Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning2017-04-21T02:33:06-04:00
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acid washing of carbon after stripping with Hydrogen peroxide (3 replies and 1 comment)

1 year ago
jovanifirebird 1 year ago

hello metallurgists. we have had an issue of importing HCL to our gold processing plant. delivery date is getting delayed. however, we do have stocks of 55% H2O2 in our site. do you think it is possible to replace HCl with 55% H2O2 for carbon washing prior to kiln regeneration furnace.

your response is highly appreciated as this will help us in going ahead or not.

Richard S
1 year ago
Richard S 1 year ago

My personal opinion is that you should not use H2O2 on the carbon as it is a strong oxidant and will likely damage the carbon surface and not necessarily strip any of the metals adsorbed on the carbon surface.  If you have been regularly acid stripping your carbon, it likely could survive a use without stripping prior to your obtaining HCl acid.  The acid removes the metal ions as a salt; H2O2 will oxidize metal ions but not necessarily remove them and will likely oxidize the carbon surface area rendering it less able to adsorb the gold cyanide complex.

Mark Morrison
1 year ago
Mark Morrison 1 year ago

Hi Jovanifirebird.  HCl is used before thermal regeneration mainly to remove Ca elements from the surface and the pores of the carbon.  Not acid washing can lead to Ca being baked into the carbon which will occlude the pores and reduce the activity ( adsorption capability) of the carbon.  Using hydrogen peroxide instead could be very dangerous as organics are not compatible with hydrogen peroxide and when the two come into contact there can be a violent exothermic reaction.

You can monitor the buildup of inorganics on and in the carbon by doing Apparent Density (AD) tests on the carbon.  New AD of carbon should be between 45 and 50, some carbons go up to 55.  If the circuit carbon is above 60, then acid washing of the carbon is definitely required.

I agree with Richard S comments above, that hydrogen peroxide should not be used, and that the circuit carbon can go without acid washing for several cycles until your HCl arrives on site.  You may have to increase the acid strength for the acid wash fior a period until the AD gets back closer to normal.  If you do increase the concentration of acid in your acid wash, you will need to extend the water wash period after acid washing of the carbon prior to regeneration in your kiln.  Monitor the pH of the water wash effluent and when it is close to neutral, then you can go ahead and regenerate the carbon in the kiln.  Hope this helps.

1 year ago

Good answer Mark

1 year ago
jovanifirebird 1 year ago

thanks guys. it helps a lot. really appreciate your ideas.

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