Sometimes, things just start to click.
Sierrita is knocking on the door of 125,000 tons of throughput per day. Leadership says the achievement is the result of contributions and successes across the site made over a span of over five years.
“It’s amazing,” said General Manager David Rhoades. “When we first did America’s Concentrator, and we would say ‘Drive to 125’, I don’t think many people believed we could get there.” 
America’s Concentrator started in 2019, where sites across the company identified and alleviated bottlenecks which could add up to a whole concentrator worth of throughput. This was when Sierrita discovered several areas of improvement, including blasting and stockpile practices. By 2021, mill throughput was 102,000 tons per day.
Sierrita still had a long way to go to reach 125.
“That led us to a LEAN study where we looked at our maintenance practices and unlocked another 7,000 tons a day,” said Concentrator Manager Graham Cooper. “After that, we kept going.”
Heading into 2024, Sierrita tightened the screen panels at the crusher to produce a finer material to the mill. Then, to take advantage of the finer crush, they made the steel balls in the ball mills smaller. This resulted in another 3,000 tons of throughput a day.
“As the ball mills spin, these steel balls circulate in water and roll on each other. This is what grinds up our material,” Cooper said. “Thanks to this finer crush, we were able to decrease the size of this grinding media which means you can fit more in and increase the amount of grinding happening.”
After adjusting the water addition strategy and upgrading the grinding control model, Sierrita had a record-breaking Fourth Quarter. November and December were historic months coming within a few thousand tons of the 125 goal. This is something that would not have been possible only a few short years ago.
“High throughputs used to result in downstream problems like an overflow in tailings. But luckily, we identified a coagulant, or ‘secret sauce’ as we like to call it, that has allowed us to push harder on tough material and not see that problem” Cooper said. “We even shared it with other sites, because it was such an effective product.”
According to Cooper and Rhoades, the combination of multiple system-wide changes has had a dramatic effect.
“It is about looking beyond your own individual area. Drilling and blasting for instance, they didn’t just look at their own efficiencies and costs, they looked at the entire process,” Rhoades said. “That meant investing more money on blasting, but it resulted in better material and the overall benefit of the site.”
“This is something everyone on site can be proud of,” Cooper said. “The geologists, mine engineers, drilling and blasting, the loading and transport guys keeping teeth out of the primary crusher, mill maintenance, the metallurgists, the electricians getting our reliability up, and tailings. It is everyone.”
Going forward, Sierrita will continue to look for new bottlenecks and areas to improve.
“For any site, it is about never being satisfied with the status quo and always looking for ways we can do better,” Rhoades said.