# Tungsten Question



## wsp_duke (Dec 23, 2009)

I have a lot of Tungsten to find a home for. It is somewhat Oxidized. I would say somewhere around WO2.25 or in that range. It is mixed with smaller amounts of copper sticks, some oxidized, some not. I can remove the copper easy enough with a Nitric Acid bath, but that is expensive and I still have to precipitate the copper to recover it. I can not melt the copper out of the mix. I tried by bringing it to 1200C for 30 minutes, but the copper did not come out. It mostly oxidized, so did not melt, but what did melt only coated my tungsten. I can take the mix up to 900-1000C and bring the Tungsten closer to WO3.0, but then I have to grind, sieve, and refire. I then can recover the Copper Sticks and reduce them. This gives me copper and high purity WO3 and there is a market, but the process seems cumbersome. 

Any thoughts on a better way to seperate the copper from my tungsten.


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## butcher (Dec 24, 2009)

how about electrolytic cell,
recovering the copper for market would be hard to accomplish,and may cost you more than its value? 
In a fire melt of copper it oxidizes easily using a flux and carbon used to convert oxides that attack copper and convert them to CO2 gas. 
there may also be people who would buy the tugsten as is.


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## wsp_duke (Dec 29, 2009)

I am not as interested in the Cu. It is the contaminant. I have maybe 1500 lbs of slightly oxidized tungsten on hand and have the opportunity to have a virtually free supply of several hundred lbs a month. I have been offered $4/lb for it as is, but that seems like robbery. I can fire it up to around 900C and get it to fully oxidize. There is a market for Yellow Tungsten Oxide. I just need to get it to WO3 at a 99.9% pure level. I am pretty sure I can do that now, just trying to work out my process. However, the more Cu I can remove before processing the W, the better off I will be in the end.


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## g_axelsson (Dec 30, 2009)

This is just an idea, I haven't tried it myself.

From wikipedia... "Tungsten typically combines with oxygen to form the yellow tungstic oxide, WO3, which dissolves in aqueous alkaline solutions to form tungstate ions, WO2−4."

If you could oxidize the alloy of copper and tungsten then you could extract the tungsten oxide by dissolving it in an alkaline solution.
As far as I could see, copper oxide isn't soluble in an alkaline solution as long as you avoid ammonia.

An alternative could be to dissolve the copper oxide in hydrochloric acid, but I'm not totally convinced that the WO3 would not go into solution also.

Good luck and let us know how it works if you try it!

/Göran


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## ander (Dec 30, 2009)

from Polish Wikipedia: tungsten reacts with molten potassium nitrate. So could it be the rigth way? You can make eutectic with sodium nitrate for easier melting then put the W/Cu mix, you should get sodium/potassium tungstate and copper oxide. How exactly do the scraps look like. Any photo? Maybe there is a physical way for separation. Copper is like twice lighter to tungsten. Hydraulic method with high density liquid could work(not the one with floating- no mercury/low melting alloys please!).


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## Palladium (Dec 30, 2009)

g_axelsson said:


> This is just an idea, I haven't tried it myself.
> 
> From wikipedia... "Tungsten typically combines with oxygen to form the yellow tungstic oxide, WO3, which dissolves in aqueous alkaline solutions to form tungstate ions, WO2−4."
> 
> ...



Sodium tungstate (Na2WO4.2H2O) - prepared as given here. 
Starting with Tungsten or Tungsten carbide powder, available at non-ferrous metal suppliers, Tungsten carbide powder being used as a grinding abrasive. 
The powder is placed on heat proof surface (fire brick) and treated with a gas (butane) torch and made to glow red. Once initiated an oxidizing process will take hold and the heat will work it's way through the powder and reduce most of it to a yellow-green powder, Tungsten oxide (WO3), and expand in volume. the powder can be stirred and again set glowing to completely oxidize the tungsten. Tungsten also exists in a lower oxidation state (WO2), which is a brown powder. 
The Tungsten oxide is now added to a solution of caustic soda (NaOH) 

Mol Wt WO3 = 231.92 
Mol wt NaOH = 40.01 

WO3 + 2 NaOH = Na2WO4 + H2O 

therefore approx. 80 gm (NaOH) to 230 gm (WO3) 
or 8 gm to 23 gm 

There should be a small excess of caustic soda. 
The solution is boiled (may be somewhat violent boiling so best with large container) until generally insoluble tungsten oxide is dissolved. 
The liquid is reduced until crystals in the form of plates appear on the surface, removed from the heat and allowed to crystallize. Sodium tungstate being less soluble than Sodium hydroxide will crystallize first. The Tungstate is removed and allowed to dry, with the remaining small amount of liquid with some caustic soda is discarded. 

Where ? I don't remember.


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## wsp_duke (Dec 31, 2009)

Here is a pic of the "raw" product:


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## wsp_duke (Dec 31, 2009)

So, I need to somehow create a marketable/sellable product. As of now, I am shooting for 99%+ pure WO3. I think that may be the most profitable end product. Here is my protocol so far:

Fire raw product at 1000*C
Rough grind fired product
Sieve powdered WO 3 out
Recombine unsieved material to raw product for refiring
Refire sieved WO 3 to ensure full oxidation


When in the powdered form, I can tap or vibrate all Cu remnants and un oxidized W to the surface and remove. I think as I scale Up I need a much easy process for that, but I will work on it. This gets my end product very pure. I am running it on the ICP next week, but I am almost positive that by the end, I have removed almost all contaminants, Cu included. I did a simple Nitric Acid test this morning and got absolutely no reaction with the powder and zero green coloring in the acid, which tells me I have eliminated all the Cu. The ICP will tell me for sure.


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## wsp_duke (Dec 31, 2009)

Hmmm, Sodium Tungstate has grabbed my attention. Cole-Parmer sells it for $650/lb.


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## goldsilverpro (Dec 31, 2009)

wsp_duke,

Cole-Parmer and other trusted lab supply companies primarily sell very pure reagent grade chemicals in small quantities. Actually, the price you gave was for a certified purity of whatever is spelled out by the ACS (American Chemical Society) specifications for that particular chemical. A large part of this price represents the very high costs involved and the facilities and knowledge required to purify these chemicals to this level. It also involves the cost of certification. These super high prices don't represent reality for you or I unless we're buying them. If you think you could get anywhere near those prices, you are dreaming. Even if you could somehow get the material to ACS specification purity levels, you are a nobody. You are not Cole-Parmer, a trusted name in chemicals for many decades.

Here's the reality of the situation. If you do the currency conversion and the math, 96% pure sodium tungstate, in bulk, sells for about $6 per pound on the international market. I would assume that 96% is about the highest purity you can get by using standard industrial purification processes. Above that, purification and other costs rise geometrically.

http://www.metalnewsnet.com/Tungsten/647crwG406648Uy8.html


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## wsp_duke (Dec 31, 2009)

I am not trying to get $650/lb out of it. But I do have the facilities available to get the purity to a much higher level; ACS grade is certainly a reasonable goal. We are not trying to be the end supplier or even necessarily supply directly to the end supplier. We are just looking to find an entry point somewhere along the chain. We have already done that with other products and I see absolutely no reason to think we can't do that with a Tungsten product as well. Although, I can appreciate you pessimism at some level, to say I am dreaming is absolutely right. Every good idea starts as a dream and this is no exception. I have a source, I can make a product, and I can find a buyer. End of story. I am not an inorganic chemist by trade, I am an organic/Biochemist, but I do understand the basic chemistry enough to know I can do this project. I came here specifically because I consider this a great source of Metals Chemistry info. We are not Cole-Parmer, that is true, but we are certainly far from being a nobody.


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## goldsilverpro (Dec 31, 2009)

I apologize. Actually, had I re-read your other posts, which I see are knowledgeable, and associated them with your name, I would have worded that differently. I just assumed you were a noobie that saw that high price and jumped on it. That has happened before on this forum. Please realize that a lot of time is spent on this forum helping the average Joe to see reality.

Chris


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## ander (Dec 31, 2009)

I have similar problem with 240g of 99,999% germanium. Noone to buy it at reasonable price. But going back to the point. I would make sieve analysis. If material is homogenous in grain size I would process it. If not I would use set of meshes to make several batches of similarly sized grains. I would process it using high density, high viscosity liquid. The idea is simple. Similar grains sink in liquids with velocities depending strictly on thei densities. The lower difference between liquid and grain material the lower the velocity, also viscosity affect on that the same way. The higher difference between separated grains densities the more accurate separation is. Other way is to use low melting alloy, but there is one 'but': If copper surface is clean, it will stick to the alloy, so oxidize it or cover with other metal. The initial cost for low melting alloy could be high, depending what temperature you would like to use. Woods alloy would work, but difference between its density and copper is just 10%- not much.


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## Lou (Jan 1, 2010)

If the material be not brazed together, it is easy to separate tungsten metal from copper by density. 

The problem with firing it without having the copper removed is that it would contaminate your tungsten. Remember the garbage in, garbage out principle!!


I know some tungsten chemistry. After my headache's gone and I'm full of food, I'll be back with some more pertinent suggestions.


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## Harold_V (Jan 2, 2010)

Lou said:


> After my headache's gone


Have a little too much fun last night, Lou? 8) 

Harold


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## Lou (Jan 3, 2010)

Harold_V said:


> Lou said:
> 
> 
> > After my headache's gone
> ...



Apparently the past couple nights. I've meant to get back to this thread.

Anyway, the key here is to remove the copper from the tungsten BEFORE any chemical processing is done. If they're just physically mingled, it can be done with density separation.

I would not heat any of this material with oxygen (or air) until the Cu has been removed. 

Is this material pure tungsten that's just mixed with copper?
You said it's partly oxidized. That's a pity, because if it were just tungsten pieces it could be ground up and then sent off to someplace that sinters...


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## wsp_duke (Jan 4, 2010)

We used pure W in our Combustion Analyzers, but in the process of emptying the tubes, we get some minor Cu contaminant in it. I try to get them to keep it seperate as much as possible, but there is some that mingles in. It is definitely partially oxidized when we collect it. You can see a sample of the "raw" product in the pic above. I was hoping to run some of the WO3 powder I have generated on the ICP today, but we are changing out the plasma torch and that put us behind on production, so I go to the back of the line since this is a side project. Maybe tomorrow.


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## wsp_duke (Jan 4, 2010)

I am considering a Nitric Acid bath of the raw product before the first firing. That should get rid of the majority, if not all, of the Cu in the mix. Thoughts? This would remove the Cu, I can water wash the W a few times and the muffle furnace should volate off any Nitric remaining. The Cu solution could be set aside for other processing I guess. I am trying to go as cheap as possible on the processing.


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