Sulfate Removal Process

Streamline your sulfate treatment process and water recycling with the Metso Outotec sulfate removal process system. This solution ensures the efficient management of sulfate and calcium in process streams for the production of water that meets discharge water quality requirements and allows for the recycling of treated water for reuse.

Results in high-quality treated water for recycling
Integrates well with other processes and plants
Expands easily for future treatment needs
Comes with process guarantees and tailoring via client water testing

Our flexible sulfate removal process consists of a sulfate precipitation stage at pH 11–13 using lime milk and aluminum, followed by a final neutralization stage using carbon dioxide. Gypsum precipitation can be included before the sulfate removal stage when required.

The process, built on easy-to-understand chemistry, can be applied to sulfate removal from gypsum saturated waters. Importantly, sulfate can be precipitated even when it is associated with highly soluble sodium and potassium sulfates. The sulfate concentration after treatment is typically 200–1000 mg/L. A level below 200 mg/L can be achieved with enhanced precipitation chemistry.

In addition to sulfate removal, the process includes advanced removal of metal impurities such as Ni, Cd, Cu, and Zn as metal hydroxides. The final product includes treated water with a low sulfate concentration for discharge or re-use, and stable, solid precipitate with a high buffer capacity.

Typical application areas:

Non-ferrous concentrators
Gold plants
Coal mining
All mine sites using sulfidic ore

Process solution examples:

Control of sulfate in discharge water: effluent treatment plant to manage sulfate concentration in concentrators, mines, and process effluents
Reduction of scaling to improve plant availability: removal of sulfate and calcium prevents scaling and reduces scaling-related maintenance costs
Efficient water recycling: removal of gypsum saturation enables water recycling within the process and decreases fresh water intake requirements
Effluent volumes can be optimized by efficient overall plant water management