The contract has an incentivised target cost of $138 million, with a guaranteed maximum price of $148 million, in line with the definitive feasibility study.
The value of the contract excludes the filter press, ball mill and high-pressure grinding rolls, which have already been procured by Pilbara.
Stage one of the contract, which will begin immediately, comprises a two-month front-end engineering and design program to determine the final scope of work, with Pilbara committing a guaranteed fixed price of $10.3 million.
Stage two will comprise construction, expected to begin in May once Pilbara has made a final investment decision and finalised financing for the $214 million project.
Plant construction is expected to take 35 weeks, with commissioning due to begin in the December quarter, followed by first concentrate on ship in February next year.
RCR's scope of work includes the EPC of the 2 million tonne per annum plant, comprising a wet and dry circuit with concentrator, associated plant and commissioning.
The company has selected Primero and Minnovo as sub-contractors to assist.
Pilbara managing director Ken Brinsden said the terms of the contract were competitive.
"The combined experience of RCR, Primero and Minnovo has made for a very compelling offer," he said.
"Primero's experience in building and operating lithium plants, Minnovo's design experience, and the construction capability of RCR ensures Pilbara will be well-served."
Earthworks started in late November and Brinsden said major construction works were due to begin by the end of March.
OTOC Australia has been awarded the $4.8 million contract to deconstruct, transport and reassemble an initial 60 rooms from the 300-room second-hand camp secured late last year.
Further contracts are under negotiation.
Average annual production over Pilgangoora's 36-year life is set to be 314,000 tonnes of 6% spodumene concentrate and 321,000 pounds of tantalite at cash operating costs of $US196 per tonne CFR in the first 15 years, and $207/t over the life of the mine.
Under the base case 2Mtpa production rate, Pilgangoora has a post-tax NPV of $A709 million, at a 10% discount rate, with a 2.7-year payback period and IRR of 38.1%.
Shares in Pilbara rose by 1.5c to 56c, while RCR was up by 2.5c to $2.855.
