Given that for the processing of minerals via hydrometallurgy and in particular in the heap leaching stage, the correct distribution of operating solutions, in this case, leaching solution on a mineralized bed, is preponderant.
The installation of an appropriate irrigation system favors the homogeneous and uniform irrigation of three essential flows for the process, these are the refining, intermediate solution and water, which are dosed according to the defined irrigation rate and the concentration of the expected loaded solution which is sent to the next process.
This system must prevent the entrainment of fine particles while avoiding high losses due to evaporation or wind and, of course, be able to cover the entire surface of the pile so that it can fully react and release the red metal.
Depending on environmental conditions and the availability of water resources, the irrigation system can distribute the solutions by means of drippers, wobblers or sprinklers.
Regarding the selection of the appropriate irrigation method, it can be noted that the drip irrigation method will be suitable,
- If the pH at which it is operated does not allow the precipitation of water hardness (clogging of drippers).
- If low temperatures generate a risk of freezing of the solution.
- If the meteorological conditions present a permanent regime of strong winds.
- If water is a scarce resource.
- If it is necessary to ensure the uniformity of the process together with a low irrigation rate.
On the other hand, the sprinkler and nozzle irrigation method will be optimal when,
- There are high levels of mineralization in the water and there is a risk of carbonate precipitation.
- Operational conditions require increased oxygenation of the solution.
- Weather conditions are moderate and/or intermittent winds.
- Water resources are not a limiting factor.
It is also possible to find mixed irrigation systems in dynamic piles, where in the first instance the crown is wetted by means of drippers followed by spraying of solution on the slopes, all this under a ratio of 11:1 hours respectively. Sprinkler irrigation is also used at the end of the cycle to wash the riprap in order to displace and recover the remaining dissolved copper.
The distribution of emitters on the screen is defined according to the uniformity of the process, so an excess of irrigators could cause the unit wettability areas to overlap, thus causing overdripping in the same cross section. By projecting this situation per irrigator, in the long run there is a loss of acid due to solution upwelling to the surface.
On the other hand, the scarcity of solution distribution points makes it impossible to properly wet the mineral particles containing the valuable metal, leaving sectors with no chance of coming into contact with the leaching fluid, thus reducing their recovery.
Along with the selection of the ideal emission system for the process in operation, in order to reduce the aging of the flow meshes, it is advisable to perform maintenance at the end of each leaching cycle. These maintenance actions include desulfation and flushing of irrigation lines to remove accumulated salts, check for possible uncoupling in the joints to avoid leaks and replace lines if necessary, all this in order to meet the strict operational requirements of the industry.
