Fresnillo says TBM ramp up steadily increasing development rates at its namesake silver mine

Mexico’s Fresnillo PLC has just released its Q4 2020 report, with some interesting updates on operational progress at its key minesites. At its namesake Fresnillo silver mine in Zacatecas, the company reported that quarterly silver production was up 4.2% versus Q3 2020 as a result of an increase in the volume of ore processed. But this followed a quarter where fewer personnel were on site following COVID-19 preventive measures affecting employee attendance, development rates and equipment availability. While these measures continue to be enforced, better personnel management has improved production.

Development rates increased to an average of 3,241 m per month in Q4 2020 (Q3 2020: 2,878 m per month), marginally missing a target of 3,300 m per month by year end, but the company believes a good performance given the impact of COVID-19 related personnel issues (including self isolation and quarantine). For the full year, development rates increased to 3,130 m per month on average, up 3.1% versus FY19 (3,037 m per month) as a result of the ramp up of the company’s tunnel boring machine and a new contractor hired at the end of 2019.

As outlined in IM‘s November/December 2020 edition, Fresnillo has partnered with tunnelling specialist Robbins, applying its TBM technology to develop the new San Alberto orebody at the Fresnillo underground mine. The machine is called the Robbins MDM 5000, and is intended to carry out 11 km of development in total for that project. From an image of the Robbins MDM 5000 released by Fresnillo, the machine appears to be a variation on traditional TBM technology designed for hard-rock mining using a unique cutting head design to create a uniform rectangular tunnel profile.

Quarterly and full year silver production remained flat versus both Q4 2019 and FY 2019 due to a higher ore grade resulting from incremental improvements achieved following the implementation of performance improvement initiatives, offset by a lower volume of ore processed for reasons explained above. “Our performance improvement plan, as set out on the Capital Markets Day in December 2019, continues to be implemented. We continue to focus on controlling dilution and enhancing blasting and drilling techniques to cope with the narrower veins.”