C. Lee said:
He was useless...because Lex had a large piece of K in his coat pocket, just feet away from him, as well as the diluted K of the island. Were his hands supposed to be burned, because I took as they were scraped by his fall (the diluted K made him vulnerable to scrapes)...if it was burns, then yes, that was from the diluted K of the island. I said it was diluted, not harmless. He was weakened by the the K being diluted, if it had been an island of pure K he would mosy likely have died from that amount of exposure.
Superman was away from the very large amount of diluted K. So only the small amount of pure K was effecting him at this time. He was able to regain a portion of his strength and abilities by the large amount being gone...so that he was able to fly up into the atmosphere. There he got a major rejuvenating shot of solar power, recharged his batteries, and was able to remove the island.
He went down below where the diluted K/crystal was growing....and after cutting it with his heat vision picked up the bottom that was still Earth material. As he flew it up, the dilutedK crystal finally started to grow down enough to start coming out of the bottom. By this time, he was high enough up that he was able to throw it out into space using the last reserves of his strength. That is why he passes out, damage from original pure K knife, pure K shard still in him, and being in close contact with big quanity of diluted K, causes him to go into a coma. After the K shard is removed at the hospital, his body is able to repair itself.