Abstract: An introduction process and apparatus is described concerning the continuous elution of a value, i.e. a metal value such as gold, from a particulate carrier by a counterflow of stripping liquid through the pressurized vessel in which the loaded particulate carrier is introduced to the vessel as a low velocity plug in a liquid carrier. The extraction process is also used with the continuous elution process in which the particulate material is extracted from the bottom part of a pressure vessel through a discharge pipe extending therefrom and in which a discharge liquid is introduced into the discharge pipe upstream of the discharge end under such pressure as to maintain a head of the discharge liquid upstream of that location and a flow of the liquid downstream from the location to transport the particulate material through the discharge pipe.