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 unit is then switched to the batch distillation mode. The process is still widely used today because of its simplicity. The main drawback to the alcohol stripping process is the potential for fires.

AARL Carbon Stripping System Operation: Elution & Electrowinning

Denver Procesa Engineers, Inc. Methanol, ethanol, and Isopropanol were all found to increase the gold desorption rate. The stripping of gold eltuion loaded carbon here involves two basic steps; Acid Washing and Elution.

Further research at the USBM showed that the atmospheric pressure Zadra stripping cycle can be made to operate much faster by the addition of alcohol to the strip solution 6. The controllers can be over-ridden to stop or reset a cycle or to start again, at any point. The loaded carbon and hot preconditioning solution move down the top section of the column together.

Buildup of miscellaneous ions in solution after continued recycling also reduces stripping efficiency. Although the sequence controllers govern the various stripping stages it is essential to monitor the plant on a regular basis so as to ensure that all equipment is operating properly and that desired temperatures are being reached and maintained within the time limitations set on the controllers.

Today, many options are available to the recovery plant designer and operator for the stripping of gold from carbon. I Need Consulting Engineering Help. Several different alcohols were investigated.


AARL Carbon Stripping System Operation: Elution & Electrowinning

The time required for pressure stripping is generally from 10 to 14 hours. 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. Procezs ExtractionGold Refining Tags: The advantage to downflow is reduced potential for binding of flow distribution screens by tramp material in the carbon. Ethanol and methanol were procses to perform almost equally, but were substantially better that Isopropanol.

Fires have been reported at several alcohol stripping operations. The micron eluted carbon also appears to have a somewhat higher level of activity than carbon eluted by other methods. Likewise it should be remembered that the controllers will not procees if a local stop switch is depressed.

Plant practice generally indicates that about deg-F warl the upper limit for maximum stripping efficiency. 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 per day.

It was not, however, until methods for chemically desorbing gold from loaded carbon were developed, that the process came into widespread use for gold recovery from ore. This idea was discarded in practice, in favor of the simpler one aal caustic cyanide elution.

Each process is briefly described. The thermocal heater and pump continue to operate throughout the preheat and subsequent elution stage so as to maintain desired operating temperatures. The stripping efficiency is virtually independent of eluant water flow rate in the range of 1 to 5 bed volumes per procesx.

Zadra, and others, at the U. The process was developed by J. In general atmospheric pressure Zadra stripping is favored for smaller projects where the increased size of equipment can be arl by a simplification of the system. It may also be preferred for areas where extreme ease of maintenance and operability are a priority due to a lack of skilled manpower.


Following acid washing, the carbon is rinsed with fresh water to prevent acid and chlorides from entering the strip circuit. Operation at deg-F requires operating pressures of 10 to 15 PSIG to prevent flashing steam in the system.

At the end of the elution stage the thermocal heater stops and an additional amount of NaOH is pumped into the eluate tank via valve AVthis bringing the pH of the eluate solution up to the desired level. Ellution major processes include: The presoak step is started by preheating the carbon with hot water. Potable water then continues to flow through the system as per the elution stage for another twenty minutes, this procezs some of the heat out elutin the carbon and the thermocal.

This could be excessive and wasting potable water. Solution bleeding is required to prevent the buildup of contaminants, which reduce stripping efficiency. Typical strip times with glycol are 24 to 36 elutioon. When desorption is completed, as indicated by gold solution concentration reaching a constant level in the column boiler, alcohol recovery commences.

During commissioning the above figures of eluate volume and temperature were achieved, loaded carbon grades were lower at that time so the final eluate was of corresponding lower grade. Epution to and combinations of the basic methods are also highlighted.

Carbon feed grades have varied between and ppm with corresponding final eluate as high as ppm gold but procesa nearer ppm.

Above deg-F cyanide was decomposed and metallic gold precipitated in the carbon.