# Cyanide Stripper Process



## scorpion1971 (Aug 9, 2017)

Dear Master GSP,

I live in turkey. I follow your forum with a super admiration. Solidarity and cooperation in this place is spectacular. I learned a lot of details that I did not know from here. I appreciate that. I'm sorry my English is not very good. I usually get translate help. I made my own efforts to advance the precious metal refining I started as a hobby. Of course I am very much behind you and there is much more to learn. I set up a small lab for this. I bought a fume oven. Security, respect for the environment and nature is more important than making money.
Master GSP, I admire your knowledge and techniques. It will be the one that is yours. I want to peel gold with sodium cyanide + oxidizer (m-NBSS or H2O2). I have some questions about that. If you teach me this method, I will be grateful for life.
1) I am thinking of using distilled water, because of the chlorine in tap water.
2) 1 lt. How much NaCN is needed for water, m-NBSS or H2O2 is needed. (Which oxidizer do you recommend?)
3) What should I do to prevent HCN from forming? I do not think there will be any problems like pH 12-13. Does M-NBSS provide that? Or how do I get it?
4) As soon as the gold is peeled off, I will remove the materials by means of a plastic sieve. Baked to attack and prevent black cement. (I learned this from you)
5) What will I do after I remove the materials? I think I need to add NaOH. Then I will settle with 325 mesh zinc dust.

There may be some missing parts, so can you give a detailed recipe for 1 liter solution from start to finish? I really want to do this job. Thank you very much already.

Best Regards,

Mehmet


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## goldsilverpro (Aug 10, 2017)

Mehmet,

A few questions.
1 - Can you obtain a small, portable cement mixer? It can have a plastic or a steel drum. This would allow you to strip about 50kg per hour. You could use a 3 gallon bucket, with holes drilled in it, inside a 5 gallon bucket and bob it up and down. That might do about 5-10 kg per hour.

2 - What type gold do you want to strip? Gold plated electronics? Gold plated jewelry? If other, please describe

3 -What amounts (kgs) do you want to strip monthly?

My cyanide/peroxide method is a "hit it fast" method - with the right chemicals and temperature, about 75% of the material can be stripped in 2 or 3 minutes. Another 23% requires more chemicals and, when the gold is very thick or when the nickel plating between the gold and copper is very thin, you might need to use a fresh solution (rare). The H2O2 kills the cyanide slowly (and heats the solution at the same time) and the solution is only used for one batch of parts. I would guess you would generate about 4 gallon of cyanide waste solution per 20kg of material. That includes the spent make up solution plus rinses. Gold in NaCN/H2O2 will zinc out fairly easily.

The m-NBSS, or Ludigol, is slower. Unlike the peroxide, m-NBSS is not destroyed. You may be able to reuse it for several batches before using the zinc. Sometimes, it takes more zinc than the H2O2 does. The only times I have used m-NBSS, it was using a plating barrel (tumbler) inside of a tank of heated solution, about 60C. With peroxide, the solution heats itself. With m-NBSS, the heating is done externally. However, with m-NBSS, you can strip without heatong, although it can be quite slow.

All in all, the H2O2 is simpler and it is what I used more often. If you run very large quantities quite often, you're probably better off with the m-NBSS.

There are other combinations of CN and oxident that people use. Some use a much weaker solution but it is much slower.

When you answer my questions, I'll go into more detail. You might look over some of my posts.
http://goldrefiningforum.com/phpBB3/search.php?keywords=cyanide+mixer+peroxide+&terms=all&author=goldsilverpro&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

Chris


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## scorpion1971 (Aug 10, 2017)

My dear Master,

Thank you again for your interest and charity. I appreciate you sharing your information. Most people are not doing this.

Answers to your questions

1 - Yesi I can obtain a small, portable cement mixe. After a few days I think of doing an experiment for another material (slag from the Roman and Ottoman Empire era). We bought a 50 kg portable concrete mixer for this. I think I can use it. Good performance at 50 kg / h. However, in order not to make black cement on copper, gold must be removed from the solution quickly. how can I do that?
I could use a 3 gallon bucket, with holes drilled in it, inside a 5 gallon bucket and bob it up and down. This is a good idea. If it is difficult with a portable mixer, I can do it. In this way, I can quickly extract the materials when the time comes.

2 - Target materials, computer memory stick rams and mobile phone boards. I will apply a separate process for IC chips. Of course after this process. First I will remove the 98% concentrated sulfuric acid + heat coatings and make the wires open. I will do this in a 316 Ti quality stainless steel container. Then filtration and rinsing process. After that, I will dissolve the base metals with concentrated nitric acid (65%) + heat. Lastly, I will deal with aqua regia.

3 - Initially 1-2 ton per month. But I think I will gradually increase this amount later.

H2O2 or m-NBSS. I can use both. What is important is the percentage of productivity. I do not know which one is better for the fault. What is your suggestion in this regard?

Thank you in advance for your help.

Best Regards,

Mehmet

Edit : It seems impossible to supply m-NBSS in a short period of time. The importer said it could take 3-4 weeks. In this case I have to use H2O2. Using H2O2 will yield less than m-NBSS? I do not mind that H2O2 consumes cyanide.


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