SENSOR DDS® technology applied to Leach Pad in gold mine
Leach Pad or Heap Leach Pad is a pond for the process where precious metals like gold, silver, copper or uranium is extracted from their ore. The ore is placed on the geomembrane (a base pad) with a heap and sprinkling of a leaching solvent. As a solvent can be used cyanide or acids. This process dissolves the metals and they collect at the bottom of the pad called the collection ditch.
If the geomembrane is installed and the Leach Pad is leaking, dissolved metals are then penetrating into the ground instead of the collection pit and so the mine is continuously losing money and environmental consequences are even more serious. In some cases, the mine is shut down for an indefinite period of time.
On a Leach Pad either our permanent geomembrane leak monitoring system or a one time survey of exposed and covered geomembrane can be used.
LEACH PAD AT ASIAN GOLD MINE – SENSOR DDS® MIT
Leach Pad’s design cross section (from bottom to top):
- Compacted clay
- Geomembrane HDPE (2.0mm)
- Protective geotextile
- Drainage layer – gravel (50cm)
The size of the Leach Pad was 300.500m2 and total number of leaks detected straight after geomembrane installation was 582. If this high number of damage was not located prior to the Leach Pads operation, this mine would lost thousands of dollars every day and would eventually end up closed until the leaks were repaired.
SENSOR DDS® MIT Arc Testing survey was completed in 27 days on this site. The client repaired located damage which were tested again afterwards. Sensor then has issued a report including official certificate of geomembrane integrity of the Leach Pad.
Examples of detected and located damage at Leach Pad project
One operator can test around 7000m² of a leach pad a day depending on site conditions.
Once a leak is localised, the gravel is excavated and liner damage on the Leach Pad is repaired.
Many times multiple damage is detected using our dipole SENSOR DDS® Mobile Technology.
Once the leak is repaired using patches and extrusion welding, the area is re-checked with the Arc Tester.
Overliner with thickness of 500mm are at most of the Leach Pads.
First step to zero leak on Leach Pad is to test exposed liner with SENSOR DDS® MIT.
The most frequent leaks found at leach pads are punctures caused by overliner penetrating through the liner.
We can deploy as many operators as needed to complete the project on time.