WATER

WHAT’S YOURS IS MINE

Mine water recycling and reuse

With the current economic climate, mining is under severe pressure from a financial front and the existing and long-standing difficulties being faced with water shortages in the country.

BY SAGISA PROCESS ENGINEERING

Wastewater produced through mining can come from many sources, including precipitation, hydrometallurgical processes, or acid mine drainage (AMD). AMD is created when sulphide minerals are exposed to air and water, producing sulphuric acid. All these wastewaters typically contain heavy metals.

Mine wastewater is collected and left untreated. Regulation requires efficient treatment of these wastewaters to reduce the risk of harm to the environment. Sagisa has been working on processes to develop water reuse applications to alleviate the demand on natural water sources without adding additional chemical waste being created by the process.

ULTRAFILTRATION

Ultrafiltration is a pressure-driven purification process that separates particulate matter from soluble compounds using ultrafine membrane media. Ultrafiltration is an excellent separation technology for wastewater reclamation.

Ultrafiltration modules feature an outside-in configuration for higher solids loading. The PVDF membrane material and very narrow pore size distribution makes the modules a perfect choice for wastewater treatment and offers high removal of suspended solids, bacteria, viruses and organics.

A typical example of such application can be found at a platinum mine. The client’s requirement was to reuse water from underground mining works to reduce intake from the local river. A process was develop using ultrafiltration membranes in combination with natural processes.

Mining water is returned to the surface and pumped into a natural pond to allow settling before flowing though several reedbed ponds for natural clarification. Water is then processed further with ultrafiltration membranes to remove all particles larger than 0.03um, including bacteria.

The water was treated to the point where it could be used on the plant as drinking water for the plant. Another big win with this process was the increased life of gland seals in the process by using ultrafiltration treated water, which is well below the required gland seal water requirement.

The total water intake at the platinum mine was greatly reduced resulting in operational cost savings and a lower impact to the environment.

By optimising the process and evaluating the application correctly, mines can achieve a close to zero effluent.

Sagisa Process Engineering is focused on advanced separation technologies for wastewater treatment, to maximize the world’s reusable water by recovering water, energy, nutrients, and other valuable components of wastewater streams.