# Flux recipes (smelting)



## twangin4u (Dec 21, 2021)

What factors determine what your flix recipe should be? Im new to this hobby and I've had a few successful smelts where the precious metal and lead collected on bottom and were well separated from matte and waste... I've had a lot more that turned out like crap. The material was too gooey. Maybe not hot enough. My grandpa had saved some ore many years ago and I decided to try and see what I could do with it. It contains quite a bit of silver. Ill attach some pictures and im interested in any opinions

The first pictures are the ore.
And a couple of what I was left with after cupeling lead..
And a couple of what the ore looks like out of the crucible


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## twangin4u (Dec 21, 2021)

Lol.. oops.. I didn't even mention my flux recipe.. I have used Chapman flux... it didn't really seem to work all that great. I mostly use borax... I think some of my problem is my furnace not quite getting hot enough. Im using a cut open propane tank (5 gal) lined with kaeowool and lined with refractory cement. Propane is my fuel with acetylene regulator and homemade nozzle


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## butcher (Dec 21, 2021)

Chapman flux is just a house flux blend, a general or basic flux mix with most of the general ingredients needed as a general flux (basic minimum ingredients), which may work on a few materials but generally will need adjustment of added flux ingredients of oxidizer, reducer, or acid or basic flux in to build a recipe that will work with different types of ore,

It is kinda like a general all-purpose flour that you add what you need to make what you need, the all-purpose flour, you may or not need eggs, and several other ingredients to make bread, or a different group of ingredients to make crackers or another recipe for cakes.

A flux recipe is made for the ore, different ores will take different mixes, you may need to experiment with your ore to find out what mix you need, and then adjust it again to improve its efficiency.

smelting is a chemical reaction, a chemical reaction that normally would not happen at normal temperatures or conditions a reaction that needs high heat to drive the reaction forward, the ore as well as you flux can determine melting points, and how well the melt becomes fluid and or flows, ore's are different complex's of minerals and metals, each ore is different, so each chemical that would be necessary to get the desired outcome will require you to adjust your (house) flux recipes, or to mix a different flux all together.

Think of it as all ore has a different chemical makeup, so in a chemical reaction, we need different flux chemical ingredients in order to bake a good cake if we want good cakes or biscuits we need to make different flux combinations of chemicals or ingredients in our flux.

Chapmans has the general ingredients of a house blend flux, but it most always needs minor adjustment in its recipe to make it work with different ore's, just as the ore has different compounds your flux need to be composed of chemicals to bring the desired results.

Just as a general-purpose flour may be used to make a lot of different types of bread or cookies or crackers, it needs different chemical added ingredients to get the desired outcome, we can't just take general purpose flour and mix it with water and bake bread and cookies.

C.W. Ammen wrote a book that you may find helpful in getting started with the general idea of how the chemistry of smelting and flux works, an understanding that you can make your own house blend of flux (much cheaper), gaining an understanding of what is needed to build or to adjust that flux recipe to work with different types of ores for the desired outcome.


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## galenrog (Dec 21, 2021)

I look at Chapman flux as a starting point. Any additives will be determined by results of ore assay. Many ores will require one or more pretreatments prior to smelting. 

Jumping in blind causes problems, so study first what the professionals do, perform small scale experiments, then adapt the techniques to your situation. 

Time for more coffee.


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## cosmetal (Dec 21, 2021)

twangin4u said:


> Lol.. oops.. I didn't even mention my flux recipe.. I have used Chapman flux... it didn't really seem to work all that great. I mostly use borax... I think some of my problem is my furnace not quite getting hot enough. Im using a cut open propane tank (5 gal) lined with kaeowool and lined with refractory cement. Propane is my fuel with acetylene regulator and homemade nozzle


Fix your propane furnace before you continue your flux journey.

From your pics, it appears you are not getting a consistent, and uniform, high heat for a smelt using your homemade furnace. If you continue to try and use this furnace, I think you need a complete overhaul of your gas feed, such as using a better regulator, one that is designed for propane and can maintain a constant uniform feed pressure. Your homemade nozzle should have (at least) the means to allow air in to create a venturi effect along with a choke to regulate the airflow. Also, use a 100# propane cylinder so you don't get a "freeze squeeze" and get a subsequent pressure drop.

Cupelling . . .

Buy a small electric furnace that will give you the uniform heat and environment that is needed for successful cupelling. Use it outside during use or under a fume hood.
Paragon Kilns

Peace and health,
James


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## orvi (Dec 21, 2021)

I would suggest basic fluxes, if not straight soda, to dissolve sulfides with the action of iron added as reducer. Direct smelt with sulfides and iron rod/chunks in basic flux will reduce all sulfides to iron sulfide, which is relatively soluble in basic slag. 
Roasting of sulfides is also an option before smelting (if you cannot figure out anything to flux the sulfide junk out without matte).
You need relatively high temperatures to liquify certain mixtures. You should be able go as high as 1200°C. Borax fluxes are easy to melt, but often won´t help with sulfides. 
Be aware of foaming when heating soda, and be careful with the slag afterwards - when wet it could cause burns (strong base created).

YTube channel mbmmllc has great videos about smelting concentrates and various funky stuff, it is very visual, with good commenting on what is going on, from watching you will get few good suggestions on various tools and "lifehacks". Watch few of his videos, it should help you with some recipees he tryied and failed/succeeded.


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## goldshark (Dec 22, 2021)

If you give more info on your ore, I'm sure this forum can figure a much closer recipe for you. As a start, you will need some basic stuff. A buckboard and muller for grinding, sieves, decent furnace, crucibles, variety of fluxing additives, scale to say .01 mg., tongs, conical mold, safety gear, a safe place to perform this work, and a whole lot more. Give the info on the ore such as in limestone or quartz, amount smelted, sulfides roasted or unroasted, other minerals in the ore, and what you have been doing up to this point. Grinding is critical.


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## cejohnsonsr1 (Dec 22, 2021)

Jason at Mount Baker Metals and Mining (mbmm) on YouTube has a whole bunch of videos about smelting and fluxes and all that stuff.


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## goldshark (Dec 23, 2021)

Get a book on fire assaying to get the basics. The principals are the same, you are just upsizing the quantity. I got a copy of " A manual of fire assaying", by Fulton and Sharwood. It is old school, but thorough. I wish I had one of their muffle furnaces to use. Awesome read


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## kurtak (Dec 23, 2021)

goldshark said:


> If you give more info on your ore, I'm sure this forum can figure a much closer recipe for you.



He is trying to smelt cinnabar - the ore mined for MERCURY (though it can also contain silver & even "some" gold)

This has already been discussed in his other thread which you can read here









Anybody know what this might be?


I had some ore which I thought may contain some silver. So I smelled it with flux in graphite crucible with lead collector. Then cupelled the lead. I split the lead in half and one half produced a small button of silver and the other looks like this... wtf? Anyone know what this is?




goldrefiningforum.com





Kurt


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## kurtak (Dec 23, 2021)

cosmetal said:


> Fix your propane furnace before you continue your flux journey.



I have already told him the problems with his furnace & how to fix then in another one of his threads 

You can read about it here









Smelting furnace


I'm new to smelting. I've come across some black sand that I want to assay and decided to build a smelting furnace. My problem is that it's not quite getting hot enough to melt the sulphides. The flux melts but the material just gets gooey and orange. I'm using a lead collector metal and...




goldrefiningforum.com





Kurt


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## kurtak (Dec 23, 2021)

goldshark said:


> Get a book on fire assaying to get the basics.



Yes - he should get a good book on fire assay 

There is also A LOT of good info right here on the forum about smelting & fluxes 

here is a good place to start









Smelting


First let me say that the majority of medium to the small side of large refiners today are running circuit boards today by smelting and refining the copper. The more time you can put into segregating and separating the material the better the payoff. That is why this is done in countries where...




goldrefiningforum.com





Kurt


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## Yggdrasil (Apr 4, 2022)

We have just smelted some ore with PbO, borax, some CaNO3, SodiumBiCarbonate, flour mostly.
But something strange happened after pouring. We did notice some bright prills emerge and disappear during smelting. The flux was quite fluid as planned. But almost immediately after pouring it was covered in a metallic shiny layer and a few bright prills.
We were a bit flabbergasted by the metallic layer.
So I'm just reaching out to see if someone else has seen this?


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## Yggdrasil (Apr 5, 2022)

Can the metallic on top actually be silicone from the crucible ? Salamander crucible.


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## kurtak (Apr 5, 2022)

Yggdrasil said:


> Can the metallic on top actually be silicone from the crucible ? Salamander crucible.


yes

Kurt


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