I’m DMing a roleplaying story set in a fantasy/medieval setting, probably equivalent to say 1200AD Europe. Our characters have purchased land and are considering a business enterprise that they can start on the frontier of an established kingdom, somewhat similar to the American frontier, but with 1200AD technology. There wouldn’t be a train, there are no established roads (not even dirt) as yet, but there could be deliveries of implements up to say 400-500 pounds by dragon at a stiff premium.
On the land that our characters purchased is a large, bowl-shaped hill with no plant life on it covered with thick dirt of a rust color. I based this on a hill that I saw once when I was young and was told that it was red because the soil had a lot of iron in it.
Would this be an indication of a good place to mine for iron ore? If so, what would have been the process to mine, plus to actually smelt it? Would a mining and smelting business be feasible given the restricted access to materials from civilization?
There was a thread around here somewhere recently where a Doper claimed (and I believe him) he accessed iron lying on the surface and smelted it and made implements from it. No special machinery or anything and all done largely by hand (maybe a few hand tools).
On the flip side if you mean full-on iron mine than that is a whole other level of sophistication. As it happens iron is hugely abundant on earth but I am not sure that surface iron means there is a good vein to mine under the ground (might or might not…geologist will have to answer that one). Nevertheless this is a fictional thing you are creating and it certainly is not unreasonable to have iron under that hill so go for it.
I don’t know about the appropriateness of your hill as a source of iron. I do know that you can have an iron smelter working away from “civilization”, provided you have enough people to run it – enough workmen is usually the biggest limitation.
I know this because it was the business of the town I now live in, which had an iron forge going in the 17th century using all-local materials. They got their iron from bogs (“Bog Iron”), their charcoal from the local woods, and the gabbro (needed as flux) from a nearby seaside community. You’re going to need something like that to convert your iron ore into iron.
The building of the furnace, the millpond, the millraces and water wheels, the bellows, the wheelbarrows and ships and all the other stuff, not to mention working all of it, required all that manpower. Originally they used LOTS of paid workmen, but workmen need a lot of money, and don’t want to work out in the middle of nowhere, so they ended up using convict labor.
You need heat. Lots of it, so are there trees nearby? Early smelting didn’t really produce the super hot temperatures associated with blast furnaces (which weren’t used until the Industrial Revolution), but by the 1200’s I am sure they were using clay kilns with bellows to at least get up to melt temperature so they could produce actual lumps of pig iron that could be worked.
The process itself is redox chemistry (isn’t everything?!) - you need to reduce the metal oxide to give you the elemental metal, as well as driving of impurities or anything else it is chemically bonded with, like sulphur, carbon and so on.
For iron the last reduction step needs to be about 1200C, which is extremely hot, but reachable with a kiln and bellows. You need a lot of fuel to keep that fire going, and a lot of manpower to keep it hot for a long time.
So, you need to dig up the ores - shovels, picks, hands.
You need a kiln, so you need clay or bricks
You need fuel - typically wood was used.
You need a reducing agent - you can use wood again (as charcoal), but you need to make it if you can’t transport it.
You need flux to help with impurities and to remove other by products of the reaction - lime usually (calcium oxide). Is there any nearby?
There’s a reason that a lot of early iron works are found near transport routes like rivers and at least one of the primary materials you need (either the ore itself or the fuel you need to smelt it. so you can bring in the thing you are missing).
Iron is present in many different rocks (as are other metals). An “ore” is simply any rock with a sufficient amount of the metal to make it worth while extracting it. Since all but the least reactive metals will form compounds, the process usually consists of 1. Breaking up the rocks to get at the iron compounds 2. Extracting the iron from the compounds and setting it into ingots.
Assuming there was iron ore under the hill (dust and soil just won’t cut it, red or not) then the process would be;
[ul]
[li]Dig the ores up.[/li][li]Crush the rocks and separate the iron oxides.[/li][li]Extract the iron from the iron oxide by using a blast furnace (basically a giant, deliberately inefficient coal furnace. The carbon in the coke forms carbon monoxide, this reacts with the iron oxide). Limestone is also added to react with some of the impurities and produce more refined iron (this forms slag that can be skimmed off the molten iron).[/li][li]The resulting iron is called “pig iron”. It contains a lot of carbon, making it brittle.[/li][li]The pig iron is usually refined into steel or cast iron, assuming the technology exists in your setting.[/li][/ul]
Before blast furnaces, iron was refined in “bloomeries”, which would probably be a better bet for a 1200ADish setting but I don’t know much about those. I learned most of this stuff in school and that was the better part of a decade ago now. =P
Hm, the Wikipedia page on bloomeries seems to be saying that fluxing wasn’t necessary, so the need for limestone wouldn’t be there.
But so if red soil isn’t a particular indication of the presence of an iron vein, how do they usually find one? Usually, there is somewhere where you can actually see the vein from the surface?
Usually by looking for a rock outcrop which contains an ore of the metal you’re looking for (between ores and oil, geology’s always been one of the most mercenary scientific disciplines).
Plenty of surface ore up in the Iron ranges of Minnesota, eg along the magnetic rock trail in the Arrowhead region. Much of the stuff up near Canada has not been mined as it was too much trouble getting equipment in and ore out back in the early 1900’s. Minnesota Museum of Mining may have a decent history of early mining attempts in the area, which would be relevent to your 13th century entrepreneurs.
The local iron furnace produced iron loaded with impurities that had to be removed by repeatedly heating and hammering the iron, working the impurities to the ends, where it could be cut off. But they still added a lot of flux to the mix.
It might not be strictly necessary, but if you want to be able to make usable cast-iron pots and the like, rather than having your output be spongy and useless, you’d apparently better add flux. It’s probably a case of “the more flux the better” in terms of “cleaning” the iron. But if you don’t want to spend all your time hammering out the crud, you’d better put some in.
I think I vaguely remember that colonial-era smelters in America would move every few years, after all the trees in the neighborhood got cut down, because it was easier moving all the equipment to where trees were (and moving the iron out) than it was to move the wood long distances to the smelter.
You can’t count on iron meteorites as a long-term solution.
If you lack the technology to exploit the iron, it’ll resist your efforts after you’ve taken the easy parts (as happened with the big Greenland meteorite now at the American Museum of Natural History. The Eskimos used it for tools, but had removed all the easy parts). If you have the technology, you’ll use it all up pretty quickly.
Nah, I have some other possibilities to explore in the world without having to just throw gold at the characters. I was interested in finding out more about this one just because it was based on something from my childhood. If there’s no reason to think red dirt means iron veins nor meteor, I’m happy enough to work on different lines.
This Wikipedia article is really informative about iron working with plenty of links to relevant articles.
Although the 13th century is a bit early for blast furnace technology in Europe (real world), it appears that other civilizations did have it much earlier (wikipedia again, see article on blast furnaces), so it’s not out of bounds to have blast furnace tech in your world.
Funnily enough, modern civilisation is sort of reliant on meteorites for technology. Semiconductor manufacture for CPUs and so on depend on Iridium, which is extremely rare in the earth’s crust (only about 3 tons or so are produced worldwide per year). The bulk of it is extraterrestrial in origin, being seeded in the ground from asteroid impacts.
Nah, there’s no dice. It’s more a collaborative storytelling thing than D&D, but I’m in charge of creating the setting, writing the dialogue and action of any NPCs, and deciding whether any attempts to try something would succeed or fail.
<Geologist hat on> A rusty coloured piece of dirt almost certainly contains some Iron Oxide, but not necessarily very much. The only way to find out is dig. </GH off>
<DM hat on> what’s all this talk of blast furnaces and large labour forces? Just get hire a dragon* and a coupla trolls already</DM>