One HR lady, two managers, one from the group I'd be in and one from a closely related group. It was 45min max, a mix of behavioural questions and technical questions--the technical questions were sourced mainly from my PhD research, which was highly related to the job role. Two separate questions on safety asking for examples of safety from previous jobs (my role includes field based components so this is very important to them). I skipped some of the up front process Rio typically has (eg phone interview, etc) as I was directly referred to the manager by a friend.