Teck Resources is spending $72 million on a new ball mill at Highland Valley Copper so it can increase efficiency as it mines poorer grades of ore.

Teck released third-quarter financial statements Thursday showing revenues, profit and production are all lower at the mine about 40 kilometres southwest of Kamloops.

The B.C.-based mining firm reported an overall profit of $621 million, up about four times from the same quarter last year. But Highland Valley was a lowlight as copper production declined due to lower grades. The corporation said grades are expected to increase slightly next year.

The mine recently signed a new contract with United Steelworkers that resulted in a one-time cost of $13 million to pay for signing bonuses of $12,000 per worker.

Teck estimates Highland Valley lost $42 million in the first nine months of the year, compared to a $94-million profit during the same period last year.

Teck said the $72-million capital project to install an additional ball mill will increase mill throughput and copper recovery.