Premier African Minerals (LON:PREM) expects to produce concentrate from its flagship RHA tungsten project by the end of the first week of June.
Progress of construction at the project in Zimbabwe is on schedule, said the firm, which is operator of the site and holds a 495 stake.
The process plant has been delivered and offloading has been completed.
George Roach, chief executive of Premier, said: "Appropriate Process Technologies (APT) the manufacturers of the process plant who are responsible for assembly on site and commissioning, undertook that commissioning would be complete by 3 June 2015.
"Mining continues to progress well and visible mineralisation continues to confirm the geological model.
"Subject to APT meeting their undertakings, we expect to produce concentrate by the end of the first week of June 2015. I look forward with great excitement to the transition from exploration and development company to producing mining company."
In January, Premier estimated the mine would generate net revenue of US$26mln over a 22 month life of mine with pre-tax cash flow of US$8.9mln.
Premier agreed a £1.65mln convertible loan facility with financier Darwin last week to complete the construction of the mine in Zimbabwe.