An expansion study on Andean Precious Metals' San Bartolome silver-tin mine in Bolivia may be delayed due to backlogs in metallurgical testing.

Delays at SGS Canada's testing facility in Lakefield, Ontario, as well as delays created by transportation, customs, and the impact of Covid-19, the company said.

Andean plans to mine a fines disposal facility, which will be adjacent to the tailings facility, to produce tin.

The company is waiting on testwork of 23 samples recovered in the resource definition drill programme, to be followed by testing on composite samples of 59 drill holes in storage at the laboratory.

Andean Precious Metals aims to produce tin at the mine, which currently produces only silver.

"Initial estimates for capital costs, operating costs, and silver recoveries are positive, and we continue to advance our understanding of tin processing options while managing test-work delays," chief executive Simon Griffiths said.

"While initial results support our thesis of pre-concentration and gravity recovery of tin, we need to work through our backlog of metallurgical testing before we make a decision to move forward with the next phase."

The FDF contains indicated mineral resources of 10.5 million tonnes, with 16.2 million silver ounces and 11,930 tonnes of tin. Inferred mineral resources at the FDF are 1.51 million tonnes, with 2.3 million ounces of silver and 1,330 tonnes of tin.

Andean has also completed a drill program at its dry stack tailings facility to define silver and tin mineral resources. The DSF contains an estimated 20 million tonnes of material.