22.0 193
Gold (g/t) 1.31 1.19 9.3 1.59


  • Quarterly silver production remained flat vs. 4Q22 as the decrease in volume of pyrite concentrates processed and lower recovery rates were offset by a higher ore grade from the Saucito’s flotation plant due to lower dilution and better ore grade at long hole drilling areas.
  • Quarterly silver production decreased 25.9% vs. 1Q22 due to the decreased volume of pyrite concentrates processed, and lower ore grade and recovery rate.

  • Quarterly gold production decreased 27.7% vs. 4Q22 due to the lower recovery rate and decreased volume of pyrite concentrates processed, partly offset by the higher ore grade from Saucito’s flotation plant.

  • Quarterly gold production decreased 47.0% vs. 1Q22 as a result of the lower ore grade and recovery rate and the decrease in volume of pyrite concentrates processed.
  • After the successful tie-in of Juanicipio mine in the 4Q22, the Pyrites Plant awaits the tie-in process to the national grid in 2Q23. Once this takes place, commissioning and ramp up will start immediately.