Sistema de revestimiento de geomembrana para balsas de residuos

Due to the flat terrain, complex water catchment conditions, and the potential pollution of surrounding soil and groundwater by tailings storage, the selection of anti-seepage and isolation materials is crucial for plain-type tailings ponds. These materials must have good impermeability, durability, and corrosion resistance, while adapting to possible geological settlement in plain areas.

The following is a classification and specific types of commonly used anti-seepage and isolation materials for plain-type tailings ponds:

Natural Anti-seepage Materials

Natural materials have low costs and are suitable for scenarios with relatively low anti-seepage requirements or as auxiliary anti-seepage layers. They need to be combined with compaction and other processes to enhance their effectiveness.

Clay and Modified Clay

Natural clay: It has low water permeability (permeability coefficient is usually less than 1×10⁻⁷ cm/s), wide sources, and low cost. However, it has low shear strength and is prone to cracking under dry-wet cycles.

Modified clay: Improved by adding cement, lime, bentonite, etc., to enhance impermeability, stability, and corrosion resistance. It is suitable for the base layer with medium anti-seepage requirements.

Bentonite

It has the property of swelling when exposed to water. After swelling, it forms a dense impermeable layer with a permeability coefficient as low as below 1×10⁻⁹ cm/s. It is often used in combination with other materials (such as bentonite waterproof blankets) to enhance the anti-seepage effect.

Synthetic Geosynthetics

Synthetic materials have excellent anti-seepage performance and strong durability, making them the mainstream choice for plain-type tailings ponds (especially in scenarios with high anti-seepage requirements). They can be divided into the following categories:

Geomembranes (Core Anti-seepage Materials)

High-Density Polyethylene (HDPE) Membrane

Advantages: Extremely low permeability coefficient (usually less than 1×10⁻¹² cm/s), good chemical stability, resistance to acid and alkali corrosion, strong anti-aging performance, and adaptability to certain deformations (high elongation at break).

Application: Used as the main anti-seepage layer, commonly applied to the bottom, slopes, and surrounding isolation zones of tailings ponds. It needs to be spliced by welding to ensure integrity.

Linear Low-Density Polyethylene (LLDPE) Membrane

It has better flexibility than HDPE membranes and strong puncture resistance, making it suitable for areas with complex terrain or possible local settlement. However, its anti-aging property is slightly inferior.

Polyvinyl Chloride (PVC) Membrane

It has good corrosion resistance but is prone to embrittlement at low temperatures, making it suitable for areas with mild climates. Its cost is lower than that of HDPE membranes.

Ethylene-Vinyl Acetate (EVA) Membrane

It has excellent flexibility and good low-temperature performance, making it suitable for cold regions. However, its UV resistance is relatively weak and needs to be used with a protective layer.

Composite Anti-seepage Materials

Geomembrane combined with geotextile

The geomembrane serves as the anti-seepage layer, and geotextiles (non-woven fabrics) are compounded on both sides to enhance puncture resistance and wear resistance, protecting the geomembrane from damage by tailings particles or sharp objects.

Bentonite Waterproof Blanket (GCL)

It is made by pressing bentonite particles between two layers of geotextiles. It combines the swelling and anti-seepage properties of bentonite with the mechanical support function of geotextiles, featuring convenient construction and adaptability to small-scale settlements.

Other Auxiliary Isolation Materials

Geomalla

Though not directly impermeable, it can enhance the integrity of the anti-seepage layer structure, reduce cracking caused by settlement, and is often used in combination with geomembranes to improve system stability.

Composite Geotextile Drainage Net

Used in the drainage system under the anti-seepage layer, it quickly drains seepage water, reduces pore water pressure, and protects the anti-seepage layer from damage by water pressure.

Rigid Anti-seepage Materials

Suitable for areas with extremely high requirements for strength and durability (such as seepage interception ditches and retaining walls around tailings ponds), but they have poor flexibility and are sensitive to settlement.

Concrete and Reinforced Concrete

Water permeability is reduced by adding anti-seepage agents (such as silica fume and fly ash), making them suitable for anti-seepage in fixed structures, such as bank retaining walls and anti-seepage walls.

Asphalt Concrete

It has certain flexibility and crack resistance, and good low-temperature performance. It is often used as a protective layer on the surface of anti-seepage layers or anti-seepage structures in specific areas.

Selection Principles

When selecting anti-seepage materials for plain-type tailings ponds, the following factors should be comprehensively considered:

Impermeability Performance: Determine the required permeability coefficient (usually ≤1×10⁻¹⁰ cm/s) according to the nature of tailings (such as acidic, high-concentration pollutants).

Geology and Terrain: To adapt to possible foundation settlement in plain areas, prioritize materials with good flexibility and strong deformation resistance (such as HDPE membranes and GCL).

Durability: Considering the service life of tailings ponds (usually 20-50 years), select materials with anti-aging and chemical corrosion resistance, and use them with protective layers (such as geotextiles and compacted soil) to extend their service life.

Construction Feasibility: Due to the open construction site in plain areas, prioritize materials that are convenient for welding or laying (such as HDPE membranes and composite geosynthetics).

By reasonably combining the above materials (such as the composite structure of “natural clay + HDPE membrane + geotextile”), an efficient and stable anti-seepage isolation system can be formed to meet the environmental protection and safety requirements of plain-type tailings ponds.