AARL process as applied at SDGM. • Identify the key elution circuit components. • Demonstrate an understanding of carbon reactivation theory. • Demonstrate an. Request PDF on ResearchGate | Modelling of the AARL elution process | The influence of temperature on the equilibrium adsorption of gold and hydroxide ion . successful methods is the carbon-in-pulp (CIP) process. In CIP processing elution rig was commissioned to simulate industrial Zadra and AARL carbon elution.

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The solution is cooled by exchanging heat with barren solution and flows through a back pressure control valve, to the pregnant solution holding tank. Thermocal temperature in ………. Carbon is loaded into the acid wash column from the loaded carbon surge hopper ;rocess opening the main inlet valve AV elutiom The condensate recycle spray is stopped and the alcohol is allowed to boil out of the pregnant solution.

Typical strip times with glycol are 24 to 36 hours. Again do not risk flooding the kiln by over flushing the line. The Micron elution procedure takes advantage of the enhanced stripping rate achieved with alcohol, but confines the alcohol to the closed stripping unit.

The other significant change was the injection of NaCN and NaOH into hot demineralized water to form barren eluate just prior to entry to the column.

When the curve flattens out, the rinsing is sufficient even if the pH is only 4.

Stripping efficiency decreases as flow rates are increased above 3 to 4 bed volumes per hour. After filling, the main valve AV is closed and dilute hydrochloric acid is injected into the bottom of the column via valve AV Activated carbon has long been known to exhibit a rpocess affinity for the extraction of gold from cyanide solutions.

Carbon Stripping – Denver Mineral Engineers

Excess water and air are bled off through a screen and valve AV to either the leach area sump or the tailings hopper. Alcohol stripping has generally fallen out of favor due to the flammability concerns. The sequence controller time for step 06 should then be reset to the time indicated by the graph. These procedures allowed the carbon to be recycled for further gold recovery.


Above deg-F cyanide was decomposed and metallic gold precipitated in the carbon. The acid rinse step 05 is currently set for 2. The Micron method involves pretreatment of loaded carbon, with a caustic cyanide solution followed by elution with an alcohol mixture. The entire stripping cycle takes about 8 hours. The final eluate exits just below the top compartment as shown in Figure 5. Organic vapors rise through the carbon bed and are condensed in the overhead condenser.

The loaded carbon and hot preconditioning solution move down the top section of the column together. The carbon is then steam stripped to recover residual alcohol.

Each process is briefly described. Operation at deg-F requires operating pressures of 10 to 15 PSIG to prevent flashing steam in the system. This stage continues until five bed volumes of water have passed through the column 2.

The process was developed by J. Each column was mm diameter by 10 metres high which for 24 tonnes per day of carbon per column was equivalent to the pilot plant operating at 1 tonne elutionn day. Should any difficulties occur during the stripping process, possible faults with remedial action have been detailed in part 4 aadl this manual.

Carbon Stripping

Acid washing has been shown to typically increase the efficiency of AARL stripping. Manual control is the standard. The AARL process should definitely be considered for large projects with sophisticated operators. It was not, however, profess methods for chemically desorbing gold from loaded carbon were developed, that the process came into widespread use for gold recovery from ore.

Stripping temperature is the most significant operating parameter so solutions are kept as close to boiling temperature as is practical.

Heat is then applied to the base of the desorption vessel. The advantages of this are dubious in that there would be more than enough time in a twenty four hour period for both steps to be completed in one column. The following is a typical operating schedule for a Pressure Zadra stripping cycle: Pregnant solution is pumped from the pregnant solution tank through electrowinning cells where gold eluion recovered by electrolysis.


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This could be excessive and wasting potable water. Gold is recovered from the pregnant eluant by electrowinning and the barren eluant is discarded See Figure 3. After rinsing the carbon is pressure transferred to the elution column. Continued research at the USBM revealed that the Zadra process stripping rate could be increased greatly by stripping at higher temperatures 4. This is due to its significant cost advantage over atmospheric pressure Zadra systems.

Part 3 outlines in full detail every action required on the part of goldroom personnel in order to operate the plant successfully. At the end of the carbon cool stage, water is pumped into the column via valve AV so as to maintain pressure within it and force the barren carbon out of the column via valve AV into the carbon transfer line.

As the solution flows through the electrowinning cell, gold is plated on to the steel wool cathodes. Most columns are operated with upflow of solution, but some plants have selected to elute by downflow. It then flows back into the eluate tank.

This is in direct contrast with the Zadra and AARL procedures, which produce eluant concentrations one or two orders of magnitude lower. The advantages and disadvantages of each procedure are discussed. Since that time, its application has become standard practice in South Africa and Australia. By L D Michaud T The tower bottoms solution is then free of alcohol and loaded with gold solution which has been stripped by the refluxing action in the column.

The stripping of gold from loaded carbon here involves two basic steps; Acid Washing and Elution. This is achieved at flow rates in the range of 2 bed volumes per hour operating in series flow with electrowinning cells.

Operators unfamiliar with The Granites stripping system should follow Part 3 directly.