TORONTO (miningweekly.com) – The world’s largest silver and eighth biggest copper producer KGHM this week reported that a 142 km sea water pipeline to the Sierra Gorda mine, in Chile, was completed on schedule.

Sierra Gorda mine is the world’s seventh largest copper project, with technical commissioning and initial production slated to start around midyear.

The Sierra Gorda project is located in the Antofagasta region within the Atacama Desert, which is Chile’s largest copper producing region. The openpit operation would produce copper, molybdenum and gold ore, while downstream processing will include crushing, grinding, flotation and drying to obtain copper and molybdenum concentrates.

When production starts, the Sierra Gorda mine would process about 110 000 t/d of ore, producing 120 000 t/y of copper. The project would also be one of the largest molybdenum producers in the world, averaging about 50-million pounds a year during the first years of the mine’s life.

Sierra Gorda would operate using sea water captured from the cooling systems at a thermal electricity generating plant, located on the coast of Mejillones. Instead of being discharged into the sea, the water would be transported to the mine and plant through the pipeline passing inland over a coastal plain and hills. Apart from the pipeline itself, its key infrastructure includes the coastal station and two inland pump stations, with a total of 24 pumps and a pumping rate of 1 500 ℓ/s. Port facilities and fibre-optic cable all along the pipeline were also provided.

“Our project is located in a desert, with extremely dry conditions and scarce water reserves. That is why our top priority was securing water supply and eliminating the risk of exhausting this resource in the region. An important design innovation was made to incorporate the use of seawater on the project site through the pipeline,” said KGHM executive VP and CFO Jarosław Romanowskis said.

The pipeline’s hydraulic tests, which were critical to the project’s commissioning, were executed from December, and successfully completed on February 28. Pumping to an accumulation pond would start this month.

After production had started, the Sierra Gorda mine would use 251 808 m³/d of water. On a yearly basis, this equals a capacity of 92-million cubic metres. Planning was already under way to increase ore processing to 190 000 t/d, which would result in average yearly copper output of about 220 000 t over a 20-year life. The would lift the amount of water used daily in the mine to 442 000 m³/d.

With this volume of water, the Sierra Gorda project has been designed so that it will not discharge effluent into the environment, ensuring that the quality of groundwater is not affected. Wells have been installed to monitor the levels and quality of the water and allow any seepage to be immediately detected and collected. Additional precautions were made to protect the nesting grounds of highly mobile fauna species, especially Peruvian terns and Garuma gulls.

The project also reported excellent health and safety performance compared with industry standards. The 2013 total recordable incident rate for Sierra Gorda employees and contractors was 0.18.