Sustainability website / Case Studies 2004 / Xstrata zinc / Water recycling at the San Juan De Nieva zinc smelter

Water recycling at the San Juan De Nieva zinc smelter

San Juan de Nieva zinc smelter in Spain has increased its use of recycled water by more than 750% from 201 megalitres in 2001 to 1716 megalitres in 2004 through improving the efficiency of the operation-s water capture systems. This substantial improvement is one of a number of efficiency programmes implemented at San Juan in 2004, which together resulted in real cost savings of $9 million from the plant during the year.

Xstrata Zinc HSEC Manager Jose Poncet said zinc hydrometallurgical processes required large volumes of water and that San Juan de Nieva consumed up to five kilolitres of water per tonne of processed zinc ore.

"We use raw water for cooling operations, steam generation, production (such as sulphuric acid production) and cleaning," he said.

"In 2000, we commissioned a study to investigate how we could increase the amount of recycled water we use on site by improving maintenance activities and working procedures, and rationalising the use of water, all without significant investment.

"Apart from reducing the cost of buying water (Euro 0.2/kL after taxes), we wanted to improve our environmental performance and address sustainability issues."

In 2001, the smelter adopted three major processes to increase water recycling:

• condensed steam from on-site electricity generation is recovered and reused as process water;
• water used for cooling the smelter-s air compressors, and roasting, leaching, electrolysis and melting plants is being captured and reused as process water and, where
• possible, as a cooling agent; and
• some waste water (such as water lost from hydraulic seal leaks) is being reused as process water.

Jose said that the success of efficiency programmes such as water recycling initiatives had contributed to San Juan de Nieva retaining its position as one of the most cost-effective zinc smelters in the world.