The company said an employee of its civil engineering subcontractor had died following an accident on April 2 involving the excavator he was operating.
PanTerra said it had informed all relevant authorities and pledged to assist with investigations.
Counselling services for family and affected employees will be provided.
The company passed on its condolences to the family and friends of the contractor.
The Las Lagunas operation comprises the reprocessing of high-grade refractory tailings.