BHP said the money "will enable the construction of a filtration plant over the next 12 months and the commencement of operation readiness activities for restart".
Samarco received a licence to resume operations at reduced capacity on October 25.
BHP said Samarco "has now obtained all environmental licenses required to progress towards operational restart".
Restart is dependent on the implementation of the filtration system, putting restart in late 2020.
Samarco is a 50/50 joint venture between BHP and Vale.