The debt facility will provide the company with up to £170mln and Hana will also provide an equity bridge loan.
The company and Hana will continue to work closely to refine the financing package during the period until financial close.
"We are delighted to enter into this agreement with Hana and are looking forward to working closely with them to achieve financial close on our flagship project,” Tim Cornelius, SIMEC chief executive said in a statement.
“Hana is a market leader and not only one of the largest financial groups in Korea but a global investor and one we are proud to work alongside. This agreement with Hana reflects the high level of international interest in our world-leading conversion project has and we believe that this is a stepping stone to further conversion opportunities across Asia and indeed globally," he added.
The debt agreement is not legally binding except for a six-month period of exclusivity. It is expected that it will be replaced by full form loan documents prior to financial close.
The Uskmouth project, in South Wales, is a power station project to convert an existing coal fired plant into a facility that generates electricity through the combustion of waste derived fuel pellets.