Water ingress poses a persistent challenge across underground and opencast mining operations. Complex hydrogeological conditions, including high-pressure aquifers, fractured ground, and voids, contribute to operational hazards such as flooding, infrastructure deterioration, and ground instability. Traditional dewatering methods are often proven insufficient, particularly in deep or highly fractured settings.
Injection-based ground control technologies offer a precise and scalable solution to mitigate these challenges. This article outlines the principal injection materials and techniques employed for water control in mining, maps common geotechnical and hydrogeological problems to injection strategies, and provides global case-based insights.
Hydrogeological hazards in mining
Mines frequently intersect fractured or faulted rock masses that serve as groundwater conduits. Excavation under such conditions may trigger sudden inflows that can exceed pumping capacity and make the operations difficult. These risks are magnified in underground settings where water can reach high temperatures and pressure can surpass 1 MPa, causing washout of conventional grouts before set. In opencast mines, water-bearing faults and weathered zones reduce slope stability by elevating pore pressures.
Weak or unconsolidated ground further complicates water control. Shear zones, karstic systems, and voids, among other structures, create unpredictable flow paths and collapse risks. Infrastructure such as shafts and tailings dams are also vulnerable to seepage and leakage, with implications for both safety and environmental compliance.
Injection technologies for water control
Injections rely on engineered grout and resin technologies, selected based on geology (structural and mineralogy), fracture scale, permeability, and water chemistry. The main families include:
- Microfine cement grouts: Fine cement (3 – 10 µm) based products, formulated for pre-excavation grouting (PEG) and ground consolidation. Suitable for fracture apertures >0.1 mm.
- Polyurethane (PU) foams/resins: Hydro-reactive products that expand upon water contact, formulated to seal even the most persistent active inflows as long as the resin can be consolidated, up to 8 – 10 bar. Non-foaming PU resins are formulated to reinforce fractured zones, or as a structural solution for some static-to-dinamic anchoring applications (e.g. repairing SAG mill foundations).
- Urea-silicate systems: Two-component, fast-setting foams and structural resins used for void filling, fractured rock support, and cable and rock bolt anchoring with a very high pull-out resistance.
- Acrylate gels: Ultra-low viscosity gels for sealing microfractures and controlling seepage. Ideal for ultra-fine fissures and interfaces.