Alright, there is a lot of misinformation and/or outdated information that is still highly rated in this thread so please allow me to clarify:
First and foremost, it is impossible to farm an infinite amount of elementium ore from a single Raid ID. While nobody knows exactly how it works, it seems that there is a set amount of ore that drops per Raid ID. It can drop from respawned technicians.
It is unclear to me exactly how much ore can drop per Raid ID. I was personally able to get 6 by only farming the first group past Broodlord before it stopped dropping for me (Killed that first group about 15 more times and then the rest without a drop). By farming I mean, I was killing all the technicians, leaving the other mobs alive, zoning out, and then zoning back in and looting the corpses. All the mobs in the group will respawn if you leave at least one mob alive and zone out. Perhaps 6 is the cap' or perhaps the amount of ore that can drop per Raid ID is random. That would require more testing to say for sure.
In any case, the safest way to maximize your elementium ore is to farm the first group after Broodlord until you believe that you have reached your 'cap' for that particular Raid ID. If you clear the group 10 times without a drop, it's probably safe to assume you reached the cap. The reason you would do this instead of just killing all the groups right away is that, it may be possible to kill all the groups without reaching your 'cap' for that Raid ID.