Copper output for the three-month period was 10,446 tonnes, up 15% year-on-year, due to a high volume of ore milled with above-budgeted metallurgical recovery rates and better-than-expected processing throughput.
The copper was mined from 2.6 million tonnes of ore, which was 13% higher than a year ago, with 2.5Mt milled, up 14% on high utilisation rates to the highest ever quarterly throughput.
The average copper head grade was 0.48%, compared to 0.49% in the June 2017 quarter, while recoveries were at 87.31%, also an increase on the corresponding period's 85.09%.
Atalaya maintained its production guidance of 37,000-40,000t for full-year 2018.
The company noted that the Riotinto expansion project to 15Mt per annum was progressing on schedule with engineering almost complete and site construction activities picking up.
"Overall progress completion at the end of the reporting quarter was 41%. Procurement has progressed to 38% completed and engineering to 82% completed. Earthworks are well advanced and are expected to be completed by mid-Q3 2018 (September quarter).
Atalaya CEO Alberto Lavandeira said the run-rate for the quarter was "excellent", leading to excellent throughout rates at the plant and better-than-budget recovery rates.
"The expansion to 15Mtpa is progressing at full speed with site activities picking up and we remain well on track for mechanical completion at the end of Q2 (June quarter) 2019," he said.