The international mining giant BHP has in a last attempt to avert the strike requested state mediation.
If it does not result in an agreement, the employees are free to close down the work.
"We hope that this clear vote is the alarm clock that BHP needs to start constructive talks, if the company wants to avoid a protracted conflict that could be the most costly in the country's union history," the union wrote in a statement.
The union is requesting a one-time bonus as a reward for the miners 'efforts during the pandemic, as well as grants for training for employees' children.
Can push up prices
In 2017, Escondida's miners went on strike for 44 days.
The conflict was the longest in the history of the Chilean mining industry and cost the owner the equivalent of SEK 6.3 billion.
Chile is the world's largest copper producer and accounts for 28 percent of global production.
A protracted strike would hit the already scarce supply of copper in the world and further push up the already high prices.