DIY Fire assay and Gold - Silver smelting furnace

[PickyPlans]

You might find my DIY fire assay furnace useful and interesting. Feel free to ask any questions—I’d be happy to answer!
Here is the link to the video

 

[goldshark]

You might find my DIY fire assay furnace useful and interesting. Feel free to ask any questions—I’d be happy to answer!
Here is the link to the video

Nice video. What kind of wire do you install in it? I saw the cupel in use. How many heat cycles is it guaranteed for?

 

[4metals]

Excellent video, you are quite talented, thank you for sharing. I was glad to see a ways into the video that you were wearing a respirator, that firebrick is dusty and can literally kill you.

I have used kilns made by Vcella Kilns of San Diego California for years and they look very much like your kiln. They have a model for dentists use which come with a front door vent and a top vent. The vents are simply a 1" hole with a swivel flap to close it off. I always recommend this option for assayers because it is beneficial for driving the lead in a cupellation. You may consider adding a similar vent to yours.

Again, nice job!

 

[nickvc]

If you have 4metals approval you are doing extremely well and I for one would have no hesitation in following his approval with mine.

 

[PickyPlans]

Nice video. What kind of wire do you install in it? I saw the cupel in use. How many heat cycles is it guaranteed for?

Thanks! I used 14-gauge Kanthal A1 wire (1.25 mm thick), which can handle up to 2800 watts of power. Given sufficient spacing in the bricks to prevent localized overheating, it has reliably lasted for 200–250 cycles in my experience, at temperatures reaching up to 1100°C.

 

[PickyPlans]

Excellent video, you are quite talented, thank you for sharing. I was glad to see a ways into the video that you were wearing a respirator, that firebrick is dusty and can literally kill you.

I have used kilns made by Vcella Kilns of San Diego California for years and they look very much like your kiln. They have a model for dentists use which come with a front door vent and a top vent. The vents are simply a 1" hole with a swivel flap to close it off. I always recommend this option for assayers because it is beneficial for driving the lead in a cupellation. You may consider adding a similar vent to yours.

Again, nice job!

Thank you so much for your kind words! I really appreciate it. Safety is super important, and I’m glad you noticed the respirator—I definitely don’t take any chances with that firebrick dust.

Vcella Kilns sound awesome! It’s great to hear from someone with experience using them. Beside that venting system sounds like a really smart addition, especially for cupellation. I hadn’t thought about adding a vent like that, but it makes a lot of sense—I’ll definitely keep it in mind for future upgrades.

Really appreciate you sharing your knowledge, and thanks again for the support!

 

[4metals]

it has reliably lasted for 200–250 cycles in my experience, at temperatures reaching up to 1100°C.

Vcella kilns use the same wire and they are rated up to 1260ºC. Possibly they use a higher ratio of coil length to box volume. As far as cycles, I have seen first hand at many refineries where the kiln is run 5 days a week all year and they always exceed 2 years between coil replacement. And their design, like yours, makes coil changes and even brick replacement (for those messy assay fusion spills) very easy.

 

[PickyPlans]

Vcella kilns use the same wire and they are rated up to 1260ºC. Possibly they use a higher ratio of coil length to box volume. As far as cycles, I have seen first hand at many refineries where the kiln is run 5 days a week all year and they always exceed 2 years between coil replacement. And their design, like yours, makes coil changes and even brick replacement (for those messy assay fusion spills) very easy.

These bricks are also rated for 1260°C, but as you mentioned, a higher coil length-to-box volume ratio is needed to reach that temperature. This is because thermal conductivity of bricks increase significantly as the temperature rises.