Ore Smelters and Iron Bar Purity

[Elcohen]

Couple of things before I get to the point:
1. I decided to put this post in "Bugs" category only because I personally enjoy the challenge and hate "easy mode" games. I expect most would consider this a welcome feature. Moderators, please move this thread at your discretion
2. Credit goes to Sevenless for his invaluable guide without which this discovery would not have been possible.

It appears that the purity of produced Iron Bar depends only on the purity of components in the last load and the purity of "leftovers" from the previous load is ignored.

I came upon this accidentally. I was smelting metal without regard for purity for a week or so now, and then finally decided to make myself a new set of dowsing rods and look for higher purity mine. After smelting 25 pieces of ore I got a bar on a first try (meaning I had at least 0.5 bar leftover from previous smelt, and the purity of that bar was the same as the ore purity). My next 25 pieces of ore produced dross only, as expected, and the third 25 ore load produced another bar of the same purity as the first one, validating my initial observation.

I think the smelter behavior should be such that the produced bar purity averages that of the current load and leftovers from the previous load.

Until (if ever) the current behavior is corrected, the optimum 3-load smelting cycle for production of both high (ore), and low (component average) purity Iron Bars would be:
Load 1: 17 ore + 8 lime = 1.7 bar (produce 1, 0.7 leftover)
Load 2: 15 ore + 10 lime = 1.8 bar + 0.7 bar leftover (produce 2, 0.5 leftover)
Load 3: 25 ore = 0.5 bar + 0.5 bar leftover (produce 1 - high purity, 0 leftover)

Overall production for the 3-load cycle:
57 ore + 18 lime = 3 low purity bars + 1 high purity bar + 29 low purity dross + 24 high purity dross

The first two loads can be done in any order. The goal is to produce 0.5 bar leftover and then smelt all ore for a complete bar thus "converting" purity of the leftover from a more productive smelt to the ore purity in the resulting bar.

I will be testing this 3-load cycle production over the next few days once I make a new smelter which I know is free from leftovers. I expect these predicted results to be confirmed given that so far I have not seen any evidence that disputes the formulae posted by Sevenless

[MagicManICT]

Looking forward to the update to this.

[Sevenless]

Yup and we use this regularly when prepping smelters for d-rod production. I don't consider it a bug personally, merely a side effect of how they coded things. Originally it wasn't an accumulator, it was random % chance (early pre-com beta, back when smelters were 4x4 grids and iron was a beach and a half to make ><). When they changed it over, they didn't change the purity formulas. The purity formulas that make sense with random chance don't really line up so well with pure accumulator though, so we get this weird system.

To be fair though: Staxjax explained to me prospecting, and my villager Drew figured out the smelters. I just wrote it and posted it ^__^

Anyway, I don't really expect any of the current mining system to be kept. The whole thing is getting some kind of overhaul. I wouldn't worry overmuch about the specifics of this system because of it.

[Sarpynom]

From my experiments the purity of the bar is solely reliant on the single piece of ore it came from. You can mix all different types of ore in a smelt but the slot that turns into a bar will be exactly the same alchemy as the piece of ore that was in that slot.

[ehnoah]

Do you know a Rotation with higher Ore? I may go and find a better Mine so purity is higher or not?