The country's central mining bureau has confirmed the earlier granting of approval by the regional body, said the firm, adding that it plans to start mining imminently.
Ortac's chief executive Vassilios Carellas said it was an important step in the project's development and came after a "thorough" engagement process.
He added that it proved projects in the natural resource sector could be moved forward in Slovakia.
"Following this announcement, we anticipate and expect to receive further requests for clarification with respect to this decision.
"We welcome such requests as they are essential ingredients in designing projects which are successful for all stakeholders."
Ortac added that Viktor Pomichal, managing director of Ortac Slovakia, will now step down having achieved the company's goal of re-establishing mining operations at Šturec.
Meanwhile, Ing Peter Čorej, a Slovak mining engineer with more than 30 years of experience, and who led the development of the trial underground application, will formally manage the mining programme.
Mining will be carried out by a local contractor selected through a procurement process.