Water and wastewater solutions com-pany Veolia Water Solutions & Tech-nologies South Africa received an award of distinction in the Industrial Water Project of the Year category at the yearly Global Water Intelligence Awards, held in Spain earlier this year, for its innovative ammonium sulphate evaporation and crystallisation plant.

Veolia designed and constructed the plant at the Ambatovy nickel mine, in Madagascar, during 2011 and it was commissioned in the latter part of 2012.

The Ambatovy mine’s primary treatment system, which is part of the mine’s nickel and cobalt refinery, uses sulphuric acid, hydrogen sulphide and ammonia to extract valuable substances from slurried ore. The plant treats effluent streams from this process using evaporation and crystallisation technology to extract the valuable ammonium sulphate by-product for resale as soil fertiliser into the agriculture industry.

Veolia MD Gunter Rencken says the com-pany is proud to have received the award and will continue to introduce innovative technologies to improve wastewater treatment.

He adds that the plant is one of the largest ammonium sulphate evaporation and crystal-lisation plants in the world and is capable of producing up to 200 000 t of ammonium sulphate a year.

According to Veolia project manager Ger-hard Vosloo, the plant enables the Ambatovy mine to meet its production objectives by recovering valuable by-products. “Additionally, the plant meets environmental objectives by reducing effluent volumes, thus limiting the mine’s impact on the area.

“The solution uses Veolia’s HPD evaporation and crystallisation technology. The solution includes a purge crystalliser that removes high chlorides from the main crystalliser section, thereby enabling the use of more traditional and less expensive 316L stainless steel materials in the construction of the process vessels and equipment without risk of chloride corrosion,” Vosloo explains.

The crystallisation vessels are housed in 10 m × 10 m and 24-m- to 32-m-high structures that are designed to withstand 280 km/h hurricane winds and mild earthquakes caused by nearby fault lines.

As an extra precaution, redundant systems have been included for the pumps and vessels to avoid shutdowns and ensure maximum performance during the cyclone season.