Mencel said the update to the 2018 DFS and 2019 optimised DFS showed that the Ardmore remained profitable and robust, however capital costs are now 14% higher at A$78 million, largely due to higher material costs and labour rates, while operating costs are up 10%, again due to labour.
GR Engineering Services completed the review, which made no changes to plant design, site layout, construction, or other design factors.
Ardmore, where there are unchanged reserves of 10.1 million at 30.2% phosphate, has a revised net present value of A$207 million, a pre-tax internal rate of return of 52% and a payback of less than two years.
That compares with the original DFS which delivered an NPV of $269 million and IRR of 63%.
Free cashflow is now expected at $429 million, down from $561 million, after gross revenue of $1.4 billion, based on a "conservative" sales price of US$135 per tonne, compared with opex that is tipped to be $92/t.
The production project target remains at 800,000 tonnes per annum over a decade.
Mencel said the company was confident to commence project financing discussions and progress product sales to customers in Australia, New Zealand, and Asia.
It will also undertake optimisation studies, such as reverse flotation to increase reserves, simplify mining and create a premium +37% product and alternative plant locations.
The company began trial mining in 2019, with a 70t per hour modular plant, but work was quickly suspended after the oversupplied phosphate market slumped,
It mined and stockpiled some 27,000t of phosphate rock earlier this year to support a crushing, screening, and bagging trial.
The results will be sent to prospective customers in the near future.
Centrex started the quarter with $2.7 million cash.
The stock has fallen from about 9c when the trials were suspended, to 4.1c, valuing the company at $15 million.
Centrex's shares have traded between 2.4-8.4c over the past year.