# microwave gold smelter



## Traveller11

Hello
Has anyone seen the microwave gold smelter kit? It sells online for $249 and all you need to go with it is a 1200 watt kitchen microwave oven and an iron mould to cast your gold into. Thirty to forty-five minutes on high and it heats your ore to 2300°.
Check it out.
Regards
Bob


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## Palladium

ROTFL !!!!
:arrow: DISCLAIMER:

No guarantee is given on the amount of gold or silver obtained from this process, as it depends upon the quality of your material to begin with. The kiln is not a toy and is not to be used by children. IT IS A KILN THAT ULTIMATELY GENERATES TEMPERATURES IN EXCESS OF 2300 DEGREES! Please do not allow small children in the same room when you are firing! Use at your own risk and follow all recommended and common-sense safety precautions! Sellers are not responsible for accidents or injuries caused by hot kilns and your using one purchased from this seller acknowledges that you use it at your own risk. Please remember that a traditional kiln is composed of fireproofed materials and a microwave oven is made of materials that can burn under certain conditions. 

I think common sense says don't put things in microwaves that they were not designed for. Will it work ????? 
Hummmmm...... Cave Man Gold !!!


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## Palladium

I knew this Microwave thing was a bad idea from the start. :shock: :shock: :shock:


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## Barren Realms 007

ROFL. Set the timer for about 10 minutes on high and you can have cat stew shortly. I don't want to hear about the mess you have to clean up. 8)


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## nickvc

I'm just imagining the sparks....have you ever accidentally put aluminium foil in one? :shock:


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## Palladium

Ding !!!!!

:twisted: :twisted: :twisted:


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## Palladium

nickvc said:


> I'm just imagining the sparks....have you ever accidentally put aluminium foil in one? :shock:



My coffee cups have a gold plated ring around the lip. It lights the microwave up.


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## nickvc

Palladium said:


> nickvc said:
> 
> 
> 
> I'm just imagining the sparks....have you ever accidentally put aluminium foil in one? :shock:
> 
> 
> 
> 
> My coffee cups have a gold plated ring around the lip. It lights the microwave up.
Click to expand...


I think this idea should be shelved.....NOW!
I'm finding the comedy in it but this could be downright lethal in the wrong hands! In the laboratory with all the necessary safety equipment it might be an interesting experiment but definitely not one for the home.


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## Harold_V

Words of wisdom, as is always the case, from Nick. 8) 

Harold


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## Irons

nickvc said:


> I'm just imagining the sparks....have you ever accidentally put aluminium foil in one? :shock:



No, but I've done it on purpose. :mrgreen:


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## martyn111

As much as I hate anything to do with animal cruelty I've just spat my coffee all over my monitor looking at the cat in the microwave.


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## butcher

From what I can gather their is a big possibility that microwave melting of gold, has merit, industries use microwave for brazing, and tool making, and from what little I have gathered a man named David Ried developed a process to melt metal in a 2.4 GHZ microwave oven like a domestic oven, by removing the rotating dish plate an taping up the air holes from box to magnetron to eliminate air circulation, he was able to melt gold in lost wax castings and small amounts of gold and silver, I have read where Industrial company's using microwave heating and ceramics are taking much of their information in this field He has lead, into their processes industrially.

There seems to be a lot to this, and it seems like an induction process of heating, some seems to depend on having a susceptor (for microwaves) (heat sink?), to receive the energy, and induce another current to the reflective metal, and since metal reflects microwave energy this susceptor absorbs heat, 

Also David seems to have used a type of refractory dome and insulation materials, also coating of washes of susceptors on crucibles in his experiments.

I have not done enough research to understand this completely yet, (even the industy doing this seems to have trouble understanding all of the factors involved, with how and why it works, there seems to be a lot of factors involved, with heating and melting using these electro magnetic waves, skin depth reflection of waves absorption, temperature and depth of penetration, frequency of different substances induction and so on.

But it does look like it is do-able and that these kits may work for small amount of melting gold and silver, if done properly it even seems safe and not damaging to the second hand microwave.

I think we should not discard this Idea too easily, at the cost of fuel and time it takes to melt metal; this may prove a do-able for us hobbyist. And this from first look seems very doable

http://www.ceralink.com/publications/2007_12-Microwave-Heating-Technologies-Heat-Treating-Progress-Mag.pdf

http://www.osti.gov/bridge/purl.cover.jsp;jsessionid=85DABCF9AC3E5B4A0DFEEC4754E09418?purl=/206628-u6ylsR/webviewable/

EDIT--link removed David Rieds method, member suspected trouble from site. 

http://www.microwavegoldkiln.com/instructions

I note here (my guess) that the “FLUX” contains the susceptor to convert microwave energy to heat,
From what I have so far this can be silicone carbide, graphite carbon, and magnetite and so on, as an absorber of the electromagnetic wave energy to convert them to heat, some use these materials as coatings for the ceramic; they may also have added common fluxes we use for metals.
The refractory contains the energy that may damage the microwave shell, and may help to contain heat for the melt, 
The house hold microwave is modified (tape over hole for air circulation into main chamber, and rotating plate removed,
Note here to they are using ore or black sand as these have suspector materials in them naturally.

This is not just get microwave and melt metal which could prove a fire hazard idea,
But with study this has merit, and nice possibilities.

I will not bore you with more links on this, as anyone interested will do their own research.


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## adam_mizer

This link has computer threats attached to it:

http://home.c2i.net/metaphor/mvpage.html


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## butcher

adam_mizer, I removed link, I did not have any trouble with it, but just in case it has been removed.


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## Palladium

Microwave technology has a place in mineral and metal processing, but the microwave frequencies used are not the same as employed in a standard microwave. The way i understand the concept of the consumer microwave oven is that it is set up for a certain resonance frequency, the frequency is that of the vibration of the H2O molecule and that is what does the heating. The heating of metals is a whole different story.


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## nickvc

Butcher I'm not against the idea been discussed as it might well have some merit but I feel trials need to be done by a knowledgeable careful and experienced person. My view was taken as a safeguard for the varying abilities and knowledge of the readers of the forum and for whom I feel at present this would not be something I would want to recommend.
This is still not something I feel should be tried by the general membership of the forum and if that point is stressed I see no problems in having discussions on it and thanks to the moderators I'm sure that will happen.


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## Harold_V

Given the least bit of thought, it becomes painfully obvious that an induction furnace is much like a microwave---the chief difference being the frequency at which each operates. 

In order to heat non-metallic objects, frequency must be increased, so microwave ovens operate at extremely high frequencies. Reflecting on that notion, it should be clear that a microwave oven would not be tuned to operate at an effective level for metals, although if the lot is small enough, that may not be the case. As induction furnaces get larger and larger, they operate at lower frequencies, even as low as line frequency. Conversely, as the capacity decreases, frequency increases. 

My induction furnace is a 50kw unit, motor generator type. It is capable of melting up to 200 pounds of material, and operates @ 3,000 Hz. It is an Ajax Magnethermic, and was offered in the same size, but one that operates @ 10,000 Hz. 

When melting, lower frequencies are less able to produce enough heat to begin melting. A heel is required, an object that is large enough to create the required heat. The size of the heel is reduced as frequency increases, so the application intended for a given furnace often dictates the frequency required. 

There is a chart that details acceptable operation levels for a given frequency. Furnaces operate above and below the projected parameters, but with less efficiency. 

Harold


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## butcher

I was not suggesting anyone try to this, much research is needed, at least understanding the safety factors involved and the dangers, some of which can be unseen (microwave leakage).
Just as with anything we do, we must learn about it and its dangers. 
I do suggest studying. And research,

AS of yet this field of microwave technology is in it's early stage of development, and it's use in metallurgy is just beginning to be explored and used, and the possibility's for its use are yet to be realized, some advance's are being made, but much progress will come in the future, with experimentation we will see this used more in the future, and I would not want to stop Thomas Edison from trying to see if he could make that piece of wire glow brightly.

Microwave technology is young and still in infancy, it was not that long ago the man working on a radar tube had a candy bar melt in his pocket, and thought he would put that radar tube in a box and cook dinner, most of us would warn him that is too dangerous.

Fact is for many many years I would not use a microwave to cook anything I ate, I did not want my food (NUKED) cooked (from the inside) with electromagnetic waves bashing water molecules un-naturally I did not trust it to cook any of my food, and I would not have one in my house, and I had some experience with microwave, working with communication towers, they told us the high power frequency's we were working with were cooking us from the inside,

Metals can be melted at 2.45 GHZ. As well as glass. But not without using another material to accept the electromagnetic wave, and induce (current?) into the object being melted (susceptor). Yes sometimes industrially the frequency is different and the chambers are different, but 2.45 GHZ is also used industrially for processing metals in sintering, brazing and other processes, some very much like the home microwave.

Although different frequency works for different materials, this also changes as the temperature changes, here with small amounts of metals
This cannot be done directly, as metals reflect the electromagnetic wave.
Although metal powder will absorb microwave energy directly and begin to heat.
Metals absorption of these waves depend on temperature seems once molecules are moving in the metal they start accepting the electro-magnetic waves easier.

Just as some type of food does not cook well in an electromagnetic wave of 2.45 GHZ, advancement in this field has made progress, and packaging microwave Susceptors (package to cook in, made to accept microwave and convert to heat) example hot pocket package to (bake bread).

I do not think the kits available, or the techniques available as of now are reliable, as the kits rely on (special brand name flux, or material sheets)(me thinks Shore), or relies on material to be melted to contain microwave susceptors, and special boxes containers or refractory shells (refractory again Shor type products), much research needs to be done to find a crucible coating, or flux ingredient (susceptor) which is reliable for this process, and also more study is needed to find a refractory that will allow electromagnetic waves to pass through shell and also contain heat of the melt reflecting the unabsorbed energy back into the melt.

If people who are interested in experimentation give up we will never invent a light bulb, yes electricity is dangerous, and what if Edison and Tesla Quit (because?). 

no harm if Edison study's. it is only when he plugs in his lamp will he get fried.

We may have to wait for it but we will see it, a microwave gold melting furnace.


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## Fournines

I think this idea is a Darwin Award in the making...


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## Barren Realms 007

http://www.youtube.com/watch?v=9bL0zwu2eOU&feature=related

Industrial microwave melting gold acording to the description.


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## butcher

Barren to me that industrial oven looked like a homade microvave oven, I do not know that I would trust it to have the safety features my home unit has.


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## Barren Realms 007

I agree there proably aren't any safety features on it. :evil:


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## turtlesteve

In the past I've played with melting metals in a microwave, eventually I'll modify one to make a full-blown furnace but haven't gotten there yet. My initial setup was to remove the turntable and line the inside of the microwave with refractory blanket. As Harold mentioned earlier in the thread, it's exactly like an induction furnace in concept but much higher frequency. Materials that will heat at this frequency are needed, such as impure silicon carbide, magnetite, MoSi2, etc. I used silicon carbide at first because it is cheap and works well. After a few minutes on high it will heat to a nice yellow-orange and will melt copper.

To build a furnace I plan to thicken the refractory lining leaving a chamber about 6" wide, in which I will place MoSi2 or SiC rods that will heat the entire furnace chamber. I will hook this up to a thermocouple & controller to set the temperature as desired.

Many lab-scale microwave furnaces are essentially this simple, and I'm surprised they aren't used for more things. Because the heating elements are not required to be mechanically durable as in resistance furnaces, they could be used at very high temperatures (i.e. >2000C) more easily than conventional furnaces. Also they can heat to these temperatures very quickly, if enough power is provided.

The main problem I see with melting metals is that the furnace has to be closed when operating, so it would be hard to watch what is happening and also hard to remove the crucible and pour the metal out.

Steve


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## Harold_V

I'm not an authority on microwave ovens, but one of the problems I'd expect you'd experience is overheating of the components. Induction furnaces are water cooled, including the heating coil. You wouldn't have that luxury with a microwave. It might be wise to increase its cooling ability via a large fan. 

Please keep everyone advised. It will be interesting to see your results. 

Harold


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## etack

this is used in glass bead making 

http://www.firemountaingems.com/details.asp?PN=H201083KT

this might work for gold also it appears to be just a round refractory box

Eric


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## Palladium

Alright! Alright! I can see now I’m going to have to jump in here with my secret, secret, weapon i was saving for Flea Bay, but this is just to revolutionary, to super duper extraordinary, to ground breaking. Science said it couldn't be done. But from our labs in Liverpool comes a break through process. From the makers of such products as the famous T-9, Megan's mysteries, and the creator of the Platinumill comes this latest break through. Ladies and gentlemen if you will be so kind as to direct your attention to the Cat standing by the microwave with a box of hot pockets. That right ladies and gents. It's your first multipurpose Cooking sleeve slash black sand smelter slash fusion reactor slash use your imagination. All for the low low price of shipping and handling. That's right ! It's free! You only pay shipping cost. Advanced orders are being taken as we speak. Hurry now in time for the Christmas rush and we will include at no extra cost to you (beside shipping) our new Flux capacitor kit. That's right. I said Flux capacitor. Don't be the last on on the block to have your own Flux Capacitor. Operators are standing by...........

Now i'm just hungry.


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## Harold_V

:lol: :lol: :lol: 

H


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## joem

I don't know what that card board microwave food crisper thingy is ( Iam sure such things are pure science fiction) but if you have a flux capacitor I will trade a transwarp drive.


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## HAuCl4

I got a continuum transfunctioner, dude. So sweet. 8)


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## Anonymous

WELL MY THINGA MAJIGGY BEATS ALL OF YALL'S CONFOUNDULATED ELECTRONICAL THINGAMABOBBERS.(sticks tongue out at the unedumacated) :mrgreen:


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## metalnuker

You may want to check out this article. The home microwave referred to in the article was unmodified. These typically won’t survive this sort of use for very long. If you install a large fan and ductwork to the magnetron, it will live longer. You will also need a crucible made primarily from silicon carbide and insulation made from pure alumina. Zircar makes the best, but it’s expensive. If you wrap the insulation casket in aluminosilicate blanket, it will work much better (and faster). 

http://www.industrialheating.com/Articles/Feature_Article/BNP_GUID_9-5-2006_A_10000000000000991975


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## bswartzwelder

The sellers of the microwave gold kiln will tell you that not just any 1200 watt microwave will work. The "inverter" type of microwave WILL NOT WORK. If you stop and think about it, a microwave oven is just funneling electrical energy into the cooking chamber. The firebricks which build the microwave gold oven act as an insulator. The energy goes in, heats the charge in the crucible, and the firebricks keep the energy (in the form of heat) inside of the kiln. If that energy leaked out, the inside of the microwave would self destruct.


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## NobleMetalWorks

bswartzwelder said:


> The sellers of the microwave gold kiln will tell you that not just any 1200 watt microwave will work. The "inverter" type of microwave WILL NOT WORK. If you stop and think about it, a microwave oven is just funneling electrical energy into the cooking chamber. The firebricks which build the microwave gold oven act as an insulator. The energy goes in, heats the charge in the crucible, and the firebricks keep the energy (in the form of heat) inside of the kiln. If that energy leaked out, the inside of the microwave would self destruct.



I am not so sure about the self destruct comment, but I do know that a Microwave works by passing high frequency microwaves through an object, exciting the molecules so that they oscillate/vibrate as such a high frequency/rate of speed that they rub up against their neighbors, creating friction which creates heat which in turn is what cooks food. 

What totally baffles me is why anyone would spend the money, time, effort and energy on anything that doesn't do the job nearly as well as something that can be easily and simply made, costs much less, is proven to work time and again, has a low failure rate and you can do far more with it.

http://www.backyardmetalcasting.com/

http://www.backyardmetalcasting.com/hmkit.html

http://www.foundry101.com/search.htm

Scott


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## Owltech

Tried it and it works I've used ceramic blanket as insulator and fused silica melting dish crucible. 700w kitchen microwave oven. 10g Ag melts in 8 min. Temperature inside oven never exceed 40c. ceramic wool was warm not HOT, crucible inside - white hot.


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## Lou

I think you'd have better luck with SiC carbide. I've been meaning to build one of these for so long. We already have a microwave ashing system that gets to 900 C. Basically an SiC plate that heats up.


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## bmgold2

etack said:


> this is used in glass bead making
> 
> http://www.firemountaingems.com/details.asp?PN=H201083KT
> 
> this might work for gold also it appears to be just a round refractory box
> 
> Eric



I got that exact kit and it works great for small glass fusing projects. It is just some kind of refractory material forming a round box with a pretty small hole in the top. The inside of the top section around the edges is coated with some black stuff that heats up from the microwaves and that transfers the heat to the glass. It also stays hot a long time so works to anneal the glass pieces but that wouldn't matter for melting PM's.

I did try putting a cupel with a piece of sterling silver in it but didn't leave it in long enough to melt it. It probably would but I felt eventually the coating would get too hot and be ruined or too much heat would be released into the microwave. The outside of the kiln gets hot enough to need gloves and the inside gets glowing hot.

I think it could work for melting gold or silver but not very large amounts and it would take a while to do. This particular kiln wouldn't be big enough to hold a crucible for a real assay or smelting but a larger model MIGHT.

There are probably better ways to smelt precious metals but this microwave idea probably does work. I have put small pieces of metal into my little microwave kiln with no sparking. I think the black coating (susceptor material) around the inside of the little kiln must keep the metal inside from sparking. Same thing if that susceptor material was mixed into the flux. I kind of wonder if the black sands (magnetite) from gold prospecting would work as the susceptor and possibly contain a bit of gold mixed in?

Brian


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## Owltech

https://www.youtube.com/watch?v=FS1qvWYUYoU


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## anachronism

I like that Owl. 

I've said before that it can be done it's good to see a proper video showing it from start to finish. 

Jon


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## nickvc

Brave guy using one hand to mess with molten metal otherwise a good video.


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## Owltech

yeah I guess the other hand holds the camera


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## Owltech

His secret is the ferrite. The melting dish sits on a bed of broken ferrite (like the one found in old CRT TVs or cable EMF shields), that absorbs the microwave energy. The generated heat is transferred to the crucible and then to the metal to be melted. I think the ferrite serves the same purpose as the graphite crucible in the induction furnace.


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## frank-20011

hello,

"His secret is the ferrite. The melting dish sits on a bed of broken ferrite"

i this video you can see ferrite:

https://www.youtube.com/watch?v=ogZvX7w9ZDo

but in this one (the same you have shown) there isn't any ferrite...so what's the explenation in this case?:

https://www.youtube.com/watch?v=1fc-YoiSKfY


greetings!


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## Owltech

in the one I've posted he uses graphite, but later on he improved his setup by replacing it with ferrite. He has many videos on the subject experimenting with different materials.


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## frank-20011

hello,

i will no doubt in your opinion but i can not see anything black.

maybe it is IN the refractory cement the whole "construct" where the melting dish is sitting in is made of?

Yes, in other videos you see a bed made of ferrite but in those you have posted i can see only the white refractory cement!

Anywhere it MUST be but i can' t see it!

best regards!


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## Owltech

it is not a refractory cement, it is an alumina silicate board. I tried to melt silver without the improvements (graphite or ferrite) and it worked but it is slow.

In this video the guy uses only kaowool board without ferrite or graphite 
https://www.youtube.com/watch?v=1xDQJYfQySk


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## JoeyJoystick

My 2 pennies worth...

I see a comparison between induction and microwave. Yes there is some common ground here but also some major differences.

An induction oven heats by Electrical Induction whereas a microwave oven heats by using microwaves. That is a significant difference.

The size of the load determines the frequency in an induction oven, and the frequency has a major impact on the penetration depth of the electrical induction into the material you want to heat. I must admit that I am not sure how the product influences the frequency though.

When using a microwave on the other hand, you are directly exciting the atoms making them move faster and hence getting hotter.

Both systems have trouble penetrating deeply. With an induction oven this is solved by varying the frequency. This can be done automatically. Not 100% sure, but I am guessing that the system tries to find its resonance frequency. This is different for every product and also the amount could have an impact on this. With a microwave you do not have the luxury of tuning during operation as far as I know.

The frequency for induction is in the range of several kHz to 10's maybe even a few 100kHz. With microwave ovens this is more in the order of GHz. 2.4GHz is the commonly used frequency in home microwave ovens. It is not true that this is the frequency that works best on water. There is plenty of microwave ovens that work on different frequencies. 900MHz is a common frequency for magnetrons used in microwave ovens as well.

Induction furnaces are cooled by water running through the coil. But they are also able to produce extremely high power. 10kWh to many MWh

Microwaves can be produced in the range of MWh but I do not know of ovens that do so. These high power ratings are often used in the military. Normally, and what is being talked about in this thread, is obviously the home use microwave ovens for cooking. These are always air cooled with a simple fan behind them. High power units are water cooled, but are very expensive.

And talking about price, the interesting thing about using a microwave oven for gold is the price. A 900W magnetron (the microwave transmitter) costs about $15.00 and the control electronics is between $10 and $15. Or you can take them from an old microwave oven for free.  

Regarding safety: Yes we should be careful using microwaves. However, when contained inside a metal box, it is safe as far as radiation goes. Microwaves are not the penetrating kind of waves as we know from x-rays or gamma rays.

Some testing would be great and I am wondering if more power would actually allow to melt more gold as well or simply melt it quicker. It would be easy to set-up an array of 4 of these transmitters on 1 side of the containment box. I have not heard of this being done before, so this should be done carefully the first time.

The good thing is that, much like the induction furnace, you are heating the product and not the crucible containing it. The heated product will obviously heat the crucible, but this way you loose way less energy than when you are heating the crucible and letting the crucible heat up the product which is what is done in a classical furnace.

I am seriously considering this as an option for a lab furnace if (a big if for now. First need to learn an awful lot more...) I am to pursue gold refining. For large amounts as mentioned by others, I would probably use an induction furnace or a gas fired furnace. What I like about electrical furnaces is the cleanliness. It is a lot less unhealthy than a fired furnace. And since both induction and microwave are contained, it will also allow you to fairly easily heat under Nitrogen or Argon.

I personally think that microwaves should be taken seriously.


Joey.


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## rickzeien

I think the industry is heading towards Solid State Microwaves. Could prove useful in melting furnaces. Zones. Inert atmosphere. Vacuum. Pressure. The potential is enormous.

https://www.macom.com/blog/the-evolution-of-the-microwave-f

Sent from my SM-G950U using Tapatalk


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## anachronism

It's really easy if you know how.


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## g_axelsson

I thought the trick of melting metal in a microwave oven was to use a silicon carbide crucible as that absorbs the microwave energy. Pure metal is a good reflector, it doesn't heat up from micro wave frequencies.

The trick of melting stuff is a balance of energy deposited and energy lost. If you can minimize the losses then you can create bigger melts or melt stuff faster. The time it takes to melt something is depending on how much build up of heat you can get combined with the weight of the charge. For example, a small charge will heat up faster than a large charge, but if it is done in the same crucible with the same insulation then the ultimate temperature will be the same in the end.

It's just simple physics!

By the way, induction ovens do work best at resonance and the larger the charge the lower the frequency.

Göran


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## SGBog

Microwaved smelting in potato for 10min no sparks because I put the top back on the potato. No metal exposed no sparks.


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## anachronism

SGBog said:


> Microwaved smelting in potato for 10min no sparks because I put the top back on the potato. No metal exposed no sparks.



Yeah I agree that would work. Same as putting things in cardboard, or using the methods mentioned above.


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