smelting?

[hermanntrude]

what's the lowest temperature smelting I can do and can it be done with a bunsen?

[UC]

what's the lowest temperature smelting I can do and can it be done with a bunsen?

 

smelting what? You need to get the temperature above the melting point of the metal. I believe that PbO with finely powdered charcoal would be workable.

[hermanntrude]

apparently some smelting can be done at lower temps than the melting point of the metal itself. I wanted to know which metals would be the easiest for me to try. I live in an area with a lot of copper ore... Although I've already pretty much ruled that out... i think it requires 1200°C, which is probably more than i can achieve

[insane_alien]

the lowest one i can think of is mercury oxide which is done at 500*C. this will result in copious amounts of gaseous mercury so probably isn't the best home experiment even with proper ventilation.

 

so your probably going to be looking at either lead or tin for the lower temperature smelting.

 

if you own an oxy-acetylene welding(or cutting) torch then it is possible to reach 1200*C easily.

[CaptainPanic]

Try to find the eutectic points of mixtures (such as alloys, but not salts with one type of cation and one type of anion).

Alloys and mixtures will (always????) have melting points lower than the pure components, if you mix then in the composition that is given by the eutectic point.

 

Check also this one for eutectic copper alloys:

http://www.engineeringtoolbox.com/copper-alloys-melting-points-d_1435.html

[John Cuthber]

Reducing copper oxide is a high school experiment and can be done with a bunsen burner as the heat source. Also a bunsen is capable of getting well over 1200 C

[hermanntrude]

Reducing copper oxide is a high school experiment and can be done with a bunsen burner as the heat source. Also a bunsen is capable of getting well over 1200 C

 

Can you link me to a write-up or describe the procedure for me? Really? bunsens get that got? i thought they managed about 700°C tops.

[nitric]

do thermite, it can be done in a test tube, most metals will work with Mg or Al

[hermanntrude]

I want specifically to do the reduction using carbon

[John Cuthber]

Can you link me to a write-up or describe the procedure for me? Really? bunsens get that got? i thought they managed about 700°C tops.

 

Well, if you put fine copper wire in a candle flame it melts so that's over 1083C.

 

Anyway, here's a demo.

It's called "Reduction of Copper Oxide"- not very original.

 

BTW, don't do thermite reactions in test tubes there's far too big a risk of flying glass.

[hermanntrude]

I dont intend to do any thermite reactions yet and certainly never in a testube.

 

Would this reaction work with malachite (basic cupric carbonate)? I think that the carbonate would decompose to form the oxide which would then form the copper.

 

I am thinking of doing a demonstration about the discovery of copper, pretending people are cavemen and turning out the lights and stuff like that. I have a dramatic script in mind

[John Cuthber]

It should work with the carbonate, but be aware that some CO will be generated.

Have fun playing at being a caveman with a bunsen burner.

[hermanntrude]

It should work with the carbonate, but be aware that some CO will be generated.

Have fun playing at being a caveman with a bunsen burner.

 

i'm going to make "stretching the imagination" part of the fun of it.

 

"I'm going to take you through the discovery of copper. This is going to take some imagination, since we're in a college, in the year 2009, and we're all wearing clothes... however, chemistry's like that... you need to use your mind..."

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OK so i tried it out with malachite (basic hydrate of copper carbonate), and it worked quite nicely. Obviously copper there but as a powder rather than a solid lump. Obviously you CAN do the smelting at a lower temperature than the melting point because my copper didnt melt and coalesce into a lump (which is what I hoped for). I have another bunsen burner with a bigger nozzle... perhaps it'll make a hotter flame?

[John Cuthber]

You will find that glass melts before copper. Do you have a fused quartz tube?

If you have some cassiterite about the place you might pretend to be bronze age. Also, bronze has a somewhat lower melting point (though probably not low enogh for a glass tube).

I think the smelting takes place below the melting point because the reaction is between CO and CuO. My guess is that the reaction wouldn't work so well in a vacuum untill the CuO melted.

[hermanntrude]

i see. Well I don't have any tin compounds, only tin... I imagine some SnO2 wouldn't be expensive, though, and tin's melting point is a LOT lower.

 

Can you make bronze by using a mixed ore?

[UC]

i see. Well I don't have any tin compounds, only tin... I imagine some SnO2 wouldn't be expensive, though, and tin's melting point is a LOT lower.

 

Can you make bronze by using a mixed ore?

 

I'm under the impression that tin doesn't reduce too cleanly, but perhaps I am wrong. Stannous oxide would be much easier to work with than stannic as well. The SnO2 of industry is a hard, calcined, largely unreactive compound. Molten alkaline fusion may be able to dissolve it as stannates though. PbO should be easy to get and use. Plus, you're making what, a couple grams of waste?

[hermanntrude]

SnO2 can probably be bought as a powder or grainy solid.

 

I did consider PbO... I have some Pb(NO3)2, and I have read that it decomposes thermally to PbO, so i had thought i might try that... trouble is that we'd then be moving away from my original idea or pretending to be cavemen

[John Cuthber]

Pb (NO3)2 and charcoal would probably be more vigorous than black powder and I wouldn't try it in a test tube.

Dissolve the stuff in water and precipitate PbCO3, then reduce that. (Also, part of what precipitates may be a basic nitrate- be careful with this- dodn't try it in front of an audience untill you have tried it outside and without the distraction of keeping the audience happy.

[hermanntrude]

thanks for the advice JC. I'd never dream of trying a demo until I had done it many times without an audience.

[Justonium]

I don't know many specific things to smelt, but if you use a better reducer than carbon, say, aluminum, you can make the smelting reaction self sustainable, so you only need to initially heat it to the activation energy. Example: iron oxide is often reduced using aluminum. Once the reaction is started, it is almost impossible to stop, and the result is white hot molten iron with aluminum oxide floating on top. This is the most common thermite reaction. Thermite reactions generally take something very hot to get them started, despite their highly exothermic nature; I don't think a bunsen burner would be hot enough, but you can certainly light a piece of magnesium ribbon on a bunsen burner, which would certainly be hot enough. If you don't have any magnesium, most sparklers contain magnesium.

Edited May 20, 2009 by Justonium
adding more information

[hermanntrude]

yes thanks. I've heard of thermite. So has everyone else on this forum. we probably have twelftyhundred threads on it.

[williamtul11]

Tin, Lead, Aluminium can be melted with a reguler tourch

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my spelling is pretty bad so dont tell me that