The Bimba mine operated by Zimplats, Zimbabwean unit of Impala Platinum Holdings, has collapsed at the Ngezi site, impacting nearly 50% of its output.
The company said that there were no casualties or damage to mobile equipment at the site.
The mine is located 150km from the capital city Harare and collapsed due to accelerated deterioration of ground conditions with the Mutambara shear. The shear extends through half of the mining area.
Zimplats has decided to abandon and permanently close half of the site as ground stability has become a recurring problem at the mine.
The deterioration of ground conditions, first identified in 2011, aggravated in 2013 along the declines and within the stoping footprint. The company spent $6m to address the problem.
Zimplats said in a statement: "Information gained from ground monitoring equipment installed to track the extent and magnitude of the deterioration has led to a decision to abandon and permanently close approximately half of the mining footprint in areas where major falls of ground have occurred."
Bimha Mine is the largest of the four mines operated by the mining company in the country and the collapse has reduced its production by 50% to 45,000oz of platinum.
"Preliminary estimates indicate that it will take 15 months (two on twin decline development) to reach full production of eight fleets and 50 months to reconnect to current declines (FY19)," Zimplats added.
The company has hired senior experts and consultants to conduct detailed investigations and provide a solution to restart full production at the mine.
Zimplats will reallocate two of the eight fleets that were deployed at Bimha Mine, to redevelop the declines to open up the bottom roadways. The rest of the fleets will either be absorbed within Bimha or with other mines.
"All statutory notifications have been completed and all emergency systems put on high alert. Daily inspections and reviews continue to be undertaken," the company added.