The disclosure relates to ferric citrate tablets and dosage forms. The clamp includes a flexible curved portion 1 including a tube insertion hole 11 provided on the proximal side and an upper member 2 and a lower member 3 connected via the curved portion 1 and which can be engaged on the distal sides thereof. A pushbutton may be positioned vertically above the contactor such that manual displacement of the pushbutton downward may provoke the elastic deformation of the contactor. A spray section is provided in which liquid is sprayed through nozzles designed to provide a mean droplet size having a terminal velocity of from about sixty percent to about ninety five percent of the superficial upward gas velocity.