Superman unpublished K-Metal story pg.20

I first heard about this story when four pages of it were printed in the Steranko History Of Comics with very little explanation. Some of the other pages and the original script have surfaced since then and the entire story has been reassembled from original pages and re-creations. Produced by the Shuster studio in 1940, Superman discovered he was from another planet and encountered Kryptonite (K-Metal) for the first time, nine years before Superman #61. He also revealed his secret identity to Lois Lane. DC decided not to publish it.