PANDA Gold Dressing Agent in Carbon-in-Pulp (CIP) Processing Under Extreme Cold Conditions
Introduction
Operating a Carbon-in-Pulp (CIP) gold processing plant in sub-zero temperatures is a significant challenge. Conventional wisdom often dictates shutting down operations when temperatures drop below 0°C. However, a recent industrial trial at the Aida Gold Mine in Gansu, China, has proven that continuous production is not only possible but highly efficient using the PANDA environmentally friendly gold dressing agent. Facing temperatures as low as -15°C, the plant achieved a remarkable 95.7% leaching rate. This article details the specific process adjustments that made this possible, providing a blueprint for other operations in cold northern regions.
The Challenge: Cold Weather and Short Operating Seasons
The Aida Gold Mine, located in a mid-low mountainous area, historically faced a major constraint: its mineral processing plant was designed to operate for only half the year. Heavy snow and freezing temperatures forced shutdowns, limiting annual production time to less than 6 months (approximately 143-171 days).
When the plant attempted to start production on April 20, 2020, the ambient temperature was minus 15°C, and the slurry temperature in the prepreg tank was only 5-8°C. Combined with a drop in raw ore grade (averaging less than 2.3 g/t) and increased sulfide content, maintaining efficiency using traditional methods seemed impossible. The critical question was: Could the PANDA gold leaching agent perform under these extreme conditions?
The Solution: 6 Key Process Adjustments for Low-Temp CIP
To combat the cold and extend the operating season by 2-3 months, the engineering team implemented six specific modifications to the carbon slurry gold leaching process. These adjustments focused on maximizing reaction time, temperature, and oxygen levels.
1. Advancing Pre-Soaking to the Grinding Stage
The most impactful change was moving the pre-soaking operation from Tank #1 to the first stage of grinding. This served three purposes:
Extended Leaching Time: By using the ball mill as a pre-soaking vessel, the team ensured the slurry received the full design requirement of 40 hours of leaching time, despite increased throughput (137t/d vs. 110t/d design).
Heat Utilization: The friction and agitation in the ball mill raised the slurry temperature to 40°C, counteracting the freezing ambient conditions.
Improved Oxygenation: The vigorous mixing in the mill increased the dissolved oxygen concentration in the PANDA gold extraction agent slurry, which is vital for gold dissolution kinetics.
2. Implementing a Strict Lead Acetate Regime
Adding lead acetate as a pre-soaking agent acted as a catalyst. By forming a "primary battery" with gold, it accelerated the dissolution process. The team established a strict system of adding 0.4 kg/t of lead acetate in dry powder form every half hour to maintain an optimal lead concentration of 0.5 mg/L in the slurry.
3. Optimizing Slurry Level and Aeration
Two mechanical adjustments ensured physical stability:
Slurry Level Gates: Installed at the pump pool outlet, these gates stabilized the slurry level, preventing air ingestion by the sand pump and improving classification fineness.
Direct Air Duct Connection: Removing complex valves and elbows in the aeration system reduced resistance. Using a direct leather air duct connection prevented blockages caused by mineral sand, ensuring a smooth airflow for agitation.
Results: Extended Operations and Higher Recovery
The implementation of these measures, particularly the shift to grinding-stage pre-soaking, yielded exceptional results. The plant successfully extended its autumn production run into mid-to-late November, operating 45 days longer than usual.
Crucially, the gold leaching rate climbed to 95.7% in Abstract, surpassing the previous year's performance (94.51% in 2019) despite the harsher conditions. This translated to an additional output value of approximately 1.79 million yuan.
Key Performance Indicators (2018 vs. 2020):
2018: Avg. Leaching Rate: 92.58% | Ambient: 20-30°C
2020: Avg. Leaching Rate: 95.7% | Ambient: 8-15°C (No heat loss mitigation)
Conclusion: A Blueprint for Cold-Region Mining
This case study conclusively demonstrates that the PANDA environmentally friendly gold leaching agent is not only applicable but superior for low-temperature carbon-in-pulp processing. By rethinking the process flow—specifically by utilizing the grinding stage for pre-soaking and aeration—mining operations in cold climates can overcome the traditional limitations of winter.
For engineers looking to extend their operating season without massive capital investment in insulation or heating, the Aida Gold Mine experience offers a proven, high-return strategy.
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FAQ for PANDA Gold Dressing Agent in Carbon-in-Pulp (CIP) Processing Under Extreme Cold Conditions
Q1: Can the PANDA gold dressing agent work effectively at -15°C?
A1: Yes, but it requires process adjustments. The industrial test at Aida Gold Mine proved that by advancing the pre-soaking operation to the grinding stage, the heat generated by the ball mill (raising slurry temp to ~40°C) can counteract the -15°C ambient temperature. This method maintained a leaching rate of 95.7% even in freezing conditions.
Q2: How do you extend the leaching time in a CIP plant with increased throughput?
A2: When the daily processing capacity exceeds the design limit (e.g., 137t/d vs. 110t/d), the hydraulic retention time in tanks decreases. The solution is to utilize the grinding stage as a pre-soaking tank. This effectively adds 12+ hours of leaching time before the slurry even enters the leaching tanks, ensuring the total contact time meets the 40-hour requirement.
Q3: What is the role of lead acetate in the PANDA leaching process?
A3: Lead acetate acts as a catalyst. At a dosage of 0.4 kg/t, it forms a "primary battery" with gold, accelerating the electrochemical dissolution process. However, precise control is vital; excessive lead can form an insoluble film (Pb(CN)2) that hinders leaching. A strict dry powder addition system every half hour is recommended.
Q4: How does cold weather affect dissolved oxygen in CIP tanks?
A4: Cold temperatures can reduce microbial activity and gas solubility, but the bigger issue is viscosity. To combat this, the Aida Mine simplified its aeration system by removing valves and elbows, using direct leather ducts. This reduced resistance and prevented blockages, ensuring adequate oxygen transfer to sustain the PANDA reaction kinetics.
Q5: Can I modify my existing CIP plant for winter operation without major construction?
A5: Yes. The case study shows that significant gains can be achieved with minimal capital expenditure. Key modifications include: 1) Installing slurry level adjustment gates