Flux Recipe

[clydeman]

I need the ratio weight or percent for the following flux:
Borax
Sodium Nitrate
Sand

I am not interested in the lead or mercury version as I can get those online somewhere. The above recipe is not so easy to find.

BTW, hello everyone, my first post

 

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[Assembler]

I would strongly suggest dropping the Sodium Nitrate from the mix. Reason is simple... sodium or potassium nitrates are extremely strong oxidizers. They will burn of as an LOI or worse yet combine with iron oxide and aluminum to form thermite. In other words, nitrates can literally "light" up your day. Caveate emptor.

Good point. However in looking at "Crucible charges" Grams of Nitre are used for Galena and Iron Pyrite.
Sodium Bicarbonate, Potassium carbonate, and Borax appear to be used a lot in different amounts depending on the Ore. One should follow Ricketts and Miller's Notes on assaying.
Fire Assaying is recognized around the world to prove values per Assay Ton tests.

 

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[ncclaymaker]

As my name is ncclaymaker, I've some experience with clay, pottery and glazes and fluxes. The kiln that I use is a Scutt computer controlled device. That being said, I can control the timing and temperature with a high degree of accuracy.

Gold has a melting point of 1064 degrees Centigrade (1947 F), fugitive or vapor temp at 2600C (4712 F)
Iron has a melting point of 1538 degrees Centigrade (2806 F) n/a
Copper has a melting point of 1084 degrees Centigrade (1954 F) fugitive or vapor temp at 2595 C (4703 F)
Lead has a melting point of 328 degrees centigrade (622F) fugitive or vapor temp at 1750 C (3182 F)

If I were to "refine" out the gold, it would be with a small amount of copper included as an alloy. I would contain the concentrates in a crucible or vessel and melt the copper and gold together. Heat would cause Galena PbS or Iron Pyrites FeS2 to disassociate the sulphur from the iron or lead as a fugitive gas/vapor, leaving iron or lead, pour off the lead. Canter off the gold/copper alloy, dump the iron residue. Now would be a good time to sell the gold as is.

 

[Assembler]

As my name is ncclaymaker, I've some experience with clay, pottery and glazes and fluxes. The kiln that I use is a Scutt computer controlled device. That being said, I can control the timing and temperature with a high degree of accuracy.

Gold has a melting point of 1064 degrees Centigrade (1947 F), fugitive or vapor temp at 2600C (4712 F)
Iron has a melting point of 1538 degrees Centigrade (2806 F) n/a
Copper has a melting point of 1084 degrees Centigrade (1954 F) fugitive or vapor temp at 2595 C (4703 F)
Lead has a melting point of 328 degrees centigrade (622F) fugitive or vapor temp at 1750 C (3182 F)

If I were to "refine" out the gold, it would be with a small amount of copper included as an alloy. I would contain the concentrates in a crucible or vessel and melt the copper and gold together. Heat would cause Galena PbS or Iron Pyrites FeS2 to disassociate the sulphur from the iron or lead as a fugitive gas/vapor, leaving iron or lead, pour off the lead. Canter off the gold/copper alloy, dump the iron residue. Now would be a good time to sell the gold as is.

A lot of 'Ore' will not have enough 'Values' it it to offset the cost of a furnace or kiln.
Only 'High grade Ore' will be worth running through a furnace or kiln for the values in the 'Ore'.

 

[KevinInColorado]

Also a quick review of metallurgy will show you that alloys (e.g. Copper and gold together) often melt at lower temps then either individual metal. It gets complicated fast!

 

[Assembler]

The best reason for a "Fire Assay".

Also a quick review of metallurgy will show you that alloys (e.g. Copper and gold together) often melt at lower temps then either individual metal. It gets complicated fast!

A good use of any flux is for the process known as "Fire Assays". The "Flux helps with both fusion as well as to help 'Pull out values and waste materials' in different "Fire Assay" steps / process. The best reason for a "Fire Assay" is to 'Prove values per Assay ton'. This will prove that there are "Valuable Minerals" or "Values" there to fend off any contest or dispute.

 

[ncclaymaker]

Also a quick review of metallurgy will show you that alloys (e.g. Copper and gold together) often melt at lower temps then either individual metal. It gets complicated fast!

Perfectly correct. By using the following ceramic glaze components I could easily capture the copper and lead in a glass matrix that most potters would call a glaze at cone 015 or about 1450F. There are formulas that can form glass at 1100F capturing the lead and copper with ease. Lead will be combined in the borosilicate to form a lead bisilicate and the copper with calcium carbonate to form copper carbonate. If there is any iron, no problem. Iron acts as an active flux along with the lithium carbonate. How much of the "glaze" to material... I have no clue. Experiment.

Frit 3134 - 79%(low alumina high calcia borosilicate frit)
Lithium carbonate - 20%
Bentonite - 1%

 

[Assembler]

Also a quick review of metallurgy will show you that alloys (e.g. Copper and gold together) often melt at lower temps then either individual metal. It gets complicated fast!

Any 'Fire Assaying book' will point out that alloys will effect the ratios of the different types of fluxes to be used as well as the different steps to take with each flux used. This could be over the head of the average person.
Again the main reason to use a given ratio of fluxes is to help the fusion process and not over reduce or oxidize in the process as to effect the next step / stage.

 

[Assembler]

Some clay / ceramic objects with a "Gold rich glaze" could be very interesting. Post some pictures if you do this thank you.

 

[ncclaymaker]

Some clay / ceramic objects with a "Gold rich glaze" could be very interesting. Post some pictures if you do this thank you.

They already exist as extremely low fire/temperature "lustre glazes" that fire at cone 019 or 1252F. Gold chloride that is suspended in lavender oil will fuse quite nicely to a low alkaline clay body, such as porcelain. Check out a good tea cup or plate that has a gold band around the edge, it's real gold. The lustre glaze is sold commercially by the gram, not the gold, but the lustre glaze itself. By the way, been a "mud-slinger" for 20 plus years.