Environmental impact
Extractive metallurgy - Hydrometallurgy

Hydrometallurgical processes have an environmental impact on water. This must be taken into account. Hydrometallurgical facilities are classified as regulated facilities; their discharges are therefore subject to permits and are regularly monitored.

Since hydrometallurgy generally involves the use of acidic or basic solutions, discharges resulting from purging or washing are unavoidable. A water treatment facility is required to remove metals from the solution before discharge into the natural environment. Since neutralization of the effluents is essential, significant amounts of salts—primarily in the form of chlorides or sulfates—will be discharged. However, numerous water treatment techniques have been developed, and “near-zero” discharge levels are sometimes achieved.

The volume of waste generated can also be very large. Because it contains...