Factorio Forums

An belt (Fast transport belt) with iron plates runs directly next to a belt (Fast transport belt) with copper plates and there is no chance the two merge somewhere. But after some time I notice that there are a few copper plates on the iron plate belt.

Installed mods:
Aircraft
Aswil
Better long handed inserter
Even distribution
Expanded rocket payloads
Factorissimo
Flare stack
Krastorio
Krastorio-graphics
Load furn (Advanced Furnaces)
Mining drill mk2
Nixie tubes
Powered belts
qol research
RSO-mod
stdlib
StoneWaterWell
VehicleSnap

In most cases the reason for "impure" belts is that something is messed up. It can easily happen while setting up the belts by misplacing one belt which leads to an unwanted merge or an imporperl belt loading. You might even have corrected that yet, but just oversaw that some copper plates sneaked onto the other belt.

First remove the copper plates from the other belt and see if it stays "clean" afterwards. If that's not the case, attach a screen shot - it's hard to say what the actual reason is without it.

Check that you don't have 'mixed' mining - where one (or more) of your miners is overlapping a copper and iron patch, and occasionally sends the wrong ore to the furnaces. Hover your mouse over each miner and it will tell you what resources it will mine - if you see one with two resources then you need to filter out the unrequired one, and send it where it is needed.

Oh nevermind I found the issue. I accidently left my aircraft on some inserter which then inputs into the aircraft and when I left it on inserters pulling out it then messed the belt up. Thanks anyway.