Once commissioned, the miner will feed the plant all output from the pit, before it goes to the existing concentrator plant.

It said this process would result in a significant upgrade in production rates.

Chairman Michael Masterman said the jig and mill plant commissioning was an important milestone as W advanced to full completion of the 2 million tonne per annum plant.

"We expect to be able to feed crushed ore to the jig and mill plant in late April and then process it through our existing concentrator plant," he said.

"This will allow a significant increase in near-term tungsten and tin production capacity and also allows us to ensure smooth autonomous operation of the jig and mill plant ahead of commissioning of the new large-scale concentrator plant later this quarter."

Construction of La Parrilla's concentrator plant is well advanced, with 90% of all structural steel and primary equipment now on-site and being installed and construction completion expected during the June quarter.

Masterman said, while there has been a delay in the delivery of steel, which had had a negative impact on the schedule of the jig and mill and concentrator plants, there were no adverse impact on budget as the cost of the plants were fixed.

"Overall the project continues to track below budget including contingency," he said.

W said the La Parrilla mine was "primed for scale-up", with both the preparatory grade control drilling and the ramp from the fast track mine area to the crusher plant completed.

During the remainder of April, the company plans to carry out the first hard-rock blasting of the 10m benches in the fast track mine area and execute the mining contract.

It is also busy with the mining fleet mobilisation after a Komatsu HD605 rigid truck arrived.