Dickinson State professor was making and grinding acetone peroxide?

A couple of days ago, there was a brief conversation on Twitter (started by Daniel Horowitz) about a reported explosion at Dickinson State University on October 4. Here's a brief report by Kalsey Stults in the West Fargo Pioneer:

DICKINSON, N.D.—Students at Dickinson State University were back to an unceremonious Wednesday, Oct. 5, 24 hours after Murphy Hall was evacuated and a faculty member was injured in a classroom explosion Tuesday afternoon. 

Chemistry professor Ken Pierce was preparing a classroom demonstration around 3:30 p.m. when an incident occurred resulting in a small explosion. [snip] 

Jack Schulz, DSU's director of security and emergency management, said the classroom showed visible signs of an explosion with parts of the counter being damaged, and blood and debris around the room. Schulz said the second floor of the building was evacuated within minutes and someone aided in helping Pierce with his injuries and giving first aid until paramedics arrived on scene. 

"There was a young lady that had some type of medical training either in the room or in the area, and she provided a little bit of first aid on him (Pierce)," Schulz said.
The professor's hands were bandaged before he was taken by ambulance. 

Schulz said the head of the chemistry department notified him immediately that there was no dangerous airborne chemicals to be concerned about in the lab and there was no fire from the explosion. Schulz said knowing that there was no immediate danger, it was about making sure students didn't panic, and said the evacuation was calm and orderly.

Yesterday, Ms. Stults (published here in the Grand Forks Herald) mentions this set of details about the incident (emphasis CJ's):

On Oct. 4 at 3:25 p.m. Pierce was conducting a chemistry demonstration in room 206 of Murphy Hall when the demonstration went awry. 

He was demonstrating flash powder—a compound made from hydrogen peroxide and acetone—for five students. After the two compounds were mixed and sat for a couple of hours to dry they then become a powder. 

During the first experiment Pierce noticed a small amount of powder in the mixture, and when he ignited the powder it flashed but the clump of powder combusted—which he thought was unusual but continued. 

He then conducted two more experiments without incident, but before the fourth experiment Pierce noted small clumps of powder in the mixture. 

Pierce then poured in mortar and pestle to grind them up, but when he started to grind the mixture, it exploded. 

Pierce suffered non-life threatening injuries and was transported to CHI St. Alexius Hospital in Dickinson before being transferred to Bismarck for surgery... 

...Pierce was wearing personal protective equipment including goggles and students had been tested on safety protocol at the beginning of the semester.

So I am open to the possibility that the details of this experiment were incorrectly reported by university officials. However, if the details are accurate (and I have no reason to doubt that they were), here's what we know:

• Professor Pierce was preparing something that sounds awfully like acetone peroxide. Couple of things:  
• Acetone peroxide is famously touchy stuff. 
• I was under the impression that acetone peroxide preparations included some acid? Apparently not needed. 
• Professor Pierce was wearing some amount of PPE. 
• The acetone peroxide mixture exploded when ground in a mortar and pestle. (Not a surprise there.) 

A few questions remain: 

• Was there an appropriate risk assessment done in regards to Professor Pierce's PPE? 
• How close or far away were the students from the bench when this happened? 
• What was the scale of the acetone peroxide experiment? 
• Were there any records of the amounts used for the experiment? 

In general, I think that pops and bangs are an integral part of chemistry demonstrations. That said, the intentional (or unintentional?) preparation of a primary explosive seems unusual at best.