DIAMO uses electrodialysis in water treatment from the uranium mining industry

DIAMO, state enterprise, GEAM spin-off plant

The GEAM Dolní Rožínka spin-off plant started uranium mining in 1957. 20,220 tons of uranium had been mined here till 2016. Intensive remediation work is now being carried out in this area as part of the mitigation of the consequences of mining activities.

The operation has also included a Chemical Treatment Plant since 1968, which currently includes two tailing ponds.

As part of the remediation of mining activities, mine water treatment is also being carried out at sites where mining activities were terminated.

Challenge

Since the beginning of mining, DIAMO has faced the problem of the deposit being in a significant water management area. It is a source of drinking water for the metropolis of Brno, where over half a million inhabitants live.

To reduce the risk of the environmental impact of mining and processing of uranium ore, it was necessary to implement closed-cycle process water treatment technology in the Chemical Treatment Plant, as well as water collection in the tailing ponds, both of which contain high levels of organic and inorganic compounds (TDS 34 g/l, SO₄^2- 21,6 g/l).

Our solution

Thanks to many years of intensive cooperation between DIAMO and MEGA, MEGA prepared customized electrodialysis units for the needs of the GEAM plant in Dolní Rožínka, giving GEAM a clear idea of the performance of the electrodialysis system and the parameters of the output product.

MEGA supplied the RALEX EWTU 30xED-II/200 electrodialysis unit, which can process 65 m³/h. The ED unit is placed in combination with the RO unit.

Results

The desalinated stream is discharged into the river after pH control, and the concentrate is evaporated to the final commercial product – pure Na₂SO₄.

Key parameters:

• resolving excess water and excess salt,
• two usable products – pure water and sodium sulfate,
• low demand for electricity and chemicals,
• high recovery.

Client benefits

Thanks to the flawless day-to-day operation of the unit, GEAM does not have to deal significantly with annual operation and maintenance (OPEX) costs.

In recent years, approximately 6.5 million m³ of water per year, including treated overbalanced tailings from the two tailings ponds of the Chemical Treatment Plant, has been discharged into watercourses through the main discharge profiles of GEAM Ltd.