Aris Mining (ARMN) said Wednesday a prefeasibility study of its 51%-owned Soto Norte Gold project in Santander, Colombia, confirmed it as a "high-quality" project with "robust" economics and low operating costs.

The company said the new study design lowers mill processing capacity to 3,500 metric tons per day from over 7,000 metric tons per day.

The reduced capacity, which includes 750 metric tons per day dedicated to local community miners, supports investment returns and extends the mine's life to over 22 years while reducing construction risk, Aris said.

The project has proven and probable resources of 20.3 million metric tons with a gold ore grade of 7 grams of gold per ton of rock, containing 4.6 million ounces of gold, the company said.

Shares were up 2.9% in recent premarket activity.