I noticed on Investor hub the discussion about how 400 tons per day throughput was impossible given the size of Silver Falcon's Mill.

I wondered if there was any truth to that or not.

What I found was that it is possible to purchase rod mills in various specifications.

Rod mills are essentially strong cylinders that rotate. Inside the cylinder are heavy steel rods. The rods turn and tumble inside they rotating cylinder. Rock is put inside this and the rods pulverize the rock making it smaller.

There are mills which rotate but have steel balls inside that tumble and pulverize the rock. But the problem with those mills is that the rock might not be evenly ground up. Some rock is larger and some is turned into almost a powder which is hard to work with. Ideally, the material is ground up to small enough rocks that any gold and silver is released but the material is large enough that it works well within their overall process. A rod mill will not tend to pulverize rock into a powder because the crushing surface is longer reducing the impact on any one small area.

Back to rod mill capacity. A 400 ton per day rod mill assuming two 10 hour shifts should be able to pulverize 20 tons per hour. Are there such mills available?

The answer is yes. Rod mills capable of that throughput are about in the middle of the capacity range according to some links I found:

http://hnzk.51ev.com/product-Mining-Machinery/41969/Rod-Mill.html