(Adds details of investment and construction in paragraphs 2, 3...

(Adds details of investment and construction in paragraphs 2, 3 and 4)

Aug 2 (Reuters) - Australia's Pilbara Minerals (PLS) said on Wednesday that the company and Calix Ltd (CXL) had received board approvals for the final investment decision on construction at their flagship Pilgangoora lithium project in Western Australia.

Pilbara, the country's largest independent lithium miner, had earlier said the investment in the Pilgangoora plant would help increase spodumene concentrate production by 47% to 1 million dry metric tonnes per annum.

As manager of the joint venture, Pilbara will handle both the construction and operational phases of the project.

The Perth-based company said the budgeted construction cost of up to A$104.9 million ($69.32 million) would be spilt with Calix in a 79-21 ratio, with the Australian government also contributing A$20 million.

The project aims to demonstrate the benefits of producing a mid-stream lithium-enriched product using Calix's patented electric kiln technology, which has the potential to reduce hard-rock lithium processing carbon emission intensity if powered by renewable energy.

Successful demonstration of the project may lead to future commercialisation of the lithium products technology, Pilbara said in a statement.

($1 = 1.5133 Australian dollars)