The whole process is going to need a ton of coal and calcium carbonate and heat, and you have to have a way to safely dispose of SO2 gases and CuSO4aq liquids. And there don't seem to be anything that sounds safe and clean about this process.
The amount of carbon used in the reaction itself is totally neglibile, compared to other overheads.
This is common for bulk industrial materials. For example, it is cheaper for many countries to send their crude oil to the US to be refined than for them to refine it themselves.
Ea-nāṣir will still receive complaints, presumably.