• To participate in the 911Metallurgist Forums, be sure to JOINLOGIN
  • Use Add New Topic to ask a New Question/Discussion about Thickening, Filtering or Tailings and Water.
  • OR Select a Topic that Interests you.
  • Use Add Reply = to Reply/Participate in a Topic/Discussion (most frequent).
    Using Add Reply allows you to Attach Images or PDF files and provide a more complete input.
  • Use Add Comment = to comment on someone else’s Reply in an already active Topic/Discussion.

Treatment CIL tail cyanide & hydrogen peroxide DETOX (3 replies)

New Era
1 month ago
New Era 1 month ago

We want to treat CIL tail cyanide with hydrogen peroxide to lower (destroy) free cyanide to less than 50ppm. We have CCD circuit after CIL tanks. I want know how effective it is and what kind of additional equipment required to prepare and use the chemical.

Cyanide
1 month ago
Cyanide 1 month ago
2 likes by Colette and Wayne

Hi, how much cyanide are you starting with? What size/tonnage of an operation? You are thinking of treating the water in your tailings pond? You can't treat slurries with H2O2.

The primary application of the hydrogen peroxide process is with waters instead of slurry. The process is typically applied to treat relatively low levels of cyanide to achieve cyanide levels that may be suitable for discharge. The hydrogen peroxide process is effective for the treatment of solutions for the oxidation of free and WAD cyanides, and iron cyanides are removed through precipitation of insoluble copper-iron-cyanide complexes and reacts to form cyanate and water.

The theoretical usage of H2O2 in the process is 1.3 grams H2O2 per gram of CN oxidized, but in practice the actual usage ranges from about 2 to 8 grams H2O2 per gram of CN- oxidized. The H2O2 used in the process is typically provided as a liquid in 50% strength.

The addition point is made in the Tailings Impoundment where water is clear and in a general area where water is discharged.

Wayne
1 month ago
Wayne 1 month ago
1 like by David

Greetings,

Cyanide is correct,  although we did have some fair results with slurry CN oxidation using H2O2.  We have tried to reduce cyanide to discharge levels using H2O2 as well in our effluent treatment plant but found that it would not get our CN down far enough that way with our discharge levels at 1.0ppm.

We had some success with 12% sodium hypochlorite but did not continue as it was uneconomic at that time due to needing to oxidize the thiocyanate to CN and more to oxidize the CN to cyanate so after first applications the CN actually goes up till thiocyanate is oxidized.

I have read (not tried) that peroxymonosulfuric acid (Caro's acid) works well even with Iron complexs

Over forgive my rambling and all.  These two sites may be of some help.

http://www.srk.com/en/newsletter/metallurgy-mineral-processing/cyanide-destruction

http://www.sciencedirect.com/science/article/pii/S0892687513000101

Cheers,

Wayne

Handerson
4 weeks ago
Handerson 4 weeks ago
1 like by David

Hello!

The hydrogen peroxide is not good efficiency in pulp, the better to apply is ammonium bisulfite and a good aeration. Testing in the laboratory to find out what best dosage for your type of ore.

Concentration (as NH4HSO3): 69 to 71%
Density 20 ° C 1,380 to 1,400g / cm3
SO2 content: 44.6 to 45.9%
pH: 4.80 to 5.60

Please join and login to participate and leave a comment.