According to a report by Mining.com, the recently closed transaction involves export pre-payment of up to $500m.
The report said that this information was provided in a document filed with the Securities and Exchange Commission of Brazil (CVM).
Other details of the deal was not disclosed in the document.
The development comes a few days after the Brazilian iron ore exporter announced capital expenditure (CAPEX) of $2.6bn for the fiscal year 2023-27.
The new investment will allow CSN Mineracao to boost iron ore availability from the existing 34Mt in the current year to 68Mt by 2027.
This iron ore deal was initiated in 2019, with announcement at that time revealing that CSN Mineração will make a pre-payment of $500m for supplying around 22Mt of iron ore over five years.
CSN Mineração is the second largest iron ore exporter in Brazil and owns two mines in the country – Casa de Pedra and Engenho.
The Joint Ore Reserves Committee (JORC) claims that the firm owns more than three billion tonnes of certified reserves.
Furthermore, the company owns a captive terminal in the Port of Itaguaí, Brazil for exporting iron ore, a Pires beneficiation complex and a stake in the MRS railroad.