Mining giant Rio Tinto said it delivered a "very strong first half" with productivity gains across the business. The iron ore business, which accounted for around half of group revenues in 2013, registered record shipments, production and rail volumes in the six months to June 30th. Shipments were up 20% at 142.4m tonnes (mt) exceeding production which rose 10% to 139.5mt as the company used stockpiles that were built ahead of the expansion of infrastructure at Pilbara. In May, Rio's Pilbara iron ore system of mines, rail and ports reached a run-rate of 290mt a year, two months ahead of schedule.Iron ore production guidance for the full year is unchanged at 295mt, "subject to weather constraints", the company said."Our iron ore expansion continues to deliver high-margin growth reinforcing our position as a low cost producer," said Chief Executive Sam Walsh. "It has allowed us to increase shipments of our Pilbara Blend products, providing our customers with reliable, long-term supply of stable quality. Healthy copper volumes reflect higher grades and recoveries at Kennecott Utah Copper, as well as the ramp up at Oyu Tolgoi," he said.Elsewhere, copper output jumped 23% year-on-year to 323,000 tonnes in the first half, prompting Rio to lift its full-year guidance from 570,000 to 585,000 tonnes.In other operations, bauxite and aluminium production was broadly in line with last year at 20.2mt and 1.67mt respectively. Hard coking coal output increased 9% to 3.9mt, while semi-soft and thermal coal rose 2% to 13.5mt. Titanium dioxide feedstock meanwhile dropped 14% to 762,000 tonnes.BC