At Minera Antucoya, the heap leaching process seeks to have a homogeneous irrigation in order to extract the maximum copper recovery per module.
Each module has a double irrigation grid with sprinklers and drippers to distribute the raffinate around the crown of the heap. PLS from each module is collected through closed pipes, which does not fully use the pipe volume. Each pipe flows into a common open channel.
Although there are systems to control the feed flow per module, the amount of solution that accumulates in some areas of the bed is unknown and outflow is only estimated as a proportion of the feed flow, which prevents an accurate determination of metallurgical recovery kinetics and can cause localized phreatic
level rises and potential landslides. These events, in addition to being a safety risk, mean lower production due to discontinuity of operations.
Technological solutions are sought to monitor online and in real time the following variables:
• Phreatic level throughout the depth of the bed.
• PLS outflow per each module.
• Uniformity of surface irrigation.
The monitoring system must provide information on the status of the heap leach for proper decision making to ensure the safety of people and the operational continuity of the process.
– The solution is expected to be integral, however, solutions that monitor one or two variables are not excluded.
– Visualization and online and real time alerts of the variables to be monitored. For each case it is required:
• Phreatic level: High water level alert, landslide risk alert.
• Outflow: Measurement of the module outflow in closed pipe (pipe volume not fully used).
• Uniformity of surface irrigation: Alert for sectors in the crown of the heap that do not have irrigation or require maintenance due to overtopping and uncoupling.
– In the case of the phreatic level and uniformity of surface irrigation, it is required to have a prototype tested in an operational environment (TRL≥7). In the case of outflow
measurement, it is required to be in the validation stage in a relevant environment (TRL ≥ 5).
– The components of the solutions, especially those considering permanent installation, must meet heavy duty standards for extreme conditions ofhumidity, dust and corrosive environment (e.g. IP 67 for water and dust).
– The solution must ensure operational continuity, be adaptable and noninvasive, i.e. the devices or components must be easy to install/maintain and must not generate significant operational interference.
– Must meet with Antofagasta Minerals security and communications standards.
– Minimal or no presence of workers at high altitude conditions on the heap leach due to risk of landslides.
A phreatic level measurement system has been evaluated and was not successful.
– Maintain copper recovery, differentiated by module.
– Control the risk of landslides due to a rise in the phreatic level.
– Maximize the irrigation area and optimize its operation.
– Operational continuity
– Number of alerts to control the risk of landslides.
– Cu concentration in PLS.
– Cu recovery.