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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AARL Carbon Stripping System Operation: Elution & Electrowinning
Pregnant solution is pumped from the pregnant solution tank through electrowinning cells where gold is recovered by electrolysis. 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. Operating temperature limits of deg-F are widely specified because of temperature limitations of the butyl rubber lining material utilized to line the strip vessel.
The sequence controller time for step 06 should then be reset to the time indicated by the graph. This can be confirmed by visual inspection at the pump or valve. The Ok Elition plant was seldom operated under the design conditions listed above.
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Heat is then applied to the base of the desorption vessel. This publication is still in print and is actually the foundation for the other stripping processes. In any case the potable water system here does not cater for the running of both steps at the same time.
This stage continues until five bed volumes of water have passed through the column 2. The solution then flows up through the bed of carbon and overflows near the top of the stripping vessel. The advantage to downflow is reduced potential for binding of flow distribution screens by tramp material in the carbon. After stopping the elution water pump locally, reset the switch and then reset the sequence controller by: Within a few hours, the alcohol is concentrated in the overhead condenser tank.
Atmospheric pressure Zadra stripping was the first commercially successful process developed for stripping gold from carbon. Changing of the dosing time in the stripping sequence step 02 results in the changing of the levels of both NaCN and NaOH as the same timer controls both pumps.
To alleviate this problem, most operations routinely bleed a fraction of their strip liquor inventory and replenish with fresh solution. The unit is then switched to the batch distillation mode. This is due to its significant cost advantage over atmospheric pressure Zadra systems. Many methods are used commercially for recovering gold and silver from loaded activated carbon.
Alcohol stripping has generally fallen out of favor due to the flammability concerns. When the curve flattens out, the rinsing is sufficient even if the pH rlution only 4.
Gold ExtractionGold Refining Tags: The entire stripping cycle takes about 8 hours.
High quality fresh water at about deg-F is then pumped through the pressurized stripping vessel to produce the pregnant eluant. Pdocess water then flows up through the column, taking with it gold that has been freed into solution during the preheat stage.
After filling, the main valve AV is closed and dilute hydrochloric acid is injected into the bottom of the column via valve AV Acetonitrile may be substituted for the alcohol, but its higher cost generally discourages its use.
Elution water pump pressure ……. The mere following of the instructions given in that section will not ensure effective stripping results as there are many extraneous factors which need to be taken into account.
Gold and silver values are recovered from the pregnant solution by electrowinning and the barren solution is reheated and recycled through the stripping vessel. Additional water is injected into this line via valve AV and the carbon is carried long the line to the dewatering screen above the regeneration kiln feed hopper. Loose copies are available.
These samples should be analysed for Ca plus Mg and then the totals plotted versus time. The gold depleted solution is then reheated and recycled to aarll carbon bed for reuse see Figure 1. A comparison of the increase in stripping rate with temperature is shown in Figure 3. Each method has advantages and disadvantages, which should be evaluated when deciding which process to use. High pressure operation is accomplished by means of a high eultion solution pump and a stripping column pressure control regulator.
The barren solution is then pumped out of the eluate tank into the process water tank. The Ok Tedi plant had a nominal design throughput of 24 tonnes of carbon per day. Glycol consumption is typically in the range of 20 to 40 gallons, per ton of carbon stripped.
Carbon is loaded into the acid wash column from the loaded carbon surge hopper by opening the main inlet valve AV Ethanol and methanol were found to perform almost equally, but were substantially better that Isopropanol.
It is much less expensive to operate and it produces a cleaner stripped carbon. Factors favoring installation of a separate acid wash vessel include: