All of them. They have machines that strip down the components:

https://www.elitedaily.com/p/heres-how-apple-recycles-old-iphones-into-new-models-by-using-actual-robots-29961761

This article is about the iPhone robots but they also have machines that do this with Macs too. Every Apple device is made with recycled content but the majority of their components are reused in remanufactured warranty devices (remanufactured rather than refurbished because refurbished reuses existing whole components, remanufacturing breaks down components, tests them, and reuses them to create entirely new components from working parts).