The 45Mt grades 4.3% lead equivalent (3.2% lead and 37 grams per tonne silver), and 0.5% zinc, and includes a 11Mt in the "measured" category, a 4Mt increase.
A fifth phase drilling campaign will look to extend the project life and expand processing capacity.
Prefeasibility work outlined a 10-year project at 1.5Mt per annum producing 50,000t of lead and 1.5 million ounces of silver yearly.
The project was estimated to cost $183 million to initially develop and have a pre-tax net present value of $303 million and internal rate of return of 46%.
Boab holds 75% of the project with the balance held by Chinese lead and silver producer Henan Yuguang.
Boab started 2021 with $15 million cash.
Shares in Boab were up 5% to 42c in late trade, capitalising the company at $64 million.