Rio Tinto chief Jean-Sebastien Jacques says he still doesn't understand how his company misunderstood traditional landowners' attitudes toward a culturally significant site, as fresh data showed the Juukan Gorge controversy had not crimped productivity in Rio's most important business.

Rio exported 86.68 million tonnes of iron ore from Western Australia over the past three months, the company's sixth-biggest quarterly export tally ever, but still slightly shy of the volumes expected by analysts at UBS and Macquarie.