As gold resource development faces challenges of "low grade, fine particles, and complexity," heap leaching technology has emerged as a core solution for the global development of low-grade gold mines, thanks to its economic and environmental advantages. This article analyzes the technological breakthroughs of iconic projects across five continents, revealing the key elements of successful heap leaching operations and providing replicable pathways for mining companies to enhance efficiency.
Carlin Trend Gold Mine, USA
Located in Nevada's "Gold Corridor," this mine employs a three-stage crushing and thin-layer heap leaching process (heap height ≤ 6m), combined with a hydrogen peroxide-enhanced oxidation system, achieving an 82% gold leaching rate from ultra-low-grade ore at 0.8 g/t. Its innovative modular heap design supports an annual dynamic adjustment of processing capacity to 2 million tons, driving the region's annual gold production beyond 1.5 million ounces.
Red Lake Mine, Canada
Faced with the unique conditions of coexisting medium to high-grade ore (5-8 g/t) and tailings (0.5-1.2 g/t), this mine adopted a two-stage development strategy: traditional flotation recovery for high-grade ore and seasonal heap leaching (winter pre-leaching and summer enhancement) for low-grade ore crushed to -10 mm using high-pressure grinding rolls. This approach extended the mine's service life by 12 years, achieving a tailings resource utilization rate of 67%.
Zijinshan Gold Mine, China
This ultra-low-grade deposit (0.3-0.7 g/t) created industry miracles through a "three-dimensional heap leaching system":
Ore Pre-Treatment: Semi-autogenous grinding + high-pressure grinding rolls in two stages (P80=8mm).
Heap Construction: Composite impermeable layer (2mm HDPE + bentonite mat).
Leaching System: Segmented liquid distribution + intelligent temperature control (maintaining 15°C in winter).
The self-developed flow injection analyzer enables real-time monitoring of leachate, ultimately controlling the cost per ton of ore at 35 yuan, setting a record for the lowest cost in domestic gold mining.
Super Pit Mine, Australia
For oxidized ores containing up to 25% clay, a "washing-mining-classified heap leaching" process was developed:
High-pressure water jets wash away fine mud (<0.075 mm).
Particles >10 mm enter the crushing system.
Material<10 mm is layered for heap leaching (increasing permeability in the coarse particle layer by 40%).
This technology shortened the leaching cycle to 45 days and increased annual processing capacity to 18 million tons.
West Wits Line Project, South Africa
Under strict environmental regulations, this project established a closed-loop circulation system:
Leachate: Three-stage countercurrent washing + biological oxidation to remove cyanide (CN⁻ concentration<0.2 ppm).
Waste Residue: Lime solidification + ecological restoration (vegetation coverage restored to 85%).
Water Resources: Zero discharge design with a reuse rate >95%.
Through an IoT monitoring platform, water savings of 0.3 m³ per ton of ore were achieved, while hazardous waste generation was reduced by 76%.
Intelligent Ore Pre-Treatment System
Particle Size Control: High-pressure grinding rolls achieve 95% material<12 mm.
Granulation Technology: Adding 3-5% cement to viscous materials for solidification.
Heap Design: Multi-stage slopes (1:3 gradient) + leachate collection ditches.
Precise Leaching Control Model
Spraying Intensity: Dynamic adjustment between 8-12 L/(h·m²).
Leaching Agent Concentration: Gradual control of cyanide concentration at 0.05-0.3%.
Redox Potential: Maintaining between +400 mV and +600 mV.
Efficient Precious Metal Recovery Chain
Activated Carbon Adsorption: Utilizing coconut shell carbon (iodine value ≥1050).
Desorption Electrolysis: High-temperature and high-pressure desorption (130°C, 0.5 MPa).
Regeneration System: Rotary kiln thermal regeneration (deactivation rate<5%).
Environmental Risk Prevention and Control System
Impermeable Layer Monitoring: Dual-electrode method for real-time monitoring (sensitivity reaching 1×10⁻⁷ cm/s).
Emergency Response: Three-stage interception ditches + 800 m³ accident pond.
Biological Monitoring: Setting up fish observation stations downstream at a distance of 3 km.
The five successful case studies demonstrate that through precise analysis of ore characteristics, innovative process design, and strict environmental management, heap leaching technology can effectively convert low-grade resources into economic value. As a professional provider of EPCM+O services, Xinhai leverages engineering optimization, equipment innovation, and intelligent operations to shorten the investment payback period for heap leaching projects to 2.8 years while enhancing overall recovery rates by 12-15 percentage points.
