The San Juan de Nieva’s plant is the world's largest zinc production unit. The following are the main products made by San Juan: special high grade zinc, continuous galvanizing grade alloys, die casting alloys, zinc oxide, silver/lead concentrates, sulphuric acid and copper cements.

The electrolytic zinc plant is located in San Juan de Nieva, in the municipality of Castrillon, Asturias, in the immediate vicinity of the Port of Avilés, an excellent location for the company to develop its commercial activity.

Following the company’s environmental management commitment the jarofix process, an environmental friendly method, is used in residue disposal.

Given its strategic geographic location a large portion of the refinery’s production is sold in the European Union.

The San Juan de Nieva smelter was commissioned in 1960 with an initial production capacity of 15,000 tonnes per year of zinc. In the past 40 years the capacity of the plant was expanded several times until it reached the current capacity of 507,000 tonnes per year, becoming the largest zinc smelter in the world.

In 2001 Xstrata acquired 100% of Asturiana de Zinc, owner of the San Juan de Nieva Smelter. Since the beginning, Asturiana de Zinc has developed its own technology and processes which are commercialised through its division AdZ Technology.