PANDA vs. Sodium Cyanide: A 100t/d Industrial Test at Hewan Gold Mine
Introduction
Replacing toxic sodium cyanide (NaCN) in gold extraction has long been an industry goal. But does the alternative truly match cyanide's performance at scale? This industrial case study, conducted at the Hewan porphyry gold mine (a subsidiary of Zijin Mining), provides definitive proof. Using the PANDA environmentally friendly gold leaching agent, the 100 tons/day full mud slurry plant achieved a gold leaching rate of over 92%. This report details how PANDA matched cyanide's technical indicators while offering superior environmental safety.
The Challenge: Finding a True Cyanide Replacement
Sodium cyanide has dominated gold mining due to its efficiency, but its high toxicity poses severe risks to human, animal, and crop safety. While various non-cyanide methods exist (like thiosulfate or polysulfide), they often suffer from high costs, instability, or equipment corrosion.
The Hewan mine processes a low-sulfur oxidized ore with a grade of 4.61 g/t. The critical objective was to find a gold leaching agent that could integrate seamlessly into the existing Carbon-in-Pulp (CIP) process without sacrificing recovery rates.
The Industrial Trial: Methodology and Scale
Unlike small-scale lab tests, this study involved a continuous 100t/d industrial application test. The goal was to compare PANDA directly against sodium cyanide under identical plant conditions.
Plant Parameters:
Throughput: 100 tons per day
Ore Type: Low-sulfur oxidized ore
Process: Carbon-in-Pulp (CIP)
Grinding Fineness: -200 mesh (85-90%)
Slurry Density: 40-45%
Performance Analysis: PANDA vs. Cyanide
The results demonstrated that PANDA is not just a substitute, but a competitive alternative. Under optimized conditions, PANDA achieved technical and economic indicators basically the same as sodium cyanide.
1. Leaching Efficiency
The industrial test showed that PANDA could achieve a stable leaching rate of 92% or higher. The agent proved to be highly stable, with adsorption rates and overall leaching performance not inferior to cyanide.
2. Optimal Dosage and Conditions
Based on the Hewan mine's specific ore characteristics, the optimal parameters were identified:
pH Level: 11-12 (maintained with lime)
Agent Concentration: 0.1%
Temperature Sensitivity: Above 10°C, PANDA performs comparably to cyanide. Below 10°C, performance drops, suggesting a need for dosage adjustment in cold climates.
Notably, PANDA demonstrated a faster leaching speed than cyanide in the initial 4 hours, indicating rapid reaction kinetics.
Environmental Impact: A Safer Tailings Solution
One of the most significant advantages of PANDA lies in tailings management. Unlike cyanide, which leaves toxic residues that can react with rainwater to form hazardous wastewater, PANDA residues are significantly safer.
Tailings Test Results:
Cyanide Tailings: Even after filtration, cyanide residues can re-form toxic solutions when exposed to rainwater.
PANDA Tailings: Testing showed the cyanide radical in PANDA tailings is "very low" and almost undetectable (< 0.06 mg/L).
This means mines can utilize dry discharge methods with PANDA without the fear of creating environmental disasters in the rainy season, drastically reducing the need for expensive wastewater treatment infrastructure.
Conclusion: A Viable Future for Gold Leaching
The successful trial at the Hewan gold mine proves that the PANDA environmentally friendly gold leaching agent is a technically sound replacement for sodium cyanide. By maintaining high recovery rates (92%+) and eliminating the high toxicity associated with traditional methods, PANDA offers a path toward "Green Mining."
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FAQ for PANDA vs. Sodium Cyanide: A 100t/d Industrial Test at Hewan Gold Mine
1. Can the PANDA leaching agent really match the recovery rate of cyanide?
Yes. The industrial application test conducted at the 100t/d scale at Hewan Gold Mine showed that the PANDA gold dressing agent achieved a gold leaching rate of over 92%. Under the same process conditions (slurry density, grinding fineness), the technical indicators were basically the same as sodium cyanide, proving its effectiveness for oxidized ores.
2. What are the optimal process parameters for using PANDA in a CIP plant?
Based on the Hewan mine trial, the optimal parameters are:
pH Value: 11-12 (adjusted with lime).
Agent Concentration: 0.1%.
Slurry Density: 40-45%.
Grinding Fineness: -200 mesh (85-90%).
Maintaining these parameters ensures stability and high adsorption rates in the Carbon-in-Pulp process.
3. Is PANDA suitable for low-temperature operations?
Performance is temperature-dependent. The test results indicate that PANDA performs comparably to cyanide when the temperature is above 10°C. However, when the temperature drops below 10°C, the leaching effect decreases. In cold climates, it may be necessary to slightly increase the dosage to maintain efficiency.
4. How does PANDA impact tailings management and environmental safety?
FKN offers a significant environmental advantage. Unlike cyanide, which leaves toxic residues that can leach into water systems, PANDA tailings have "very low" cyanide content (tested at < 0.06 mg/L). This allows for safer dry discharge of tailings, eliminating the risk of toxic wastewater formation during rainfall and reducing the need for expensive water treatment facilities.
5. Does switching to PANDA require changes to existing CIP (Carbon-in-Pulp) infrastructure?
No. The industrial test confirmed that PANDA has no adverse impact on the carbon slurry process