Testwork aimed to develop a flowsheet using standard flotation for the zinc mineralisation at West and South Ayawilca, which was successfully achieved. The results showed recoveries of 92% zinc at a concentrate grade of 50% zinc consistently achieved using a standard flotation process.

The studies also showed that potentially deleterious elements in zinc concentrates such as silica, manganese, cadmium, mercury and arsenic were well below standard smelter penalty levels, although a small penalty is anticipated for iron content in the concentrate.

The company also found that indium content in the zinc concentrates is potentially payable, subject to the smelter and commercial arrangements.

"We believe the Ayawilca zinc concentrate will be desirable for many smelters due to the low levels of silica, manganese and other deleterious elements, as well as for the high indium levels. We look forward to completing our PEA before the end of June," said president and CEO Dr Graham Carman in a statement.

The Ayawilca zinc zone hosts 11.7 million tonnes of indicated resources grading 6.9% zinc, 0.2% lead, 15 grams per tonne of silver and 84g/t indium, and 45Mt of inferred resources grading 5.6% zinc, 0.2% lead, 17g/t silver and 67g/t indium.

Shares in Tinka Resources (TSXV:TK) opened 3% higher at C32c valuing the company at $82 million. Its share price has fallen 3% so far this year.