# Reducing Agents for copper in ore



## goldandsilver123 (Apr 10, 2017)

Hello,

I got called to work with an investor that recently bought 100 tonnes of ore that was extracted in the 1960s, the mine at the time was closed by the governement and the ore was just sitting in a pile (just this year he got the paperwork right), the mine will only be explored once this pile is processed.

The copper content is around 2 - 4 %, flotation is not in mind because of the cost and area needed.

What we tested was mix the grounded ore (60 mesh) with fluorite and the reducing agent and melt everything in a furnace.

In small scale we used flour, 1 kg batch. In the medium sized test (200 kg of ore) we used "heavy oil".

In the ore there's a mix of sulfides and carbonates/hydroxides of copper.

In the next step we want to use a rotatory furnace with around 1000 kg.

Do you have any suggestion about the reducing agent?




The copper was sampled to test for the precious metals content.

Thanks


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## g_axelsson (Apr 10, 2017)

I would recommend the book "Extractive Metallurgy of Copper by G.W.DAVENPORT".
https://books.google.se/books?id=sXcorPHuHowC&printsec=frontcover&dq=Extractive+Metallurgy+of+Copper+davenport&hl=sv&sa=X&redir_esc=y#v=onepage&q=Extractive%20Metallurgy%20of%20Copper%20davenport&f=false

Göran


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## Deano (Apr 10, 2017)

Worth trying old exhausted fines carbon from the gold industry.

This material is usually carrying around 50ppm or so of gold, this should be recoverable in the copper.

Deano


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## goldandsilver123 (Apr 10, 2017)

g_axelsson said:


> I would recommend the book "Extractive Metallurgy of Copper by G.W.DAVENPORT".
> https://books.google.se/books?id=sXcorPHuHowC&printsec=frontcover&dq=Extractive+Metallurgy+of+Copper+davenport&hl=sv&sa=X&redir_esc=y#v=onepage&q=Extractive%20Metallurgy%20of%20Copper%20davenport&f=false
> 
> Göran



Thanks for your response.

I know this book and already have read it.

For sulfide ore it's to setup a flotation then smelt the CuS to impure Cu. This process is for large amounts of ore, from 2000 tonnes to 100000 tonnes day of production. The whole pile is 100000 tonnes, flotation doesn't seems to be viable in this small scale, so we're tending to do a melting operation with fluorite to lower the viscosity and a reduction agent (we tried "heavy oil"). The copper in the photo is from the process with the oil.


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## goldandsilver123 (Apr 10, 2017)

Deano said:


> Worth trying old exhausted fines carbon from the gold industry.
> 
> This material is usually carrying around 50ppm or so of gold, this should be recoverable in the copper.
> 
> Deano



That's definitely a good idea.

I will try with powdered charcoal first!

Thanks


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## g_axelsson (Apr 11, 2017)

There is nothing in froth flotation that requires large scale extraction. You can test it on a beaker scale. This is what a member built himself.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=44&t=11656
Cheap to build and can be run in a garage.

There is another thread with a more continuous usage unit developed by a member but I couldn't find it with a 2 minute search.

If you have a hard time to make a froth flotation work on a 100.000 ton scale then I seriously doubt you can extract 2-4% copper by direct smelting with any economy. We are talking about 100 ton per day for three years to get through that pile.
Large scale gives better economy, but that is true for smelting too. If you try direct smelting of the whole pile then you will have a slag pile that is even bigger in the end and it will be your responsibility to secure it on an environmental sound way. Flotation would make that pile a lot smaller.

Göran


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## goldandsilver123 (Apr 11, 2017)

Thanks Göran, that was one of the answers that I was looking. He called me to handle the precious metals, I got in this part of the process because the other people handling the concentration of the metals in the ore weren't progressing. My work so far had been a shot in the dark, I would never imagine if you put common looking dirt with flour and melt it you would have copper.

Everyone that I talked so far about the flotation, always says that is a expensive process to be made in large scales only. Even in the copper book that you recommended, the most expensive part of the plant run is the flotation step.

Curious enough he can profitable melt it directly, and there's a cement factory right beside (they use slag as feedstock).

Flotation also require to grind to about 100 mesh, this is a expensive step.

I started a conversation with a professor from my university, but until now I didn't got a response. Do you know someone that worked with flotation and is willing to share/make a deal?


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## g_axelsson (Apr 11, 2017)

Sorry, I have no experience working with flotation myself so I don't know anything about the costs associated with it. I have only visited a couple of plants but that was large scale operations, 300.000 tons per year or more. Then I've seen the posts here on the forum and thought that it might be possible to run it in small scale too.

Maybe there is some active miners here on the forum that could help you further.

Göran


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## anachronism (Apr 11, 2017)

Dean's your man for flotation.


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## Deano (Apr 12, 2017)

Direct smelting will cause you more pain both financially and mentally than you could believe.

Government agencies will be lining up to ensure that you have full permitting and environmental safeguards in place.

Not only will this cost you large sums of money but you will be audited on a frequent basis.

If you enjoy operating with not only the government agencies scrutinising every aspect of what you do but with all the environmental groups giving you legal and other forms of curry then you will have a real treat in front of you.

My recommendation is to approach your state mines department and ask them who in the region is using small scale flotation for copper ores.

Most of these departmental staff will be incredibly helpful if approached nicely.

Go and ask these operators if you can have a look at their plant in operation and explain why, most people will help you.

When you have had a look at some plants then you will have some basis for deciding how you will proceed.

Generally float plants are relatively easy and relatively cheap to operate.

The big advantage of having a float concentrate is that you can sell it as a con and get paid a percentage of the precious metals in that con as well as the copper value.

Most operators will look to do a deal with an in-country smelter for convenience sake but the best returns will come from japanese smelters.


Deano


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## Deano (Apr 12, 2017)

I was in a lot of a hurry when I wrote about flotation.

What I missed out was to point out that the worst copper ore type is one with half the copper as carbonates (green malachite and blue azurite) and half the copper as sulfides.

The float for carbonates is more difficult, read more expensive, than for sulfides, you will end up doing two floats for full recovery.

Most copper ores are treated by sulfuric acid heap leaching, acid at pH 1.

In large scale the leachate is contacted with an organic extractant and the copper is electrowon from the organic phase.

In smaller scale the copper is recovered from the acid by displacement on scrap steel.

The carbonate ores will leach rapidly and thoroughly, the sulfide ores will take months to leach.


Deano


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## goldandsilver123 (Apr 17, 2017)

Thanks Deano!!

I read it when you posted via cellphone, but I just had time to respond now.

This type of ore is a mix of carbonates and sulfides, you can see the blueish and greenish tone on the raw ore and when you roast it you can smell SO2.

May I ask, whats the tons/day processed by a small scale copper ore flotation? I will search for them!

Thanks again!


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## Deano (Apr 17, 2017)

Small scale flotation is usually looked on as being less than 10 tons per hour of head ore through the plant.

Second hand float cells come in a large range of sizes, see what is available from used mining machinery suppliers.

Always get some experience at looking at an operating plant, you will then have some idea what you are looking for in a second hand plant.

Talk to the plant operators about what problems they see with their plant, this tells you what to look for in a second hand plant.

Always keep in mind that used machinery dealers are there to sell equipment, usually they will not know what problems you can have with these plants.

It is up to you to educate yourself in the problem spotting areas.

I would take a representative sample of your ore to a lab and have them carry out a test to see what % of the copper is present as carbonates and what % is present as sulfides.

If the majority is carbonates you do not want to be floating the ore, you are looking at acid treatment.

In small scale you will lose precious metals in an acid leach, have the lab see what levels of gold and pgms are present so that you can see what losing these will mean to your returns.


Deano


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