# sulfuric acid usage in copper leaching



## kjavanb123 (Oct 15, 2010)

All,

In my previous post, i dropped 25litre of water plus 5 litre of 98% sulfuric acid for 90kg or copper ore. Is there any formula to know how much pure sufuric acid and water should be mixed for leaching reagent?

Thanks
Kev


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## Juan Manuel Arcos Frank (Oct 15, 2010)

Kev:

It depends on how many copper is present in the ore.

I have read your old post and I think you are using to much sulphuric acid because copper is redissolved,so try to use less acid or once that you get the copper solution add some water,here is what is happening:

Copper sulfate+Aluminium=Aluminium sulfate+Copper

if you have any sulphuric acid it reacts with copper redissolving it and this is why the brown mud adhered to aluminium disappers.

Recovering and refining are different matters...working with ore is recovering copper,now you have got to refine the brown mud using an electrolytic cell,this is the only way you can produce pure copper.First,tune up ore process then work on refining process.

Hope it helps.

Regards

Manuel


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## kjavanb123 (Dec 11, 2010)

Thanks Maneul,

Can you give me more details on how to build the electrolyt cell to refine the brown mud? I did search the forum for electrolyt cell and all turned out to be for silver refining. 

Regards
Kev


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## samuel-a (Dec 11, 2010)

kjavanb123 said:


> I did search the forum for electrolyt cell and all turned out to be for silver refining



did you try searching "copper sulfate cell" ?


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## kjavanb123 (Dec 11, 2010)

yes, no use. I can recover copper sulfate from copper ore by dropping iron scrap into the blue-color solution which produces brown mud after like a week. Now do I dissolve the brown mud in diluted sulfuric acid then use anode/cathod on the this new solution? I read something about the voltage/amps used per anode/cathode but it's not clear the distance between each anode/cathodes or the size of each cathode. I read somewhere here the material used for cathode is 304 stainless steel and anode to be lead/graphite. I wish there was a single thread just talking about building a small-scale copper sulfate electrolyt cell with all the dimension etc.etc.

Thanks
Kev


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## orecart531 (Mar 4, 2012)

To Kev (kjavanb123),

Did you ever get the information about the electrowinning process? The size & number of cathodes? what type of anode? How much power to use?

I am also setting up a copper ore leaching system. I have ore that runs from 3% to 35% copper. The leaching tank holds about 225 pounds of ore - much of which is native copper in matrix. It also contains small amounts of silver.

Any help is much appreciated. If I'm doing something incorrect with this posting - please let me know. I'm brand new to "forums".

Many Thanks, Jim


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## nickvc (Mar 5, 2012)

Welcome to the forum Jim.
We tend to concentrate on the precious metals here on the forum but copper recovery has it's place amongst the techniques to recover precious metals. Rusty has a thread going where he has set up a copper cell but essentially to recover the slimes, gold, silver and platinum group metals for refining.
All cells require very pure metals to work properly 95%+ or you get co deposits or fouling of the electrolyte so you need to feed purer copper than you seem to have or else your going to be constantly having to change your electrolyte.
Copper refining is one of the oldest electro technologies around and information is everywhere but it's usually done on a vast scale with hundreds of cells running 24/7 but I'm sure you can scale it down.
You mention silver is present so it's possible you may have gold as well but either way you need to bag your anodes and collect the slimes which will contain any values.


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## james122964 (Jan 1, 2014)

use 1 to 2 percent sulfuric and cement with iron this will work better


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## chlaurite (Jan 1, 2014)

james122964 said:


> use 1 to 2 percent sulfuric and cement with iron this will work better



Clearly I have this wrong, but I thought only sufficiently concentrated sulfuric acid would react with metallic copper?


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## butcher (Jan 1, 2014)

Actually dilute the acid is stronger, concentrated sulfuric acid can passivate metals like iron or copper.

concentrated sulfuric can be used in iron vessels because the iron passivates but if we added water we would dissolve the iron pot.

Look at the concentrated sulfuric acid cell used to remove gold plate from copper we passivate the copper (here we can actually use a copper screen wire as an anode basket, were normally the electrolysis of the anode will force a reaction to occur that normally will not (or dissolve a metal into an acid that would not dissolve into the acid without it being the anode), but if we dilute the concentrated H2SO4 acid we can easily put copper into solution or dissolve our copper anode basket...

Nitric can also passivate metals when concentrated, take silver for example, concentrated nitric has much less reaction to attack silver, (at least in the beginning until we form NOx gases in solution), but a more dilute nitric will readily attack the silver and actually dissolve more silver into solution than the concentrated nitric acid will.

concentrated nitric can be stored in aluminum, (or stainless steel), where the dilute acid would attack the metal.


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## tomiyet (Feb 1, 2014)

Hello seniors, great I recently found myself in a site where the coppepre is rich 39% copper, 200g per ton silver and 17g per ton gold. I got d copper out successfully but stocked with d silver and gold in d concentration. I ground the ore to finest and add sulPhuric acid 5% to 95% water. I intend adding nitric after many wash to get d silver out of the residue and later add sodium chloride to d solution and I think running the remains on slouch box will help or any other info on how to remove d gold Any helpful info on how to make it better will be appreciated


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## Smack (Feb 1, 2014)

Do you have a fetish with the sexy letter d ?


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## cmiller92 (Feb 1, 2014)

I see you have been on the forum since 2012, so I would assume that you have read many posts where members were threatened to have their membership revoked for typing like a 16 year old school girl. Do take this as a attack but when you spell "The" with "D" in the same paragraph you have the term sulfuric acid your credibility, as well as members responses to your question will decrease. :|


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## butcher (Feb 1, 2014)

His language is probably not English, and he may have a hard time with some of the words.

Tomiyet, I think you meant the word (the) where you had the letter d.

Just do the best you can, and try using spell check. 

Sorry I cannot be much help on the ore, but it sounds like you have a plan to try.


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## solar_plasma (Feb 2, 2014)

...maybe he means the slang term "da" (example: "in da house")?


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## tomiyet (Feb 2, 2014)

Hello seniors, I'm sorry I was on byke while typing because there was no Internet on the site and I just got the Internet on my phone on my way on the mountain and I was trying to write fast then. My "d" is the pls. Compliments to all


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## solar_plasma (Feb 2, 2014)

When I visited the area around the river Humber as a kid, people over there pronounced "the" like "t" or "d", so now I had a look on wiki:http://en.wikipedia.org/wiki/The#Definite_article :lol: and in fact that's a local dialect in Northern England.


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## solar_plasma (Feb 2, 2014)

By the way, this book will probably be helpful for everyone interested in this thread:

http://www.uctm.edu/departments/MCM...ve_Metallurgy_of_Copper_-_G._W._DAVENPORT.pdf


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## Smack (Feb 2, 2014)

tomiyet said:


> Hello seniors, I'm sorry I was on byke while typing because there was no Internet on the site and I just got the Internet on my phone on my way on the mountain and I was trying to write fast then. My "d" is the pls. Compliments to all



lol you were typing while riding your bike? It's probably not your fault your still alive.


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## Richard NL (Dec 14, 2014)

solar_plasma said:


> By the way, this book will probably be helpful for everyone interested in this thread:
> 
> http://www.uctm.edu/departments/MCM...ve_Metallurgy_of_Copper_-_G._W._DAVENPORT.pdf


That is a "404 not found"

A older version of this book: https://www.scribd.com/doc/250109296/Metallurgy-Of-Copper-Joseph-Newton

A newer version of this book: http://bookzz.org/book/943943/aa509e or the attachment.

Best regard, 
Richard.


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## bluebirdiran (Feb 4, 2016)

Well it seems you are all off the mark by a long way. You have to keep the pH of the slurry of copper powder and sulfuric acid solution at about 1.5 to 2 for maximum recovery of copper in the ore. You have to keep mixing it for about 1 to 2 hours for Malachite and a bit longer for chrysocolla type of ores. Azorite is also soluble . These are the main soluble copper compounds found in copper ore. The ore has to be well crushed preferably to less than 20 mesh. Leaching works only on so called oxide ores. Sulfide ores will not leach unless you do bioleaching. So how much sulfuric acid you will need depends on the assay of the ore. The more calcium in the form of Lime and magnesium in the form of dolomite you have in the ore , the more acid you will need to neutralize these elements first and then dissolve the copper content. What you get after filtration of the slurry is copper sulfate. Now if you decide to do cementation by adding iron scrap you will get a brown powder precipitating. For each kg of expected copper, you will need slightly bigger amounts of iron scrap. You cannot do electrowining on this product. you can smelt it and get copper matte of about 96% purity. The other choice is to do electrowining of the solution provided you can enrich the copper content of the solution to at least 35 g/l and an acid content of about 180 g/l if I remember correctly. You will need about 2 volts DC for this at an ampere density of about 200A/m2. This is direct electrowining which is not recommended because you will not get 99.99% pure copper at the cathode barring other likely problems. So you have to do what is called solution extraction using an organic oil called by the commercial name of Lix. This is too complicated to do at home I think.


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## kjavanb123 (Feb 4, 2016)

Hi bluebirdiran,

First I like to welcome you to the greatest communities online. This was an old project and very first ones before I got hooked on e-waste. Thanks so much for your informative post. The price of copper is in the lowests nowdays, so any types of leaching would make it unprofitable for home scale.

Regards
Kj


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