That is a crazy number, i needed to do some math here.
My source says Pangolin can vary greatly based on which type it is, but the average is ~35lbs for the Common Pangolin(ironic name) or ~ 16kg. It also mentions that a Pangolin's scales are ~20% of its weight.
I'm gonna assume average is 16kg which means the average amount of scales on one of these guys is 3.2kg or 7 lbs.
I'd rather deal with freedom units here, so 6800 lbs(3.4 tons) / 7 lbs = ~974 Pangolins were killed for this single shipment. (IMO this is much lower than the real number, some Pangolin are as little as 4 lbs, but with so little data I have to make estimates)
Not to mention that since July 19th of this year 15.4 tonnes were already seized, and with almost no data on how much of the population is left, it does not bode well for our scaly friends.
Sources:
http://annamiticus.com/2016/07/19/2016-far-deadly-year-pangolins-especially-african-species/
http://voices.nationalgeographic.com/2016/09/28/pangolins-on-the-brink/