The issue price is 14c per share, a 33.3% discount to the last closing price.

The company has also launched a five-for-42 pro-rata, non-renounceable entitlement offer to raise up to a further $8 million at the same price.

Lead manager Taylor Collison has obtained firm sub-underwriting commitments totalling about $8 million.

"We are delighted with the strong support we have received for the capital raising from high-quality new and existing sophisticated and institutional investors," Centrex managing director Robert Mencel said.

"The capital raising marks an important milestone for the company, allowing us to continue to develop the Ardmore project at a time of globally high rock phosphate prices.

"The capital raised will allow Agriflex [Centrex's wholly owned subsidiary] to grow Ardmore's resource and reserves, lift production levels, reduce operating costs and increase the project's value."

About $5.6 million of the proceeds will be used to buy plant and equipment for Ardmore, which is in Queensland, while $4.7 million will be used for front-end engineering design and full plant engineering.

Earlier this week, Centrex reached agreement with New Zealand-owned Ravensdown for a trial shipment of 5000 wet tonnes of beneficiated phosphate rock from Ardmore.

The agreement included a first right of refusal for Ravensdown to purchase 20% of Ardmore's production under a three-year offtake agreement.

Centrex shares fell 21% to 16.5c.