Orion is one of the market’s largest financiers of mining projects with around US$5.1bn currently under management.
Horizonte said Orion will provide the funds up front in exchange for a 2.25% royalty on the project, which would apply to the first 426,429 tonnes of nickel produced and sold, equivalent to the estimated nickel production over the life of the Araguaia mine according to a feasibility study at the site.
The funds from Orion would enable the company to build out its owner’s team at Araguaia as well as advancing engineering and early works packages before starting full construction of the mine.
Jeremy Martin, Horizonte's chief executive, said the financing was "non-dilutive" for shareholders and had been designed to be compatible with the funding package for the project.
He added that nickel prices had delivered an "outstanding" performance during the year, with the metal currently trading around 50% higher than it was at the start of 2019 at US$15,500 per tonne.
In early London trading, the shares were 44.6% higher at 4.9p.