Input (grade 12): Any impurities remain solid while the nickel carbonyl gas passes into a large chamber at high temperatures in which tens of thousands of nickel spheres, called pellets, are constantly stirred. The nickel carbonyl decomposes, depositing pure nickel onto the nickel spheres.
Output (grade 9): The nickel carbonyl is blown into nickel pellets, where it coats the pellets with pure nickel and puts out carbon monoxide.