all of this is just for giggles and nothing else, realistically if you build this in a server, there's a 95% chance you're not staying in there for over 24 hours, as both the lag from this, and accompanying cobble generators will destroy any system, and cause lag.

requires an input of around 1000 cobblestone per second, and also requires a source of blaze cake fuel, as this schematic does not come with one.

this design if fully stackable, and can be made smaller for a more sensible 15K/hr iron ingots per layer that you add on, the schematic I uploaded has 4 layers, and fully uses up 1 maxed boiler, so it uses up around 290K SU, when stacking the design, make sure all main components are connected to each other, such as the main power for the system, the fans to wash the gravel, and all the chutes and storage drawers.

I also went a bit fancy with what I did to bump up the amount of iron I could produce, instead of just using the crushing wheels and gravity to crush cobble to gravel, I used fans to push the cobble up into the crushing wheels and turn that into gravel, so only using 4 crushing wheels for 3 different outputs, and also saves on SU.