The closure plan approved for Codelco Chile’s Andina
Division considers measures to mitigate the
environmental impact of the waste dump known as the
Botadero de Lastre Norte (DLN), which will contain 1,160
million tons of material with a mineralogical composition
of sulfide ore and gangue (see Annex 1) and will cover a
total area of 403 ha Considering the mineralogical composition of the material and its contact with water from precipitation and snowmelt, a significant generation of acid waters is foreseen, which must be treated in accordance with environmental regulations.

Identify technological solutions and/or operating
methodologies to eliminate, prevent or reduce the
generation of acid water at the DLN waste dump.
The proposed technologies and/or methodologies may be applied before, during or after the deposition of the material in the waste dump.

The proposed technological solution must comply with
the following requirements:
• Not to generate pollution and damage to the
environment, both for solutions that consider the use of chemical reagents and for those of other nature.
• Compatibility with human contact, so that it does not
represent special requirements for use and
application.
• Its application should not interfere with the fulfillment
of the mine’s production plans.
• Minimum maintainability requirements and Heavy
Duty constructability characteristics in the case of
equipment.
• The optimum application site will be determined at a later stage.
• Comply with Codelco Andina’s safety and environmental standards.

Currently, the acid waters generated by
the waste dump are neutralized in a
treatment plant before being sent to the
Blanco river. Once the operation of
División Andina is stopped, the dump will
continue to produce acid waters for a
number of years, which must be treated
according to environmental regulations for
the same period of time.

• High cost associated with the closure
plan.
• Risk of environmental incidents

Permanently.

Neutralization of acid water in HDS plant.

Currently, acid waters already generated
at the HDS plant are neutralized. No
technologies have been tested to prevent
the generation of acidic water from waste
dumps.

The following will not be considered in the background evaluation process:
• Advisories, consultancies or engineering studies.
• Solutions that consider acid water treatment.