Question

Why do we care about Cu waste reclamation and extracting the copper from the solution?

What is in solution immediately after you've finished adding 6 M NaOH to your waste penny solution and adjusted the pH to ~8 (Before the addition of Calgon)?  What would do you suspect would happen if you attempted to filter the solution at this point?

Answer 1

The value of copper metal is on par with the value of the coin. That is the reason why copper is extracted
You will be left out with Zn(OH)₄^2- which is a soluble complex ion formed by the excess addition of NaOH
to the Zn(OH)₂ and also Cu(OH)₂ is formed . Actually NaOH is added to seperate Zinc but as Zn(OH)₂ is sparingly soluble we end up adding excess NaOH to make soluble. Remember Cu(OH)₂ is also insoluble.
So, at this point if you attempt to filter the solution you will not be able to recover or reclaim the total
amount of copper.