ISIS has 40 kg of Uranium Compounds

After my last highly speculative post about ISIS, the terrorist group in Iraq, possibly acquiring Uranium, from used weapons, I researched breeder reactors more. I convinced myself that even possessing a large quantity of depleted (or natural) would not afford even a slight chance to the group to develop a nuclear weapon.  The main reason is that while the breeder reactor can create fissile Plutonium from standard or depleted Uranium, the task of separating it from Uranium is chemically very challenging.  

Never-the-less I thought it quite odd that 2 days after my post, stories came out reporting that ISIS had successfully obtained about 40 kg of "Uranium Compounds" from a lab in Mosul University.

http://www.reuters.com/article/2014/07/09/us-iraq-security-nuclear-idUSKBN0FE2KT20140709

Most reports (correctly, IMHO) dismissed the prospect of any fission weapon being made from this haul.  Some commentators threatened that this made a dirty bomb possible.   (Conventional explosives used to disperse somewhat radioactive compounds like U238).     I don't see how this "dirty bomb" scenario, even at its worst represents a significant threat by ISIS beyond their current capabilities (explosives and guns).   Since depleted uranium is scattered over the  country, left over from the US-Iraq war, adding some more doesn't seem like such a scary change.   Whatever harm scattering non-fissile Uranium around can cause, it has already happened.   The conventional explosives can clearly kill more people...not to mention guns and what ever other horrific methods that group may be using.