Australian mining company PanAust has agreed to buy an 80 per cent stake in Glencore Xstrata's Frieda River copper and gold project in Papua New Guinea for 75m dollars.Glencore will receive a royalty of up to $50m once the company starts producing metals from the mine. The remaining 20% holding is owned by joint-venture partner Highlands Pacific.Glencore inherited the Frieda River project following its takeover of Xstrata in May.The news comes after Glencore reported a rise in copper output in the third quarter, driven by improvements in Chilean and Congolese mines.Total own sourced copper production rose 23% year-on-year to 1,070,900 tonnes. Coal production was up 6%, reflecting successful delivery of the various current expansion projects, including Prodeco in Colombia.An increase in copper and coal production offset weakness in nickel and zinc production where ageing or costly mines closed. Shares were down 0.74% to 337.50p at 11:27 on Friday.RD