I would translate it like this:
["Cardboard"] = "Karton",
["Cardboard Factory"] = "Kartonfabrik",
["Cartons"] = "Kartonagen",
["Carton factory"] = "Kartonagenfabrik".
["Sand Quarry"] = "Sandsteinbruch", thats more like sandstone mine, i´d use "Sandgrube".
["Galvanised Steel Mill"] "Verzinkerei" is a good word i think.
["Separation Plant"] = "Trennanlage", yeah, no! Meaningwise it´s correct, but i think the oilsand seperation plant hat a very specific name in german too, but it won´t come to my mind at the moment...