Old furnace

[chickenminer]

Hi Lanny,
Lots of old hand work on this bench I'm working. Old timers open cut the shallow edges and did a bunch of hydraulic work. I'm the first to use equipment on it and I'm stripping 25' of overburden now to hit the pay gravels.
Yes, very good pay.
Here is a photo of the bench now, you can see the overburden I had to strip.

stonehouse 2018 cut.jpg

The furnace is way cool. Never seen anything like it before. Real curious what they were using for a heat source.

[Lanny]

Love the picture! That's sure some nice equipment you've got in your cut. (Are you on a soft bedrock there?)

I'm glad you're getting nice gold. Where those old boys worked hard, there's usually good gold, so, nicely done! (A bit daunting to have to remove that overburden I'd imagine, but that's why the gold's still there, right? The shallow, easy stuff went long ago.)

I too wondered what they used for fuel to melt the gold; it's an intriguing mystery as they'd have had to get that place awful hot for a sustained period of time to achieve the proper temperature in that furnace. What a great find! Moreover, how ingenious for whoever built it.

Where I'm at now with the placer miners, they have to take off 50-60 feet of overburden to reach the bottom of the ancient channel, with the pay being in the last six feet to bedrock.

Thanks for the picture and the note, much appreciated, and all the best,

Lanny

[Jim_Alaska]

Dick, any coal seams in the area? Some places n Alaska have them and I thought that this could be the heating source. Other than that it must certainly have been wood heat. Since it was done so long ago that would have been the only heat source they had.

I have probably asked you before and forgot the answer, but do you winter over in Chicken or elsewhere?

[chickenminer]

Jim,
I've been living here year round for almost 45 yrs now. Alaska mining has been very good to me
and my family!

There are small coal seams on Chicken creek, but it isn't a good grade of coal. When the dredge was running they tried to use the Chicken coal to power it but gave it up.

I've looked real close at that old furnace and there isn't a buildup of wood ashes or coal residue in the bottom.
I'd say this furnace dates to around 1910 from what the old paperwork I have indicates. So don't know what source they had available other than wood or carbide to make acetylene gas.

[Slatco]

Alcohol fired lol?

[Lanny]

I wonder, could they have made any coke from the low-grade coal? I really don't know that much about coke or coal, but I seem to remember that coal could be used to make coke, as the coke could then be used to keep a much hotter fire going?

I could just be losing my mind, again . . .

Regardless of what fired it to melt (oops, not smelt) the gold, fascinating find nonetheless.

All the best,

Lanny

[Geowizard]

Mystery furnace;

Furnaces come in different varieties...

Is it a coke oven?

Coke ovens remain in use today in South America. They burn wood. The ovens are "charged" with iron sulfide ore,,, brought up to temperature and sealed. The result is "pig iron". There are coke ovens here in Arizona that were used in the early days to smelt sulfide Copper ore that contained byproduct Silver and Gold.

https://www.jeeptheusa.com/coke-ovens-30.html

Early Spanish explorers came into southern Arizona (Patagonia) and after finding silver, they made furnaces that roasted the crushed silver sulfide ore, then the furnaces were driven by a bellows to increase the heat to smelt silver. When white hot, the ovens were sealed with abundant carbon inside to "reduce" the oxidized ore to silver metal. Carbon combines with Oxygen and produces CO2 in a closed furnace. Starving the oxygen reduces the oxide ore to metal.

Is it a blast furnace?

Muffle furnaces are designed to have cross flow. That works for burning off sulfide from sulfide ore. A muffle furnace can have "vents" closed and smelting takes place. There's no history of a massive GOLD sulfide deposit in or around Stonehouse. No smelting took place around Chicken, Alaska.

A blast furnace needs ventilation for air flow. Air flow is what gives needed oxygen for high temperature melting or smelting. There's no apparent ventilation.

From the photos, this furnace was never used. No soot...

From what can be seen, Dicks furnace has no chimney.

A fire cannot be sustained in a closed chamber... No oxygen... No fire.

Placer GOLD miners don't need to "Fire" their GOLD...

It's a mystery.

- Geowizard

[Geowizard]

Melting and smelting;

Placer GOLD is often "Melted" to produce GOLD bars!

Melting is not the same as "smelting"...

- Geowizard

[Lanny]

Melting and smelting;

Placer GOLD is often "Melted" to produce GOLD bars!

Melting is not the same as "smelting"...

- Geowizard

Touché as the French say.

I totally used the wrong word and really did mean melt, so I went back and changed my post as smelting is the process used to extract metal from some type of ore. Moreover, I've seen lots of gold bars poured at placer operations after the gold has been melted in furnaces to make doré bars to be sent to the refiner's (but all of the furnaces were either propane fuelled, or they were small pours without a furnace using an acetylene cutting torch to melt the gold and accompanying impurities before the pour). To elaborate, placer miners do melt their gold to make doré bars as it's an easier way to transport the gold than messing with large bags of nuggets and fines. So, thanks for clarifying my misuse of the term.

As for coking ovens, I've visited some very large ones built from brick (lots of them in a row at the site I visited, have some pictures somewhere), and lots of black soot inside, but you provided a great explanation on how the coking process worked/works, thanks.

As for ventilation on the mystery furnace, perhaps it once was? Maybe something made of metal rotted away (especially if it's over a hundred years old?), then the dirt slumped in and now it's grown over? Or, maybe there were vents through the slabs of rock that are now compressed? These are all just suppositions . . .

It would be an interesting place to detect for metal to see what kind of artifacts might be in the vicinity.

Regardless of its true purpose, I found it a fascinating find.

All the best,

Lanny

[Lanny]

Question: Is using flux while melting gold a form of smelting?

All the best,

Lanny