"There was some idle rumour floating about last week that Rio was interested in SQM but it got denied?"
Potash Corp want to sell their 32% holding in SQM. This isn't new news. They stated this long before SQM bought in to Mt Holland.
The rumour started doing the rounds that RIO were looking to buy Potash's stake, which RIO didn't confirm or deny. RIO holding a part of SQM would make sense - it gets them exposure to the existing lithium market as they attempt to develop Jadar. I have no doubt that they are running the ruler over the Potash Corp deal, but they aren't ready to pull the trigger and I think the problems with the Chilean government and the 60% royalties might be what is giving them pause.
It could be the sentiment on KDR is disappointment about RIO based on the false idea Rio was going to TO KDR. If so, good riddance to those weak hands.
