ABSTRACT
The chapter studies the method which consists in extracting a solute S from a solvent A by a solvent B immiscible to A according to a process called countercurrent, which functions continuously. Phase A and Phase B are respectively introduced at each extremity of an extraction column with a determined outflow. The two phases are collected at the opposite extremity. Thus, both phases run through the column according to an inverse direction. During the process, the extracted phase becomes progressively poorer in Solute S and inversely the extractive phase becomes progressively richer. One regularly analyses both phases at the comings out. After a certain time interval, their compositions in the outflows no longer change. The stationary state is reached. The study shows that this method is the best extractive method from the standpoint of yield. Reasonings, together algebraic and geometric, permit the calculation of all the parameters characterizing the process, including the number of elementary stages of extractions it uses in the stationary state. This method is purely an industrial one.
