Peran penting geomembran HDPE dalam proses pelindian timbunan emas

Geomembranes play a crucial role in gold mines, primarily in the following aspects:

1. Seepage Prevention and Isolation:

Preventing tailings pollution: In gold mine tailings ponds, geomembrane is laid on the pond bottom and dam body to effectively block heavy metals (such as gold, silver, copper), acidic substances, and harmful chemicals in tailings water from seeping into the ground, thus avoiding pollution of surrounding soil and groundwater and protecting the ecological environment and residents’ drinking water safety. Heap leach pad seepage prevention: In gold mine heap leaching processes, geosynthetic membranes are laid at the bottom of the heap leach pads to prevent toxic solutions generated after contact between leaching agents (such as cyanide solutions) and ore heaps from leaking, ensuring that the leaching solution circulates within a controllable range and avoiding pollution of the surrounding environment.

2. Resource Recovery and Utilization:

Leaching solution recovery: The sealed space formed by geosynthetic membranes can collect the leaching solution produced during heap leaching, allowing solutions containing precious metals such as gold to be recovered. Through subsequent treatment processes, this achieves efficient resource utilization and improves the economic benefits of gold mining. Reducing water resource waste: In arid or water-scarce areas, the seepage prevention function of geosynthetic membranes can reduce evaporation and leakage of water during heap leaching, lower water consumption, and achieve recycling of water resources.

3. Safety Protection:

Enhancing slope stability: Rough-surface geomembrane, through their unique surface structure, can significantly increase friction with soil or other materials, effectively preventing sliding of ores, tailings sand, and other materials on the slopes of tailings ponds or heap leach pads, thereby reducing safety risks such as slope collapse and dam breach. Withstanding extreme environments: Some high-performance geomembrane can withstand extreme environmental conditions such as high temperatures, low temperatures, and strong ultraviolet radiation, ensuring performance stability in the complex climate and geological conditions of gold mining areas and guaranteeing the long-term effectiveness of seepage prevention and safety protection functions.

4. Environmental Compliance: Meeting environmental requirements:

The application of geosynthetic membranes is an important measure for gold mining enterprises to meet environmental regulations and standards. By effectively preventing leakage of harmful substances and reducing pollution of soil, water bodies, and air, it helps enterprises avoid risks such as fines and production suspension due to environmental issues, maintaining the company’s social image and sustainable development capabilities.

Overview of Heap Leaching Process

1:Ore Pretreatment

◦ Crushing and Screening: Crush the raw ore to 10~30mm or finer to increase gold exposure.

◦ Pelletizing (for fine ore): Add cement (3%~5%) or lime as a binder to form 5~20mm pellets, improving permeability.

2:Stockpile Construction

• Impermeable Treatment: Lay HDPE geomembrane (≥1.5mm) or clay layer (permeability coefficient <10⁻⁷cm/s) to prevent leakage and pollution.

• Drainage System: Underlay with gravel and perforated pipes to collect leachate (pregnant solution).

3.Pile Construction

• Layered ore stacking, total height up to 10~50m, with flat pile top to avoid solution channeling.

4.Cyanide Leaching

• Spraying System: Install drip irrigation pipes or rotating nozzles, spraying intensity 5~20 L/(h·m²), sodium cyanide concentration 0.03%~0.1%, pH 10~11.

• Leaching Cycle: 30~90 days, gold leaching rate typically 50%~80%.

5.Pregnant Solution Treatment

• Activated Carbon Adsorption: Pregnant solution passes through carbon adsorption columns (CIL process), gold品位 of loaded carbon can reach 3000~6000g/t.

• Zinc Powder Displacement (for high-grade solution): After deoxygenation, pregnant solution reacts with zinc powder (Zn:Au=5~10:1) to generate gold sludge.

6.Metal Recovery

• Carbon Stripping and Electrolysis: Loaded carbon is stripped with hot NaOH + sodium cyanide solution, and gold sludge is obtained by electrolysis (purity ≥95%).

• Smelting: Gold sludge is washed with acid, smelted at 1200℃, and cast into gold ingots (purity ≥99%).

7.Tailings Treatment

• Cyanide Degradation: Tail liquid is treated with bleaching powder (available chlorine >6g/L) or SO₂/air method (INCO process) to oxidize and decompose cyanide to <0.2mg/L.

• Stockpile Closure: Soil covering and vegetation restoration, with long-term groundwater monitoring.