Cape Flattery has ore reserves of 47Mt grading 99.18% silica, which will be processed over a 15-year life-of-mine.
Metallica Minerals has updated the July DFS with a second processing plant, stockpile and stacker.
A second mining face will also be established, with two extra wheel loaders and an extra mobile feeder unit to be used to supply the second plant with run-of-mine sand.
The two systems will operate independently of each other and mine, process and feed product onto their own stockpiles.
Final product will come from both stockpiles by way of a single conveyor, to load the transhipment vessel.
Metallica Minerals executive chairman Theo Psaros said economies of scale would be achieved with only modest increases in capital costs.
Project capital costs are expected to be $236.7 million, with payback 3.2 years after production starts.
Other metrics in the updated DFS include $3.07 billion LoM revenue, a $702.4 million net present value and a 37.2% internal rate of return.
Average cash margins increase to $53.06 per tonne and average earnings before income, taxes, depreciation, and amortisation will be $134.6 million per annum.
Psaros said he continued to be impressed with the economic potential of the project.
"The updated DFS strengthens Cape Flattery silica sand's status as a low-cost, high-purity silica sand project that can achieve attractive profit margins," he said.
"Our initial project scope is to start with the July 2023 DFS production tonnage of 1.8Mtpa and, subject to end user demand and the capital markets, we can efficiently construct the mine infrastructure to double production."
Psaros said the ramp-up of the second processing plant would start in the third year of mining.
"We will continue to monitor the expected growth in demand for high-purity silica sand as we work our way through the approvals processes at federal and state level," he said.
"The improvement in the project economics from the updated DFS illustrates the benefit of economies of scale, a shorter mine life with no change to the total project footprint and delivery of the same level of economic contribution to the local communities in a shorter timeframe."
