Incusa - Saint Gobain

Potential impact on water or groundwater

The site is in an ecological area with a high level of protection.

The water is discharged into a mountain river with salmon fisheries.

The water consumption for cleaning is 1500 m3/h with two circuits: neutral an acid (feldspar production).

Aggregates are by-products.

Action on

Treatment plant/Mining waste treatment.

Description of the good practice

95% of water recovery and recirculation;

5% of loss due to wet content in products and to the fresh water needed in acid circuit.

In the beginning, acid water was neutralized in a sedimentation pond by precipitation of pollutant elements with excess of calcium hydroxide in a 12 hours reaction process. A new plant designed for a continuous pH monitoring and control, with addition of calcium hydroxide according to the pH of water and continuous extraction of the precipitate (solid) fraction in a 14 hours. A press filter reduces humidity to less than 5%.

Description of the positive effects on water/groundwater

A better control of pH.

Disposal of the solid fraction with less water content.

Elimination of the risk of acid water drainage.

Status

In 2018, the project was still on going.