Gold CIP Production Line

Process Introduction

CIP (Carbon in Pulp) is a mature process for adsorbing and recovering gold from gold leaching solution. It is mainly suitable for treating oxidized ores or flotation tailings containing fine gold. Its core is to dissolve gold through activated carbon adsorption, and then obtain high-purity gold mud through analytical electrolysis.

Workflow Introduction

1. Ore Preparation Stage

(1) Crushing and Grinding

Coarse Crushing: The raw ore is crushed to <50mm by jaw crusher or cone crusher.

Fine Crushing: The ore is further grinded to about 0.074mm (200 mesh) by ball mill or rod mill to dissociate the gold.

Classification: Separate qualified particles by spiral classifier, and return coarse particles to regrind.

(2) Slurry preparation

Mix the finely ground ore with water to form a slurry with a concentration of 35%-45% (weight of solids).

Add lime (CaO) to adjust the pH to 10-11 to inhibit the volatilisation of cyanide and neutralise the acid.

2. Cyanide leaching stage

(3) Cyanide dissolution of gold

The slurry enters the tandem leaching tanks (usually 4-8) and sodium cyanide (NaCN, concentration 0.02%-0.05%) is added.

Air or oxygen is added and the reaction takes place. The leaching time is 24-48 hours, and the gold is dissolved into gold-cyanide complexes (Au(CN)₂-). 3.

3. Activated carbon adsorption stage

(4) Carbon slurry mixing

Activated carbon (coconut shell charcoal or apricot shell charcoal, particle size 6-16 mesh) is added to the leached slurry at a concentration of 10-25g/L.

The charcoal is fully contacted with the slurry by air lifter or mechanical stirring, and the gold complex is adsorbed into the charcoal pores.

(5) Multi-stage countercurrent adsorption

The slurry and activated carbon flow countercurrently in 5-7 adsorption tanks:

Fresh charcoal is added to the last tank to adsorb residual gold.

The gold-carrying carbon is discharged from the first tank (gold adsorption capacity up to 3000-6000g/t carbon).

The adsorption time for each stage is 1-2 hours and the total adsorption rate is >95%.

4. Gold-carrying charcoal treatment stage

(6) Gold-carrying charcoal screening and washing

Separate gold-carrying charcoal and slurry by vibrating screen, and the slurry is returned to the leaching system.

The gold-carrying charcoal is washed with dilute hydrochloric acid (3%-5%) to remove calcium carbonate and other impurities.

(7) Electrolytic desorption

Electrolytic method (commonly used):

The gold-loaded charcoal is put into the desorption column, and a hot solution of 1% NaOH + 0.1% NaCN (90-110°C) is passed through.

Apply current, the gold complexes are desorbed and electrolytically deposited on the cathode steel wool, forming gold sludge.

(8) Carbon regeneration

The desorbed lean carbon is soaked in 5% nitric acid and then activated in a rotary kiln at 500-700°C to restore the adsorption capacity.

5. Gold recovery and refining

(9) Gold sludge treatment

The gold sludge obtained from electrolysis is washed with dilute nitric acid to remove impurities (e.g. copper, zinc).

After drying, add borax + sodium carbonate flux, and melt into crude gold ingot at 1200℃.

(10) Electrolytic refining

Crude gold is used as the anode, and pure gold sheet is used as the cathode, and put into gold chloride (HAuCl₄) electrolyte.

The anode is dissolved and pure gold (purity ≥99.99%) is precipitated at the cathode.

Process Advantages:

• Precise adsorption, leading recovery rate：
  Gold recovery rate of 95%~98.5%, selective adsorption of activated carbon, effectively avoiding the interference of impurities
• Step-by-step optimisation, flexible control：
  Leaching and adsorption are independently regulated to adapt to changes in complex minerality
• Outstanding quality of gold-loaded charcoal：
  Charcoal loaded with gold up to 3,000~8,000g/t, desorption efficiency>99%, electrolysis directly produces 99.5%+ gold ingots
• Wide applicability, strong resistance to fluctuations：
  Excellent adsorption effect on high silver ores (Ag:Au>5:1), and the carbon loss rate is 30% lower than that of CIL when treating clay/fine mud ores.

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