Metso’s installation base, process know how, and complete system offering allow Metso to deliver a complete packaged system that is ready to exceed expectations.

Features

Metso’s carbon regeneration systems utilize thermal regeneration technology. Some industries call the product “AC” for activated carbon. The process uses an indirect fired kiln to heat the activated carbon to 700°C, driving off the organic and inorganic contaminants. The system uses a recycle duct to improve energy efficiency.

Benefits

 Metso system advantages are:

  • Years of experience with all types of rotary kilns
  • Capable of installation anywhere in world
  • True understanding of process conditions
  • In house engineering for custom fit applications and process knowledge
  • Complete system offering feed screw to product takeaway and fuel delivery to PLC.

Process overview

Activated Carbon is used in many industries as an absorber from waste water, to slurries and gases.  The absorptive properties of activated carbon are due to the micro-porous structure of each grain resulting into large surface area per unit column of carbon.

In the gold industry, activated carbon is utilized in CIP/ CIL process to transfer dissolved gold from cyanide leached slurry to elution column where gold is desorbed from the carbon.

The stripped carbon will retrain significant quantity of organic and inorganic contaminants (foulants) present in the cyanide slurry. Prior to returning the barren carbon to the process, it is necessary to regenerate the carbon by removing these contaminants (foulants).  This is essential in order to retain adsorptive properties of the carbon to be close as possible to that of new/ fresh carbon.

The Metso Carbon Regeneration System sufficiently processes the carbon and reactivates the carbon to be used back in the original intended process.  Each system is indirectly heated, and uses a rotary kiln to process and convey the material through each zone – drying, heating, regeneration, and cooling phases in one machine.   

Additional step

Carbon is not selective. It adsorbs other substances very readily. As the cyanide solution percolates through the ore mass it will pick up other elements that it is compatible with. These are often organic in nature. The stripping process regularly leaves these substances behind in the carbon. After a time they restrict the carbon's ability to absorb. Removal of organics from water by AC is predictable and yields important information about the chemicals on the spent AC.

When this occurs, the carbon must be refreshed by having the stray substances removed. To do this the carbon is heated to above 700°C. The problem is that the carbon is flammable at that temperature. To prevent this from happening, heat is applied in a negative or very low oxygen atmosphere. This is easily achieved in an indirect kiln, since the heat is applied to the outside of the kiln shell. Heat is transferred through the kiln shell into the carbon bed and the carbon regeneration process occurs.

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