I'm not sure what the 22,000 MPH reference is to, but it could be referring to the closing speed just before the impact. The last sentence of the article says,
The collision between the projectile and the comet, at a speed of 22,000 mph, will take place 83 million miles away from Earth.Man, 800 LBS at 32,000 feet per second .. that is one whopper of a projectile!
Point this thing @ Mosul !
The hammer will be vaporized, perhaps ionized immediately. The flash spectrum should show the atomic constitution of the hammer and some of the comet itself. We may discover commercial quantities of water and other minerals.