Spring was very rainy this year, which made it harder to work than I was expecting. The terrain where I've been working is craggy, as I've mentioned a few times, which means there are a lot of small but steep valleys with little flat land. That meant that during rain, all that water from on the mountain would run down the cracks in the mountain, rushing quickly along. By the time it got down to the altitude where I was building, it would run very swiftly with a decent volume behind it.
Ultimately, that meant that I had to build even more infrastructure around the area I was working to handle the water, and prevent it from damaging ores. Given the craggy terrain, I had been digging into the mountain to make flat areas that were easier to work with, and I had replaced the floors with a few inches of solid lightstone. The intent was to make a covered area, with chimneys that reach through the cover, to billow out the sulfur dioxide gas. I realized as the rains came that a simple gutter around the covering won't be enough to handle the occasional torrent of water that makes its way down the mountain.
What I ended up spending a lot of time doing was redirecting the water that would cascade down the valley. I tried a few things, like cutting a simple channel around the area, but ultimately, I ended up ascending a few hundred feet above the work area, and cutting a path from my bit of valley into the next one over, and then making a wide and tall redirection for that water. Due to the speed and volume of water during intense rain, anything less than a full redirection was just resulting in mud, rocks, and plant matter clogging any smaller scale structure. At least this should last quite a few years without much maintenance, and the previously cut channels more than suffice for the rain that falls between the redirection and the work area.
Though all that work meant that I hadn't finished the work area by the middle of the fourth month, and we moved the crystal back to the far valley to assist with all the city's construction projects. Though most of the large scale work that I was doing was able to be completed for the project at least. I also cut three decently sized storage areas into the mountain along the back wall of the work area, so that a fairly large quantity of roasted and unroasted ores could be kept onsite.
At that point, all I had left to build were the roasting ovens and the windmill. For the windmill, I went for a size in between a well pump's windmill and the full sized ones by the coast. I once again had Karsh assist with the construction of components, including a simple gearbox for allowing any of the four ovens to have their intake propellers powered or unpowered.
Three of the roasting ovens are of similar design to each other. Though one is larger than the other two. They contain a large, round, flat bed where crushed ore can be distributed with a shovel and special rake. From the back of the oven, a pipe ascends into the heating area. That pipe contains the fan further away from the oven, to force air through. The front of the oven can then close, to ensure that escaping gas leaves through the chimney near the front. When it comes time to roast the ore, wood or charcoal is set on fire on top of the ore, and once it's burning well, the door can be closed. There is an extra system that I installed on the flat bed, that they can then engage, which is a large, flat stirring stick which fits in the diameter of the bed, and will slowly rotate, ensuring that the ore is well mixed.
The fourth oven is of quite a different design than the others though. Unlike the others, where the resultant material is still a rocky substance, this is the oven for galena, where even a wood fire is likely to produce molten lead. That being the case, this oven is much more similar to the furnace up on the mountain, where crucibles can be used to smelt the galena directly, and the lead can be poured off to make ingots. Those ingots will be quite impure, and need reprocessing later, unless they're used for certain materials, like artillery shells, where we only really care about their density.
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In the future, those chimneys could be attached to a gathering chamber of some kind to collect the sulfur dioxide gas, but for now, they'll function fine just venting to atmosphere.
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By the time everything was complete, and I'd tested all the components to make sure they'd work, it was the 18th of the 6th month, or roughly mid-summer. Which meant it was time to start doing a trial run of the sphalerite and galena, as well as giving the pyrite a try in one of the smaller ovens. In the time I spent while building this whole facility, the mine itself has started to decrease in productivity, and it's about to the level where I'm going to direct the mining team to start a new exploratory mine shaft.
The galena did partially melt to produce lead, but it also left behind a lot of slag materials, which I've decided to save. The density of that slag material is still quite high, so I suspect there are more metals trapped in it. Konkur's notes also mentioned that these ores are likely going to contain a mix of the other metals that can be found in the area, so it'll take some work to purify them properly.
The sphalerite processing went well, and, according to Konkur's notes, it seemed to properly reduce the sphalerite to zinc oxide. For the pyrite though, I'm essentially flying blind. Though the pyrite powder did seem to change from it's brassy color to a darker gray color during it's roasting process, so I'm taking that as a good sign that it has turned into an iron oxide from an iron sulfide. I'll do some experiments with the first batch of this once-roasted pyrite to see what kind of quality the resultant iron will be.
Overall, the facility here only produces some low-quality lead, and some partially processed ore materials for the time being. We'll need an entirely different facility for processing Zinc, as its processing has some extra steps, requiring a very high temperature furnace to vaporize the reducing zinc oxide. The iron oxide made from processing the pyrite should be able to be smelted somewhat normally, however.
With the three roasting processes tested, I feel comfortable with the idea of making a few permanent positions for jobs of roasting ores, to start they'll just be roasting the galena and sphalerite. I want to wait until I'm confident in the pyrite processing before I leave it to some relatively untrained individuals to work on, though.
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I established a permanent position for six goblins to work roasting ores. For the most part, the job is relatively easy, since the ores just need to be loaded, then they roast relatively unattended for quite a while. Most of their work comes from hauling the product around. Basically, four of the six at any given time are hauling the ores while the other two keep an eye on the roasting ovens.
In the twenty days they've been working, I've started to notice the plant life in the immediate surroundings, and especially downwind, has started to look unhealthy. Ultimately, that led me to make sure the goblins working at the site took turns being the ones hauling the ores, so that individually, they don't spend a long period of time in the area. I also decided that every five days, they should take two days off completely, for health reasons.
I tried breathing both under the large covered area, and a little outside it, and the air is quite a bit worse outside and downwind than it is underneath the covering, so I'm not concerned with concentrated poisoning at least. The roof does seem to be doing its job, with the wind generally pushing the gases away.
The first roast of the pyrite, however, didn't go as well. The resultant iron from smelting was extremely brittle, and barely useful at all. I suspect that the cause lies between impurities of other metals and residual sulfur. I have two options for attempting to fix the issue, though I'm leaning more towards one than the other.
The first option is attempting to fix the ore during the roasting phase. This would be difficult, because the amount of mixed in other minerals is actually quite high. The pyrite we're using isn't that pure, and has a lot of crushed rock mixed in. The second option is a bit of a pain as well. Since the iron is so brittle, it involves re-processing that iron again with a large amount of charcoal to remove as much of the sulfur as is possible, while also attempting to to remove as many of the other metal impurities using lime, though we'd still have to do more to remove copper impurities if they're too much of a problem.