Chile's fourth biggest copper mine, Codelco's El Teniente, was producing at less than half of capacity for a second day on Sunday after most staff workers stayed home to avoid violence by striking contractors, the company said.
El Teniente, which produces about 2.5 percent of the world's mined copper or 404,000 tons-a-year, continued to work with a skeleton staff to keep production at 40 percent of capacity by processing stocked material.
It was not clear how long those operations could last but staff union leaders have warned workers will not return to the job until their safety is guaranteed.
Thousands of striking subcontractors demanding higher wages threw rocks at buses carrying staff workers to the mine site earlier this week.
Codelco and its unions agreed to keep most staff workers away from the mine to prevent further violence. Protest leaders have said demonstrations will continue until their employees and Codelco raises wages and improve working conditions.