Case Study: PANDA Leaching Agent Replaces Cyanidot in Carbon-in-Pulp (CIP) Process with 92%+ Recovery
Executive Summary
Transitioning from toxic cyanide to eco-friendly leaching agents is often hindered by the need to improve existing infrastructure. This case study details the successful industrial application of the PANDA Environmentally Friendly Gold Leaching Agent at Wangcheng Mining in Hebei, China.
Crucially, the PANDA agent was implemented as a direct replacement in their existing Full-Mud Carbon-in-Pulp (CIP) circuit. The results were exceptional: the gold leaching rate reached 92.83%, surpassing the previous cyanide performance. Furthermore, the environmental impact was drastically reduced, with cyanide (CN-) levels in tailings falling below the detection limit, effectively downgrading the waste from hazardous to non-hazardous.
The Operational Context: A Standard CIP Circuit
Wangcheng Mining operates a standard all-mud cyanidation carbon slurry adsorption process with a capacity of 3,400 tons per day. Their circuit includes 1 pre-soak tank and 6 leaching tanks. The ore is ground to -0.074mm (90% passing), and the slurry concentration is tightly controlled between 39% and 41%.
The primary challenge was the high toxicity risk associated with liquid sodium cyanide. The goal was to maintain the high recovery rate (historically ~88.30%) while eliminating cyanide from the tailings stream.
Figure 1: The chemical structure of cyanuric acid, the core component of PANDA, which stabilizes the molecule and prevents the release of free cyanide ions in alkaline environments.
The Laboratory Screening: Proving Equivalence
Before the industrial trial, small-scale tests were conducted to optimize the PANDA dosage. The tests mimicked the site conditions: 40% slurry density, pH 10.5-11.0, and 36 hours of leaching.
The results were clear. At a dosage of 650 g/t, the PANDA agent achieved a gold leaching rate of 91.35%, outperforming the sodium cyanide control group which achieved 88.30% at a dosage of 583 g/t. This 3.05 percentage point increase in recovery confirmed that PANDA could not only match but exceed the metallurgical performance of cyanide in this specific ore type.
The Industrial Trial: A Seamless Transition
From April to May 2020, Wangcheng Mining conducted a 24-day industrial trial. The PANDA agent was fed directly into the existing CIP circuit without any structural modifications.
The data from the trial is presented in the table below, showing the performance across different phases of the test.
| Phase Period | Avg. Ore Grade (g/t) | PANDA Dosage (g/t) | Tailings Grade (g/t) | Recovery Rate (%) |
|---|---|---|---|---|
| Phase 1 (Early) | 1.77 | 770.14 | 0.132 | 92.26% |
| Phase 2 | 1.66 | 966.30 | 0.144 | 90.97% |
| Phase 3 | 1.68 | 883.90 | 0.118 | 92.83% |
| Phase 4 (Late) | 1.64 | 929.20 | 0.160 | 90.03% |
Key Observations:
The highest recovery rate of 92.83% was achieved in Phase 3.
The average recovery rate across the trial was consistently above 90%, meeting the industrial requirements.
The fluctuation in dosage was necessary to adapt to varying ore grades, demonstrating the reagent's robustness.
The Environmental Verdict: Eliminating Cyanide
The most significant outcome was the environmental impact. As shown in Tables 4 and 5 (referencing the source data), after a period of using the PANDA agent, the concentration of cyanide (CN-) in the tailings was reduced to levels below the detection limit.
This is a game-changer for mine operators. By eliminating cyanide from the tailings, the waste classification changes. As noted in the study, using sodium cyanide resulted in tailings classified as hazardous waste (with CN- levels around 4.5 mg/L). In contrast, the PANDA process produced tailings that are environmentally safer, significantly reducing the long-term liability and environmental management costs.
Conclusion: A Viable Path to Green Mining
For mines operating Carbon-in-Pulp (CIP) or Carbon-in-Leach (CIL) circuits, the PANDA agent offers a compelling solution. It requires no capital investment in new equipment, works at ambient temperatures, and maintains high recovery rates.
The Wangcheng Mining case study proves that "going green" does not mean sacrificing efficiency. By switching to PANDA, mines can achieve superior gold recovery and drastically reduce their environmental footprint
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FAQ for PANDA Leaching Agent Replaces Cyanidot in Carbon-in-Pulp (CIP) Process with 92%+ Recovery
1. Can the PANDA leaching agent be used as a direct replacement for cyanide in a Carbon-in-Pulp (CIP) plant?
Yes. The industrial trial at Wangcheng Mining demonstrated that the PANDA agent can be used as a direct replacement in an existing CIP circuit. The process required no structural modifications to the plant infrastructure, including the pre-soak and leaching tanks. The agent was successfully fed into the circuit, maintaining slurry characteristics and flow rates similar to the previous cyanide operation.
2. What is the gold recovery rate when using PANDA compared to sodium cyanide in a CIP process?
The PANDA agent outperformed sodium cyanide in the Hebei case study. In laboratory tests, PANDA achieved a recovery rate of 91.85% compared to 88.30% for sodium cyanide. In the industrial trial, the PANDA process achieved a peak recovery rate of 92.83%, consistently maintaining rates above 90% across the 24-day test period.
3. Does the PANDA agent eliminate cyanide from the tailings?
Yes. One of the most significant environmental benefits is the reduction of cyanide in the tailings. After a period of using the PANDA agent, the concentration of cyanide (CN-) in the tailings was measured to be below the detection limit. This effectively downgrades the tailings from "hazardous waste" (associated with cyanide use) to a safer classification, drastically reducing environmental liability.
4. What are the optimal process conditions for PANDA in a carbon slurry adsorption circuit?
Based on the successful trial, the optimal conditions are:
Grinding Fineness: -0.074mm (90% passing)
Slurry Concentration: 39% to 41%
pH Value: 10.5 to 11.0 (maintained using lime)
Dosage: The industrial trial used an average dosage of approximately 895.5 g/t, though this can vary based on ore grade and reactivity.
5. Is the PANDA agent safe to handle compared to liquid sodium cyanide?
Yes, the PANDA agent presents significantly lower safety risks. Unlike liquid sodium cyanide, which is highly toxic and requires stringent transportation and storage protocols, the PANDA agent is a low-toxicity solid powder. This simplifies storage logistics and reduces the risk of poisoning accidents for personnel and nearby communities.