Metso recently reported that Codelco’s El Teniente operation is the first mining company to use the latest version of Metso’s Poly-Met discharge grates for SAG mills. According to the company, implementation of this product was instrumental in enabling El Teniente to set a mine record for commercial production in 2015, with substantially lower operating costs.

According to Metso, for years, El Teniente has encountered problems with grate piece breakage in its SAG mill, resulting in low mill availability and operational instability. Starting in 2010, El Teniente began to collaborate with Metso to solve the problem. As a result, the “next level” of Metso’s Poly-Met discharge grates were put into use in a SAG mill for the first time. This innovative technology, said Metso, improves the copper production process by increasing throughput and pebble production while decreasing wear rates. Discharge grates are designed to retain oversize material and balls in the mill, while allowing slurry and pebbles to move on.

In 2015, El Teniente claimed record commercial production of more than 71,000 tons of fine copper at one of the industry’s lowest cost levels. An increase in slot size and operational stability increased throughput by 7%. Pebble production rose by 24% during the first 50 days of operation, while the wear rate dropped from 0.26 mm per day (mm/d) to 0.11 mm/d. Mill availability increased due to the elimination of pinning and breakage. El Teniente also achieved historical-best safety results in 2015 with an accumulated frequency rate of 1.

The Poly-Met discharge grates are made of metal and rubber, combining less weight with greater elasticity. The composite material was identified as the best solution for this type of application after a series of trials with Codelco El Teniente during 2012-2014.

“At Codelco El Teniente, we are constantly innovating to improve our processes and maximize results. In this specific case, we incorporated Metso’s solution into our processes. We have already seen substantial improvements in operations and maintenance,” said Mauricio Larraín, general manager, Codelco El Teniente.

Metso said it is planning the global launch of Poly-Met grates in late 2016.