YPT Carbon Columns

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Precision Adsorption Systems for Gold and Silver Recovery

YPT Carbon Columns

A Carbon Column, in the context of gold recovery and adsorption processes, is a vertical or slightly inclined packed-bed vessel through which a pregnant solution (containing dissolved gold-cyanide complexes) flows upward (or downward) through a stationary bed of activated carbon.
The dissolved gold adsorbs onto the carbon granules, and the treated solution exits with reduced gold concentration.
This process is often referred to as Carbon-in-Columns (CIC) and is especially used when treating solutions rather than high-density slurries.
In these columns, the carbon bed remains largely static (though carbon may be periodically replaced or refreshed); the fluid motion is the key driver of adsorption.
The design allows for high throughput of liquid with minimal solids handling complexity, and is particularly advantageous for solution-phase recovery such as heap-leach solutions or overflow liquors.

Areas of Application

Carbon Columns are used in a variety of contexts including;
  • Gold recovery circuits where the feed to the adsorption stage is a clarified solution rather than a dense slurry (e.g., after heap leaching or after solid-liquid separation).
  • Secondary adsorption of low-grade gold solutions, electrowinning rinse liquors, or eluate polishing.
  • Other hydrometallurgical systems where activated carbon adsorption is used for impurity removal or precious-metal capture from solution (not just gold).
  • Water treatment or chemical processing where a liquid stream passes through carbon beds for pollutant adsorption (though for your mineral-processing website the primary focus is gold recovery).

Principle of Operation

The fundamental mechanism of a Carbon Column includes:

  • Solution Feed:

    A gold-bearing solution (pregnant leach solution) enters the base (or top, depending on design) of the column and flows through the carbon bed.

  • Adsorption:

    As the solution passes through the carbon bed, the gold-cyanide complexes are adsorbed onto the activated carbon granules due to surface interactions and pore diffusion. (Activated carbon typically has huge internal surface area, e.g., ~1000 m²/g, facilitating rapid adsorption.)

  • Bed Dynamics and Flow Path:

    The upward (or downward) flow ensures uniform contact between solution and carbon, allowing adsorption to proceed until breakthrough occurs. Column height, bed depth, flow rate and carbon particle size are balanced to avoid early saturation.

  • Effluent Exit:

    The treated solution (with significantly lower gold concentration) exits the top (or bottom) of the column and proceeds to further processing or discharge.

  • Carbon Handling:

    After adsorption, loaded carbon may be removed for elution/stripping to recover the gold. In some systems the carbon is replaced in situ or refreshed; in others, multiple columns operate in parallel so one can be offline for stripping.
Thus the Carbon Column is essentially a fixed-bed adsorption reactor where the carbon remains stationary (or semi-stationary) and the liquid flows through

Engineered Flow for Maximum Loading Efficiency

YPT Carbon Columns Highlights

Efficient, Scalable Carbon Management Technology

Design Criteria

When designing a carbon column for gold adsorption (or similar application), key criteria include:

Bed Depth &
Carbon Volume:

Sufficient bed mass (carbon tonnes) must be provided to achieve target gold removal (e.g., from X g/m³ to

Flow Rate &
Residence Time:

The volumetric flow of solution through the column must allow enough contact time with the carbon bed for adsorption kinetics to operate.

Carbon Particle
Size & Voidage:

Smaller carbon granules enhance kinetics but may increase pressure drop; typical carbon size in gold circuits is 6 × 16 mesh.

Hydraulic Head &
Pressure Drop:

The design must ensure acceptable pressure drop through the carbon bed and avoid channeling or bypassing

Loading &
Regeneration Strategy:

Columns must be designed with a schedule for when carbon becomes saturated and must be removed for elution/stripping; flow through spare columns ensures continuity

Carbon Retention &
Control:

Ensure carbon remains in the column and does not bypass into the liquid stream (via screens, bed support plates).

Material of
Construction &
Corrosion:

The fluids (cyanide, high pH, oxygenated) require materials compatible with chemical environment.

Instrumentation
& Monitoring:

Gold concentration of feed/effluent, carbon activity, carbon mass balance, flow rates, and pressure drop

Parallel/Series
Columns:

Often multiple columns operate in parallel for continuous operation (one on-line, one offline for regeneration).

Breakthrough Margin &
Safety Factors:

Design includes margin so that effluent gold concentration remains below acceptable limit even near end of life of carbon bed.

Technical Specifications

Here are guideline specification values (actual design must be based on test-work and site conditions):

Carbon bed depth:

2 – 6 mDepends on flow rate, adsorption kinetics

Carbon particle size:

6 × 16 mesh (≈2.8–3.35 mm)Common in gold adsorption circuits

Solution flow rate through column:

Variable; designed per plant tonnageMust match carbon bed capacity

Gold influent concentration:

0.1–1 g/m³ or higher depending on circuitSite specific

Effluent target gold concentration:

≤0.03 g/m³ or lowerIndicates adsorption performance

Number of columns:

Usually 2 or more in parallelAllows one off-line for regeneration

Material of construction:

Carbon steel with FRP epoxy or stainless steel (if corrosive)Based on fluid chemistry

Pressure drop:

Low (often < 0.1 bar)Minimise pump head and maintain flow
These values are illustrative; detailed calculations require adsorption isotherms, kinetics and plant flow rates.

Important Considerations:

  • Breakthrough and bed exhaustion

    Failure to size the carbon bed properly or replace/regenerate carbon timely leads to gold loss in effluent.

  • Channeling and bypass:

    Poor flow distribution or improper column internals can lead to parts of the bed under-utilised and early breakthrough.

  • Carbon particle attrition and fines generation:

    If carbon degrades, fines may pass through the bed and affect downstream processes.

  • Regeneration schedule and carbon life-cycle:

    Carbon cost, life span, adsorption capacity and regeneration frequency affect operating cost significantly.

  • Integration with upstream leach/clarification and downstream elution/stripping:

    Column performance is only as good as the feed solution clarity, cyanide/O₂ levels and downstream carbon handling.

  • Chemical environment & fouling:

    Solution contaminants (e.g., copper, organics) may poison the carbon or alter adsorption behaviour; the column must be designed to handle such influences.