A stamp mill pulverized precious metal ores by pounding the raw rock with hammers operated by a big cam shaft. If they weren't located right at the mouth of a mine, the ore had to be moved from mine to mill. Most were steam powered, and coal had to be brought in for the boilers. The high-grade output wasn't very bulky - a carload a week would be unusually high production for a single mill - and would be moved under armed guard in a heavily built express car.
The raw ore entered at the top, was crushed to gravel size, spread to the hammers (stamps) where it was powdered, then moved to separation tables where the values were separated from the far greater mass of worthless waste. The waste would be dumped in the immediate area.
Chuck (Modeling Central Japan in September, 1964)
Stamp mills pound rock that contained higher amounts of gold (typically but silver too) into fine powder (think talc). It would be combined with water to create a slurry. The slurry would be gently washed over copper plates that were coated with mercury. Gold having a great affection for mercury would "stay" with it on the copper plates. The copper plates would be scraped off and the "pregnant" merc would either be retorted (separated by heat) or just plain burned off leaving just the gold. The gold would be smelted into a "dory" (big bar of gold, not pure but close). It would then be transported to a refinery for further purification.
High grade ore is heavy. Waste rock is light (relatively speaking), Gold is really HEAVY!! It's almost twice as heavy as lead. It would often be loaded just over the trucks it is that heavy. A typical dory of about the size of two bricks could easily be over 100 pounds (avoirdupois , however gold is measured in Troy and always in ounces - last year the TG4466 mine produced just over 300,000 ounces). So when shipping think heavy loads in small volumes.
Mercury would also have to be shipped in. It would usually come from California in flasks that weighed 72 pounds each. These would be almost 2' tall and look like a thermos. These would be another thing shipped heavy but in small volumes- hence the need for the trains.
Timber would have to be shipped in since most of the wood would already have stripped in the area for buildings, the mine and fuel.
As a side note, stamp mills typically came in 1, 3, 5 7 and 10 mill stamps (looks like an upside down piston and rod from a car motor) Sometimes they would be combined them into sets-ie three 3 stamp mills for a total of 9. They were often added on to as the mine became more productive and could get more equipment. More equipment was heavy and need to be shipped in via a train- never shipped out though. Shipping out costs money... just move it over there and out of the way
Sorry about the long answer, I hope there was something in there you could use
ratled
Modeling the Klamath River area in HO on a proto-lanced sub of the SP “The State of Jefferson Line”
The shippable output from a stamp mill would be shipped under armed guard in a heavily-constructed express car, probably to the nearest branch of the US Mint. We're talking about gold and/or silver. The all-time production from a large California gold mine that operated for over half a century, refined to .99 purity on-site, wouldn't make a full load for a Minnesota ore car.
The non-shippable output or waste would simply be dumped on the ground downhill from the mill.
The more usual scenario would be for the mine(s) to be at the far ends of branches and the stamp mill to be located in a more accessible place.
Chuck (Modeling Centrl Japan in September, 1964
Try getting your hands on some volumes of the RGS Story series or other books on Colorado mining. There is a lot of good information out there on the mines and mills.
Most of the ore concentrate on the D&RGW/RGS seemed to movein bags in plain old boxcars, which were often stenciled "concentrate loading only" to prevent cross-contamination with other cargoes. Inbound shipments likewise were mostly in boxcars, with an occasional flatcar load of a large piece of machinery. Movements of raw ore from mine to mill weren't especially common; the typical mill received ore by way of bucket trams or 18-inch gauge tram cars directly from the mines. Networks of such things could feed a single large mill.
Modelers have gotten used to calling these industries "stamp mills," but stamp batteries were often replaced with ball crushers by the early 20th century, and mills could change from mercury amalgamation to processes like cyanide flotation. (I haven't read up on the subject in a few years, so could be missing a step there.) Modeling changes to the mill's equipment and structures can make for an interesting scene.
Rob Spangler
trainguy4466so would you suggest simply replicating ball/stamp mill car movements by delivering 2-3 boxcars a session to the mill, and perhaps one express car going out?
More like a few boxcars a week going out loaded, maybe one a month going in with supplies. Admittedly I'm not familiar with all eras and locations for such mills, but for typical D&RGW/RGS operations I'm aware of, the "express car" isn't what's used for shipments of concentrate. It's a plain old boxcar stenciled for concentrate loading. Concentrate goes to a smelter, and that's where it gets refined into nearly pure metal.
on a related note, having a large ore mine at the end of the line, where would be the best on-line location for, say, a 7-10 car long train of ore hoppers to travel for unloading?
It's of course your railroad, so route as you'd like. You could justify sending the shipments to a mill if that's your thing. The process for an ore mill typically used gravity, with the raw ore arriving at the highest point. You could unload into a bin that feeds the rest of the mill. You could also just route such shipments off-line to staging.
On the Colorado narrow gauge and standard gauge both, gondolas were and are more likely to be used for ore shipments than hoppers.
tomikawaTT The shippable output from a stamp mill would be shipped under armed guard in a heavily-constructed express car, probably to the nearest branch of the US Mint. We're talking about gold and/or silver. The all-time production from a large California gold mine that operated for over half a century, refined to .99 purity on-site, wouldn't make a full load for a Minnesota ore car. The non-shippable output or waste would simply be dumped on the ground downhill from the mill. The more usual scenario would be for the mine(s) to be at the far ends of branches and the stamp mill to be located in a more accessible place. Chuck (Modeling Centrl Japan in September, 1964
This may be true some places, but not on the Colorado narrow gauge lines. There were no special express cars, just ordinary boxcars. And despite some widely-spread urban myths about the RGS role in the Manhattan Project, armed guards probably never played any part in security.
Also, the crushed ore from a stamp (or ball) mill is nowhere near ready to be made into coins or anything else - the crushing is just the first part of the refining process, and from the mill the material would be bagged and sent to a smelter.
It was common on the Colorado 3' gauge lines for ore to be loaded directly into boxcars at the mine (literally piled over the trucks for weight distribution purposes, from my understanding), so incoming and outgoing cars to a mill would be predominantly boxcars. Very low grade ore might be shipped in gondolas, but neither the RGS nor the D&RG(W) ever owned any narrow gauge hoppers.
I'm at the stage where I'd like to put a "Stamp/ball/crusher" near my mine site. Where could I find a kit or plans to build one. I'm g-scale in the high country in AZ.
Rex
for plans try this and search for stampmill drawings , after that click on the surveys box http://www.loc.gov/pictures/collection/hh/
A useful thread on a similar question from a few years back here:
http://cs.trains.com/mrr/f/13/t/204643.aspx
Here a little more that relates specifically to the ops around Silverton and Durango. Several attempts to run smelting ops in Silverton were made, but they all tended to founder on the same issue: it took lots more fuel at Silverton's altitude to process the ore than it did in Durango. Think of how much more energy it takes to boil water at altitude if this isn't obvious. The exception was the North Star mill, which reinvented itself into a sampler mill, wiith limited success.
Rather than hauling fuel and supplies uphill to Silverton, it went to more efficient operations in Durango, primarily the big ASARCO mill there. Since ore was processed using water to carry it along, wamer, lower Durango had another advantage in getting away from Silverton's chill.
At the mine, the primary use of a stamp is to break up the raw ore as it comes out from underground so it can be easily moved and to ready it for further processing. Many mines had additional processing facilities to refine the ore into concentrate, which at its most refined looks a lot like sand. This depended a lot on what era (later had more of this), the type of ore, etc.
Sorting cars out by their loading classification is an important part of my ops. Most cars bringing in supplies can't be used to ship ore out, so the mill side of things often needs to order in thise cars to be spotted later to load ore, Typically, the ore is dumped in a pile over the truck centers. These loaded cars then move to Durango, where they are emptied, then shipped out again toward the mines to be reloaded.
Mike Lehman
Urbana, IL
If you want to see a real one, there's a stamp mill on display on its foundation at the old Calumet and Hecla Stamp Mill site on M26 near Lake Linden, MI. They were used for breaking up native copper ore there. You can see it but you can't get next to it to lay a tape on it.