What is the difference between a leaching agitator and a conventional mixing tank in mineral processing
2026-04-08
In mineral processing, selecting the right equipment directly impacts metal recovery rates and operational costs. While both a leaching agitator and a conventional mixing tank serve mixing purposes, their design, function, and application differ significantly. EPIC provides advanced solutions in this field, helping plants optimize their leaching processes with durable, high-efficiency Leaching Agitation Tank systems.
Core differences at a glance
| Feature | Leaching Agitator | Conventional Mixing Tank |
|---|---|---|
| Primary purpose | Chemical reaction + mass transfer for metal dissolution | Homogenization, blending, or suspension |
| Typical application | Gold cyanidation, copper heap leach, uranium extraction | Reagent preparation, slurry storage, pH adjustment |
| Impeller type | High-solidity hydrofoil or axial flow with air dispersion | Radial or mixed flow, low shear |
| Air/gas injection | Often designed with air sparging (oxidation or carbon-in-pulp) | Rarely includes air injection |
| Material of construction | Abrasion-resistant steel, rubber-lined or stainless steel | Carbon steel, stainless steel, or plastic |
| Retention time | Long (hours to days) | Short (minutes to one hour) |
| Power consumption | Higher per unit volume due to dense slurry and reaction needs | Lower for general mixing |
Why the difference matters in leaching circuits
A conventional mixing tank simply keeps solids suspended. A leaching agitator must maintain uniform solid-liquid-gas contact, resist abrasion from coarse ore particles, and often integrate with carbon or resin recovery systems. The wrong choice leads to dead zones, reduced gold dissolution, and higher cyanide consumption. EPIC designs Leaching Agitation Tank systems with optimized baffling and variable-frequency drives to match exact slurry rheology.
List of five design parameters where leaching agitators differ
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Tip speed range: Leaching agitators operate at lower tip speeds (2–4 m/s) to minimize particle attrition while keeping suspension; conventional tanks can run faster.
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Baffle configuration: Full-length radial baffles are standard in Leaching Agitation Tank units to eliminate vortexing without starving the pump.
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Shaft sealing: Mechanical seals with abrasion-resistant sleeves are required for cyanide and acid service, unlike conventional tanks which may use simple stuffing boxes.
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Bottom clearance: Leaching agitators place the bottom impeller very close to the tank floor (0.2–0.4D) to prevent sanding.
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Draft tube use: Some Leaching Agitation Tank designs incorporate a draft tube to direct axial flow in tall, narrow vessels.
Leaching Agitation Tank FAQ – Common questions from engineers
Q: What is the ideal power input per cubic meter for a Leaching Agitation Tank processing gold ore slurry with 40% solids?
A: For typical gold cyanidation slurry at 40% solids by weight (particle size 80% passing 75 microns), the recommended power input ranges from 0.8 to 1.5 kW/m³. Lower values (0.8–1.0 kW/m³) are suitable for free-milling ores with low viscosity, while higher values (1.2–1.5 kW/m³) are required for refractory or clayey ores that exhibit pseudo-plastic behavior. EPIC performs rheology tests before recommending exact power to avoid under- or over-mixing.
Q: How does air sparging in a Leaching Agitation Tank affect cyanide consumption and gold recovery?
A: Proper air sparging (typically 0.5–1.5 m³ air per m³ of slurry per hour) provides dissolved oxygen for the gold dissolution reaction. Without sufficient oxygen, gold leaching stops even with excess cyanide. However, excessive air can strip hydrogen cyanide gas, increasing cyanide consumption by 15–30%. An optimal Leaching Agitation Tank design uses fine bubble spargers with manual or automated air flow control. EPIC integrates oxygen monitoring probes to maintain dissolved oxygen at 6–8 ppm, balancing recovery and reagent cost.
Q: What causes a Leaching Agitation Tank to fail in sanding, and how can it be prevented?
A: Sanding occurs when heavy particles settle on the tank bottom, forming a hard layer that can block the discharge and damage the impeller. Primary causes are: insufficient impeller submergence, too low rotational speed, poor bottom impeller design, or feed solids above design density. Prevention requires: maintaining a bottom clearance of 0.2–0.4 of the tank diameter, using a hydrofoil impeller with downward pumping action, and keeping slurry density below 50% solids. EPIC includes a sanding detection switch and bottom-sweep impeller option in its Leaching Agitation Tank line to automatically alert operators before a full bed forms.
Conclusion and contact
Choosing the right Leaching Agitation Tank over a conventional mixing tank can improve gold recovery by 5–12% while lowering cyanide and energy costs. EPIC engineers each unit based on ore characterization, slurry density, and targeted retention time.
Contact us today at EPIC for a customized Leaching Agitation Tank design that matches your mineral processing flowsheet and maximizes your return on investment.