Process fingers with Nitric acid+H2O2

[Goerg]

Hi

This is my first post, but I`ve been reading the forum and its books (Hokes included) for 8 months. I`m a chemical technician not working in chemistry for the last 30 years. 3 months ago I began processing fingers and cpus.
In my country, there are several chemicals almost forbidden because they are used in the drugs process, they include HCl, NaOH, Solvay soda, SO4H, etc. Muriatic acid is still available but not know for how long. On the other hand, nitric acid is cheap and with no restrictions.
So I`m processing fingers with NO3H+H2O2 3%, with some heating. From time to time I give some temperature to the process (45º C), and I`ve found this method to be shorter in time that the usual AP process which I also tried.
The use I give to the H2O2 is to speed up the process and to diminish the NOxx gases.
Then filter and refine twice with AR. That`s it.

I also process the cpus with the same method: nitric+peroxide+some heating for dissolving the base metals, and AR process twice.
Question: do you think bubbling with air in the bucket will speed up the process the same way that H2O2?

 

[Oz]

Welcome to the forum.

Question: do you think bubbling with air in the bucket will speed up the process the same way that H2O2?

Yes

Unless there is a language error, muriatic acid is the same thing as HCl.

 

[Goerg]

Thank you for the answer Oz.
About muriatic acid, as it is diluted HCl, it is available as for law reasons. By the way, the muriatic I`m buying has a kind of glicol smell, or some kind of that. I guess it`s used to avoid the fumes. Do you think it can affect the reactions in some way?

Goerg

 

[jimdoc]

Is there an ingredient list on the bottle? Does it list a percentage like 37% or 20%?

Jim

 

[Palladium]

Welcome to the forum.

Question: do you think bubbling with air in the bucket will speed up the process the same way that H2O2?

Yes

Unless there is a language error, muriatic acid is the same thing as HCl.

I think he was asking if air would be of any benefit in the process he's using with nitric, not sure.

If your adding h2o2 to nitric i can see where it helps with the noxx fumes, but i don't see any benefit other than that unless you count the extra water to dilute it if your using concentrated nitric. H2o2 is an oxidizing agent. If your using it with hcl then it forms a layer copper oxide on the surface which allows the hcl to put it into solution. With nitric acid it is a self oxidizing acid which means it does both. Air would be of no benefit. For example, copper metal cannot be oxidized by and dissolved in a non-oxidizing acid ( Hcl), because it is lower on the reactivity series than acidic hydrogen, but an oxidizing acid such as nitric acid can oxidize the copper, and allow it to react. Some acids contain other structures that act as stronger oxidizing agents than hydrogen. Generally, they contain oxygen in the anionic structure. Nitric is one of them.

 

[Goerg]

Is there an ingredient list on the bottle? Does it list a percentage like 37% or 20%?

Jim

It only says "30/33 % Clorhidric acid, 100% water" but "pure" HCl is really 37%, so , it may be 30 % of 37% HCl?

 

[Goerg]

I think he was asking if air would be of any benefit in the process he's using with nitric, not sure.

If your adding h2o2 to nitric i can see where it helps with the noxx fumes, but i don't see any benefit other than that unless you count the extra water to dilute it if your using concentrated nitric. H2o2 is an oxidizing agent. If your using it with hcl then it forms a layer copper oxide on the surface which allows the hcl to put it into solution. With nitric acid it is a self oxidizing acid which means it does both. Air would be of no benefit. For example, copper metal cannot be oxidized by and dissolved in a non-oxidizing acid ( Hcl), because it is lower on the reactivity series than acidic hydrogen, but an oxidizing acid such as nitric acid can oxidize the copper, and allow it to react. Some acids contain other structures that act as stronger oxidizing agents than hydrogen. Generally, they contain oxygen in the anionic structure. Nitric is one of them.

Thank you Palladium for the explanation. I`m processing batches of 40 cpus (486 and Pentium) and taking out the base metals is longer of what I expected, around a week. Now I'm breaking the cpus which is accelerating the process indeed.

 

[dtectr]

Is there an ingredient list on the bottle? Does it list a percentage like 37% or 20%?

Jim

It only says "30/33 % Clorhidric acid, 100% water" but "pure" HCl is really 37%, so , it may be 30 % of 37% HCl?

According to Terrace Chemicals (KC, MO) Hydrochloric is 37%, that is 37 parts HCl to 63 parts water; whereas Muriatic is 31%, 31 parts HCl to 69 parts water. Not enough difference to affect our use, as HCl usually works best dissolving base metals when diluted. Muriatic is most often sold in the U.S. at hardware stores & building centers as "concrete cleaner" (though I'm sure it has other uses). The lower percentage is supposed to make it more "user friendly, I guess.

Also, the price difference, 1 gallon lots - $8.50 USD vs. $5.00 USD, isn't worth it, as the results are just as satisfactory.

Do they have Material Safety Data Sheets (MSDS here) in your country? It should list any other additives.