Just wanted to give some thoughts here.

I have all BZ mods except salt + cholorine installed. My current core mining for nauvis fragments gives the following yields, per 20 fragments
8 Iron Ore
8 Copper Ore
4 Coal Ore
8 Stone
32% Uranium ore
8 Raw rare metals
6 Titanium
5 Wolframite
5 Zirconium
8 Flake Graphite
6 ALuminum Ore
4 Tin ore
32 Crude Oil
16 Mineral Water
24 Natural Gas
4 Pyroflux

I'm somewhat deep into SE, have a space platform, working my way through the science packs there.

Overall, my observations are:
1. Raw Rare metals: Far, far, far too much. I have >25000 landfill from 'rare' metals sitting around.
- Suggestion: Cut this down to 1/fragment, at MOST. Even then I'd probably still not need to mine for it until I am making material testing packs, in which its fortunately included.
- Alternative suggestion: Still needs to be cut down, but it'd be cool to see a processing chain for this, and useage in some of the higher-tier SE techs

1. Titanium - Too much. I have a bunch of boxes of it, and I've never bothered enriching it. Not nearly as out of whack as rare metals, I haven't landfilled it, but still..
2. Suggestion: Cut to 4/fragment. Maybe 3.

3. Alternative Suggestion: Add it to the material testing pack. Also add a bit of it to scrap if you do this.

4. Zircon:

5. Had a glut of this near the start, its somewhat balanced out later, but I never had to mine too much. Feels like it could be cut to 4/fragment

6. Aluminium

7. This is the only resource I'd really consider actually buffing. 8/fragment would be better, maybe even 10/fragment tas its consumption seems to be on par with iron/copper, and also a lot of alumina gets used in other processes, which gets far less benefit from productivity, and can't be pyrofluxed/refracted. until it gets to the plate stage.

8. Tin

9. Tin consumption - mostly to make solder - is a bit high. I'd consider adding a bit more to core fragments - though really I think the solder recipe could just use a bit less tin. It's mostly ok though

10. Mineral water
    Routinely have to flush or flare this. But that's mostly true of non-BZ core mining too, so probably not something you need to address.

The other resources I think are all ok. Coal can pile up, but at least can be liquified. I just saw the change to graphite use in basic circuits though - might need to look at that, especially if someone's not enabling ore refraction.

I will say that, overall, due to all the additional resources, and especially now with refraction, ore useage is much lighter than in 'base' K2+SE. If I wasn't playing a game with multiplied tech costs, core mining could be my primary source of ore. I'd consider making the base core mining recipe use more fragments to offset this - 40 fragments instead of 20 for instance. Hard to judge what the balance should be with only some BZ mods installed.

Thanks for all the feedback on this. Very helpful. I will look into some of these changes as I keep working on the mods.

Maybe you could use this, I programmed today. It may have too much dependecies but works just fine. ^^

https://mods.factorio.com/mod/deep-core-fragment-balancer

Hey Brevven, great job on these mods! Firstly, I have thoroughly been impressed with how you have broadened the vanilla play - playing all your mods with K2+SE and I am 120hrs in barely ready to launch into space (though I'm also a very slow player).

I mostly have to echo Maxsimal's feedback. I feel like a good fix would be to implement further processing of rare metals into the relevant metals/ores that your mod implements, b/c a lot of the recipes where K2 used to use rare metals (such as chlorine production in the early stages) use your metals instead of rare metals, so that is why rare metals piles up (in native SE/K2 games, I didn't run into this issue). I feel like if you included a chem plant recipe that uses some way of further processing rare metals into more useful ores would be a decent solution. I can' t think off the top of my head what would be appropriate ores, but I can do some research and provide more suggestions if you're interested in taking this route.