Nova Minerals (ASX:NVA) achieved gold recoveries of up to 69% through heap leaching of lower-grade ore during its RPM deposit pre-feasibility metallurgical test work at the Estelle project in Alaska, according to a Monday filing with the Australian bourse.

High-grade ore over 2 grams per tonne grade of gold was fed directly into the carbon-in-pulp/carbon-in-leach circuit, and ore below 2 g/t grade of gold processed through an ore sorter, resulting in a 4.33 times increase in gold content in a single pass, the filing said.

Additionally, high-pressure grinding rolls test work is underway to refine the flowsheet and provide power cost efficiencies, per the filing.

Shares rose 7% in morning trade on Monday.