Column Flotation
Better Recovery for a Lower Cost
Eriez Column Flotation delivers step-change improvements in concentrate grade and recovery, with up to 50% lower energy costs and up to 40% less capital than equivalent mechanical circuits. Proven across over 1,200 installations in over 40 countries.
Advantages Over Conventional Flotation
Mechanical cells have dominated flotation for over a century, but their design imposes fundamental constraints that limit metallurgical performance and inflate both capital and operating costs. More equipment, more energy, more maintenance — yet still compromised grade and recovery.
- Coarse Bubble Generation: Rotor-stator shear produces bubble diameters typically greater than 1 mm — significantly reducing collision probability for fine and ultrafine particles, where an increasing proportion of ore value is locked as orebodies grow more complex.
- High Entrainment, Poor Selectivity: Shallow froths limit wash water use, allowing fine gangue to report to concentrate and dilute product grade. Multiple cleaning stages are required just to reach acceptable quality — adding cost, footprint, and complexity.
- Energy Wasted on Suspension: The majority of a mechanical cell's power draw goes to keeping solids suspended — not to flotation. That's energy cost with no metallurgical return. Power runs 40–50% higher than equivalent column circuits.
- Poorly Mixed Reactor Behaviour: Mechanical cells operate as nearly perfectly mixed reactors with inherent bypassing and dead zones. Industry practice requires a minimum of three cells in series to compensate — increasing capital before you've floated a single tonne.
Three Design Principles for Measurable Performance Gains
Flotation columns were engineered to overcome the fundamental limitations of mechanical cells. Every performance advantage flows from three structural design characteristics, each delivering a quantifiable improvement in metallurgical outcome and operating cost.
Counter-Current Contacting
Feed slurry flows down while fine bubbles rise up, maximising contact time and attachment probability. Columns operate with a higher Péclet number, closer to plug flow, delivering higher recovery for the same residence time.
Lower Energy Cost: No rotor-stator means no energy wasted on mechanical agitation. Eriez columns consume 40–50% less power than mechanical circuits, and up to 68% less than downcomer-aspirated pneumatic cells.
Deep Froth Washing
Positive bias wash water displaces entrained gangue back to pulp while retaining attached hydrophobic particles. A single column routinely replaces two to three mechanical cleaner stages with equivalent or superior metallurgical results.
Circuit Simplification: Fewer cells means 15–40% lower total installed CAPEX, 50–75% reduction in structural and civil requirements, and less piping, electrical, and instrumentation — with freed floor space for additional capacity.
Fine Bubble Sparging
Eriez sparging systems generate bubbles up to 20× finer than mechanical cell aeration — exponentially more surface area per unit of air and a directly proportional increase in the flotation rate constant.
Low Maintenance Requirements: No rotating internals, no high-wear rotor-stator components. SlamJet spargers are externally serviceable without draining the column — supporting high availability and lower total lifecycle cost.
Two Spargers — One for Every Application
SlamJet
Internal Lance Sparger
Proven in thousands of flotation applications worldwide, the SlamJet forces high-pressure air through a converging nozzle, generating microbubbles averaging 0.8 mm in diameter. Its fail-closed self-sealing mechanism prevents slurry backflow — eliminating plugging and fouling common in other systems. High-wear components are externally replaceable without draining the column or interrupting operation.
The SlamJet improves the operating efficiency of flotation columns, leach tanks, and other processes that depend on the generation of fine gas bubbles.
Benefits
- 2.5× Increase in bubble surface area flux vs. mechanical cell aeration — directly proportional increase in flotation rate constant k
- 0.8mm Mean bubble diameter — versus >1 mm for rotor-stator shear
Applications
- Feeds containing large tramp items that cause plugging in recirculating spargers
- Cost-constrained applications requiring high upgrading performance
- Mineralogy where quiescent conditions and counter-current contacting are preferred
- Retrofit into existing column infrastructure
CavTube
External Cavitation Sparger
The only technology to simultaneously leverage two kinetic intensification mechanisms, the CavTube recirculates a slipstream of slurry through an external manifold where hydrodynamic cavitation generates a bimodal bubble size distribution: ~100 µm microbubbles from high-shear fragmentation, and ~1 µm picobubbles nucleated directly on hydrophobic particle surfaces — bypassing the conventional collision-attachment limitation for ultrafine particles.
Benefits
- 6×+ Improvement in flotation kinetics vs. mechanical cell bubble sizes — from ~0.1 mm mean bubble diameter
- +20% Fine particle recovery improvement achievable versus conventional sparging systems
- –50% Reduction in collector consumption for certain ores through picobubble pre-coating
Applications
- Fine and ultrafine particle recovery as the primary metallurgical objective
- Complex or finely disseminated ores with slow flotation kinetics
- Rougher and scavenger duties — previously considered unsuitable for columns
- Retrofit of existing conventional columns without column replacement
Industrial Results Across Major Applications
Copper Cleaner and Cleaner-Scavenger Duties
Column flotation is the industry standard for copper cleaner and polymetallic final cleaning duties. CavTube columns deliver their greatest kinetic advantage precisely where mechanical cells are most constrained: ultrafine particle recovery and gangue rejection in the cleaner circuit.
Prior to column installation, the all-mechanical cleaner circuit was chronically overloaded — operators were forced to choose between recovery and grade, with cleaner block copper recovery averaging 67–80%. A single 4,250 mm diameter CavTube column installed as a cleaner scalper transformed circuit performance.
98.5% Cleaner block copper recovery: Up from 67–80% prior to column installation
+2.6pp Global plant copper recovery: From 89.1% to 91.7% — from a single column
Eliminated Circulating load: Between cleaner scavenger tailings and scavenger feed — reducing regrind mill load
$9M+ Indicative annual revenue uplift: At 10 Mt/y, 0.5% Cu — a 2pp recovery gain equals ~1,000 additional payable tonnes at $9,000/t
Case Study: DeGrussa Copper-Gold Concentrator, WA (Sandfire Resources, 1.5 Mtpa)
What the Numbers Look Like Across the Install Base
Documented Performance Range
| Performance Metric | Typical Improvement | Primary Mechanism |
|---|---|---|
| Concentrate grade | +3–8% | Froth washing, positive bias flow, reduced gangue entrainment — at equivalent recovery |
| Cleaner circuit recovery | +2–20% | Higher Peclet number approaching plug flow; higher bubble surface area flux; fine particle kinetics |
| Global plant recovery | +2–5% | Reduced circulating loads, elimination of cleaner tailings recycle, improved fine fraction recovery |
| Fine particle recovery (CavTube) | Up to +20% | Bimodal bubble generation — picobubbles nucleated on hydrophobic surfaces bypass collision-attachment limits |
| Reagent consumption | Up to –50% | Improved selectivity and picobubble pre-coating reduce collector dosage required for equivalent flotation response |
| Power vs. mechanical cells | –40–50% | No rotor-stator — low-intensity bubble field replaces high-energy mechanical mixing |
| Power vs. pneumatic cells (CavTube) | Up to –68% | CavTube air efficiency — lower superficial gas velocity delivers superior kinetic performance |
| Total installed CAPEX | –15–40% | Fewer stages, less auxiliary equipment, reduced structural and civil requirements |
Eriez Column vs. Pneumatic Cells
Technology Comparison
For fine particle selectivity, deep cleaning duty, energy efficiency, and installation base, Eriez Column Flotation is the superior choice. Downcomer-aspirated pneumatic flotation cells are marketed as a replacement for column technology. Here's how the technologies compare across the criteria that matter most — on concentrator performance, operating cost, and confidence to capital.
| Criteria | Eriez Column | Pneumatic Cell |
|---|---|---|
| Fine Particle Selectivity Separation of fine hydrophilic / hydrophobic particles |
Superior — deep froth wash |
Moderate |
| Wash Water / Froth Cleaning Elimination of entrained gangue in concentrate |
|
Limited froth depth |
| Energy Consumption vs. equivalent mechanical flotation circuit |
Up to 68% lower (CavTube) |
Moderate reduction |
| Circuit Simplification Ability to replace multiple cleaner stages |
Replaces 2–3 stages |
Single stage |
| Fine and Ultrafine Recovery CavTube picobubble mechanism |
Up to +20% vs. conventional sparging |
Standard kinetics |
| Sparger Customisation Optimise bubble size for feed characteristics |
SlamJet or CavTube |
Fixed internal downcomer |
| Retrofit / In-Situ Upgrade Upgrade existing column infrastructure |
CavTube retrofit — no column replacement |
Full unit replacement |
| Global Installations Proven operating references worldwide |
1,280+ across 45 countries |
Fewer references |
| Proven for Scale-Up Lab-to-industrial scale-up reliability |
Validated 5 cm to 6 m diameter |
Limited published scale-up data |
DeGrussa Copper-Gold Concentrator
A single CavTube column transformed a chronically overloaded cleaner circuit — eliminating the circulating load, recovering fine particles mechanical cells could not treat, and adding 2.6 percentage points to global plant copper recovery.
Operation: Sandfire Resources, Western Australia
Technology: 4,250 mm CavTube Column
Duty: Copper Cleaner Scalper
- 98.5% Cleaner block copper recovery
Up from 67 to 80% — mechanical cells were forcing a grade vs. recovery trade-off
- +2.6 pp Global plant copper recovery
From 89.1% to 91.7% at a 1.5 Mtpa operation — from a single column
- Eliminated Circulating load
Between cleaner scavenger tailings and scavenger feed — reducing regrind mill load and simplifying the circuit
- 30× Scale-up ratio confirmed
Grade-recovery curves from 150 mm lab, 500 mm pilot, and 4,250 mm industrial column all fell on the same curve
Lab Testing Available On-Site
Mobile test columns can be brought to your site to predict metallurgical performance and de-risk installation before capital commitment.
We run pilot programs across all major mineral applications.
Technical Papers, Case Studies & Brochures
Column Flotation White Paper - Benchmarking Performance of Eriez Phospro Column Flotation cells against mechanical cells for reverse flotation of a sedimentary phosphate ore.
Improved Cleaner Circuit Performance - Improved Cleaner circuit performance at the degrussa copper mine with an in situ column sparging system.
Knoblauch et al CMP 2016 Copper Cleaner Paper - Improved Cleaner Circuit Performance at The Degrussa Copper Mine with An In Situ Column Sparging System
