HELM joins Redox, Migao and Mitsui as the four offtake parties so far signed up by APC for a total of 130,000tpa of production versus the 150,000tpa expected from Lake Wells, 500km northeast of Kalgoorlie in Western Australia.
Meanwhile, APC is continuing down the financing route, with a final investment decision targeted for the end of March 2021.
Lake Wells has a development capital cost estimate of A$208 million.
In terms of metrics, a pre-tax net present value of $665 million and an internal rate of return of 25% has been calculated.
APC had cash at the start of the current quarter of $3.4 million.
Shares in APC were up 2.5% to 7.8c in afternoon trade, capitalising the company at $30 million.
APC is one of a handful of ASX-listed potash companies currently closing in on development and production.