Abstract: There is disclosed a dual jet crystallizer apparatus comprising a crystallization or mixing chamber having opposed angularly disposed arms which removably receive jet nozzles. One end of the chamber is provided with means to discharge crystallized product therefrom while the other end is equipped with means to adjust the crystallization volume within the chamber. The angular arms are disposed within specified angular tolerances with respect to the longitudinal axis of the chamber. One of the jet nozzles is provided with means at one end to receive and deliver to the chamber compound to be crystallized while one end of the other jet nozzle is provided with means to receive and deliver to the chamber a crystallization agent for the compound. The opposite ends of each of the jet nozzles have means to removably secure them to the angular arms and the ends thus secured have a nozzle tip section formed therein defining an orefice having an elongated bore.