Yes we also know that the plant is running for the full night...

Yes we also know that the plant is running for the full night shift and partially processing and maintenance during the day shift. Mike has also stated the plant is producing tonnes per hour when in operation.
for a 12 hour night shift and a very modest count of 2 tonnes per hour that gives 24 tonnes per night shift. They only have to be producing for 3 hours during day shift to make the 30 bags a day.
These are all backed by Mikes statements and using the minimum number for definition of his words.