Testing is done internally. Not every 100 tons because that would be constant testing but probably every 1000. The quality of wood used for industrial pellets puts them right around the 1% ash, or slightly over. I only mentioned that scenario because I've heard that has happened and a huge mill in the southern US was put out of business. I haven't talked to anyone directly involved so I consider it just a rumor.
I believe the Canadian government financed a big chunk of the Trebio start-up in 2010 or 2011. (Read 4 million somewhere last year.) A venture capital firm bought a failed pulp operation and the Trebio plant was the poster child to get the whole industrial park off the ground.
I don't think it's done at a higher temperature. Industrial users usually have an ash fusion temperature requirement also. Ash testing is done in a muffle furnace and the burn is done pretty slowly (don't want a fire, just a smoldering burn). Mine does the moisture test at 180°C and then the ash test at 600°C. I'm pretty sure the industrial test is done exactly the same as the test for residential pellets.
Also, European industrial users have some other requirements. They want the pellets to meet the DIN standards. They also might have a particle size distribution requirement.
