Peak's largest shareholder, China's Shenghe Resources, together with several new institutional investors have agreed to pump $27.5 million in at 50c per share, a 25% discount, as the company readies itself for the start of construction in October.
Barrenjoey and Canaccord Genuity managed the placement.
If approved by shareholders, Shenghe will increase its stake in Peak to 19.9%.
Peak had most recently reported cash of $2.8 million at the end of March.
Peak chair Russell Scrimshaw said the placement, together with the recent signing of a critical framework agreement and issue of a special mining licence, positioned Peak to make a final investment decision in September and start delivering rare earths to the market in 2025.
The cash will support early works, front-end engineering and design contracts, and updated environment and social studies.
Peak completed a bankable feasibility study last October, electing to defer a rare earth refinery in the UK in favour of accelerating development of the Ngualla carbonate as a provider of a rare earth concentrate to third party processors.
Shenghe has signed a non-binding agreement to take up to 100% of offtake over the first seven years.
The project, which Peak has worked on for almost 20 years, has a post-tax net present value of US$1.48 billion with an equity internal rate of return of 37.3% based on expected pricing for neodymium and praseodymium.
Ngualla has an upfront capital cost of $321 million, with an initial 24 years of mine life based on reserves of 18.5 million tonnes grading 4.8% total rare earth oxides and average production of 16,000t of concentrate grading 45% TREO, with NdPr about 22% of the total.
Resources of 214Mt at 2.15% TREO suggest future upside.
The BFS indicated annual earnings of A$711 million and an annual cashflow of $458 million.
Shares in the company dropped 12% to 55c. It has traded at 29-74c over the past year.