Chile is the global center for copper mining and the world's third-largest country in terms of tailings storage facilities. The tailings dams scattered across the arid north store millions of cubic meters of water. Against the backdrop of an increasingly severe water crisis and the imperative for sustainable mining development, how to safely recover water resources from these "dormant" tailings dams and return them to the production cycle or the natural environment has become a major technical challenge for mining nations.

On July 23, 2026, the Advanced Mining Technology Center (AMTC) of the University of Chile officially unveiled a new prototype system for integrated tailings water treatment and recovery. Through a three-stage technology integration, it achieves, for the first time, the simultaneous removal of sulfates, heavy metals, and metalloids from chemically complex tailings water, elevating the treated water quality to standards suitable for agricultural irrigation or safe discharge into aquifers. The project is funded by the ANID FONDEF IDeA I+D 2024 grant (Project ID: ID24I10113) and supported jointly by Codelco Innovación and Glauben Ecology.

Millions of Cubic Meters of "Mine Water" Trapped in Tailings Dams

As the world's largest copper producer, Chile has a vast number of tailings dams. The volume of water stored in these dams is substantial. However, due to prolonged contact with processing reagents and mineral particles, the composition of tailings water is extremely complex—high sulfate concentrations, coexistence of various heavy metals (molybdenum, manganese, copper, iron, etc.), and in some mining areas, contamination by the metalloid arsenic. Traditional water treatment technologies often can only handle single pollutants, are costly, and consume significant energy, making large-scale application at mining sites difficult.

Three-Stage Synergy Achieves "Full Recovery" of Tailings Water

The AMTC team has developed an integrated system composed of three stages: nanofiltration membrane separation, nano-adsorption materials, and a bioreactor. Each stage precisely targets specific pollutants in the tailings water, adhering throughout to circular economy principles.

Stage One: Nanofiltration Membrane Separation – "Precision Retention" of Sulfates

The first stage of the system employs nanofiltration membrane separation technology. Utilizing the selective permeability of the membrane, it efficiently retains major pollutants like sulfates from the tailings water. The "concentrate" (containing high concentrations of pollutants) and "permeate" (initially purified water) produced in this step proceed to different subsequent treatment pathways, achieving initial pollutant separation and volume reduction.

Stage Two: SolArsenic Nano-Adsorption System – AMTC's Core Patented Technology

Both the permeate and concentrate enter the SolArsenic system, which is independently developed and patented by AMTC. This system uses nano-adsorption materials to efficiently capture and encapsulate heavy metals and arsenic from the water.

Key Technological Advantages: The adsorption material in the SolArsenic system is not only regenerable and reusable but also possesses the ability to selectively adsorb valuable metals (molybdenum, manganese, copper, iron, etc.). This means that while treating wastewater, the system can simultaneously recover valuable metal components from the tailings water—extracting "secondary resources" from "pollutants," opening an additional value recovery pathway for tailings water treatment.

Stage Three: Agricultural-Mining Waste-Based Bioreactor – A Circular Loop from Waste to Fertilizer

Water treated by the first two stages enters the bioreactor. The core innovation of this reactor lies in its mixed reaction medium based on agricultural and mining wastes.

Dual Benefits:

Efficient Removal of Residual Sulfates: The bioreactor utilizes the metabolic activity of microorganisms within the waste matrix to further degrade and remove residual sulfates from the water;

Waste Transformed into Fertilizer: The solid residue generated during the reaction is not "secondary waste" but has been validated as "bio-compost" suitable for phytoremediation of tailings dams.

Dr. Yasna Tapia, AMTC researcher and scholar at the Faculty of Agricultural Sciences, University of Chile, stated: "The innovation of the bioreactor lies in the fact that it not only removes sulfates from the water but also converts the resulting residue into bio-compost, which has been proven effective for the phytoremediation of tailings. We are moving towards a solution based on circular economy principles—waste is no longer a problem, but a new resource."

From Laboratory to Industrial Site

Currently, the integrated system prototype has been fully validated at the laboratory scale using real tailings dam water samples. The project team is working to advance testing under representative operating conditions and ultimately achieve technology scale-up and on-site validation in an industrial environment.

From Chile to Global Mining

Alleviating Mining Water Scarcity

This project directly responds to Chile's National Tailings Dam Sustainable Management Plan, aiming to transform tailings dams from an "environmental liability" into a "strategic water reserve." The water recovered by the system can be safely used for agricultural irrigation or aquifer recharge, offering a solution to the structural conflict between mining and agriculture for water—"from the mine, back to nature."

Valuable Metal Recovery and Resource Valorization

The selective adsorption capability of the SolArsenic system for valuable metals such as molybdenum, manganese, copper, and iron upgrades tailings water from "wastewater requiring treatment" to a "liquid mine awaiting extraction." This added value is expected to significantly reduce the overall operating cost of the water treatment system.

Circular Economy Paradigm: Full-Process "Zero Waste" Design

From the nanofiltration concentrate entering SolArsenic for further treatment, to the bioreactor residue being converted into tailings remediation compost, and the regeneration and reuse of nano-adsorption materials—the system is designed from the outset to minimize waste and valorize by-products throughout the entire process. This design philosophy, where "the treatment process itself generates no secondary pollution," sets a new benchmark for environmental management in the mining industry.

Scalability: A Universal Technical Solution for Global Tailings Dams

Chile is the world's third-largest country in terms of tailings storage facilities, and the global mining industry generally faces the common challenge of tailings water treatment. Due to its modular design and adaptability to different tailings water qualities, the three-stage integrated system developed by AMTC has the technical potential for export to major mining nations such as Peru, Australia, and South Africa.

Rewriting the "Environmental Ledger" of Tailings Dams

Dr. Andreina García, AMTC project leader, stated: "The main challenge of this project was to demonstrate that it is feasible to treat chemically complex water from tailings dams through sustainable, integrated processes. We aim to recover water resources, achieving a quality standard that allows it to be reused for agriculture or safely discharged into aquifers, thereby contributing to a more circular and environmentally positive mining industry."

When tailings dams are no longer just "environmental liabilities" for storing waste rock, but become "resource complexes" capable of simultaneously producing clean water, valuable metals, and ecological restoration materials, the path to sustainable development for the global mining industry will be fundamentally rewritten.