# Need some advice on Melting Gold



## Aeon13 (Mar 17, 2016)

Good day to everyone! First I want to thank this forum for letting me learn so many things about gold refining. The members here are so helpful and accommodating. Thank you everyone!

I started buying gold from the miners here in our place (Benguet Province, Philippines) for about 3 months now. I sell them to a buyer also and gives me little profit for every transaction. After reading things here in the forum, I learned many things (especially the refining part). I am planning to purify the gold that I am buying and find someone that will buy this high purity gold for me to have a better profit. I read Hoke's book already and many topics here about the process. 

I have low budget for now that's why I will do the process done by kadriver which only involve the use of nitric acid and not aqua regia. The process involves inquarting and boiling of nitric acid then rinsing. My question for now is the type of torch/fire that I will use for melting. Oxy-acetylene is a bit hard for me to use because of it's hard to transport those heavy tanks here in our place. I am left with the available options here: 1. Air compressor- gasoline combination. This method is used here in our place. 2. Air compressor- LPG( Liquefied Petroleum Gas). Some use this and told me it is more economical and produce more heat. 

Please help me choose which method will I use for melting.I also want to ask the type of air compressor that is best for this task. I will appreciate any suggestion/comment/criticism. I will continue to read and learn from this forum and from you guys. Thank you so much!

Mohammed


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## Barren Realms 007 (Mar 17, 2016)

You can look at set called a B-tank that is an oxygen tank with a regulator. Or you can look at using MAPP gas.

Here is a MAPP gas setup.
[youtube]http://www.youtube.com/watch?v=tWkxtwIebLw[/youtube]

Here is a B-tank set up just showing melting some copper tubing for a demonstration.
[youtube]http://www.youtube.com/watch?v=cDI3pP1suLA[/youtube]

Melting gold with a MAPP gas set up
[youtube]http://www.youtube.com/watch?v=e4jjOmUrWpo[/youtube]


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## 4metals (Mar 17, 2016)

I think you need to build your own gas melting furnace. A hand held torch will work fine if you're buying a few pieces at a time and melting a few ounces. But considering the fuels you have available from what you said;


> 1. Air compressor- gasoline combination. This method is used here in our place. 2. Air compressor- LPG( Liquefied Petroleum Gas). Some use this and told me it is more economical and produce more heat.



In my opinion a gas fired pot furnace with a propane (LPG) fuel and a blower will serve you well. The trouble is you cannot afford to go out and buy one. We get that a lot here at GRF. 

So to build your own furnace, I would start out with one which holds up to a #3 crucible. That should suffice from a few ounces to a few hundred ounces. Once you see how easy it is to cast one of these and make a good functional furnace capable of melting gold and silver all day long, you will realize that scaling up to larger and larger models is pretty simple so you can really melt whatever quantity of gold you can lift to pour and customize your melt furnace to accommodate your needs. 

You will need to form your furnace from either refractory cement or a much lighter insulating fabric which I will give you a link to later. For longevity, I would be using refractory cement. Then you will need some pipe to deliver the gas to your burner and a valve to control the gas flow and a valve to control the output from your blower. Last you need a blower. You can buy a blower made for this purpose but they are pricey at about $500 US for the 27 CFM you need for the small unit I am suggesting. Pricey but they do last. Then there is the good old affordable route which is to use a vacuum cleaner blower. This is the $500 blower I dug out of my barn to show you.





The burner is just the length of pipe, you can see where the gas feed tee's in with a shut off valve (blue handle) and the airflow is controlled with a gate valve (Red handle) for a small furnace there is no need for a mixing chamber. For larger furnaces a mixing chamber blends the gas and air coming into the piping before the jets. This is a pearl I picked up at an auction for $10. AGF made equipment that was essentially bullet proof and lasted forever. Shame they're gone.


I built a gas manifold for this melter, added a refractory melt chamber and can melt Pt by adding pure O2 to the mix. This is the mixing valve.



So to start you need to make yourself the melting chamber. In Loewens excellent book "Small Scale Refining of Jewelers Waste" he gives details to build a furnace body. This image is from that book which you can purchase from a link in the library (worthwhile investment)


The dimensions for the small furnace which refer to the drawing are as follows;
OD 11 1/4" (A metal 5 gallon pail is excellent for this form and makes a nice finished outside to the furnace.)
H 11"
B 4"
L 1 1/2"
O 2 3/4" 
The wall thickness is approximately 2" and the crucible rest height (this is made like a puck to be removed) is such that the height of the crucible plus the height of the crucible rest leaves about 1/2" clearance at the top (C in the drawing) 

Two things to note; The gas comes in tangent to the inside diameter so it swirls around without hitting the crucible rest. And 2, the crucible rest should be tall enough so the flame is just below the bottom of the crucible. If the flame hits too high you can have solid unmelted metal in the bottom and a liquid top. 

Samuel-A a valuable contributing member of GRF posted this thread which shows his melt furnace made with the insulating wool fabric. http://goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=20501 The burner described above will work in his unit as well. 

Another home made furnace can be seen operating in the video in the link posted here; http://goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=21967&hilit=melting

I think with a little research you can build a nice effective air blower and LPG fueled melt furnace that will serve your needs for years to come. 

Good luck


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## nickvc (Mar 17, 2016)

Well what can I say, brilliant Chris, if that doesn't make sense try reading some more.


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## Barren Realms 007 (Mar 17, 2016)

If you want to go that way 4metals is talking about here is a picture of one and it will hold a #6 crucible. This is a propane furnace.


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## 4metals (Mar 17, 2016)

This is the American Gas Furnace melt furnace catalog page. Starting price $110. How old is that picture??????


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## Topher_osAUrus (Mar 17, 2016)

This thread is brilliant.

4metals, you are a golden god!

I am building one of these right now, and you have shed a wonderful ray of light in the dark corners of my mind, and noe, my roadblock will easily be overcome!

To say i am appreciative of everything you have contributed to the forum, is an understatement (BEYOND, an understatement)


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## upcyclist (Mar 17, 2016)

A Gingery Furnace is the same concept but I'm guessing it wouldn't take the heat very well. 

Another quick, non-permanent option is acetlyene-air. Not sure how available that is in your neck of the woods, though.


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## 4metals (Mar 17, 2016)

A Gingery furnace as shown in the link I posted made with the right refractory will take the heat.


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## Anonymous (Mar 17, 2016)

nickvc said:


> Well what can I say, brilliant Chris, if that doesn't make sense try reading some more.




Nick my old mate are you getting 4metals confused with GSP? 

Brilliant post though 4metals- I like it a lot. Thank you.

Jon


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## UncleBenBen (Mar 17, 2016)

Great thread. Now I know what will happen to the nearly new (old) pottery kiln I was given a couple months ago. Just a bit more studying over it and oh yeah.

Thank you 4metals, you are a man amongst men, and absolutely one of my favorite "authors to search."


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## nickvc (Mar 18, 2016)

spaceships said:


> nickvc said:
> 
> 
> > Well what can I say, brilliant Chris, if that doesn't make sense try reading some more.
> ...




Darn need to change my glasses again  :lol: 
Sorry 4metals my bad.


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## 4metals (Mar 18, 2016)

> > Nick my old mate are you getting 4metals confused with GSP?
> 
> 
> 
> ...



Being mistaken for Chris is more a compliment in my book.


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## 4metals (Mar 18, 2016)

I looked up the burner type used on the propane furnace Barren posted, this is what the unit looks like.




I do not know if this will generate the heat required to melt gold. There does not seem to be a way to control the gas flow and the air mix. This will limit your ability to generate either a reducing flame or an oxidizing flame. 

The up side is it does not require a blower, the down side is what I said about types of flame. I would like to hear from members using this type of burner for melting in a crucible to get some feedback as to its versatility. I see Barren is using it to incinerate e-scrap. I am interested in its ability to do crucible melts.


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## Palladium (Mar 18, 2016)

I use that exact same burn design. I bought both mine from a guy on ebay a couple of years ago who made them ($40/piece). I use one of them out on the farm to melt silver 5 lbs at a time. I now have a butter fly valve on the back to regulate air flow. I can jack the gas up and adjust the air and it will definitely put out some heat. From my previous work with furnaces i have learned that not only burner output is important, but more important is refractory. All I've use mine for is melting silver. I'm happy !


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## Barren Realms 007 (Mar 19, 2016)

4metals said:


> I looked up the burner type used on the propane furnace Barren posted, this is what the unit looks like.
> 
> View attachment 3
> 
> ...



That is pretty much close to the way mine is set up. It doesn't have the flared end on the end of the burner like the one you are showing, but from what I have seen on videos I feel it will generate more heat with the flared end. Mine is just a straight 3/4" pipe set into the refractory of the furnace. If I remember right I think on other builds of similar furnaces it calls for a #64 bit to drill out the orifice hole in the nipple running through the reducer for the gas flow. This site will help if anyone wants to build their own furnace. http://backyardmetalcasting.com/

I have watched a number of video's on people that have taken the burners and veined them to burn hotter and get better air flow but IMHO it is a waste of time. The flared end it supposed to help to some degree but I really don't see the necessity of it unless you are running one the size that Ralph has and you are trying to max out the size crucible that you can put into it. My furnace will hold up to a #6 and if I m correct it looks like Ralph's will hold up to a #12 crucible.

Ralph's furnace looks a little bit bigger than the one I have. He should not have any problem maxing out the crucible size for the furnace for melting silver. And I think he would be ok melting gold and copper in it if he wanted to, but I do have some reservations about saying that, and if I were building one that size I would probably upsize the burner to a 1" pipe just for the added capacity.

Kurt uses one that is the same size as mine and he doesn't seem to have any problems with it as far as I know. He was having some heat retention problems with it and had mentioned about building a new one and I suggested to him to close the hole in the top up to retain more of his heat but I haven't asked him if he tried it and if so if it helped him any.

The furnace I have came from Legend's. They do not carry or build the same furnace any longer as far as I know. What they carry now has the same bottom made from refractory cement but the sides and top are made from refractory fiber from the looks of it. It will probably hold up but if I had my way I would stick with the refractory cement for the whole unit. It will last longer and can take more abuse. My guess is they changed the design to save on shipping charges to customers.




When I was doing a lot of silver with the furnace I have I was using the clay crucibles that Steve sold.




I could top the crucible off with cemented silver and it took about 30-45 minutes for the 1 round to melt, I could generally top the crucible off about 3 times with additions of silver then make a pour into my 2 Lb. mold. After the first round it only took about 10-15 minutes to melt a topped out crucible once the furnace got up to operating temperature. I could generally get 8 melts from a full crucible before it would start to fail and develop holes in the sides. There was only enough borax used to coat the sides of the crucible. 

As for melting copper or gold. My furnace has no problem handling the melting of them. Most of what I have done with it has been copper using a #4 crucible. It takes about 45 minutes for the furnace to make the first melt and reach operating temperature then after that your looking at about 20 minutes for the melt for full crucibles. If you are going to go up to this size change to a salamander graphite crucible. I tried with the clay crucible and got 2 melts from one and didn't even get a complete melt from another one before they failed. I don't use any flux when working with this material.




The first copper run that I did I was making shot from the copper as shown in the picture above. I was pouring into a 2 gallon stainless pot. At the end of the pour I must have let a large glob go into the bucket. When it did it exploded on me. There was about 3 Lbs' of copper in the pour. When it exploded it was equal to some of the pipe bombs I have made. You think to yourself that you will have time to react when something like that happens to you. But I will tell you that you don't, it happens in a split second. The pot held together, but it made the bottom conform to the contour of the surface it was setting on. The only thing that was left in the pot was maybe 50g of copper and just a little bit of water. Water and copper shot rained down all around me in a 60' circle with me in the middle. It was a stroke of God's fate that I didn't get injured. I was wearing a zip up hoodie coat at the time and when I stood up I could see the back of it glowing in a window payne. I took it off and got the burning stopped and there are holes bigger than my fist in the hood part, and it is missing about 1/3 of the hood that burnt away. After that I went and got a 30 gal steel trash can to pour into.

Hope this information helps and it is not too long winded.


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## g_axelsson (Mar 19, 2016)

Barren Realms 007 said:


> Hope this information helps and it is not too long winded.


On the contrary, I would especially like to thank you for sharing the story about exploding copper. I don't have a melting furnace yet but I can see myself building one in the future. Copper would be one thing I would use it for. By sharing your story that's one potential accident that I will not have in the future.

Thanks for the shared wisdom!

Göran


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## Aeon13 (Mar 19, 2016)

Wow! So much information. It will take me a while to digest all. I will take time to read and understand all information by you guys. Thanks you so much! 
Forgive me for not replying fast because internet connection here is still a problem. 
I hope I can do these furnaces that you guys showed. For the mean time because of my limited budget, i will be using a compressor gasoline set up. This will do the job for now. I am buying small pieces (100 grams is my biggest piece as of the moment). I will try to post pics/vids for you guys to comment/suggest/critisize.
Again thank you so much!

Mohammed


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## kurtak (Mar 19, 2016)

Barren Realms 007 said:


> Kurt uses one that is the same size as mine and he doesn't seem to have any problems with it as far as I know. He was having some heat retention problems with it and had mentioned about building a new one and I suggested to him to close the hole in the top up to retain more of his heat but I haven't asked him if he tried it and if so if it helped him any.



Correct per the underlined above --- the heat retention problem is due to the fact that my furnace (my small one) has done soooo much work for me (including smelting - so we are talking "aggressive" flux involved) so the center hole in the lid has eroded & become "much" larger then it was when new so a lot of heat is being lost out the hole --- I am waiting for warmer temps so I can knock out the old refractory of the lid & re-pour a new lid --- I was considering just doing a repair (drill & pin around the inside of the hole & then do a refractory patch) but am afraid the patch wont really hold up well - so decided to wait & do a complete new pour of refractory

The heat retention problem is only a problem if I am trying to melt copper (with out adding air) - it still melts silver no problem 

You will notice that my burner is set up so you can add compressed air (at the back of the burner) so I am actually able to over come the heat retention problem by increasing the burner heat out put by mixing 3 - 5 psi of compressed air --- so I am getting by with it as is until weather warms up enough so I can pour a new lid with a smaller center hole

Kurt


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## kurtak (Mar 19, 2016)

Barren Realms 007 said:


> The first copper run that I did I was making shot from the copper as shown in the picture above. I was pouring into a 2 gallon stainless pot. At the end of the pour I must have let a large glob go into the bucket. When it did it exploded on me. There was about 3 Lbs' of copper in the pour. When it exploded it was equal to some of the pipe bombs I have made. You think to yourself that you will have time to react when something like that happens to you. But I will tell you that you don't, it happens in a split second. The pot held together, but it made the bottom conform to the contour of the surface it was setting on. The only thing that was left in the pot was maybe 50g of copper and just a little bit of water. Water and copper shot rained down all around me in a 60' circle with me in the middle. It was a stroke of God's fate that I didn't get injured. I was wearing a zip up hoodie coat at the time and when I stood up I could see the back of it glowing in a window payne. I took it off and got the burning stopped and there are holes bigger than my fist in the hood part, and it is missing about 1/3 of the hood that burnt away. After that I went and got a 30 gal steel trash can to pour into.
> 
> Hope this information helps and it is not too long winded.



:shock: I will bet you never let that happen again :lol: 

I had a similar thing happen the "first" time I was doing a smelt on some bonding wire from chip ash concentrates --- I mixed my concentrates with my flux & some silver cement as my collector, loaded the crucible & put it in the furnace --- when it all got molten I remembered that I had a couple sterling chains & a couple sterling rings & I thought - what the heck - I might as well add that in & it should give me a nice size silver anode to run in my silver cell - the problem was I didn't preheat the sterling - so when I dumped the cold sterling in on top of the hot molten smelt - KA-BOOM --- it blow "everything" out of the crucible, busted the crucible & hot slag/metal came raining down on me - it wasn't hot enough to burn me but it did burn holes in the top layer of my insulated jack & made burn marks on my hat --- I think I was able to pick up like 1 - 1.5 oz metal of what should have been more like 2 lbs metal   

I learned two things --- you can't duck fast enough - & - don't EVER add large pieces of "cold" metal to a molten melt/smelt  :lol: 

Kurt


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## maynman1751 (Mar 19, 2016)

Great 'heads up' guys, Thanks!!!!


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## 4metals (Mar 20, 2016)

I have always followed the rule that says never add anything to a melt that has completely melted. It is very common to scoop in more metal as a melt settles down in a crucible from the bottom melting but never when it is all molten. 

Once, years ago, I was pouring copper into water making shot, the crucible was a #50 and it was in a cradle on a pivot pouring into a 100 gallon tank recessed in the floor. Sure enough, we poured too much too fast and it erupted, emptied the tank and thankfully only soaked us. The metal stayed in the tank. It turns out there was enough water to handle the quantity we were pouring but the water was stagnant, no circulation. When the water circulates it can distribute the heat faster. Without circulation the bottom water surrounding the hot copper turned to steam and exploded upward. Identical pours with circulation never had eruptions.

It is good to talk about these experiences, and sooner or later we all have them. It is a real success story to prevent someone from hurting themselves because they read about us talking about our own screw ups!


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## Barren Realms 007 (Mar 20, 2016)

4metals said:


> I have always followed the rule that says never add anything to a melt that has completely melted. It is very common to scoop in more metal as a melt settles down in a crucible from the bottom melting but never when it is all molten.
> 
> Once, years ago, I was pouring copper into water making shot, the crucible was a #50 and it was in a cradle on a pivot pouring into a 100 gallon tank recessed in the floor. Sure enough, we poured too much too fast and it erupted, emptied the tank and thankfully only soaked us. The metal stayed in the tank. It turns out there was enough water to handle the quantity we were pouring but the water was stagnant, no circulation. When the water circulates it can distribute the heat faster. Without circulation the bottom water surrounding the hot copper turned to steam and exploded upward. Identical pours with circulation never had eruptions.
> 
> It is good to talk about these experiences, and sooner or later we all have them. It is a real success story to prevent someone from hurting themselves because they read about us talking about our own screw ups!



Ok that explains why mine did what it did. Mine was only a 2 gallon pot. I can only imagine the violent reaction of a 100 gallon tank.


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## 4metals (Mar 23, 2016)

This site may be interesting to anyone wanting to build the burners that Barren, Kurtak, and Palladium have had such success with.

http://metalcast.boorman.us/reil_1.html

This is the burner being tested by the author of the site in the link.


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## Aeon13 (Mar 24, 2016)

Thanks for the inputs guys!

Here is my update about my melting.

I melted a couple of buttons already. These are the ones the miners sold to me. These are elemental gold already melted into buttons but they used blower-charcoal set up. I remelted these buttons and had a good results for the first 3 buttons. I had a problem with the next buttons though. There is a black coating on top being formed (Am I correct that these are oxides being formed?). I read about the types of flames (reducing and oxidizing). I tried to minimize the air supply near the end of the melt to lessen oxygen being blown into the molten gold and thus finishing with a much yellow flame but still the black coating is present.I also tried to sprinkle borax on top of the molten gold. The coating is thin and will be removed if I file it but I am hesitant do it. Please comment/suggest/criticize.
Thanks guys and more power!


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## ettran (Mar 24, 2016)

kurtak said:


> Barren Realms 007 said:
> 
> 
> > Kurt uses one that is the same size as mine and he doesn't seem to have any problems with it as far as I know. He was having some heat retention problems with it and had mentioned about building a new one and I suggested to him to close the hole in the top up to retain more of his heat but I haven't asked him if he tried it and if so if it helped him any.
> ...


hi , where can I buy crucibles , ed.


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## 4metals (Mar 24, 2016)

Budget casting supply crucible page

http://www.budgetcastingsupply.com/Foundry-Crucibles-s/1830.htm


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## 4metals (Mar 24, 2016)

> There is a black coating on top being formed (Am I correct that these are oxides being formed?).



The metal is not refined so you cannot expect to get oxide free melts every time. You could try to burn off some of the oxides while melting by using potassium nitrate on the molten metal but that will not work if the contamination is high. 

I would melt with enough borax to cover the melt, oxides can dissolve in the borax and a pinch of potassium nitrate will help, then remove the beads when they solidify before the borax hardens around the bead and quench it in cold water. That should thermally shock off the excess borax, if not a dilute sulfuric soak will dissolve the borax.


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## Smack (Mar 24, 2016)

I screwed up recently on the precipitation of gold in an A/R solution. I was in the process of dropping with SMB on a known amount (53g) of gold and was going to stop short of a full drop and decant the remaining gold bearing solution to keep drag down to a minimum but got distracted and added more SMB and as soon as it started to settle I noticed I just screwed up. You could clearly see (and I thought about taking a picture to show but didn't) a darker precipitate settling on top of a beautiful orangish gold precipitate.


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## Aeon13 (Mar 25, 2016)

4metals said:


> > There is a black coating on top being formed (Am I correct that these are oxides being formed?).
> 
> 
> 
> ...



Thanks 4metals. I tried to add more borax that the button is submerged with it. I will try to find potassium nitrate and try to add. Is there a possibility that I am using the wrong type/mixture of air-gasoline combination? I am using an Air compressor- gasoline set up for melting.

Thanks again.
Mohammed


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## Aeon13 (Mar 25, 2016)

Smack said:


> I screwed up recently on the precipitation of gold in an A/R solution. I was in the process of dropping with SMB on a known amount (53g) of gold and was going to stop short of a full drop and decant the remaining gold bearing solution to keep drag down to a minimum but got distracted and added more SMB and as soon as it started to settle I noticed I just screwed up. You could clearly see (and I thought about taking a picture to show but didn't) a darker precipitate settling on top of a beautiful orangish gold precipitate.



Thanks for sharing Smack. I am not into refining yet for now but I will eventually go there in the near future. This forum and you guys are big help. More power to all.

Mohammed


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## Lou (Mar 25, 2016)

4metals,

You've melted platinum in this?


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## 4metals (Mar 25, 2016)

I assume you mean in the furnace I cast and posted the picture of?

Yes with oxygen injected into the chamber. The air is cut way back and the oxygen is fed into one of the valved gas feeds. It eats up oxygen like crazy, it gets hot enough to melt Pt but if you consider the oxygen usage it is not worth the price.


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## kurtak (Mar 25, 2016)

4metals said:


> Budget casting supply crucible page
> 
> http://www.budgetcastingsupply.com/Foundry-Crucibles-s/1830.htm



Although these crucibles from budget casting supply work I have found that they don't hold up quite as well as these :arrow: http://www.morganmms.com/produtos/cadinhos/salamander-super

The Morgan crucibles cost a little more but IMO are worth it in the extend life/use you get out of them - they are just a better crucible then the budget ones (again IMO) 

I have been wanting to try Morgan's "ultra melt" crucibles as they are supposed to hold up even better to aggressive flux's - but have enough of the salamander super's to last me for awhile yet & so can't justify spending money on crucible at the moment

Kurt


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## 4metals (Mar 25, 2016)

I agree, Salamander's are better crucibles by far. But I have also learned here in the land of GRF that we go the full enchilada, from people wanting the best, to people wanting to make their own for free from rocks in their backyard! So, thanks to Kurt, you now have have a choice.


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## Lou (Mar 25, 2016)

We order through Mifco


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## jason_recliner (Mar 26, 2016)

Aeon13 said:


> Thanks 4metals. I tried to add more borax that the button is submerged with it. I will try to find potassium nitrate and try to add. Is there a possibility that I am using the wrong type/mixture of air-gasoline combination? I am using an Air compressor- gasoline set up for melting.
> 
> Thanks again.
> Mohammed


As someone also struggling with melting, I've been following this thread keenly but I suspect this post became a little lost, being the final one on the previous page.
For anyone confused by the term "air-gasoline" I only presume it means what we would call LPG: or some country-specific ratio of propane + butane.

I am busting to hear any advice relating to oxidising/reducing flames. But back to Mohammed...


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## Aeon13 (Mar 26, 2016)

jason_recliner said:


> Aeon13 said:
> 
> 
> > Thanks 4metals. I tried to add more borax that the button is submerged with it. I will try to find potassium nitrate and try to add. Is there a possibility that I am using the wrong type/mixture of air-gasoline combination? I am using an Air compressor- gasoline set up for melting.
> ...



Hello there jason. The "air-gasoline" I am using is gasoline that is liquid and is the one used in gasoline engines. I think propane and butane are different with gasoline? Forgive me, I'm not sure if we have same terms. I am from the Philippines and some terms used here in our place is hard to translate.

I have read Hoke's book,but I know I have to repeat again. I also read lots of topics here and gave me great help. Still, I am struggling now (which I suppose is natural),but I am hopeful that by further reading and asking from guys here in the forum I will be able to make some progress. 

Acquiring materials(chemicals,melt dishes,torches,crucibles) that you guys use is also a struggle for me here. I am trying my best to find these chemicals. Until now, I am not able to find Sodium Metabisulfite-very easy one to buy there. 

I have a small knowledge about the type of flame. I just know that Oxidizing flame is rich in oxygen and is not recommended for melting,. I read that neutral flame is the best in melting but is on the process of learning through experience how to make the correct mixture.

I hope to learn more from you guys.

Thank you.

Mohammed


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## jason_recliner (Mar 26, 2016)

The fact that you are reading, and actively willing to learn means that the majority of people here do their utmost to help you. It's only when one shows laziness and a lack of willingness to acquire knowledge, that they are shunned. I am also still a minor, still gleaning knowledge from the edges.

Sodium Metabisulfite Na2S2O5 is commonly used as a steriliser, available at brewing shops, at least in AU/US/UK. It would be worth investigating that source in Filo as well. My local brew shop isn't even sure their sodium met from potassium met (they were busy re-labelling it during my last visit) - K2S2O5 should work too, in theory you would just need a bit more of it.

The idea of using automotive gasoline / petrol, kind of scares me somewhat. There's an awful lot to go wrong. Gas (as in literally, the physical state of gas) is much easier to control than a liquid that is on fire. I say that as a former firefighter. This is why I presumed when you said air/gas that you probably (or hopefully) meant barbecue type LPG cylinders? Other than that, I can't speak for the process. Still playing with it myself, I'm behind most regulars here when it comes to melting. That's why I'm also following this thread so tightly.


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## Aeon13 (Mar 26, 2016)

jason_recliner said:


> The fact that you are reading, and actively willing to learn means that the majority of people here do their utmost to help you. It's only when one shows laziness and a lack of willingness to acquire knowledge, that they are shunned. I am also still a minor, still gleaning knowledge from the edges.
> 
> Sodium Metabisulfite Na2S2O5 is commonly used as a steriliser, available at brewing shops, at least in AU/US/UK. It would be worth investigating that source in Filo as well. My local brew shop isn't even sure their sodium met from potassium met (they were busy re-labelling it during my last visit) - K2S2O5 should work too, in theory you would just need a bit more of it.
> 
> The idea of using automotive gasoline / petrol, kind of scares me somewhat. There's an awful lot to go wrong. Gas (as in literally, the physical state of gas) is much easier to control than a liquid that is on fire. I say that as a former firefighter. This is why I presumed when you said air/gas that you probably (or hopefully) meant barbecue type LPG cylinders? Other than that, I can't speak for the process. Still playing with it myself, I'm behind most regulars here when it comes to melting. That's why I'm also following this thread so tightly.



You are right jason. many guys here including you are very helpful and accommodating. I learned a lot here in the forum for only a couple of months. I could only imagine what can I acquire after a year or two here.

As for the SMB, I asked a reagent dealer and they told me they will contact me if it is available.

This method of air-gasoline is being used here for some time already. I think it has the same principle because the air compressor is connected to a tank which contains a small amount of gasoline(about two cups) and this liquid gasoline evaporates the gas state which I think is the ones being pumped out together with air to the torch. I will upload a picture of this set up tomorrow for you guys to comment/suggest.

I'm a super newbie compared to you guys though. :mrgreen: But I'm willing to learn from the best.

Thanks again.

Mohammed


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## butcher (Mar 26, 2016)

Ferrous sulfate can be used to precipitate gold, and can easily be made from soft pure iron, transformer iron laminates is a good source for the iron (normal steel metals will not work as well for the iron source), dilute 10% sulfuric acid to dissolve the iron and make the iron sulfate solution.

Electronic transformers can be used, most of the iron laminates are welded, cutting the weld and separate the iron plates, burn off the oils or any varnish, wash the iron (do this only when you ready to make your sulfate, so the iron will not rust), cut the thin iron plate to smaller pieces so they dissolve in the dilute sulfuric acid easier, the iron will dissolve in the dilute sulfuric acid, a little heat will help the process, this will give you a green solution of iron sulfate, also called copperas, or FeSO4, (what you have read about in Hokes book), after the iron dissolve let the solution sit and settle, decant (pour off liquid without disturbing any solid materials), filter this solution, it can be used as is, or made into crystals with evaporation to drive off the liquid until the iron salt forms.

The green ferrous sulfate crystals, need a few drops of sulfuric acid for storage, and will need to be stored to keep the air from them, keeping them stored under a small amount of the acidic solution in an air tight container, will keep the green copperas crystals from oxidation. 

Oxidation of air can change the chemistry of the iron salt turning it white or brown which would no longer be good for precipitating or testing for gold in solution.

These green crystals are easily made from materials most all of us can get, and can be used to precipitate gold from solution, or test for gold in solution.

https://en.wikipedia.org/wiki/Iron%28II%29_sulfate

I have made several more posts on how to make the ferrous sulfate and how to use it, and there are many posts on the forum and in Hokes book on using it, and the tests for gold, a nice thing about ferrous sulfate, unlike stannous chloride in a test for gold, the ferrous sulfate precipitates the gold in the test as brown, then remainder of this solution can be tested further for other metals (PGM) without the gold interfering with the test.

Harold, and many others have made many posts on using ferrous sulfate for testing solutions, well worth searching for and studying.

As far as using gasoline, liquid gasoline does not burn, it is its gas (or fumes) in air or oxygen that burn.
All flammable liquids, or gases can be dangerous, even with burning wood, the wood gases can create explosions and be dangerous if not done or used properly.

I have not used the gasoline burners or furnaces they use in your country, although I would like to make and try one, I see no reason why if properly built and used, they would not be safe and work fairly well for gold or silver or other base metals, but for metals like platinum the carbon from them would be a problem.

Maybe you can help me with learning to build me one of the gas burners?


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## 4metals (Mar 26, 2016)

*Types of flames for melting*

When melting the 2 fuel sources mix together to form a specific type of flame depending on their ratio. Those 3 types are the Oxidizing flame, the Neutral flame, and the Reducing flame (also called the carburizing flame)




So by controlling the airflow to the fuel and the quantity of fuel you control the flame. Some torches burn oxygen and a pressurized gas but blower type furnaces use air but the thing in the air that is doing the work is the oxygen.

A reducing flame is a flame that is starved of oxygen, when a flame is starved of oxygen it tries to make it up wherever it can. A potential source is metals that are oxidized in the melt. The flame wants that oxygen bad and it grabs it from the oxidized metals in the melt and in the process reduces those metals. A reducing flame is made by cutting back the oxygen supply by throttling down the air supply. This makes the flame start to roar. A reducing flame is the loudest flame in a melt furnace. 

A neutral flame is a flame burning with a balanced quantity of oxygen and fuel. For metals melting it will get your charge hot enough to melt but will neither oxidize or reduce any of the charge.

An oxidizing flame is one that has an excess of oxygen and it gives up oxygen to any metals in the melt that can be oxidized. Fortunately for precious metal refiners the Noble Metals are noble because they resist corrosion and oxidation so they will not come out of the charge as an oxide. 

In practice you never have the gas or the air wide open, usually you set both to light the furnace and get it pre heated and then start lowering each independently a little at a time to get the flame you desire. 

The catch in all of this is that in a crucible melt, it really has little effect because the flame does not contact the charge other than passing over the surface of the melt which usually has some sort of flux covering it. 

When incinerating and having an open flame on the charge it does make a difference as the flame (and the excess or lack of oxygen) reacts directly with the charge. I have also done quite a bit of sweeps melting using a rotary kiln which actually uses the kiln as the crucible and the flame heats the charge directly. For this type of melting the ability to control the reducing power or oxidizing power of the flame matters. 

For crucible melting if you desire to remove metals from a melt and encourage them to collect in the flux, an oxygen wand immersed in the molten pool with a slow steady flow of oxygen rising through the melt is very effective at removing a lot of metals. The exception being obviously the noble metals and copper. Copper doesn't like to gas off into the flux with oxygen. While in theory it should, in practice it just doesn't. The trick here is to have an open center of molten metal in the crucible and a donut shaped pool of flux to collect the oxides when gassing oxygen with a wand.

I have found most melt and incineration setups lack the sophisticated gauges and valves to precisely control either the gas or the oxidized. So you learn to work the valves and listen to the sound of the burner. Remember, louder is reducing, a more quiet roar is oxidizing. You can also judge from the flame color coming out of the top of the furnace when it is running. 

This furnace is running an oxidizing flame



And this furnace is running a lean or a reducing flame, and quite likely more noisy than the previous furnace.



I have seen large gas melt furnaces that have the mass to absorb the sound (my guess) combined with a large top hole that only produce a gentle roar regardless of the type of flame. But the flame color coming out the top is still an indication.


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## Aeon13 (Mar 26, 2016)

butcher said:


> Ferrous sulfate can be used to precipitate gold, and can easily be made from soft pure iron, transformer iron laminates is a good source for the iron (normal steel metals will not work as well for the iron source), dilute 10% sulfuric acid to dissolve the iron and make the iron sulfate solution.
> 
> Electronic transformers can be used, most of the iron laminates are welded, cutting the weld and separate the iron plates, burn off the oils or any varnish, wash the iron (do this only when you ready to make your sulfate, so the iron will not rust), cut the thin iron plate to smaller pieces so they dissolve in the dilute sulfuric acid easier, the iron will dissolve in the dilute sulfuric acid, a little heat will help the process, this will give you a green solution of iron sulfate, also called copperas, or FeSO4, (what you have read about in Hokes book), after the iron dissolve let the solution sit and settle, decant (pour off liquid without disturbing any solid materials), filter this solution, it can be used as is, or made into crystals with evaporation to drive off the liquid until the iron salt forms.
> 
> ...



Thank you butcher for suggesting Ferrous sulfate. I will read further about it to be sure I understood the process. 

I will also post pictures of the set up that I use for you guys to see. I think this set up can have improvements specially from you guys here that has better knowledge on torches/mixtures and the like.

I included pictures of where I melt and the melt dish I am using. I cannot find the same melting dish that you guys use here.

Butcher I am not the one who made the tank and torch. I only connected the set up together. I hope the pics help.

Thank you again.

Mohammed


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## Aeon13 (Mar 27, 2016)

4metals said:


> *Types of flames for melting*
> 
> When melting the 2 fuel sources mix together to form a specific type of flame depending on their ratio. Those 3 types are the Oxidizing flame, the Neutral flame, and the Reducing flame (also called the carburizing flame)
> 
> ...



Thank you 4metals. Saved your comment on a document because of its importance and for further understanding the whole comment.

Seen the pics of the furnaces. Am I wrong that the more yellowish flame is a reducing flame?


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## butcher (Mar 27, 2016)

Thank you for posting pictures of your gasoline torch.
I have several questions.

What pressure does the air compressor regulator run at?
I assume a very low pressure like two to five pounds?

The air tube from the air compressor going to the refrigeration tank, does this pipe go to the bottom to bubble the air through the little bit of gas in that tank (like a dip tube inside), or does it just go into the top of the refrigeration tank like the discharge tube going to the torch?

Can you provide any detail on how the torch head is made, it looks like a piece of pipe with a welded elbow,and a valve for gas fumes/air control the small tube or wire welded to the back of the elbow does it serve any purpose besides holding the handle?

What concerns me at this point is there any back-flash valve, and check valves for safety?
If not I would add then to the line going to the torch head.

Does the torch pick up any atmospheric air at the torch head, besides air supplied by the air compressor?

Is there anything special about the torch tip, orifices or jets?

I find this very interesting, I have worked on many different types of industrial burners, and torches, and made many different types of my own, any time I can learn about another kind, or learn to make another type, it peaks my interest.

Any more detail you can provide would be appreciated.


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## 4metals (Mar 27, 2016)

Something like this maybe?

https://books.google.com/books?id=o...rful gasoline torch popular mechanics&f=false


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## butcher (Mar 27, 2016)

Thanks that explains a lot, the small tube bypasses the valve acting as a pilot.


Here is some things I have been looking into:
petrogen:
http://www.ct.gov/demhs/lib/demhs/usr/training/petrogen_torch.pdf
https://www.youtube.com/watch?v=zC_5_TYWhbA
https://www.youtube.com/watch?v=ojhjYdoNs7w
https://www.youtube.com/watch?v=SabpLuqd2ZA


Unrelated:
Thermal lance:
https://www.youtube.com/watch?v=EA-VCaBUsCA
https://www.youtube.com/watch?v=E-EZZeg81bo
https://www.youtube.com/watch?v=ReBBELs_Xg0


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## richard2013 (Mar 29, 2016)

Hello Aeon13,

I'm from Ph Cebu, I bought my 1kilo SMB in manila 2 years ago. check in olx link below
https://www.olx.ph/item/sodium-metabisulfite-ID6XGKj.html?p=1&h=daa2f9625e#daa2f9625e

Regards,
Richard


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## Aeon13 (Mar 29, 2016)

butcher said:


> Thank you for posting pictures of your gasoline torch.
> I have several questions.
> 
> What pressure does the air compressor regulator run at?
> ...




My apologies for my late reply butcher.

This set up does not have a regulator I just slowly and carefully add the strength of the air coming out from the compressor and observe the flame. I can add a regulator though for me to monitor the right pressure of air coming out. It does not involve bubbling, the pipe going out to the torch is located in the upper part of the tank. Sadly though there are no back-flash valve, and check valves. I need to study how to install it first. I will be posting some close up pictures for further information. Thanks for your comments.

Mohammed


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## Aeon13 (Mar 29, 2016)

richard2013 said:


> Hello Aeon13,
> 
> I'm from Ph Cebu, I bought my 1kilo SMB in manila 2 years ago. check in olx link below
> https://www.olx.ph/item/sodium-metabisulfite-ID6XGKj.html?p=1&h=daa2f9625e#daa2f9625e
> ...




Hi there richard2013!!kabayan!  . It's nice to meet you here on the forum. I contacted that supplier already yesterday. Thanks for your post. Are you into refining too? I'm from Baguio City. What do you think about th torch that I use?Maybe you can give me your contact number for us to know each other.

Thanks again
Mohammed


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## richard2013 (Mar 29, 2016)

Aeon13 said:


> richard2013 said:
> 
> 
> > Hello Aeon13,
> ...



Hello Aeon13,

The torch you are using is just a powerful version of all those smaller units with manual air pump used by jewelers around the country. I would say gasoline is cheaper and economical now presently.

I have been to baguio once year 1999  I wish I could come visit back someday.


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## autumnwillow (Apr 12, 2016)

This setup is safe, reliable and economical. But not for melting large quantities of gold.

You don't need a flashback arrestors or regulators as your air compressor is already pumping gasoline vapors/air mix out to the hose.
Your gasoline content acts as your fuel, while the air compressors psi acts as your oxygen in this state.

There is only one danger for this kind of setup though, when you have too much gasoline in the tank and the gasoline (liquid form) starts to pour out from your torch. This will immediately ignite and spread causing fire.

Also since your gasoline acts as your fuel, as soon as it depletes while you are in the middle of the melting process you would have to shut off the torch, add gasoline, then melt again.

I am also from the same country as you are and have been into refining for years experimenting with small amounts outdoors (1-2g). It is only now that I am going for the large lots (up to 1kg). I own a very small jewelry manufacturing shop.

Also, Hyatt jewelry tools, where you buy your SMB is not a good supplier. They overcharge and send defective items. They used to be my supplier until they sent me a foredom machine that was broken, I tried to return it but they keep on making false promises. I also paid for a customization of an engraving block which they never delivered. That SMB price for 500/kilo (approximately 13$/kilo) is very much overpriced. I have a lot of refining chemicals in bulk, if you do not need that much you can buy from me.

My business also needs a stable supply of gold, if you are willing to deliver in Manila and sell for the right price then I am willing to buy your gold.

Also, maybe you could talk to your miners and try to see if we can help them out with regards to the process of extracting gold? They could already be using an efficient system but I doubt as most of the small scale miners here are not really educated and uses the very old techniques.


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## Aeon13 (Apr 13, 2016)

autumnwillow said:


> This setup is safe, reliable and economical. But not for melting large quantities of gold.
> 
> You don't need a flashback arrestors or regulators as your air compressor is already pumping gasoline vapors/air mix out to the hose.
> Your gasoline content acts as your fuel, while the air compressors psi acts as your oxygen in this state.
> ...




Thanks for the comment sir autumnwillow! Nice to see another kabayan here in the forum!

Yes sir you are right about the danger of this set up. That is why I always check if the tank is half full and if so I will empty it and put a cup of gasoline which will be able to finish one to four melting of gold buttons. (I melt 1-50 grams only). It is good to know that you are also from small beginnings. I am new in gold buying and refining and this field is so interesting. I sent you a private message sir about the supplies and gold.

Actually I started helping these small scale miners here in our place (my uncle is one of them). This is my main purpose in joining this forum. My past topic is about getting information here to help their process become better and of course safer. Sadly, you are right. I know some miners here that use mercury and doesn't know the harmful effect. I hope by learning things here in the forum with the help of kind members, I could help these miners also knowing the hardships they encounter every day in the mines. This is my contact number sir: 09087317672

Thank you again.

Regards,
Mohammed


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## saadat68 (Dec 3, 2016)

Hi
I bought a small blower for my melting furnace but now I think it is small and can not pump enough air in furnace 
It doesn't have specifications but I think it is 70 to 80 CFM
Is it enough for a small furnace (2 KG) ?


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## butcher (Dec 3, 2016)

I would judge the air needed by the flame from the burner, note the pictures above.


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## goldrecovery (Jul 22, 2017)

goldenscrap.com/2017/03/gold-melting
Read this complete guide


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## jimdoc (Jul 22, 2017)

goldrecovery said:


> [goldenscrap.com/2017/03/gold-melting]
> Read this complete guide



Now you are just spamming.


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## 4metals (Jul 22, 2017)

> Now you are just spamming.



He's on thin ice, and falling through fast!


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## goldsilverpro (Jul 24, 2017)

Concerning "goldrecovery"

I think it would be OK if his posted his stuff ONLY on the Refiners, Buyers, Assayers, etc. forum Category. Although I would doubt that anyone in the US would buy from him in Pakistan, we do have members which are from his part of the world. 

By posting his obvious spam in the other forum categories, he is seriously disrupting the threads. Also, everything that I have seen on his website is extremely basic. The info posted on this forum is far more complete and viable than anything on his site. If he wants to participate in the other threads without any of his blatant advertising, he is very welcome to do so. However, if he continues to spam in these other categories, I would think we would ban him.


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## g_axelsson (Jul 24, 2017)

I'm with you, guys. At this stage his posts are just annoying and doesn't contribute.

But I would like to see him comment on the thread where we already is discussing his videos. That would be appropriate.

Göran


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## Topher_osAUrus (Jul 24, 2017)

g_axelsson said:


> I'm with you, guys. At this stage his posts are just annoying and doesn't contribute.
> 
> But I would like to see him comment on the thread where we already is discussing his videos. That would be appropriate.
> 
> Göran



Dont hold your breath.. He hasnt ever answered a single question.. And any comments on his youtube videos that are less than praising, get deleted..

Edit for spelling


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## g_axelsson (Jul 24, 2017)

He's been banned and the site reported to google spam.

He made one more post with links to his site as well as deleting the comment I added on his blog.

I just wish I could see his face when he tries to log in again... time to remove some links and posts.

Göran


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## g_axelsson (Jul 24, 2017)

Update, he is banned although I didn't ban his IP as he had a different IP for each post. If he returns under another username we can ban the whole IP-block.

The single posts without answers have been deleted as well as one of the threads that didn't have any meaning after his post was deleted. A few jokes got lost in collateral damage as well as the turd emoji.
In the threads where we was asked critical questions I left the original link, just disabled it enough so computers doesn't follow it but people could. I also did it with quotes.

If another moderator thinks the threads needs more pruning, just go ahead.

Göran


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## Topher_osAUrus (Jul 24, 2017)

g_axelsson said:


> ... A few jokes got lost in collateral damage as well as the turd emoji.



I suppose the needs of the many, outweigh the needs of the few, or the one... Poop emoji.. ...I think I can live with that  

Not to beat a (long since) dead horse, but, remember .. This guys videos were the ones guarev34 (? I think) posted initially... There was some argument that ensued on a couple of those threads as well. (delete this post too, if need be. Just thought I should mention his videos are still strewn about the place)


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## g_axelsson (Jul 24, 2017)

I don't see posting links to his videos like a bad thing. At least we are discussing the pro's and con's without silencing any criticism. The youtube world is it's own small cosmos and people will find his videos whatever we are doing.

Direct links to his blog on the other hand is giving him higher rankings in searches and steers people googling about refining gold in his direction. There are no reasons to help him in that matter.

Göran


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## Geo (Jul 26, 2017)

He is Umar Iqbal and his videos are dangerous. It was his video on smelting MLCC's that eventually got Ken banned. He was a member of a facebook group that I moderate. He posted a video on wet ashing where they were boiling IC's in a big metal pot of sulfuric acid in an open courtyard while his workers walked around it with no respirator, no shoes, no shirts and short pants. He was summarily banned from the group. His plagiarized website "goldenscrap" is just videos of him putting everyone around him at risk. He and I exchanged words a couple of times and I am not ashamed to say that I told him exactly what I thought about his processes and about him as a person.


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