Shares rose to a 52-week high of 0.918p, up 26.6% on the day, after the company said clearance was granted by the Ministry of Environment and Tourism of the Republic of Namibia for the proposed recommissioning of the mine.
The company has been in talks with consultants about elevating its mine development plan (MDP), released on 30 June 2014, to a full feasibility study (FS).
North River said that process will involve a new resource estimate plus verification and mine design work.
The company has also commissioned a magnetic separation study, and lock-cycle testing from a diversified sample of recently-drilled core, to optimise the metallurgy of the project.
Martin French, managing director of North River Resources said: "Environmental clearance is a major milestone, and is a prerequisite for the granting of a mining licence for Namib. Detailed implementation planning and site preparation is also underway at Namib. Site offices are being installed and heavy equipment procurement is being evaluated."