In its recently released 2021 financial results, Fresnillo confirmed it had completed the conversion of its haul truck fleet at the Herradura gold mine in Mexico to a dual-fuel system leveraging both diesel and liquefied natural gas (LNG).

The company started its dual-fuel journey all the way back in 2016 when, together with Caterpillar, it trialled/piloted the mining OEM’s Dynamic Gas Blending™ (DGB) dual-fuel technology on two prototype trucks as part of a strategy at Herradura to reduce both its carbon footprint and costs.

Caterpillar’s dual-fuel DGB technology works by blending lower cost LNG with diesel fuel, with the resultant improvements in fuel, emissions and maintenance adding up to millions of dollars each year in cost savings, the mining OEM says.

Following some good initial results from Herradura, the company made plans to roll out this technology across its fleet, converting its haulage fleet’s diesel engines to a dual-fuel system, which optimises consumption by automatically switching between diesel and LNG depending on the terrain.

The Herradura fleet consists of Cat 785C and 793D haul trucks, among others.

A Fresnillo spokesperson told IM: “The 785C series consume approximately a 40:60 diesel-LNG mix, while the 793D has a 65:35 ratio, thus achieving, in 2021, a reduced energy factor of 20.97% and 18.68%, respectively.

“To date, we’ve recovered 35% of our investment through fuel savings, which considers both the LNG conversion kits and the biomodal supply station.”

The company has now converted 31 of its 785Cs to run on this mix, along with 10 793Ds. It has also invested in infrastructure to ensure it has the appropriate LNG storage capacity at Herradura.