Shipsure,
So I think the Blair Line model is of a dealer/distributor. So they get inbound loads of stuff like amonium nitrate by covered hopper and the dealer keeps it in binds and mixes the dry materials together to get the right blend of nitrogen and potassium and stuff like that per what the customer needs.
Look at El Dorado Chemicals in Giddings TX on Google Maps. The structure is larger than the Blair Line kit but is similar in style.